Biogas upgrading and membrane anti-fouling mechanisms in electrochemical anaerobic membrane bioreactor (EC-AnMBR): Focusing on spatio-temporal distribution of metabolic functionality of microorganisms

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.

Distribution, seasonal variation and influencing factors of total dissolved inorganic arsenic in the middle and lower reaches of the Yellow River

The concentrations of dissolved arsenate in natural water has an important impact on human health. The distributions, seasonal variation and major influencing factors of total dissolved inorganic arsenic (TDIAs) were studied in the Yellow River. The concentrations of TDIAs in the middle and lower reaches of the Yellow River ranged from 4.3 to 42.4 nmol/L, which met the standards for drinking water of WHO. The seasonal variation of TDIAs concentration in the middle and lower reaches of the Yellow River was highest in summer, followed by autumn and winter, and lowest in spring. The influencing factors of TDIAs concentration in the middle and lower reaches of the Yellow River mainly include the hydrological conditions, topographical variation, the adsorption and desorption of suspended particulate matter (SPM) and the intervention of human activities. The absorption of TDIAs by phytoplankton in the Xiaolangdi Reservoir (XLD) is an important factor affecting its distributions and seasonal variation. The annual flux of TDIAs transported from the Yellow River into the Bohai Sea ranged from 1.1 × 105 to 4.5 × 105 mol from 2016 to 2018, which is lower than the flux in 1985 and 2009. The carcinogenic risks (CR) of TDIAs for children and adults were all within acceptable levels (<10-6).

Comparative analysis of climate-induced changes in distribution of representative fish species in the Yellow Sea

Climate changes are posing remarkable impacts on marine fish and fisheries. Although many studies have addressed the distributional effects of climate change on single fish species or taxa in recent years, comparative studies focusing on different types of fish are still lacking. In this study, we applied dynamic bioclimate envelop models (DBEM), based on three earth system models, to predict sea surface and bottom temperature, as well as the spatial and temporal distribution of nine representative fishes in the Yellow Sea, contain two habitats, i.e., continental shelf benthopelagic (CBD) and continental shelf pelagic-neritic (CPN) fishes, and two thermophilies, i.e., warm temperate (WT) and warm water (WW) fishes. Under a low emissions scenario (RCP 2.6) and a high emissions scenario (RCP 8.5) between 1970 and 2060, results reveal that: a) CPN fishes show a distinct tendency to move to higher latitudes than CBD fishes, and WW fishes show a significant tendency to migrate more widely to the north than WT fishes; b) The relative abundance of CPN fishes is expected to be higher than that of CBD fishes, while there is no apparent difference in relative abundance between WW fishes and WT fishes. The main reasons for this difference are presumed to be: variance of temperature rise between the sea surface and bottom layers, divergent adaptations of the species, and disparate degrees of anthropogenic influence.

Spatio-temporal distribution of macrobenthos and benthic ecological health status in the Bohai Sea and the northern Yellow Sea, China

The Bohai Sea (BS) and the northern Yellow Sea (NYS) are threatened by anthropogenic activities and climate change. To accurately assess the benthic ecological quality status in this region, macrobenthos were selected as the research subject in this investigation. The results showed that the macrobenthos community structure had spatio-temporal differences in the BS and the NYS through principal coordinate analysis, especially in Laizhou Bay, and the Yellow River Delta was significantly different from that in the NYS. Specifically, in the BS, the abundance of macrobenthos in autumn was significantly higher than that in summer (p = 0.003). The dominant species composition also had seasonal differences. Overall, the macrobenthic community was slightly disturbed, but the benthic ecological health was "good". The values of negative cohesion were higher than those of positive cohesion in the macrobenthos community, revealing that there was more competition, ensuring that the community was relatively stable.

Spatio-temporal disparities of Clonorchis sinensis infection in animal hosts in China: a systematic review and meta-analysis

BACKGROUND

Clonorchis sinensis, one of the most important food-borne zoonotic trematodes, remains prevalent in China. Understanding its infection status in animals is crucial for controlling human clonorchiasis. Here we conducted a systematic review and meta-analysis to focus on the spatio-temporal disparities of C. sinensis infection in animals in China.

METHODS

Data on C. sinensis prevalence in snails, the second intermediate hosts, or animal reservoirs in China were extracted from electronic databases including PubMed, Embase, Web of Science, Chinese Wanfang database, CNKI, VIP, and China Biomedical Literature database. A random-effects meta-analysis model was utilized to estimate the pooled prevalence in each of the above animal hosts. Subgroup analysis and multivariable meta-regression were performed to explore potential sources of heterogeneity across studies and compare the temporal disparity of infection rates between high and low epidemic areas. Scatter plots were used to depict the biogeographical characteristics of regions reporting C. sinensis infection in animals.

RESULTS

The overall pooled prevalence of C. sinensis was 0.9% (95% CI: 0.6-1.2%) in snails, 14.2% (12.7-15.7%) in the second intermediate host, and 14.3% (11.4-17.6%) in animal reservoirs. Prevalence in low epidemic areas (with human prevalence < 1%) decreased from 0.6% (0.2-1.2%) before 1990 to 0.0% (0.0-3.6%) after 2010 in snails (P = 0.0499), from 20.3% (15.6-25.3%) to 8.8% (5.6-12.6%) in the second intermediate hosts (P = 0.0002), and from 18.3% (12.7-24.7%) to 4.7% (1.0-10.4%) in animal reservoirs. However, no similar decrease in prevalence was observed in high epidemic areas (with human prevalence ≥ 1.0%). C. sinensis infections were predominantly reported in areas with altitudes below 2346 m and annual cumulative precipitation above 345 mm and were mostly concentrated in eastern China.

CONCLUSIONS

There are spatio-temporal disparities in the animal infections of C. sinensis in different areas of China. Animal infections are primarily concentrated in regions with low altitude and high precipitation. The results suggest that implementing One Health-based comprehensive measures targeting both humans and animals, especially in high epidemic areas, is essential for successful eradication of C. sinensis in China.

Tracking spatio-temporal distribution and transmission of antibiotic resistance in aquatic environments by using ESBL-producing Escherichia coli as an indicator

Wastewater treatment plants (WWTPs) play an important role in the production, and transmission of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) as a convergence for human, animal, and environmental wastewater. The aim of this study was to investigate the spatio-temporal variation and influencing factors of ARB in different functional areas of the urban WWTP and the connecting rivers for 1-year monitoring using extended-spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) as an indicator bacteria, and to study the transmission patterns of ARB in the aquatic environment. The results showed that ESBL-Ec isolates were identified from the WWTP (n = 219), including influent (n = 53), anaerobiotic tank (n = 40), aerobiotic tank (n = 36), activated sludge tank (n = 31), sludge thickner tank (n = 30), effluent (n = 16), and mudcake storage area (n = 13). The dehydration process can significantly remove the ESBL-Ec isolates; however, ESBL-Ec was still detected in samples collected from the effluent of the WWTP (37.0%). The detection rate of ESBL-Ec was significantly different across seasons (P < 0.05), and ambient temperature was negatively correlated with the detection rate of ESBL-Ec (P < 0.05). Furthermore, a high prevalence of ESBL-Ec isolates (29/187, 15.5%) was detected in samples collected from the river system. These findings emphasize that the high majority of ESBL-Ec in aquatic environments is alarming because it poses a significant threat to public health. Clonal transmission of ESBL-Ec isolates between the WWTP and rivers based on the spatio-temporal scale was observed by pulsed-field gel electrophoresis analysis, ST38 and ST69 ESBL-Ec clone were selected as prioritized isolates for antibiotic resistance monitoring in the aquatic environment. Further phylogenetic analysis showed human-associated (feces, blood) E. coli was the main source contributing to the presence of antibiotic resistance in aquatic environments. Longitudinal and targeted monitoring of ESBL-Ec in WWTPs and the development of effective wastewater disinfection strategies before effluent discharge from WWTPs are urgently required, to prevent and control the spread of antibiotic resistance in the environment.

Occurrence, distribution, and potential ecological risks of antibiotics in a seasonal freeze-thaw basin

Antibiotics have gained increasing attention as pharmaceuticals widely existing in human society. Under low temperature conditions, antibiotics tend to have higher environmental persistence, which poses a potential threat to ecological environment, but research on antibiotics in low-temperature basins is still lacking. Therefore, for investigating occurrence, spatio-temporal distributions, and ecological risks of antibiotics in a seasonal freeze-thaw basin, rivers in Tumen River basin were selected and sampled, including 25 samples during the river-freezing season and 27 samples during the non-freezing season. Overall, climate characteristics of different latitudes and renewal frequency of antibiotics are important factors that lead to diversity of antibiotics in basins. Eleven target antibiotics were detected and their average concentrations during the river-freezing season (0.83-27.5 ng L-1) were lower than that during the non-freezing season (2.80-45.30 ng L-1), severely impacted by river flow, ice sealed-melting, and local feeding practices. In addition, total antibiotic concentrations are usually highest in downstream areas of human settlements, receiving input from husbandry and sewage, respectively. Through ecological risk assessment, norfloxacin and amoxicillin posed high risks to algae, which were identified as high-risk pollutants in basin.

Analysis of the impact of high-speed rail on the spatio-temporal distribution of residential population and industrial structure

With the development of high-speed rail, the spatiotemporal distance among regions has been shortened. However, the research on the spatiotemporal distribution and correlation of resident population and industrial structure caused by the opening of high-speed railway is relatively few. This study is aimed to explore the impact of high-speed rail on resident population and industrial structure, as well as the spatiotemporal agglomeration and evolution trend. The spatial-temporal distribution of the resident population, industrial structure, and the influence of high-speed rail was studied using panel data from 31 Chinese provinces from 2006 to 2018 using spatial autocorrelation analysis, standard deviation ellipse method, and DID model. The experimental results indicate that: (1) The resident population shows a significant positive spatial autocorrelation, while the industrial structure is vice versa. (2) The resident population and industrial structure are primarily centralized in the eastern and central areas, showing a "northeast-southwest" spatial distribution pattern. (3) High-speed rail and the resident population are negatively correlated, and there is heterogeneity. Although there is an association between high-speed rail and industrial structure that is positive, there is also a clear regional variability. This study contributes to providing the corresponding theoretical support and basis for the high-speed rail line planning in different regions and the relevant departments to formulate effective economic policies.

Spatio-temporal distribution of microplastic pollution in surface sediments along the coastal areas of Istanbul, Turkey

Microplastics (MPs) have become prevalent in various environmental compartments, including air, water, and soil, attracting attention as significant pollutant parameters. This study investigated the prevalence of MP pollution in surface sediments along Istanbul's Marmara Sea, encompassing the megacity and the Bosphorus. A comprehensive sampling approach was employed, covering 43 stations across four seasons and depths ranging from 5 to 70 m. The objective was to assess the impact of terrestrial, social, and industrial activities on MPs. The average concentrations varied per season, with fall, winter, spring, and summer values recorded as 2000 ± 4100, 1600 ± 3900, 4300 ± 12,000, and 9500 ± 20,300 particles/kg-DW. The study identified river stations in the Golden Horn and sea discharge locations as hotspots for high concentrations. Notably, the dominant shape shifted from fibers in fall, winter, and spring to fragments during summer, coinciding with mucilage occurrences. The study identified 11 different polymers, with polyethylene (44 %) and polypropylene (31 %) being the most common.

Screening and prioritization of organic chemicals in a large river basin by suspect and non-target analysis

Many organic chemicals are present in aquatic environments, but how to screen and prioritize these chemicals has always been a difficult task. Here we investigated organic chemicals in the West River Basin by using a developed non-target identification workflow. A total of 957 chemicals were tentatively identified, with 96 assigned as high confidence levels by matching with reference standards, MassBank spectral library, and using CompTox Chemistry Dashboard database as the compound library for MetFrag. More pesticides and their transformation products (e.g., metolachlor ESA, acetochlor ESA, deethylatrazine, and hydroxyatrazine) were detected in the wet season due to the increasing usage. High detection of pharmaceutical and personal care products and their transformation products in the tributaries was linked to rural farming and human activities. Irbesartan that is used to treat high blood pressure was recognized in the river and positive correlations between some detected chemicals and irbesartan were observed, indicating a domestic wastewater source. Ecological risks of the identified chemicals were calculated by toxicological prioritization ranking schemes, and 24 chemicals showed high ToxPi scores in the river. The results from this study show the presence of a large number of emerging organic chemicals in our waterways, and demonstrated conceptual schemes for integrating risk assessment into a non-target screening workflow.

BTEX in Ambient Air of Zarand, the Industrial City in Southeast of Iran: Concentration, Spatio-temporal Variation and Health Risk Assessment

The existence of several industries in Zarand, a city in Southeastern Iran, caused challenges for the residents about air pollutants and associated health effects. In the present study, the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX), spatio-temporal distribution and related health risks were evaluated. Passive samplers were used to collect 30 samples in the over the hot and cold periods in 2020. The ordinary Kriging method was used to predict the spatio-temporal distribution of BTEXs. Also, the Monte Carlo simulation was used to evaluate the related carcinogenic and non-carcinogenic risks of BTEX for adults. The ranking of mean concentration of overall toluene, xylene, ethylbenzene, and benzene followed as 82.49 ± 26.86, 30.91 ± 14.04, 4.75 ± 3.28, and 0.91 ± 0.18 µg/m3, respectively. The mean value of lifetime carcinogenic risk (LTCR) for residents related to benzene was 7.52 × 10- 6, indicating a negligible carcinogenic risk for them. Furthermore, the ranking of non-carcinogenic risk calculated through hazard quotient (HQ) for investigated BTEX compounds followed as xylene > benzene > toluene > ethylbenzene over the hot period and xylene > toluene > ethylbenzene over the cold period which all points had HQ < 1. Additionally, according to the findings of the sensitivity analysis, the concentration of benzene was the main contributor in increasing the carcinogenic risk. According to our results, it can be stated that the existence of several industries in the study area could not possibly occur the significant carcinogenic and non-carcinogenic risks to the adults residents in the study period. Human studies are recommended to determine definite results.

Human anthrax in India in recent times: A systematic review & risk mapping

The disease anthrax occurs generally in herbivores and the causative organism (Bacillus anthracis) infects humans who come in contact with infected animals or their products. The persistence of anthrax spores for decades and its lethality contribute to its biowarfare potential. We conducted this systematic review along with risk mapping to investigate the spatio-temporal distribution, clinico-epidemiological, socio-behavioural and programmatic issues pertaining to anthrax in India over the last two decades. Peer reviewed quantitative and qualitative studies and grey literature comprising weekly reports of the 'Integrated Disease Surveillance Program' (IDSP), were accessed for extracting data. IDSP data were used for geo-referencing of the villages of anthrax cases; Pseudo-absence was generated to fit a Bayesian Additive Regression Trees (BART) model to develop anthrax risk map. The case fatality rate of cutaneous anthrax ranged from 2% to 38%, while the gastrointestinal and inhalational types were 100% fatal. Our synthesis revealed that human anthrax outbreaks in India were clustered around the eastern coastal regions. The states of Odisha, West Bengal, Andhra Pradesh and Jharkhand reported maximum number of outbreaks. Odisha reported a maximum number of 439 human anthrax cases since 2009, of which Koraput district contributed to 200 cases (46%). While handling or consumption of infected animal product were proximal drivers of these events, poverty, lack of awareness, traditional beliefs and local practices served as facilitatory factors. Other structural determinants were wild life-livestock interface, historical forest loss, soil pH, soil-water balance, organic carbon content, temperature, rainfall and humidity. The programmatic issues identified through this review were lack of active surveillance, non-availability of diagnostic facility at the periphery, delayed reporting, absence of routine livestock vaccination and lack of adequate veterinary services. Interventions based on One-health approach in the country merit immediate policy and program attention; high risk zones for anthrax identified during present investigation, should be prioritized.

Per- and polyfluoroalkyl substances (PFASs) in water and sediment from a temperate watershed in China: Occurrence, sources, and ecological risks

Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic organic fluorides that have been widely used in various industrial and consumer applications. However, their potential ecological risks have raised concerns. In this study, PFASs were investigated in different environmental media in the Jiulong River and Xiamen Bay regions of China, revealing widespread contamination of PFASs in the watershed. PFBA, PFPeA, PFOA, and PFOS were detected in all 56 sites, with short-chain PFASs dominating (72 % of the total). Novel PFAS alternatives, including F53B, HFPO-DA, and NaDONA, were detected in >90 % of the water samples. Seasonal and spatial variations in PFAS concentrations were observed in the Jiulong River estuary, while Xiamen Bay was not significantly affected by seasonal changes. In sediment, PFSAs were dominant with long-chains while PFCAs with short-chains, and the occurrence was influenced by water depth and salinity. PFSAs were more inclined to be adsorbed in sediments than PFCAs, and log K_d of PFCAs increased with the numbers of -CF₂-. Paper packaging, machinery manufacturing, WWTP discharge, airport and dock activities were the dominant sources of PFASs. Risk quotient showed that PFOS or PFOA may pose high toxicity to Danio rerio and Chironomus riparius. Although the overall ecological risk in the catchment is still low, the hazard of bio-concentration under long-term exposure and multi-pollutant synergistic toxicity cannot be ignored.

Development and assessment of an epidemiologic dashboard for surveillance of Varroa destructor in Ontario apiaries

Varroosis (caused by the Varroa destructor mite) is a key health issue for honey bees in North America. Because these mites can exist in reservoirs of feral honey bee colonies, eradication is impossible, and instead efforts are made to maintain mites below a critical threshold. Monitoring for Varroa mites within a population is key for allocating resources and targeting interventions but surveillance can be difficult and/or expensive. This project aims to reflect on the success of data dashboards developed throughout the 2019-coronavirus pandemic and showcase how these methods can improve surveillance of Varroa mite infestations in Ontario, Canada. Dashboards provide a consistent source of information and epidemiologic metrics through data visualizations, and mobilize data otherwise bound to tables and intermittent reports. In the present work, an interactive dashboard for the surveillance of Varroa mite infestations across the province is proposed. This dashboard was developed using routine ministry inspection data to depict the spatio-temporal distribution of mites across a five-year data collection period. Through interactive figures and plots, able to be disaggregated to a specific region and time frame, this dashboard will allow for members of the beekeeping community to monitor provincial mite levels throughout the season. Seven criteria found to be common across highly actionable COVID-19 dashboards were used in a beta testing stage of development to assess the quality of the dashboard, and critically reflect on its strengths and weaknesses. Furthermore, future directions for surveillance dashboards are explored, including integration with citizen science data collection to develop a comprehensive province-wide surveillance system. The outcome of this project is a functional dashboard proof-of-concept for population-level monitoring of Varroa mites and a model for future tools designed for other species and diseases.

Estimation of photovoltaic waste spatio-temporal distribution by 2060 in the context of carbon neutrality

In recent decades, large-scale deployment of photovoltaic (PV) power leads to management challenges for recycling PV module waste in China. With the growth of waste PV volumes, it is necessary to figure out the spatio-temporal distribution of PV waste at the provincial level. Based on China's carbon neutrality goal by 2060, six development pathways of PV installed capacity are proposed to identify in-use stocks of PV capacity. In particular, we develop the retired flow estimation model for PV modules that is constructed by three PV module degradation scenarios. The results show that a relatively large scale of PV waste will be started to emerge in China by 2030 and the cumulative waste is expected to reach 1100[Formula: see text]1450 GW by 2060. Our findings also indicate an unequal distribution of PV waste across regions and the highest PV waste volumes by 2060 is the East China region at 31.4%, with Shandong (8.99%) and Hebei(8.65%) ranking as the top provinces. This prospective research will help the PV industry plan the location and capacity of recovery facilities at an appropriate time to advance toward a more resource efficient and circular economy.

Two-year online measurements of volatile organic compounds (VOCs) at four sites in a Chinese city: Significant impact of petrochemical industry

Volatile organic compounds (VOCs) management has been recently given a high priority in China to mitigate ozone (O₃) air pollution. However, there is a relatively poor understanding of VOCs due to their complexity and fewer observations. To better understand the pollution characteristics of VOCs and their impact on O₃ pollution, two-year continuous measurements were conducted at four representative sites in Ji'nan, eastern China. These four sites cover urban, background, and industrial areas (within a petroleum refinery). Ambient VOCs showed higher concentrations at industrial site than at urban and background sites, owing to intensive emissions from petrochemical industry. The VOCs compositions present spatial heterogeneity with alkenes dominated in total reactivity at urban and background sites, while alkenes and aromatics together dominated at industrial site. The VOCs emission profile from petrochemical industry was calculated based on observational data, which revealed a huge impact on light alkanes (C₂-C₅), light alkenes (ethene), and aromatics (toluene and m/p-xylene). The positive matrix factorization (PMF) model analysis further refined the impact of different petrochemical industrial processes. Alkanes and alkenes dominated the emissions during refining process, while aromatics dominated during solvent usage process. Analysis by an observation-based model indicated stronger in-situ O₃ production and higher sensitivity to nitrogen oxides at industrial site compared to urban and background sites. The reduction of VOCs emissions from petrochemical industry would significantly reduce the O₃ concentrations. The analyses underline the significant impact of petrochemical industry on VOCs and O₃ pollution, and provide important reference for the formulation of refined and effective control strategies.

Spatiotemporal PAH levels in surface water of the Southeastern Black Sea; baseline study from the Giresun shores

Samples of surface water were collected seasonally along the 121 km long Giresun coastline to comparatively evaluate the source, distribution, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs). The total PAHs levels, varied between 47.42 and 576.69 ng L^-1 with the mean of 161.5 ng L^-1, were consistent with seawater studies worldwide. Diagnosis rates evinced that PAHs in seawater along the Giresun coastline are primarily sourced from biomass, coal and petroleum combustion and petroleum at lesser extent. The three-ring PAHs (40.2 %) was proportionally high, followed by 2-ring PAHs (26.5 %). The toxicity equivalent quotient (TEQ) and risk quotients (RQ) were employed to assess ecological risk posed by PAHs in Giresun coastal seawater. As a result, the ecological risk in all seasons was at moderate to high risk level, except for autumn, which shows low to moderate risk according to TEQ. RQ values of ∑PAHs displayed low to moderate ecological risk.

Size distribution patterns of silky shark Carcharhinus falciformis shaped by environmental factors in the Pacific Ocean

Commercial fisheries, especially pelagic longline fisheries targeting tuna and/or swordfish, often land silky sharks (Carcharhinus falciformis), which are currently listed as vulnerable by the International Union for Conservation of Nature (IUCN). Due to increasing fishing effort and the fact that they overlap in habitat with target species, the population trend of silky sharks is declining worldwide. Understanding their relationships with environmental variables that lead to their capture by fisheries is critical for their management and conservation. Nevertheless, little is known about their size distribution in relation to environmental variables in the Pacific Ocean. Using data from the Chinese Observer Tuna Longline fishery from 2010 to 2020, this study developed a species distribution model (SDM) to analyze the relationships between silky shark size distribution patterns and environmental variables and spatio-temporal variability at fishing locations. Observed sizes ranged from 36 to 269 cm fork length (FL). The final model suggests that sea surface temperature (SST), primary production (photosynthetically available radiation, PAR), and ocean surface winds were the key environmental variables shaping size distribution patterns of silky sharks in the Pacific. A high proportion of larger silky sharks has been predicted in areas associated with productive upwelling systems. In addition, the model predicted that larger specimens (>140 cm FL) occur near the equator, and smaller specimens farther from the equator but still in tropical regions. Two regions in the eastern Pacific (the coastal upwelling area off northern Peru and the waters around the Galapagos Islands) seem to be important locations for larger specimens. The size distribution patterns of silky sharks in relation to environmental variables presented in this study illustrate how this species segregates spatially and temporally and presents potential habitat preference areas. The information obtained in the present study is critical in the quest for management and conservation of menaced species such as the silky shark.

Characteristics analysis of water pollutants in Cihu Lake, China, based on a multivariate statistical analysis method

In order to understand the sources of pollutants and the temporal and spatial distribution characteristics of the water quality in Cihu Lake, China, the monitoring data of seven water quality indicators from 12 sampling sites from 2015 to 2019 were selected, and the temporal and spatial variation laws of the water quality and pollution sources were analyzed by the use of the multivariate statistical analysis method. The results show that nitrogen and phosphorus pollution in the lake is dominant. The average concentrations of total nitrogen (TN) and total phosphorus (TP) exceed the surface water quality Class III standards by 1.6 and 2.2 times, respectively. Spatially, the results of the cluster analysis showed that the water quality in Cihu Lake can be categorized into three regions: the northern half of the lake, the southern half of the lake, and the canal entering the lake. Temporally, the water quality in these three regions can be classified into three categories: March to May (the northern half of Cihu Lake), September to November (the southern half of Cihu Lake), and September (the canal entering Cihu Lake). The discriminant analysis results showed that NH₃-N, TN, COD_Cr, and BOD₅ are the main factors that affect the uneven spatial distribution of the water quality of Cihu Lake, while TN, DO, and COD_Mn are the main factors that affect the temporal difference in the northern half of Cihu Lake, and NH₃-N, TP, COD_Cr, DO, COD_Mn, TN, and TP are the main factors affecting the temporal difference in the southern half of Cihu Lake and the canal entering Cihu Lake. It was found that the water pollution in the study area can be mainly attributed to the incoming water and urban domestic pollution. The main pollution sources for the canal entering Cihu Lake and the southern half of Cihu Lake are the water from the sewage treatment plant and the domestic sewage that has not been intercepted, while the northern half of Cihu Lake is mainly affected by surface runoff, mixed rainwater and sewage, and internal pollution.

[Spatio-temporal distribution characteristics of soil-transmitted nematodiasis in Sichuan Province from 2016 to 2021]

OBJECTIVE

To investigate the trends in the prevalence of soil-transmitted nematode infections and the spatio-temporal distribution characteristics of soil-transmitted nematodiasis in Sichuan Province from 2016 to 2021, so as to provide the evidence for formulating the soil-transmitted nematodiasis elimination strategy in Sichuan Province.

METHODS

The soil-transmitted nematodiasis surveillance data in Sichuan Province from 2016 to 2021 were collected, and the epidemic trend of soil-transmitted nematode infections was identified. The distribution maps of soil-transmitted nematode infections in Sichuan Province were plotted to identify their spatial distribution characteristics. In addition, the spatial clusters of soil-transmitted nematode infections were detected using globa and local spatial autocorrelation analyses.

RESULTS

The prevalence of soil-transmitted nematode infections appeared a decline with time in Sichuan Province from 2016 to 2021 (χ²= 400.24, P < 0.01). Global spatial autocorrelation analysis identified positive spatial autocorrelations in the prevalence of soil-transmitted nematode infections (Moran's I = 0.322, Z = 16.293, P < 0.01), hookworm infections (Moran's I = 0.425, Z = 21.290, P < 0.01), Ascaris lumbricoides infections (Moran's I = 0.102, Z = 5.782, P < 0.01) and Trichuris trichiura infections (Moran's I = 0.084, Z = 6.873, P < 0.01). Local spatial autocorrelation analysis showed that the high-high clusters of soil-transmitted nematode infections were mainly located in 37 counties (cities, districts) of Sichuan Province, and the high-high clusters of hookworm, A. lumbricoides and T. trichiura infections were mainly identified in 39 counties (cities, districts) in mountainous areas around Sichuan Basin and hilly areas, 9 counties (cities, districts) in mountainous areas in southwestern Sichuan Province, and 8 counties (cities, districts) in mountainous areas in southwestern Sichuan Province, respectively.

CONCLUSIONS

The prevalence of soil-transmitted nematode infections appeared a tendency towards a decline in Sichuan Province from 2016 to 2021, which showed spatial clusters. The management of soil-transmitted nematodiasis requires to be reinforced in high-risk areas of Sichuan Province with adaptations to local epidemiological features.

Spatio-temporal variation of net anthropogenic nitrogen inputs (NANI) from 1991 to 2019 and its impacts analysis from parameters in Northwest China

At present, excessive nutrient inputs caused by human activities have resulted in environmental problems such as agricultural non-point source pollution and water eutrophication. The Net Anthropogenic Nitrogen Inputs (NANI) model can be used to estimate the nitrogen (N) inputs to a region that are related to human activities. To explore the net nitrogen input of human activities in the main grain-producing areas of Northwestern China, the county-level statistical data for the Ningxia province and NANI model parameters were collected, the spatio-temporal distribution characteristics of NANI were analyzed and the uncertainty and sensitivity of the parameters for each component of NANI were quantitatively studied. The results showed that: (1) The average value of NANI in Ningxia from 1991 to 2019 was 7752 kg N km^-2 yr^-1. Over the study period, the inputs first showed an overall increase, followed by a decrease, and then tended to stabilize. Fertilizer N application was the main contributing factor, accounting for 55.6%. The high value of NANI in Ningxia was mainly concentrated in the Yellow River Diversion Irrigation Area. (2) The 95% confidence interval of NANI obtained by the Monte Carlo approach was compared with the results from common parameters in existing literature. The simulation results varied from -6.4% to 27.4% under the influence of the changing parameters. Net food and animal feed imports were the most uncertain input components affected by parameters, the variation range was -20.7%-77%. (3) The parameters of inputs that accounted for higher proportions of the NANI were more sensitive than the inputs with lower contributions. The sensitivity indexes of the parameters contained in the fertilizer N applications were higher than those of net food and animal feed imports and agricultural N-fixation. This study quantified the uncertainty and sensitivity of parameters in the process of NANI simulation and provides a reference for global peers in the application and selection of parameters to obtain more accurate simulation results.

Spatio-temporal distribution of tuberculosis and the effects of environmental factors in China

Background

Although the World Health Organization reports that the incidence of tuberculosis in China is decreasing every year, the burden of tuberculosis in China is still very heavy. Understanding the spatial and temporal distribution pattern of tuberculosis in China and its influencing environmental factors will provide effective reference for the prevention and treatment of tuberculosis.

Methods

Data of TB incidence from 2010 to 2017 were collected. Time series and global spatial autocorrelation were used to analyze the temporal and spatial distribution pattern of tuberculosis incidence in China, Geodetector and Geographically Weighted Regression model were used to analyze the environmental factors affecting the TB incidence.

Results

In addition to 2007 and 2008, the TB incidence decreased in general. TB has a strong spatial aggregation. Cities in Northwest China have been showing a trend of high-value aggregation. In recent years, the center of gravity of high-value aggregation area in South China has moved further south. Temperature, humidity, precipitation, PM₁₀, PM_2.5, O₃, NO₂ and SO₂ have impacts on TB incidence, and in different regions, the environmental factors show regional differences.

Conclusions

Residents should pay more attention to the risk of developing TB caused by climate change and air pollutant exposure. Increased efforts should be placed on areas with high-value clustering in future public resource configurations.

Variation of spatio-temporal distribution of on-road vehicle emissions based on real-time RFID data

High-resolution vehicular emissions inventories are important for managing vehicular pollution and improving urban air quality. This study developed a vehicular emission inventory with high spatio-temporal resolution in the main urban area of Chongqing, based on real-time traffic data from 820 RFID detectors covering 454 roads, and the differences in spatio-temporal emission characteristics between inner and outer districts were analysed. The result showed that the daily vehicular emission intensities of CO, hydrocarbons, PM_2.5, PM₁₀, and NOx were 30.24, 3.83, 0.18, 0.20, and 8.65 kg/km per day, respectively, in the study area during 2018. The pollutants emission intensities in inner district were higher than those in outer district. Light passenger cars (LPCs) were the main contributors of all-day CO emissions in the inner and outer districts, from which the contributors of NOx emissions were different. Diesel and natural gas buses were major contributors of daytime NOx emissions in inner districts, accounting for 40.40%, but buses and heavy duty trucks (HDTs) were major contributors in outer districts. At nighttime, due to the lifting of truck restrictions and suspension of buses, HDTs become the main NOx contributor in both inner and outer districts, and its three NOx emission peak hours were found, which are different to the peak hours of total NOx emission by all vehicles. Unlike most other cities, bridges and connecting channels are always emission hotspots due to long-time traffic congestion. This knowledge will help fully understand vehicular emissions characteristics and is useful for policymakers to design precise prevention and control measures.

Spatial and temporal variation, source identification, and toxicity evaluation of brominated/chlorinated/nitrated/oxygenated-PAHs at a heavily industrialized area in eastern China

Some derivatives of polycyclic aromatic hydrocarbons (PAHs) such as chlorinated and brominated PAHs (Cl/BrPAHs), nitrated and oxygenated PAHs (N/OPAHs) have attracted significant concern due to their high toxicity. Knowledge of the profiles, formation mechanisms, and potential sources of these toxic chemicals near the industrial complexes is essential for their pollution control and management. In this study, we monitored Cl/BrPAHs, N/OPAHs, and PAHs at 24 sampling sites near a heavily industrialized area (steel, chemical, and rubber plants) using passive air samplers during the heating period (7 December 2019 to 15 April 2020) and the non-heating period (2 June 2020 to 4 October 2020). The total average concentrations of 16 BrPAHs, 8 ClPAHs, 17 NPAHs, 6 OPAHs, and 18 PAHs during both sampling periods were 471 pg/m³, 229 pg/m³, 312 pg/m³, 2120 pg/m³, and 63.1 ng/m³, respectively. Except for NPAHs, BrPAHs, ClPAHs, OPAHs, and PAHs all showed higher levels during the heating period. The spatial distributions of Cl/BrPAHs, N/OPAHs, and PAHs exhibited a similar pattern, with the highest concentrations detected in the vicinity of the steel industry. Congener profiles of PAH derivatives indicated that mono-substituted low molecular weight compounds (2-3 rings) were dominant. The major formation mechanisms of halogenated PAHs were discussed by correlation analysis and relative Gibbs free energies, and direct bromination of parent PAHs could be the major formation mechanism of BrPAHs in this study. Diagnostic ratios showed that NPAHs were mainly derived from primary emissions, but the contribution of secondary formation was increased at heavily contaminated sites. The positive matrix factorization model extracted four Cl/BrPAHs, three N/OPAHs, and four PAHs factors, and the result showed that PAHs and their derivatives mainly derived from industrial and combustion sources, photochemical reactions, vehicle emissions, and crude oil volatilization, etc.

Combined suppression effects on hydrodynamic cavitation performance in Venturi-type reactor for process intensification

Hydrodynamic cavitation is an emerging intensification technology in water treatment or chemical processing, and Venturi-type cavitation reactors exhibit advantages for industrial-scale production. The effects of temperature on hydrodynamic cavitating flows are investigated to find the optimum reaction conditions enhancing cavitating treatment intensity. Results show that the cavitation performance, including the cavitation intensity and cavitation unsteady behavior, is influenced by (1) cavitation number σ (the pressure difference affecting the vaporization process), (2) Reynolds number Re (the inertial/viscous ratio affecting the bubble size and liquid-vapor interface area), and (3) thermodynamic parameter Σ (the thermal effect affecting the temperature drop). With increasing temperature, the cavitation length first increases and then decreases, with a cavitation intensity peak at the transition temperature of 58 °C. With the growth of cavitation extent, the cavity-shedding regimes tend to transition from the attached sheet cavity to the periodic cloud cavity, and the vapor volume fluctuating frequency decreases accordingly. A combined suppression parameter (CSP) is provided to predict that, with increasing CSP value, the cavitation intensity can be decreased. Recommendations are given that working under the low-CSP range (55-60 °C) could enhance the intensification of the cavitation process.

Analysis of spatio-temporal distribution characteristics and socioeconomic drivers of urban air quality in China

Having high spatio-temporal resolution data of pollutants is critical to understand environmental pollution patterns and their mechanisms. Our research employs the hourly average concentration data on the air quality index (AQI) and its six component pollutants (PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃) in 336 Chinese cities from 2014 to 2019. We analyze annual, seasonal, monthly, hourly, and spatial variations of different air pollutants and their socioeconomic factors. The results are as follows. (1) Air pollutants' concentration in Chinese cities decreased year by year during 2014-2019. Among the primary pollutants, PM_2.5 dominated pollution days, accounting for 38.46%, followed by PM₁₀. Monthly concentration curves of AQI, PM_2.5, NO₂, SO₂, and CO showed a U-shaped trend from January to December, while that of O₃ presented an inverted U-shaped unimodal pattern. Regarding daily variation, urban air quality tended to be worse around sunrise compared with sunset. (2) Chinese cities' air quality decreased from north to south and from inland to coastal areas. Recently, air quality has improved, and polluted areas have shrunk. The six pollutant types showed different spatial agglomeration characteristics. (3) Industrial pollution emissions were the main source of urban air pollutants. Energy-intensive industries, dominated by coal combustion, had the greatest impact on SO₂ concentration. A "pollution shelter" was established in China because foreign investment introduced more pollution-intensive industries. Thus, China has crossed the Kuznets U-curve inflection point. In addition, population agglomeration contributed the most to PM_2.5 concentration, increasing the PM_2.5 exposure risk and causing disease, and vehicle exhaust aggravated the pollution of NO₂ and CO. The higher China's per capita gross domestic product, the more significant the effect of economic development is on reducing pollutant concentration.

Spatio-temporal distribution characteristics of COVID-19 in China: a city-level modeling study

Background

The coronavirus disease 2019 (COVID-19) has become a pandemic. Few studies have been conducted to investigate the spatio-temporal distribution of COVID-19 on nationwide city-level in China.

Objective

To analyze and visualize the spatiotemporal distribution characteristics and clustering pattern of COVID-19 cases from 362 cities of 31 provinces, municipalities and autonomous regions in mainland China.

Methods

A spatiotemporal statistical analysis of COVID-19 cases was carried out by collecting the confirmed COVID-19 cases in mainland China from January 10, 2020 to October 5, 2020. Methods including statistical charts, hotspot analysis, spatial autocorrelation, and Poisson space–time scan statistic were conducted.

Results

The high incidence stage of China’s COVID-19 epidemic was from January 17 to February 9, 2020 with daily increase rate greater than 7.5%. The hot spot analysis suggested that the cities including Wuhan, Huangshi, Ezhou, Xiaogan, Jingzhou, Huanggang, Xianning, and Xiantao, were the hot spots with statistical significance. Spatial autocorrelation analysis indicated a moderately correlated pattern of spatial clustering of COVID-19 cases across China in the early phase, with Moran’s I statistic reaching maximum value on January 31, at 0.235 (Z = 12.344, P = 0.001), but the spatial correlation gradually decreased later and showed a discrete trend to a random distribution. Considering both space and time, 19 statistically significant clusters were identified. 63.16% of the clusters occurred from January to February. Larger clusters were located in central and southern China. The most likely cluster (RR = 845.01, P < 0.01) included 6 cities in Hubei province with Wuhan as the centre. Overall, the clusters with larger coverage were in the early stage of the epidemic, while it changed to only gather in a specific city in the later period. The pattern and scope of clusters changed and reduced over time in China.

Conclusions

Spatio-temporal cluster detection plays a vital role in the exploration of epidemic evolution and early warning of disease outbreaks and recurrences. This study can provide scientific reference for the allocation of medical resources and monitoring potential rebound of the COVID-19 epidemic in China.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06515-8.

Spatio-temporal distribution and source identification of heavy metals in particle size fractions of road dust from a typical industrial district

Seasonally distribution and source apportionment of Cr, Mn, Ni, Cu, Zn, Cd, and Pb in the road dust (RD) with the four size fraction sizes (<45 μm, 45-63 μm, 63-150 μm and all sizes) in a typical industrial district were investigated using a combination of Moran index, Principal component analysis (PCA), and Positive matrix factorization (PMF). Results showed that from winter to summer, the proportion of the <45 μm fraction dust in the total RD mass increased from 6.72% to 15.92% and that of 63-150 μm dust particles decreased from 31.13% to 21.76%. The proportion of the enrichment factors (EF) at moderate pollution level in winter was higher than that in summer, especially for Cu, Cd and Pb. Further, the heavy metals were relatively enriched in particles 63-150 μm in summer, while in particles <45 μm in winter. Spatially, the distribution of heavy metal concentrations was more concentrated in the winter and showed low levels of regional diffusion. Based on the pollution mapping and PCA-PMF, the integrated source appointment showed that the industrial sources are the main sources of Zn, Cd and Pb, and their contributions are higher at a particle below 45 μm in winter. The construction source significantly influenced Cr, Mn and Cu in summer with little diversity among particle size ranges. Therefore, the <45 μm particles from industrial emission in winter is suggested to be under priority control. And the industrial transformation demonstration area in the Qingshan district should upgrade heavy pollution industry lines and strengthen the monitoring of soot emissions. Further, emissions from coal-fired enterprises should be restricted in winter. Besides, the attention should be paid to avoid urban traffic jams around construction projects and increase enclosed construction ratio.

Spatio-temporal modelling of Culicoides Latreille (Diptera: Ceratopogonidae) populations on Reunion Island (Indian Ocean)

BACKGROUND

Reunion Island regularly faces outbreaks of bluetongue and epizootic hemorrhagic diseases, two insect-borne orbiviral diseases of ruminants. Hematophagous midges of the genus Culicoides (Diptera: Ceratopogonidae) are the vectors of bluetongue (BTV) and epizootic hemorrhagic disease (EHDV) viruses. In a previous study, statistical models based on environmental and meteorological data were developed for the five Culicoides species present in the island to provide a better understanding of their ecology and predict their presence and abundance. The purpose of this study was to couple these statistical models with a Geographic Information System (GIS) to produce dynamic maps of the distribution of Culicoides throughout the island.

METHODS

Based on meteorological data from ground weather stations and satellite-derived environmental data, the abundance of each of the five Culicoides species was estimated for the 2214 husbandry locations on the island for the period ranging from February 2016 to June 2018. A large-scale Culicoides sampling campaign including 100 farms was carried out in March 2018 to validate the model.

RESULTS

According to the model predictions, no husbandry location was free of Culicoides throughout the study period. The five Culicoides species were present on average in 57.0% of the husbandry locations for C. bolitinos Meiswinkel, 40.7% for C. enderleini Cornet & Brunhes, 26.5% for C. grahamii Austen, 87.1% for C. imicola Kieffer and 91.8% for C. kibatiensis Goetghebuer. The models also showed high seasonal variations in their distribution. During the validation process, predictions were acceptable for C. bolitinos, C. enderleini and C. kibatiensis, with normalized root mean square errors (NRMSE) of 15.4%, 13.6% and 16.5%, respectively. The NRMSE was 27.4% for C. grahamii. For C. imicola, the NRMSE was acceptable (11.9%) considering all husbandry locations except in two specific areas, the Cirque de Salazie-an inner mountainous part of the island-and the sea edge, where the model overestimated its abundance.

CONCLUSIONS

Our model provides, for the first time to our knowledge, an operational tool to better understand and predict the distribution of Culicoides in Reunion Island. As it predicts a wide spatial distribution of the five Culicoides species throughout the year and taking into consideration their vector competence, our results suggest that BTV and EHDV can circulate continuously on the island. As further actions, our model could be coupled with an epidemiological model of BTV and EHDV transmission to improve risk assessment of Culicoides-borne diseases on the island.

Polycyclic aromatic hydrocarbons in surface waters from the seven main river basins of China: Spatial distribution, source apportionment, and potential risk assessment

In this study, we report long-term measurements of Polycyclic Aromatic Hydrocarbons (PAHs) collected from the surface waters of seven river basins across China. The spatial distribution, source apportionment, and potential risk assessment of 16 USEPA designated PAHs were reviewed. Water samples were collected from the Songhua River Basin (SRB), Yangtze River Basin (YtRB), Yellow River Basin (YRB), Pearl River Basin (PRB), Huai River Basin (HuRB), Liao River Basin (LRB), and Hai River Basin (HRB). Our results show that the total PAH concentration in the surface waters from primary river basins ranged from 99.60 to 3805.00 ng/L in the dry season with a geometric mean value of 797.96 ng/L, and from 235.84 to 11,812.20 ng/L in the wet season with a geometric mean value of 820.75 ng/L. In the river basins examined, the geometric concentration of Σ₁₆PAHs ranged from 215.50 ng/L to 1969.91 ng/L, with a median value of 837.73 ng/L. In the decreasing order across seven river basins, the geometric mean Σ₁₆PAHs content varied as: SRB (1969.91 ng/L) > LRB (1155.87 ng/L) > YRB (884.06 ng/L) > PRB (837.73 ng/L) > HuRB (559.10 ng/L) > HRB (261.84 ng/L) > YtRB (215.50 ng/L). Moreover, the total PAH concentration was slightly lower in the dry season than in the wet season. The pollution level of PAHs in North China was higher than in South China. No discernible temporal trend was observed in Σ₁₆PAHs observed in China during the past decade. Overall, PAHs designated for priority control measures were Nap, Phe, and Flu; as 2- and 3-ring PAHs were the dominant compounds in the river basins, accounting for 33.7% and 36.9% of the total PAHs, respectively. Source analysis revealed that coal and biomass combustion were the main contributors to PAHs in the river basins, accounting for about 40% of the total. The geometric mean concentrations of individual PAH, including BaP, BaA, BbF, BkF, Ind, and DaA in some water samples exceeded the environmental quality standards of both China and the United States. According to metrics describing eco-toxicity from water contamination, the river basin was at moderate risk in YtRB, YRB, PRB, HuRB, and HRB, but at high risk in SRB and LRB, suggesting that targeted control measures or remedial actions should be undertaken to decrease PAH contamination in China.

[Epidemic characteristics and dynamic changes of spatio-temporal distribution of hemorrhagic fever with renal syndrome in Guangzhou, 2010-2019]

Objective: To analyze the epidemic characteristics and spatio-temporal distribution of hemorrhagic fever with renal syndrome (HFRS) in Guangzhou from 2010 to 2019 and provide a basis for prevention and control strategies. Methods: The data of HFRS was from National Disease Reporting Information System and the epidemic investigation. A descriptive analysis was used. OpenGeoDa 1.2.0 software was used for global spatial autocorrelation and local spatial autocorrelation analysis. SatScan 9.6 software was used for detecting the hot spot area in time and space. ArcGIS 10.2 software was used for map visualization. Results: 1 298 cases of HFRS were reported, and three patients died in Guangzhou in 2010-2019. The annual incidence rate was 0.99/100 000. The proportion of 21-50 years old cases accounted for 70.88% and the male to female ratio was 2.98∶1. Most patients were house workers or unemployed, accounting for 31.28%, followed by business servants (accounting for 17.33%). The incidence peak in spring and winter accounted for 33.74% and 26.35% of the year. All districts reported cases in recent ten years. A total of 407 cases had been reported in Haizhu district, accounting for 31.36% of the total number of cases in the whole city. The annual incidence rate was 2.52/100 000. The number of reported cases and the annual incidence rate were the highest in Guangzhou. The clustered area showed that there was spatio-temporal clustering in Guangzhou. The aggregation area was mainly concentrated in the urban villages adjacent to Wan-mu orchard and the Haizhu Lake Wetland Park in Haizhu district (logarithmic likelihood ratio was 44.08, P<0.001). Conclusions: The prevalence and concentration of HFRS in winter and spring Guangzhou city from 2010 to 2019, showed a high incidence. Young and middle-aged men engaged in domestic and unemployed, and commercial services appeared the main risk groups. The urban-rural junction with many immigrants and low health environment, streets adjacent to Wan-mu orchard, and the Haizhu Lake Wetland Park in Haizhu district were the important regions for preventing and controlling HFRS. The government should formulate prevention and control measures to curb the rise and spread of the HFRS epidemic.

[Epidemiological characteristics of COVID-19 in Wuchang district of Wuhan]

Objective: To analyzes epidemiological characteristics of COVID-19 and provide evidence for adjustment for COVID-19 prevention and control strategies. Methods: The data of COVID-19 cases in Wuchang district reported as of 19 March, 2020 were obtained from National Notifiable Disease Report System of Chinese Disease Prevention and Control Information System. The software's of Excel 2010, SPSSS 22.0, Arc GIS10.2 and Joinpoint regression program 4.8.0.0 were used for statistical analysis. Results: A total of 7547 COVID-19 cases had been reported as of 19 March, 2020 in Wuchang district, including 5 448 confirmed cases (72.19%), 2009 clinical diagnosed cases (26.62%) and 90 asymptomatic cases case (1.19%). The age of the cases was (56.65±16.25) years and age ranged from 2 days to 105 years among confirmed cases, 2634 were males (48.35%) and 2814 were females (51.65%), 2 492 were retirees (45.74%). A total of 545 health workers were infected with SARS-CoV-2 (7.22% of all cases) including 365 confirmed cases and 5 cases have died. A total of 430 cases of death were reported with case fatality rate of 7.89% (430/5 448), case fatality rate of males (10.9%, 266/2 634) was higher than that of females (5.82%, 164/2 814). The first phase of epidemic peak was from January 24 to January 26, the second phase of epidemic peak was from February 1 to February 5 and there was no one of new confirmed case in one day for the first time on March 18. The first four Streets with the highest incidence rates of confirmed cases were Huanghelou Street (1 043.77/100 000), Ziyang Street (627.97/100 000), Yangyuan Street (503.67/100 000) and Shuiguohu Street (486.02/100 000). Compared with females, aged ≤50 years and mild cases of clinical classification respectively, males (RR=0.690, 95%CI: 0.322-1.478), aged >50 years (RR=11.745, 95%CI: 6.878-20.058), severe cases (RR=2.317, 95%CI: 1.789-3.000) and critical cases of clinical classification (RR=10.794, 95%CI: 7.997-14.569), and gender time-dependent covariate (RR=1.392, 95%CI: 1.053-1.840) were major influencing factors of prognosis of COVID-19 confirmed cases. Conclusions: The gender, ages and occupation of distribution were wide among COVID-19 cases in Wuchang district. Males, aged >50 years, severe cases and critical cases of clinical classification were influencing factors of prognosis of COVID-19 confirmed cases. The standardized management of discharged cases, asymptomatic infected cases and close contact persons were main measures to reduce incidence rates of COVID-19 cases.

Heavy metal pollution in the East China Sea: A review

Due to rapid urbanization and industrialization, heavy metal (HM) pollution in coastal areas of the East China Sea (ECS) has attracted extensive attention. This article attempts to review recent studies on the temporal and spatial distributions, ecological risks, and possible sources of HMs in typical bays and estuaries of ECS. The levels of HMs are closely related to local economic development and local characteristics. The anthropogenic activities and the particle size of sediments are important factors affecting the distribution of HMs. During the late 1970s to the 1990s, HMs levels in the Yangtze Estuary (YRE) sediments showed an upward tendency due to the increased emissions. However, HMs levels in the early 2000s were lower than that in the late 1970s to the mid-1990s. Cd caused serious pollution and brought potential ecological risks in the Yangtze Estuary, Hangzhou Bay (HZB), Sanmen Bay (SMB), and Quanzhou Bay (QZB). In Fujian province of China, the Quanzhou Bay was heavily polluted by HMs and high contents of HMs were found in biota. Among different species, molluscs in the coastal areas of ECS have the highest levels of HMs exceeding safety limits.

Characterization of microplastics in the surface seawater of the South Yellow Sea as affected by season

Microplastic pollution in global marine environments has attracted significant concerns; however, the environmental factors that influence the distribution and characteristics of microplastics are still unclear. In this study, 100 L of surface seawater samples collected from 16 different stations of the South Yellow Sea in January, April, and August 2018 were analyzed to investigate the relationship between spatio-temporal distribution of microplastics and environment variables. Results showed that the abundance of microplastics in January (6.5 ± 2.1 items/L) was higher than that in April (4.9 ± 2.1 items/L) and August (4.5 ± 1.8 items/L). On the whole, 78% of the total microplastics were <500 μm, ~90% were fibers, 73.2%-81.7% were transparent, and the two most abundant polymer types were polyethylene and polypropylene. The highest variability of microplastic characteristics (colour, size, and shape) and composition were observed in August, thereby showing the apparent features of terrestrial sources of microplastic pollution. Principal components analysis distinguished the spatio-temporal distribution of the microplastics, and significant difference in plastic sizes was found between microplastics in January and those in the other two months, which could be attributed to the Yellow Sea Warm Current and/or winter monsoon. Additionally, the abundance of microplastics, especially small-sized microplastics (<500 μm), was positively correlated with seawater salinity. These results suggest that microplastic pollution in surface waters of the South Yellow Sea varies with seasons owing to differences in the terrestrial sources and marine hydrological dynamics.

Continental-scale spatio-temporal distribution of antibiotic resistance genes in coastal waters along coastline of China

Antibiotic resistance genes (ARGs) have been frequently detected in various matrices all over the world to attract wide attention due to the potential risks. Rare information is available on the pollution of ARGs in the waters of critical ecologically fragile regions such as the coastal zone at a continental scale. Therefore, this study performed field sampling during winter and summer along 18000 km coastline of China to investigate the distribution of target ARGs in coastal waters at a continental scale. The absolute abundances of ARGs in coastal waters showed drastic spatio-temporal variation with a mean value of 8.79 × 10⁴/1.39 × 10⁵ copies/mL in summer/winter, much lower than those in tail water from the maricultural zone or wastewater. The average absolute abundance of class 1 integron-integrase gene (intI1) in coastal waters was 9.68 × 10³/4.15 × 10⁴ copies/mL in summer/winter, still lower than that in tail water or wastewater. Quinolone resistance genes were the dominant ARGs in coastal waters to account for over 50% of total ARGs in most of sampling sites. Bacterial communities in coastal waters showed significant difference both at phylum and genus levels. Abundances of ARGs in coastal waters of this study were comparable with those in other regions previously reported. Tail water and wastewater might be the essential sources of ARGs in coastal waters. The findings of this study provided comprehensive information on the pollution status of ARGs in coastal waters at a continental scale, indicating that ARGs pollution has become a crucial stress affecting the sustainable development of coastal regions.

Spatio-temporal distribution and ecological risk assessment of pesticides in the water resources of Abou Ali River, Northern Lebanon

The objective of this study is to assess the occurrence, spatial, and temporal distribution of forty-eight multiclass pesticides in surface and groundwater samples of the Abou Ali River, located in the North of Lebanon. A 3-year monitoring program (six batches from August 2015 to March 2017) was implemented, and thirty sampling points were selected along the river for analysis. The analysis was executed using a previously developed and optimized solid-phase micro-extraction (SPME) gas-chromatography-mass spectrometry (GC-MS) method. Statistical analysis, using Kolmogorov-Smirnov, Kruskal-Wallis, and Dunnet T3 multiple comparison tests, was applied to compare mean concentrations of pesticides between the different sampling sites and the batches taken. The pesticides that had the highest frequency of detection in the surface and groundwater samples were alachlor, α-endosulfan, and methomyl. For surface water samples, high mean concentrations were perceived for two stations in the upper stream (S5 and S7), two stations (S11 and S14) in the middle stream, and one station (S16) in the lower stream of the river. The highest mean concentrations were observed in October 2015 and August 2016, the time of the year which correlates with the period of pesticide application. Considering groundwater samples, high mean concentrations of pesticides were detected in sites G4, G9, G10, and G12 and during October 2015 and March 2016, following the rainy season. Ecotoxicological risk assessment using the risk quotient (RQ) methodology revealed high risk for five pesticides under average conditions and fourteen under extreme conditions. This study presents, for the first time, a statistical analysis showing the quantification of pesticides in the water resources of the Abou Ali River. In conclusion, it reveals the need to apply a complete pesticide monitoring program, not only for the Abou Ali River but for all the water resources in Lebanon.

Geospatial clustering, seasonal trend and forecasting of Kyasanur Forest Disease in the state of Goa, India, 2015-2018

Introduction

Five states in India are reporting sporadic outbreaks of Kyasanur Forest Disease (KFD). Goa experienced an outbreak of KFD in 2015. It remains as an important differential diagnosis for tropical fever in the endemic regions. Few studies among neighboring two states (Karnataka and Kerala) have described the epidemiological characteristics of KFD. However, there is no study which describes the same among cases in the state of Goa. Hence, we planned to understand the epidemiology (time, place, and person distribution) of the disease including seasonal pattern with forecasting using zero-inflated negative binomial regression and time series models. We also explored geo-spatial clustering of KFD cases in Goa during 2015–2018 which would help design effective intervention to curb its transmission in Goa.

Results

Blood samples of all suspected cases of KFD during 2015 to 2018 were tested using reverse transcriptase-polymerase chain reaction technique. Reports of these results were periodically shared with the state surveillance unit. Records of 448 confirmed cases of KFD available at the State Integrated Disease Surveillance Programme were analyzed. The mean (SD) age of the patients was 41.6 (14.9) years. Of 143 cases with documented travel history, 135 (94.4%) had history of travel to forest for cashew plucking. Two thirds of cases (66.3%) did not receive KFD vaccine prior to the disease. Case fatality rate of 0.9% was reported. Seasonal peaks were observed during January to April, and forecasting demonstrated a peak in cases in the subsequent year also during January–April persisting till May. Around 40 villages located along the Western Ghats had reported KFD, and affected villages continued to report cases in the subsequent years also. Case density-based geographic maps show clustering of cases around the index village.

Conclusion

Most of the confirmed cases did not receive any vaccination. KFD cases in Goa followed a specific seasonal pattern, and clustering of cases occurred in selected villages located in North Goa. Most of the patients who had suffered from the disease had visited the forest for cashew plucking. Planning for public health interventions such as health education and vaccination campaigns should consider these epidemiological features.

Spatio-temporal distribution of ammonia (NH3) emissions in agricultural fields across North China

Ammonia (NH₃) is one of the main polluted gases in the atmosphere, and its emission has markedly increased in recent years. In China, NH₃ is mainly emitted from agricultural fields. Using city-wide data on NH₃ emissions in agricultural fields, the spatio-temporal emission of NH₃ was estimated for North China. This included emissions from nitrogen fertilizers, field straws, background soil, nitrogen-fixing plants, human feces, and livestock/poultry manure. Based on the results, the range of NH₃ emission in agricultural lands was 1623.0-1801.5 Gg/year. The rate of increase in NH₃ emission in the period 2003-2015 was 0.74% per year, which was relatively stable. The leading sources of NH₃ emission included the excessive use of chemical fertilizers in agriculture and the continuous expansion of livestock and poultry industries scale, accounting respectively for 44.9% and 43.9% NH₃ emission in the study area, respectively. Hebei and Shandong provinces contributed the highest NH₃ emission in North China. The contribution rate of NH₃ emission in each province varied with sources, agricultural development, and population density. Based on the 1 km × 1 km grid resolution map for NH₃ emission, the range and average of emission were 9.72-10.13 kg/ha and 9.95 kg/ha, respectively. High emissions were in the southeast of Hebei province and most of Shandong province. For these regions, there is a need for changes in policies relating to the use of chemical fertilizers in agriculture and the management methods of livestock production in the region.

Assessment of the spatial distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in urban soil of China

Long-term (2004-2018) persistent organic pollutants (POPs) data were collected for urban soils of China. The dataset included concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in soils, comprising a range of different compounds. Understanding the source of OCP and PCB pollution is an important step in controlling and reducing pollution levels in the environment. This study aimed to analyze the spatio-temporal distribution, pollution sources, and potential health risks of OCPs and PCBs in urban soils in different regions of China. It was found that the total OCP concentrations ranged from 7.6 to 37331 μg/kg with a mean value of 2861 μg/kg, and PCBs concentrations ranged from 0.3 to 123467 μg/kg with a mean value of 4984 μg/kg. The highest OCP concentrations were observed in Beijing and Hebei, whereas the highest PCB concentrations were found in the Zhejiang province. The geographical distribution showed that the total mean concentration of POPs of urban soil was much higher in East China than in West China. According to the isomer ratios, about 64% of provinces and cities showed new sources of dichlorodiphenyltrichloroethane (DDT) input and dicofol input was found in 30% of China. Hexachlorocyclohexane (HCH) in urban soils was mainly derived from fresh usage of lindane (γ-HCH) in most regions of China. Lifetime carcinogenic and non-carcinogenic risks of OCPs and PCBs through ingestion, inhalation, and dermal contact indicated that PCBs in urban soils of China often exceeded safe levels. The total lifetime carcinogenic risk values of PCBs were higher than the individual lifetime acceptable risk level (10^-4) in 64% of the studied regions and the non-carcinogenic risk values exceeded the target risk level (10^-1) in 53% of the regions. The improved knowledge of the distribution and main pollution sources of POPs in urban soil of China as a result of this study can contribute to better decision-making support for soil pollution control and monitoring.

[Spatio-temporal distribution of Oncomelania hupensis snails along the Danyang section of the Beijing-Hangzhou Grand Canal and the Danyang-Jintan-Liyang Canal]

OBJECTIVE

To explore the spatio-temporal characteristics of Oncomelania hupensis snails along the Danyang section of the Beijing-Hangzhou Grand Canal and the Danyang-Jintan-Liyang Canal, so as to provide scientific evidence for the dynamic assessment of the risk of snail spread in this region.

METHODS

O. hupensis snail status was collected in the plain regions with waterway networks in the study area from 2012 to 2017. The spatio-temporal variations of snail distribution were investigated along the Danyang section of the Beijing-Hangzhou Grand Canal and the Danyang-Jintan-Liyang Canal using buffer zone analysis, spatial autocorrelation, hotspot analysis and standard deviational ellipse with the geographical information system (GIS) tools.

RESULTS

The number of snail habitats showed a tendency towards a rise in the study area from 2012 to 2017, and snail habitats were predominantly distributed in the 1 000 m long buffer zone of the Danyang-Jintan-Liyang Canal, notably along the Jiuqu River at the junction between the Beijing-Hangzhou Grand Canal and the Danyang-Jintan-Liyang Canal. The distribution of snail habitats appeared spatial autocorrelations in 2014, 2016 and 2017, and the hotspot areas were mainly identified at the junction between the Danyang-Jintan-Liyang Canal and the Beijing-Hangzhou Grand Canal. In addition, the overall distribution of snail habitats was located in the northeastern-southwestern part of the study aera, and gradually shifted to the southern and northern parts with the time.

CONCLUSIONS

The spatial distribution of O. hupensis snails is complex along the Danyang section of the Beijing-Hangzhou Grand Canal and the Danyang-Jintan-Liyang Canal, and there is a risk of snail spread from the upper reaches to the lower reaches, where snail control needs to be intensified.

Assessment of German population exposure levels to PM10 based on multiple spatial-temporal data

Particulate matter is the key to increasing urban air pollution, and research into pollution exposure assessment is an important part of environmental health. In order to classify PM₁₀ air pollution and to investigate the population exposure to the distribution of PM₁₀, daily and monthly PM₁₀ concentrations of 379 air pollution monitoring stations were obtained for a period from 01/01/2017 to 31/12/2017. Firstly, PM₁₀ concentrations were classified using the head/tail break clustering algorithm to identify locations with elevated PM₁₀ levels. Subsequently, population exposure levels were calculated using population-weighted PM₁₀ concentrations. Finally, the power-law distribution was used to test the distribution of PM₁₀ polluted areas. Our results indicate that the head/tail break algorithm, with an appropriate segmentation threshold, can effectively identify areas with high PM₁₀ concentrations. The distribution of the population according to exposure level shows that the majority of people is living in polluted areas. The distribution of heavily PM₁₀ polluted areas in Germany follows the power-law distribution well, but their boundaries differ from the boundaries of administrative cities; some even cross several administrative cities. These classification results can guide policymakers in dividing the country into several areas for pollution control.

Impact of urbanization factors on mortality due to unintentional injuries using panel data regression model and spatial-temporal analysis

Unintentional injuries pose a great risk for human health in China. Few studies have focused on unintentional injuries at national level from urbanization perspective. The panel data of mortality rate of transportation accidents (TA), fall and drowning and sinking (DS) is investigated, and urbanization development index is collected. Global Moran's I and linear regression of panel data are applied to determine the spatial distribution and spatial influencing factors of unintentional injuries. The results are the following: (1) The unintentional injury such as TA, fall, and DS shows clear non-uniformity of spatial distribution and relative immobility through time. (2) A 10,000 tons increase in SO₂ emission amount (SO₂ EA) and emission of smoke and dust (ESD) can result in 15.7 and 12.5 increases in TA death in eastern region, respectively. Meanwhile, A 10,000 tons increase in NO_x emission amount can cause 15.1 increase in TA death in western region. For every 100 billion yuan increase in GDP, the fall death can reduce by 8.4 in central region. One bed increase in number of hospital beds per 10,000 population (NHBP) is favorable for decreasing in fall death by 16.7 in eastern region. However, increase in number of workers enjoying industrial injury (NEWII) does not reduce the fall death in eastern region. (3) For every 1 ten thousand people increase in number of students in ordinary high schools (NSOHS) is conductive to reducing DS death by 7.8 in the western region. Our findings show that there exist spatial differences for urbanization influencing TA, fall, and DS death in eastern, western, and central regions. This study is expected to provide a reference for unintentional injuries control in those three regions.

Spatial and temporal variation of inorganic ions in rainwater in Sichuan province from 2011 to 2016

China continues to suffer from severe acid deposition, despite the government implying a series of policies to control air pollution. In this study, rainwater samples were collected from 2011 to 2016 in Sichuan province to measure the pH values and the concentrations of nine inorganic ions (SO₄^2-, NO₃^-, NH₄⁺, Cl^-, Na⁺, Ca²⁺, K⁺, Mg²⁺, and F^-), and then to investigate their spatiotemporal variations. Besides, the dominant sources for the acidic ions in the precipitation were also revealed by statistical model. The results showed that the rainwater continued to be highly acidic, and the Volume-Weighted Mean (VWM) pH value was calculated to be 5.18 during 2011 and 2016. NH₄⁺, Ca²⁺, NO₃^-, and SO₄^2- were the dominant water-soluble inorganic ions, accounting for 79.2% of the total ions on average. The remarkable decrease in NO₃^- and SO₄^2- concentrations (from 75.9 to 54.3 μeq L^-1 and from 285 to 145 μeq L^-1, respectively) resulted in an increase in the pH value of rainwater from 5.24 in 2011 to 5.70 in 2016. The concentrations of SO₄^2-, NO₃^-, F^-, Na⁺, and K⁺ showed remarkably seasonal variation, with the highest value observed in winter, followed by spring and autumn, and the lowest value observed in summer. High VWM concentration of these ions in winter were mainly due to adverse meteorological conditions (e.g., rare rainfall, lower planetary boundary height, and stagnant air) and intensive anthropogenic emissions. SO₄^2-, NO₃^-, and F^- ions peaked in the southeastern Sichuan province, which is a typical industrial region. NH₄⁺ concentrations decreased from 268 μeq L^-1 in the east to 10.4 μeq L^-1 in the western Sichuan province, which could be related to the development of agriculture in the eastern Sichuan province. Ca²⁺ peaked in southeastern Sichuan province due to intensive construction activities and severe stone desertification. On the basis of Positive Matrix Factorization (PMF) analysis, four sources of inorganic ions in rainwater were identified, including anthropogenic source, crust, biomass burning, and aging sea salt aerosol. Geographically Weighted Regression (GWR) was used to find the spatial correlations between the socio-economic factors and ions in the rainwater. At the regional scale, the influence of fertilizer consumption and Gross Agricultural Production (GAP) on NH₄⁺ increased from east to west; moreover the influence of Gross Industrial Production (GIP) on SO₄^2- and NO₃^- also increased.

[Spatio-temporal analysis of Oncomelania hupensis along Jiangsu section of the Yangtze River from 2015 to 2017]

OBJECTIVE

To investigate the spatio-temporal characteristics of Oncomelania hupensis snails along the Jiangsu section of the Yangtze River, so as to provide evidence for eliminating schistosomiasis and formulating precision control measures in Jiangsu Province.

METHODS

A total of 75 marshlands were randomly sampled from Nanjing, Zhenjiang and Yangzhou cities along the Jiangsu section of the Yangtze River basin, and the spatio-temporal distribution and changing patterns of O. hupensis snails were investigated using the spatial autocorrelation analysis, kernel density analysis and hotspot analysis during the period from 2015 through 2017.

RESULTS

There was a spatial autocorrelation in the mean snail density along the Jiangsu section of the Yangtze River basin during the period from 2015 through 2017. The number of living snails and the density of living snails showed an overall decline in Yangzhou City; however, both showed a slight increase in 2016. Kernel density analysis and hotspot analysis showed that the hotspots of living snails were located in the regions neighboring the marshlands at the Yangzhou-Zhenjiang boundary areas along the Jiangsu section of the Yangtze River basin.

CONCLUSIONS

There is a spatial autocorrelation in the snail distribution with hotspots along the Jiangsu section of the Yangtze River basin, and the surveillance of snails should not be neglected in the marshlands in Jiangsu Province.

Collaborative RNAS+ research: Priorities and outcomes

Over the past 20 years, RNAS⁺ has been generating research results from highly collaborative projects meant to promote and advance understanding in various aspects of schistosomiasis. Epidemiological studies in endemic countries like the Philippines, the People's Republic of China (PR China), the Lao People's Democratic Republic (Lao PDR) and Cambodia clarified the role of reservoir hosts in transmission and the use of spatio-temporal methods such as remote sensing and geographical information systems (GIS) in surveillance of schistosomiasis. Morbidity studies proposed factors that might influence development of fibrosis, anaemia and malnutrition in schistosomiasis. Immune responses in schistosomiasis continue to be an interesting focus in research to explain possible development of resistance with age. Results of evaluation of candidate vaccine molecules are also presented. New diagnostics are continually being developed in response to the call for more sensitive and field applicable techniques that will be used for surveillance in areas nearing elimination of the disease. Several studies presented here show the insufficiency of mass drug administration (MDA) with praziquantel in eliminating the disease. Emphasis is given to an integrated control approach that can be accomplished through intensive and extensive intersectoral collaboration.

Assessing the combined effects of household type and insecticide effectiveness for kala-azar vector control using indoor residual spraying: a case study from North Bihar, India

BACKGROUND

Indoor residual spraying (IRS) is the mainstay for vector control intervention of visceral leishmaniasis (VL) in India. Little is known on the control effects of IRS on different household types. Here, we assessed if IRS with insecticides has an equal residual and interventional effect on all household types in a village. We also developed a combined spatial-risk map and a sand fly, Phlebotomus argentipes density analytical model based on household characteristics, insecticide susceptibility and IRS-status to explore the spatio-temporal distributions of the vector at a micro-scale level.

METHODS

This study was carried out in two villages of Mahnar block in Vaishali district, Bihar. IRS using two insecticides [dichlorodiphenyltrichloroethane (DDT 50%) and synthetic pyrethroid (SP 5%)] was evaluated for VL-vector (P. argentipes) control. Temporal residual efficacy of the insecticides on different wall-surface types was evaluated using the cone-bioassay technique according to WHO guidelines. Insecticide susceptibility of local P. argentipes was explored using the tube-bioassay method. Pre- and post-IRS sand fly densities were monitored in human dwellings and animal shelters using Centers for Disease Control light-traps installed between 18:00-6:00 h. A best-fit model for sand fly density analysis was developed using multiple logistic regression analysis. Geographical information system based spatial analysis techniques were employed to map the household type distribution of insecticide susceptibility of the vector, and IRS-status of the households to interpret the spatio-temporal distributions of P. argentipes.

RESULTS

Phlebotomus argentipes was highly susceptible to SP (100%) but showed high resistance to DDT with a 49.1% mortality rate. SP-IRS has been reported as having better community acceptance than DDT-IRS in all household types. Residual efficacies were varied between wall-surfaces; both insecticides failed to achieve the duration of IRS effectiveness recommended by the WHO. Reduction in P. argentipes counts due to SP-IRS was higher than DDT-IRS between household groups (i.e. sprayed and sentinel), in all intervals post-IRS. Combined spatial risk-maps revealed a better control effect of SP-IRS on sand flies than DDT-IRS in all household types risk-zones. The multilevel logistic regression analysis explored five risk-factors that were strongly associated with the density of P. argentipes.

CONCLUSIONS

The results contribute to furthering current understanding of IRS-practices for control of visceral leishmaniasis in endemic Bihar, which may help in future actions for improvements.

Time, geography and weather provide insights into the ecological strategy of a migrant species

Farmland and migratory bird populations are in decline. The Common quail (Coturnix coturnix) provides an exception to this trend and its populations have remained stable over the last two decades. However, some basic facts regarding quail biology and ecology, such as the geographic distribution of age and sex classes during the summer, remain poorly understood. We analyzed 43,194 Spanish quail ringing records from 1961 to 2014 to assess the effects of geography and weather conditions on the probability that individuals will be ringed during the various stages of their annual cycle (arrival -spring migration-, stationary breeding period, departure -autumn migration- and winter) for the different quail age-sex classes over time. We found that spatial distribution of the age and sex classes can be explained by date, latitude, longitude, altitude, rainfall, and temperature. Our results suggest that date accounts for most of the variation in the distribution of quail age classes, followed by the weather variables, and then latitude, and altitude. Similarly, date also accounts for most of the variation in the distribution of the two sexes. These results could partially explain why this species has avoided population decline, since its ecological strategy is based on its temporal and spatial distribution combined with the segregation of age and sex groups. We hypothesize that the distribution of quail age and sex classes follows variations in weather and habitat suitability to exploit seasonal and geographic variations in resource availability. The migratory and nomadic movements of quail, combined with the occurrence of multiple breeding attempts within a single season, may also allow these birds to overcome the impacts of predators and anthropogenic environmental change. Conservation and management efforts should therefore take account of these age and sex related temporal and spatial patterns.

The annual, temporal and spatial pattern of Setaria tundra outbreaks in Finnish reindeer: a mechanistic transmission model approach

Background

In northern Finland (Lapland), reindeer are reared as semi-domesticated animals. The region has a short summer season of 2–3 months, yet reindeer are infected with the mosquito-borne filarioid parasite Setaria tundra. The infection causes peritonitis and perihepatitis, which cause significant economic losses due to reduced body weight of infected animals. The objective of this study was to: (i) describe the spatial and temporal pattern of outbreaks in three different areas across Finnish Lapland; and (ii) construct a temperature-driven mechanistic transmission model to quantify the potential role of temperature on intensity of S. tundra transmission in reindeer.

Methods

We developed a temperature-driven transmission model able to predict the number of S. tundra potentially transmitted from an infectious reindeer. We applied the model to the years 2004–2015, and compared the predictions to the proportion of reindeer whose livers were condemned due to S. tundra infection at the time of slaughter.

Results

The mean proportion of liver condemnation increased in reindeer slaughtered in late autumn/winter compared to earlier dates. The outbreaks were geographically clustered each year but there were no fixed foci where outbreaks occurred. Larger outbreaks were recorded in the southern regions of reindeer-herding areas compared to the central or northern parts of Lapland. Our model showed that temperatures never allowed for transmission of more than a single generation of S. tundra each season. In southern (Kuusamo) and central (Sodankylä) Lapland, our model predicted an increasing trend from 1979 to 2015 for both the duration of the effective transmission period of S. tundra (P < 0.001) and for the potential number of L3 S. tundra larvae being transmitted from an infectious reindeer (P < 0.001).

Conclusions

The effective transmission period for S. tundra in reindeer is very short in Lapland, but it increased over the period studied. Only one generation of S. tundra can be transmitted in one season among reindeer in Lapland. Increasing temperatures may facilitate a range expansion and increasing duration of effective transmission period for S. tundra.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3159-z) contains supplementary material, which is available to authorized users.

Structural and functional shifts of bacterioplanktonic communities associated with spatiotemporal gradients in river outlets of the subtropical Pearl River Estuary, South China

In this study, we used high-throughput sequencing of 16S rRNA gene amplicons, to investigate the spatio-temporal variation in bacterial communities in surface-waters collected from eight major outlets of the Pearl River Estuary, South China. Betaproteobacteria were the most abundant class among the communities, followed by Gammaproteobacteria, Alphaproteobacteria, Actinobacteria, and Acidimicrobiia. Generally, alpha-diversity increased in winter communities and the taxonomic diversity of bacterial communities differed with seasonal and spatial differences. Temperature, conductivity, salinity, pH and nutrients were the crucial environmental factors associated with shifts in the bacterial community composition. Furthermore, inferred community functions that were associated with amino acid, carbohydrate and energy metabolisms were lower in winter, whereas the relative abundance of inferred functions associated with membrane transport, bacterial motility proteins, and xenobiotics biodegradation and metabolism, were enriched in winter. These results provide new insights into the dynamics of bacterial communities within estuarine ecosystems.

Use of resources and microplastic contamination throughout the life cycle of grunts (Haemulidae) in a tropical estuary

The distribution, feeding ecology and microplastic contamination were assessed in different ontogenetic phases of Haemulidae species inhabiting the Goiana Estuary, over a seasonal cycle. Pomadasys ramosus and Haemulopsis corvinaeformis are estuarine dependent species that use habitats with specific environmental conditions each season. Pomadasys ramosus was found in the upper and middle estuaries during the rainy season, when salinity showed the lowest values. Haemulopsis corvinaeformis was found in the lower estuary during the dry season, when salinity increased in the estuary. Juveniles of P. ramosus are zooplanktivores, feeding mainly on calanoid copepods. Sub-adults and adults are zoobenthivores, feeding on invertebrates associated to the bottom, mainly Polychaeta. Juveniles of H. corvinaeformis were not found in the main channel, but sub-adults and adults showed a zoobenthivore habit, feeding mainly on Anomalocardia flexuosa (Mollusca: Bivalvia). Dietary shifts along the life cycle and the spatio-temporal relationship between their distribution and the availability of microplastics along the estuary seem to have a strong influence in the ingestion of microfilaments. The highest average ingestion of microfilaments by P. ramosus coincided with the peak of ingestion of Polychaeta by sub-adults in the upper estuary during the late rainy season. For H. corvinaeformis the highest ingestion of microfilaments coincided with the peak of ingestion of A. flexuosa by adults in the lower estuary during the late dry season. Such contamination might be attributed to the time when these phases shifted to a more diverse diet and began to forage on benthic invertebrates. Research on microplastic contamination must consider species-specific behaviour, since the intake of microplastics is dependent on patterns of distribution and trophic guild within fish assemblages.