Long-term variations in surface ozone at the Longfengshan Regional Atmosphere Background Station in Northeast China and related influencing factors

Surface ozone (O3) is a crucial air pollutant that affects air quality, human health, agricultural production, and climate change. Studies on long-term O3 variations and their influencing factors are essential for understanding O3 pollution and its impact. Here, we conducted an analysis of long-term variations in O3 during 2006-2022 at the Longfengshan Regional Atmosphere Background Station (LFS; 44.44°N, 127.36°E, 330.5 m a.s.l.) situated on the northeastern edge of the Northeast China Plains. The maximum daily 8-h average (MDA8) O3 fluctuated substantially, with the annual MDA8 decreasing significantly during 2006-2015 (-0.62 ppb yr-1, p < 0.05), jumping during 2015-2016 and increasing clearly during 2020-2022. Step multiple linear regression models for MDA8 were obtained using meteorological variables, to decompose anthropogenic and meteorological contributions to O3 variations. Anthropogenic activities acted as the primary drivers of the long-term trends of MDA8 O3, contributing 73% of annual MDA8 O3 variability, whereas meteorology played less important roles (27%). Elevated O3 at LFS were primarily associated with airflows originating from the North China Plain, Northeast China Plain, and coastal areas of North China, primarily occurring during the warm months (May-October). Based on satellite products of NO2 and HCHO columns, the O3 photochemical regimes over LFS revealed NOx-limited throughout the period. NO2 increased first, reaching peak in 2011, followed by substantial decrease; while HCHO exhibited significant increase, contributing to decreasing trend in MDA8 O3 during 2006-2015. The plateauing NO2 and decreasing HCHO may contribute to the increase in MDA8 O3 in 2016. Subsequently, both NO2 and HCHO exhibited notable fluctuations, leading to significant changes in O3. The study results fill the gap in the understanding of long-term O3 trends in high-latitude areas in the Northeast China Plain and offer valuable insights for assessing the impact of O3 on crop yields, forest productivity, and climate change.

High aerosol loading over the Bohai Sea: Long-term trend, potential sources, and impacts on surrounding cities

Air pollution over the oceans has received less attention compared to densely populated urban areas of continents. The Bohai Sea, a semi-enclosed sea in northern China, is surrounded by thirteen industrial cities that have experienced significant improvements in air quality over the past decade. However, the changes in air pollution over the Bohai Sea and its impacts on surrounding cities remain poorly understood. To address this, this study investigated the evolution of air pollution and its chemical composition in the Bohai Sea over four decades, utilizing satellite remote sensing data, reanalysis datasets, emissions inventories, and statistical modeling. Historically, the region has suffered from severe air pollution, resulting from a combination of continental emissions and marine inputs (e.g., sea salt, ports and maritime vessel activities). The aerosol optical depth (AOD) over the sea was higher than the mean levels observed in its surrounding coastal cities. Statistically, 45% of the air masses reaching the Bohai Sea are associated with natural sources (dust- and marine-rich), while the remainder carry anthropogenic pollutants from continental regions. With the exception of Cangzhou city, these coastal cities suffer from air pollutants originating from the Bohai Sea. Cities in the northern region of the sea, spanning from Tianjin to Yingkou, are particularly impacted. The majority of the surrounding cities are affected by a large proportion of anthropogenic aerosol types transported through air masses from the Bohai Sea, including those from biomass burning and industrial activities. These findings emphasize the considerable influence of human-induced sources in the Bohai Sea on neighboring urban areas. Furthermore, being a maritime region, natural sources like sea salt and dust from the sea may also exert a discernible impact on the neighboring environment.

Reassessment of the declines in the largest freshwater lake in China (Poyang Lake): uneven trends, risks and underlying causes

Water level decline in the largest freshwater lake in China (Poyang Lake) has raised grave concerns and continuous debates regarding the proposal of a water control project. Previous hydrologic investigations on the water level decline in Poyang Lake were conducted mostly during recession season and typical dry years and hence lacked the comprehensive view of associated risks and possible spatial heterogeneity of trend during low water level periods. The present study reassessed the long-term trend and regime shift of low water level variations and their associated risks based on hydrological data across multiple stations in Poyang Lake during 1952-2021. The underlying causes of the trends of water level decline were further investigated. Results showed uneven trends and risks of water level variations in different seasons and across different lake regions. The water level of all five hydrological stations in Poyang Lake significantly dropped in the recession season, and the risks of water level decline evidently increased since 2003, which could be largely attributed to the water level drop in the Yangtze River. In terms of the dry season, clear spatial differences of long-term trend of water level were found, with water level in the central and southern lake regions significantly dropping, which was probably caused by dramatic bathymetry undercutting in the central and northern lake regions. In addition, the impacts of topographic changes became significant when water level of Hukou fell below 13.8 and 11.8m for the northern and southern lake regions, respectively. By contrast, water level in the northern lake region showed increasing trends in the dry season. In addition, only the occurrence time of water level under moderate risk significantly advanced for all stations except for Hukou. The present study could provide a full picture of low water level trends, associated risks across different lake regions and underlying causes in Poyang Lake, thus providing insights into adaptive water resources management.

Three Gorges Dam: the changing trend of snail density in the Yangtze River basin between 1990 and 2019

BACKGROUND

The area of Oncomelania hupensis snail remains around 3.6 billion m², with newly emerging and reemergent habitats continuing to appear in recent years. This study aimed to explore the long-term dynamics of snail density before and after the operation of Three Gorges Dam (TGD).

METHODS

Data of snail survey between 1990 and 2019 were collected from electronic databases and national schistosomiasis surveillance. Meta-analysis was conducted to estimate the snail density. Joinpoint model was used to identify the changing trend and inflection point. Inverse distance weighted interpolation (IDW) was used to determine the spatial distribution of recent snail density.

RESULTS

A total of 3777 snail survey sites with a precise location of village or beach were identified. For the downstream area, snail density peaked in 1998 (1.635/0.11 m², 95% CI: 1.220, 2.189) and fluctuated at a relatively high level before 2003, then declined steadily from 2003 to 2012. Snail density maintained lower than 0.150/0.11 m² between 2012 and 2019. Joinpoint model identified the inflection of 2003, and a significant decreasing trend from 2003 to 2012 with an annual percentage change (APC) being - 20.56% (95% CI: - 24.15, - 16.80). For the upstream area, snail density peaked in 2005 (0.760/0.11 m², 95% CI: 0.479, 1.207) and was generally greater than 0.300/0.11 m² before 2005. Snail density was generally lower than 0.150/0.11 m² after 2011. Snail density showed a significant decreasing trend from 1990 to 2019 with an APC being - 6.05% (95% CI: - 7.97, - 7.09), and no inflection was identified. IDW showed the areas with a high snail density existed in Poyang Lake, Dongting Lake, Jianghan Plain, and the Anhui branch of the Yangtze River between 2015 and 2019.

CONCLUSIONS

Snail density exhibited a fluctuating downward trend in the Yangtze River basin. In the downstream area, the operation of TGD accelerated the decline of snail density during the first decade period, then snail density fluctuated at a relatively low level. There still exists local areas with a high snail density. Long-term control and monitoring of snails need to be insisted on and strengthened.

Deriving a high-quality daily dataset of large-pan evaporation over China using a hybrid model

Global warming is expected to increase the atmospheric evaporative demand and make more surface water for evapotranspiration, aggerating water sources' social and ecological shortage. Pan evaporation, as a routine observation worldwide, is an excellent metric to indicate the response of terrestrial evaporation to global warming. However, several non-climatic effects, such as instrument upgrades, have destroyed the homogenization of pan evaporation and limited its applications. In China, 2400s meteorological stations have observed daily pan evaporation since 1951. The observed records became discontinuous and inconsistent due to the instrument upgrade from micro-pan D20 to large-pan E601. Here, combining the Penpan model (PM) and random forest model (RFM), we developed a hybrid model to assimilate different types of pan evaporation into a consistent dataset. Based on the cross-validation test, on a daily scale, the hybrid model has a lower bias (RMSE=0.41 mm day^-1) and better stability (NSE=0.94) than the two sub-models and the conversion coefficient method. Finally, we produced a homogenized daily dataset of E601 across China from 1961 to 2018. Based on this dataset, we analyzed the long-term trend of pan evaporation. Pan evaporation showed a -1.23±0.57 mm a^-2 downward trend from 1961-1993, primarily caused by decreased pan evaporation in warm seasons over North China. After 1993, the pan evaporation in South China increased significantly, resulting in a 1.83±0.87 mm a^-2 upward trend across China. With better homogeneity and higher temporal resolution, the new dataset is expected to promote drought monitoring, hydrological modeling, and water resources management. Free access to the dataset can be found at https://figshare.com/s/0cdbd6b1dbf1e22d757e.

Effects of regional climate, hydrology and river impoundment on long-term patterns and characteristics of dissolved organic matter in semi-arid northern plains rivers

Diverse environmental and anthropogenic factors, such as the ongoing reservoir constructions may influence riverine dissolved organic matter (DOM) properties. This has important implications for river water quality, particularly when reservoirs are a source of drinking water. Simultaneous studies of multidecadal trends in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are scarce. We studied the patterns in DOC and DON concentration in two major rivers of the South Saskatchewan River (SSR) basin over a 42-year period (1978-2019). We also examined the impact of a large reservoir on riverine DOC properties. Contrary to many studies, we did not find a long-term increase in DOC and DON concentration, and DOC and DON patterns were not always synchronous. In an agriculture dominated watershed like the SSR basin, agricultural land use (e.g., nitrogen-fertilizer application) could influence DOC and DON concentration differently, potentially resulting in asynchronous patterns over time. River discharge was an important driver of DOM patterns. Regional precipitation in the lower SSR basin may also influence DOM patterns in locations where runoff contribution is greater. These regional factors explained greater variability in DOM compared to global scale indices (e.g., Pacific decadal oscillation) due to their direct control on DOM. A travel time corrected approach to account for the lengthy reservoir turnover time showed that a large reservoir caused a reduction in allochthonous DOC characteristics through photodegradation and perhaps, an increase in autochthonous characteristics. Our results illustrate: 1) the increase in DOM concentrations seen in the northern hemisphere is not present in semi-arid prairie rivers, 2) Controls on different DOM components could be different, and 3) large reservoirs may modify riverine DOC composition due to longer water residence time.

Linking downstream river water quality to urbanization signatures in subtropical climate

Urbanization has several hydro-ecological effects on receiving waters. Hence, understanding how urbanization influences river water quality is essential for proper river management. However, an inappropriate approach that correlates urbanization signatures with water quality may result in spurious correlations. This study aimed to investigate the relationship of urbanization signatures with two key pollutants of stream flows: nutrients and pathogens. In contrast to the commonly used approaches that are based on economic or demographic metrics, our approach represents urbanization signatures using related anthropogenic activities and evaluates the effect of such activities on water quality parameters. The approach was also applied to evaluate the impacts of urbanization on nutrient and pathogen trends in the river waters of Hong Kong. The data were collected for the period of 1986-2020 from the Environmental Protection Department and monthly measurements were performed. Total nitrogen (TN), total phosphorus (TP), Escherichia. coli (E. coli), and fecal coliforms (FC) showed consistently decreasing trends. However, the long-term seasonality of nutrients differed from that of pathogens. TP and TN exhibited homogenous seasonality with an approximately sinusoidal relationship from January to December, whereas the seasonality of pathogens was more complex and not dependent on river flow dilution effects. Additionally, urbanization impacts on station nutrients and pathogen characteristics were found to be unevenly distributed; under high water temperatures, nutrient concentrations were found to be decreased because of the rainfall dilution effect on river flows. Both urban point and diffuse sources of pollution significantly contributed to nutrient pollution in rivers. Furthermore, the concentrations of FC were not highly influenced by suspended solids, and dissolved oxygen was negatively correlated with all pathogens. Furthermore, the river flow rate was found to improve the water quality in terms of both nutrients and pathogens; urban point source pollution and river temperature alteration were shown to mainly contribute to seasonal variations in both nutrients and pathogens.

Increased incidence among the very elderly in the 2020 Niigata Prefecture Osteoporotic Hip Fracture Study

INTRODUCTION

A 2015 study showed a decreasing trend in the incidence of osteoporotic hip fractures in Niigata Prefecture, Japan, which had been increasing. This study aimed to investigate the incidence of osteoporotic hip fractures in 2020, determine the long-term change in the incidence of hip fractures from 1985 to 2020, and assess whether the decline in fracture incidence since 2010 has continued.

MATERIALS AND METHODS

We obtained data from the registration forms submitted by hospitals and clinics of patients who lived in Niigata Prefecture and were diagnosed with osteoporotic hip fracture through a survey conducted from January 1, 2020 to December 31, 2020.

RESULTS

In 2020, 3,369 hip fractures were recorded in Niigata Prefecture. Although the overall incidence of age-specific hip fractures decreased, it increased in patients aged ≥ 90 years, regardless of sex. The proportion of patients receiving anti-osteoporosis drugs prior to hip fracture increased from 7.6% in 2004 to 17.3% in 2020. Notably, surgical treatment should be performed as early as possible, and the preoperative waiting time was 2.9 days, which was mainly due to holidays.

CONCLUSION

The incidence of hip fractures in Niigata Prefecture has gradually increased over the past 35 years, with an increasing change observed in the very elderly recently in 2020. Although the treatment of osteoporotic hip fractures in Niigata Prefecture is adequate, improvements may include increasing the rate of adoption of osteoporosis treatment further and decreasing the number of days of preoperative waiting.

First long-term surface ozone variations at an agricultural site in the North China Plain: Evolution under changing meteorology and emissions

Significant upward trends in surface ozone (O₃) have been widely reported in China during recent years, especially during warm seasons in the North China Plain (NCP), exerting adverse environmental effects on human health and agriculture. Quantifying long-term O₃ variations and their attributions helps to understand the causes of regional O₃ pollution and to formulate according control strategy. In this study, we present long-term trends of O₃ in the warm seasons (April-September) during 2006-2019 at an agricultural site in the NCP and investigate the relative contributions of meteorological and anthropogenic factors. Overall, the maximum daily 8-h average (MDA8) O₃ exhibited a weak decreasing trend with large interannual variability. < 6 % of the observed trend could be explained by changes in meteorological conditions, while the remaining 94 % was attributed to anthropogenic impacts. However, the interannual variability of warm season MDA8 O₃ was driven by both meteorology (36 ± 28 %) and anthropogenic factors (64 ± 27 %). Daily maximum temperature was the most essential factor affecting O₃ variations, followed by ultraviolet radiation b (UVB) and boundary layer height (BLH), with rising temperature trends inducing O₃ inclines throughout April to August, while UVB mainly influenced O₃ during summer months. Under changes in emissions and air quality, warm season O₃ production regime gradually shifted from dominantly VOCs-limited during 2006-2015 to NO_x-limited afterwards. Relatively steady HCHO and remarkably rising NO_x levels resulted in the fast decreasing MDA8 O₃ (-2.87 ppb yr^-1) during 2006-2012. Rapidly decreasing NO_x, flat or slightly increasing HCHO promoted O₃ increases during 2012-2015 (9.76 ppb yr^-1). While afterwards, slow increases in HCHO and downwards fluctuating NO_x led to decreases in MDA8 O₃ (-4.97 ppb yr^-1). Additionally, continuous warming trends might promote natural emissions of O₃ precursors and magnify their impacts on agricultural O₃ by inducing high variability, which would require even more anthropogenic reduction to compensate for.

Long-term trends in mortality risk associated with short-term exposure to air pollution in 10 Japanese cities between 1977 and 2015

BACKGROUND AND AIM

Short-term associations between air pollution and mortality have been well reported in Japan, but the historical changes in mortality risk remain unknown. We examined temporal changes in the mortality risks associated with short-term exposure to four criteria air pollutants in selected Japanese cities.

METHODS

We collected daily mortality data for non-accidental causes (n = 5,748,206), cardiovascular (n = 1,938,743) and respiratory diseases (n = 777,266), and air pollutants (sulfur dioxide [SO₂], nitrogen dioxide [NO₂], suspended particulate matter [SPM], and oxidants [Ox]) in 10 cities from 1977 to 2015. We performed two-stage analysis with 5-year stratification to estimate the relative risk (RR) of mortality per 10-unit increase in the 2-day moving average of air pollutant concentrations. In the first stage, city-specific associations were assessed using a quasi-Poisson generalized linear regression model. In the second stage, city-specific estimates were pooled using a random-effects meta-analysis. Linear trend and ratio of relative risks (RRR) were computed to examine temporal changes.

RESULTS

When stratifying the analysis by every 5 years, average concentrations in each sub-period decreased for SO₂, NO₂, and SPM (14.2-2.3 ppb, 29.4-17.5 ppb, 52.1-20.6 μg/m³, respectively) but increased for Ox (29.1-39.1 ppb) over the study period. We found evidence of a negative linear trend in the risk of cardiovascular mortality associated with SPM across sub-periods. However, the risks of non-accidental and respiratory mortality per 10-unit increase in SPM concentration were significantly higher in the most recent period than in the earliest period. Other gaseous pollutants did not show such temporal risk change. The risks posed by these pollutants were slightly to moderately heterogeneous in the different cities.

CONCLUSIONS

The mortality risks associated with short-term exposure to SPM changed, with different trends by cause of death, in 10 cities over 39 years whereas the risks for other gaseous pollutants were relatively stable.

Estimates of PM2.5 concentrations spatiotemporal evolution across China considering aerosol components in the context of the Reform and Opening-up

With astonishing and rapid development in China since the Reform and Opening-up in 1978, serious air pollution has become a great challenge. A better understanding of the response of PM_2.5 pollution to socioeconomic development after the Reform and Opening-up policy is benefit for pollution control. However, heterogeneous influences of biophysical and socioeconomic activities on PM_2.5 pollution pose great challenges in statistical simulation of PM_2.5. Few statistical model regards aerosol species as the explanatory variables for heterogeneous formation mechanism to retrieve PM_2.5 concentration. In this research, monthly PM_2.5 concentration in China during 1980-2020 was reconstructed by a novel statistical strategy considering aerosol components (AC-RF). Three cross-validation (CV) methods, sample-based CV, spatial-based CV and temporal-based CV results indicated satisfactory performance of AC-RF model with correlation coefficient (R) of 0.92, 0.90, 0.86, respectively. A three-stage concluded on PM_2.5 concentration annual variation in China was drawn as followed: Before 2000, PM_2.5 level in China represented smooth evolution and mainly influenced by natural events with polluted region locating in Xinjiang province, North China and Central China. Since 2000, PM_2.5 concentration increased to high level in the context of rapid socioeconomic development. Severe air pollution covered Jing-Jin-Ji agglomeration, Central China and Sichuan Basin. During 2012-2020, PM_2.5 declined and polluted region shrank, which was benefited by the strictest-ever air pollution control measures. Based on aerosol components analysis, sulfate aerosol exhibited the most significant increase trend in recent 40 years and black aerosol variation is the most closely related to PM_2.5 pollution. In conclusion, unsustainable development is the culprit for air quality deterioration. Strict and continuous air pollution control strategies are effective for air quality improvement.

Analysis of the reasons for the outbreak of Yellow Sea green tide in 2021 based on long-term multi-source data

The green tide disaster is the result of human activities changing the natural environment conditions. What changes have occurred in the environmental factors that affect the green tide outbreak over a long period, and what is the impact of this change on the green tide outbreak? To further understand the outbreak mechanism of green tide, in this study, we used the Google Earth Engine (GEE) platform to extract and analyze the green tide from 2007 to 2021, analyze the long-term trend of various influencing factors (sea surface temperature (SST), sea surface salinity (SSS), photosynthetically available radiation (PAR), precipitation, eutrophication, "nori" aquaculture) in the past 30 years, and explore the impact of each factor on the outbreak of green tide. We found that: 1) SST, seawater eutrophication, and "nori" aquaculture worked together to promote the large-scale outbreak of green tide in 2007; 2) In the context of eutrophication is not effectively controlled, elevated SST, SSS, and PAR will be more conducive to the germination of green tide algae and promote green tide to form a floating state on the sea surface earlier, after that, once there is a year with abundant precipitation, the green tide will break out on a large scale, which is exactly the case in 2021. Exploring the environmental conditions and the long-term regularity of green tide outbreaks to provide a basis for scientific and rational control of green tides.

Long-term declining in carbon monoxide (CO) at a rural site of Beijing during 2006-2018 implies the improved combustion efficiency and effective emission control

Carbon monoxide (CO) is primarily the result of incomplete combustion, which has important impacts on the atmospheric chemical cycle and climate. Improved quantitative characterization of long-term CO trends is important for both atmospheric modeling and the design and implementation of policies to efficiently control multiple pollutants. Due to the limitations of high time-resolution and high-quality long-term observational data, studies on long-term trends in the CO concentration in China are quite limited. In this study, the observational data of the concentration of CO in a rural site of Beijing during 2006-2018 was used to analyze the long-term trend in CO concentration in Beijing. The Theil-Sen method and the generalized additive model (GAM)-based method, were used to conduct the trend estimation analysis. We found that the concentration of CO at the Shangdianzi site showed a significant downward trend during 2006-2018, with a decline rate of 22.8 ± 5.1 ppbV per year. The declining trend in CO also showed phasic characteristics, with a fast decreasing rate during the period of 2006-2008, stable variations during the period of 2009-2013 and a continuous downward trend after 2013. The declining trend in the CO concentration in the south to west (S-W) sectors where the polluted air masses come from is more rapid than that in the sectors where the clean air masses come from. The declining trend in the CO concentration implies the improved combustion efficiency and the successful air pollution control policies in Beijing and the surrounding area.

Long-term trend of new particle formation events in the Yangtze River Delta, China and its influencing factors: 7-year dataset analysis

To evaluate the influence of anthropogenic emission reductions since 2013 in China, a long-term trend analysis of the particle number size distribution (PNSD) and new particle formation (NPF) events in the Yangtze River Delta (YRD) region was conducted based on the PNSD measurement (diameter ranging from 3 to 850 nm) at the Lin'an (LAN) regional background station from 2013 to 2019. A modified Mann-Kendall test and a Theil-Sen estimator were used to calculate the overall trend of particle number concentrations in different modes and the relevant influencing factors. We observed a significant decreasing trend in the Aitken and accumulation mode number concentrations, with annual decrease rates of approximately 5.6% and 8.2%, respectively, resulting in an approximately 6.0% decline in total particles annually. However, the nucleation mode particle number concentration showed no significant trend from 2013 to 2016, but an increasing trend from 2016 to 2019, which was related to the NPF events occurrence frequency. The regional NPF events of "banana shape" accounted for an increasing fraction of all NPF events. As a key parameter influencing the NPF event, the condensation sink decreased by approximately 63% from 2013 to 2019. Moreover, the estimated sulfuric acid concentration decreased by approximately 50%, with a higher reduction rate occurring during 2013-2016 as result of the effective SO₂ reduction. Surface meteorological factors (including the air temperature, relative humidity, air pressure, and wind) and the air masses origin were found to played minor roles in the long-term trend of NPF events. As PNSD and NPF events are closely related to changes in the particle emissions and regional air pollution levels, studies concerning PNSD and NPF are necessary to provide important information regarding air quality improvements and evaluating the efficacy of climate change mitigation strategies.

Monitoring, modeling and projection of harmful algal blooms in China

This review assesses monitoring, modeling and projection of harmful algal blooms (HABs) in China, with a focus on near-term warning and long-term trend projection. We reviewed phytoplankton monitoring as early warning, remote sensing for offshore environments, building models to describe ecological processes, modeling and forecasting near-term or seasonal HAB events, and projection of long-term HAB trend in China. Over the past 40 years, great progresses were made in traditional observation capability of HABs, and some reliable remote sensing algorithms were developed for HABs in optically complex coastal waters in Chinese seas. Numerical models have been applied to simulating real-world algal bloom events successfully; and these models, to some degree, are capable of predicting the time and place of HAB occurrence. In terms of long-term trend, HABs appeared to have shown diversified forms, being more miniaturized and more harmful. The development of an integrated monitoring and early-warning system of algal blooms and HABs should be a necessary first step to provide an effective management tool for mitigating damages associated with the occurrence of HABs in China.

Birth cohort differences in height, weight and BMI among Indian women aged 15-30 years: analyses based on three cross-sectional surveys

OBJECTIVE

To explore long-term trends in height, weight and BMI across birth cohorts among Indian women aged 15-30 years.

DESIGN

Nationally representative cross-sectional surveys.

SETTING

Data from three National Family Health Surveys were conducted in 1998-1999, 2005-2006 and 2015-2016. Height and weight were modelled jointly, employing a multivariate regression model with age and birth cohorts as explanatory variables. The largest birth cohort (born 1988-1992) was the reference cohort. Stratified analyses by place of residence and by marital status and dichotomised parity were also performed.

PARTICIPANTS

437 753 non-pregnant women aged 15-30 years.

RESULTS

The rate of increase in height, weight and BMI differed across birth cohorts. The rate of increase was much lower for height than weight, which was reflected in an increasing trend in BMI across all birth cohorts. In the stratified analyses, increase in height was found to be similar across urban and rural areas. Rural women born in the latest birth cohort (1998-2001) were lighter, whereas urban women were heavier compared to the reference cohort. A relatively larger increase in regression coefficients was observed among women born between 1978 and 1982 compared to women born between 1973 and 1977 when considering unmarried and nulliparous ever-married women and, one cohort later (1983-1987 v. 1978-1982), among parous ever-married women.

CONCLUSION

As the rate of increase was much larger for weight than for height, increasing trends in BMI were observed across the birth cohorts. Thus, cohort effects show an important contributory role in explaining increasing trends in BMI among young Indian women.

Urbanization-driven increases in summertime compound heat extremes across China

Summertime extreme heat events exert severe impacts on the natural environment and human society, especially in densely populated and highly urbanized regions. While previous studies have focused on independent heat day/night, there is a lack of attention to the changes in compound events with cooccurring daytime and nighttime extreme temperature on the same day. In this study, we examine the spatio-temporal changes of summertime compound heat extremes (including compound heat day and compound heatwave) across China, with a particular focus on 20 major urban agglomerations (UAs), and quantify the urbanization effects on these changes. We find that the frequency and fraction of compound heat events show obvious spatial disparities across China. The compound heat events occur more frequently in highly populated and urbanized areas such as the Pearl River Delta. Moreover, the frequency and fraction of compound heat events have significantly increased in recent decades in most parts of China, especially in more developed UAs. These intensifying trends have even accelerated in more recent decades. Our further investigations suggest that most UAs of China experienced an intensifying urbanization effect on compound heat events, and few UAs in northwestern and central China (e.g., UAs of the north Tianshan mountain and the middle reaches of the Yangtze River) display a weakening effect of urbanization. Our findings highlight the important role of urbanization in increasing compound heat extremes and suggest that the increasing threats of compound events in urban areas should be given more attention under the context of global warming and local urbanization.

A Comparison of Epidemiological Characteristics of Central Nervous System Tumours in China and Globally from 1990 to 2019

BACKGROUND

Despite their great disease burden, there have been few studies on the epidemiology of central nervous system tumours (CNSTs) in China. We used the latest data updated by GBD to analyse the trends of incidence, mortality, and disability-adjusted life years (DALYs) for CNSTs in China versus globally.

METHODS

Epidemiological data on CNSTs were extracted from GBD 2019. We used Joinpoint regression analysis to calculate the magnitude and direction of the trends and the age-period-cohort method to analyse the age, period, and cohort effects of the trend.

RESULTS

From 1990 to 2019, the 106.52% increase in Chinese incident cases was higher than the global increase (94.35%). The 67.32% increase in cancer deaths and 16.03% increase in DALYs were lower than the global increases (cancer death: 76.36%; DALYs: 40.06%). The age-standardized incidence rates (ASIRs) in China were higher than the global ASIRs, and the increase in China was higher than that globally. Although the age-standardized mortality rates and age-standardized DALY rates in China were higher, their increases in China were less than those globally. Both in China and globally, the number and incidence, mortality, and DALYs by age group showed a bimodal distribution (younger than 5 years and older), and the peak in the older age group showed a backwards trend. The proportion of incident cases, cancer deaths, and DALYs also increased in the older age group. In the age-period-cohort model, the local drifts in the older age group were above zero.

CONCLUSIONS

The burden of CNSTs is very serious in China, and we should pay attention to the key populations, early diagnosis technology, improvements in medical technology, and ways to reduce medical costs. We believe our results could help policymakers allocate resources efficiently to reduce the burden of CNSTs.

Satellite-derived 1-km estimates and long-term trends of PM2.5 concentrations in China from 2000 to 2018

Exposure to ambient PM_2.5 (fine particulate matter) can cause adverse effects on human health. China has been experiencing dramatic changes in air pollution over the past two decades. Statistically deriving ground-level PM_2.5 from satellite aerosol optical depth (AOD) has been an emerging attempt to provide such PM_2.5 data for environmental monitoring and PM_2.5-related epidemiologic study. However, current countrywide datasets in China have generally lower accuracies with lower spatiotemporal resolutions because surface PM_2.5 level was rarely recorded in historical years (i.e., preceding 2013). This study aimed to reconstruct daily ambient PM_2.5 concentrations from 2000 to 2018 over China at a fine scale of 1 km using advanced satellite datasets and ground measurements. Taking advantage of the newly released Multi-Angle Implementation of Atmospheric Correction (MAIAC) 1-km AOD dataset, we developed a novel statistical strategy by establishing an advanced spatiotemporal model relying on adaptive model structures with linear and non-linear predictors. The estimates in historical years were validated against surface observations using a strict leave-one-year-out cross-validation (CV) technique. The overall daily leave-one-year-out CV R² and root-mean-square-deviation values were 0.59 and 27.18 μg/m³, respectively. The resultant monthly (R² = 0.74) and yearly (0.77) mean predictions were highly consistent with surface measurements. The national PM_2.5 levels experienced a rapid increase in 2001-2007 and significantly declined between 2013 and 2018. Most of the discernable decreasing trends occurred in eastern and southern areas, while air quality in western China changed slightly in the recent two decades. Our model can deliver reliable historical PM_2.5 estimates in China at a finer spatiotemporal resolution than previous approaches, which could advance epidemiologic studies on the health impacts of both short- and long-term exposure to PM_2.5 at both a large and a fine scale in China.

A long-term spatiotemporal analysis of biocrusts across a diverse arid environment: The case of the Israeli-Egyptian sandfield

Spatiotemporal data can be analyzed using spatial, time-series, and machine learning algorithms to extract regional biocrust trends. Analyzing the spatial trends of biocrusts through time, using satellite imagery, may improve the quantification and understanding of their change drivers. The current work strives to develop a unique framework for analyzing spatiotemporal trends of the spectral Crust Index (CI), thus identifying the drivers of the biocrusts' spatial and temporal patterns. To fulfill this goal, CI maps, derived from 31 annual Landsat images, were analyzed by applying advanced statistical and machine learning algorithms. A comprehensive overview of biocrusts' spatiotemporal patterns was achieved using an integrative approach, including a long-term analysis, using the Mann-Kendall (MK) statistical test, and a short-term analysis, using a rolling MK with a window size of five years. Additionally, temporal clustering, using the partition around medoids (PAM) algorithm, was applied to model the spatial multi-annual dynamics of the CI. A Granger Causality test was then applied to quantify the relations between CI dynamics and precipitation. The findings show that 88.7% of pixels experienced a significant negative change, and only 0.5% experienced a significant positive change. A strong association was found in temporal trends among all clusters (0.67 ≤ r ≤ 0.8), signifying a regional effect due to precipitation levels (p < 0.05 for most clusters). The biocrust dynamics were also locally affected by anthropogenic factors (0.58 > CI > 0.64 and 0.64 > CI > 0.71 for strongly and weakly affected regions, respectively). A spatiotemporal analysis of a series of spaceborne images may improve conservation management by evaluating biocrust development in drylands. The suggested framework may also by applied to various disciplines related to quantifying spatial and temporal trends.

Environmental behavior and potential driving force of bisphenol A in the Elbe River: A long-term trend study

As an endocrine disruptor, a deep understanding of the environmental behavior and potential driving force of bisphenol A (BPA) is helpful for developing a mitigation strategy and reducing the exposure risk to the public. Based on long-term monitoring data from 2004 to 2016, this study systematically evaluated the long-term trend, periodic characteristics, and potential risks of BPA in the Elbe River in the state of Saxony, Germany. Multiple advanced statistical approaches were employed for data mining. Pettitt's test was used to determine the main change points of BPA that occurred from 2008 to 2011. The Mann-Kendall test showed a decreasing trend in BPA concentrations (slope: -0.087 to -0.112, P < 0.05) over the past 13 years, particularly in the wet seasons (slope: -0.730 to -0.038, P < 0.05). Wavelet analysis revealed similar periodicities of BPA among stations (which experienced 4-5 oscillations in the first major period). The ARIMA model forecasted the mean BPA concentration as ranging from 9 to 41 ng L^-1 in the subsequent 3 months, which was similar to that in the last 3 months (20-42 ng L^-1). Besides, the highest hazard quotients (>0.3) were documented for Chironomus riparius, Oryzias latipes, Potamopyrgus antipodarum, and Hydra vulgar, which indicates that BPA may threaten their growth and development. The hazard index values for non-cancer risk of BPA no greater than 6.47 × 10^-9 (HQ far below 1), which suggests that BPA did not pose a significant threat to human health. Because BPA pollution is closely related to industrial activities, a long-term decline in BPA concentrations could be attributed to the reduced number of factories, limited discharge, and improved decontamination efficiency. However, the minimal change in the BPA concentration in the near future could reflect periodic fluctuations.

Long-term variations of C1-C5 alkyl nitrates and their sources in Hong Kong

Investigating the long-term trends of alkyl nitrates (RONO₂) is of great importance for evaluating the variations of photochemical pollution. Mixing ratios of C₁-C₅ RONO₂ were measured in autumn Hong Kong from 2002 to 2016, and the average level of 2-butyl nitrate (2-BuONO₂) always ranked first. The C₁-C₄ RONO₂ all showed increasing trends (p < 0.05), and 2-BuONO₂ had the largest increase rate. The enhancement in C₃ RONO₂ was partially related to elevated propane, and dramatic decreases (p < 0.05) in both nitrogen monoxide (NO) and nitrogen dioxide (NO₂) also led to the increased RONO₂ formation. In addition, an increase of hydroxyl (OH) and hydroperoxyl (HO₂) radicals (p < 0.05) suggested enhanced atmospheric oxidative capacity, further resulting in the increases of RONO₂. Source apportionment of C₁-C₄ RONO₂ specified three typical sources of RONO₂, including biomass burning emission, oceanic emission, and secondary formation, of which secondary formation was the largest contributor to ambient RONO₂ levels. Mixing ratios of total RONO₂ from each source were quantified and their temporal variations were investigated. Elevated RONO₂ from secondary formation and biomass burning emission were two likely causes of increased ambient RONO₂. By looking into the spatial distributions of C₁-C₅ RONO₂, regional transport from the Pearl River Delta (PRD) was inferred to build up RONO₂ levels in Hong Kong, especially in the northwestern part. In addition, more serious RONO₂ pollution was found in western PRD region. This study helps build a comprehensive understanding of RONO₂ pollution in Hong Kong and even the entire PRD.

Contribution of urbanization to the changes in extreme climate events in urban agglomerations across China

Unprecedented urbanization in China facilitates the rapid development of urban agglomerations (UAs) and may exert prominent effects on regional climate and environment change. By analyzing a set of 27 extreme temperature and precipitation indices, this study examines the changes in extreme climate events in 20 UAs in China and evaluates the urbanization effects using a dynamic classification of urban and rural stations by time-varying land use/cover maps. The regional differences of the urbanization effects on extreme climate events are also investigated by a k-means clustering. It is found that, for both temperature and precipitation extremes, the urban and rural areas exhibit remarkably distinct changes and demonstrate significant urbanization effect, which also varies across different climate backgrounds. Urbanization profoundly contributes to increasing hot extremes and reducing cold extremes in most UAs, while it seems to pose the opposite effects in several UAs of arid and high-latitude regions. On average, the urbanization effect accounts for around 30% of the total change in extreme temperature events over the urban core areas of 20 UAs. On the other hand, the urbanization effects on extreme precipitation indices display stronger regional discrepancies than temperature extremes. Urbanization tends to have weakening effects on extreme precipitation events in UAs over coastal regions and intensifying influences on those in central/west China. It causes more (less) frequent and more (less) intense precipitation in UAs of inland central/west (coastal) areas. Our findings provide a systematic understanding of the urbanization effects on extreme climate and may have important implications for the mitigation of urban disasters.

Abundance and sources of benzo[a]pyrene and other PAHs in ambient air in Hong Kong: A review of 20-year measurements (1997-2016)

The polycyclic aromatic hydrocarbon (PAH) family is of environmental concern due to its toxicity, prompting the need of monitoring their long-term trends. Three monitoring programs in Hong Kong report concentrations of ambient PAHs, namely (1) respirable suspending particle (RSP) speciation program that monitored benzo[a]pyrene (BaP) (1997 to March 2000), (2) total suspended particle speciation program that monitored BaP (1997-1999), and (3) toxic air pollutant monitoring program that monitors BaP and 16 other PAHs in the combined gas and particulate phases at two general urban stations once or twice a month since January 1998. In this work, we review all the available PAH measurements in Hong Kong during 1997-2016, with emphasis on the temporal trends of BaP and the other 16 PAHs. PAHs of 5-6 rings exhibit an ambiguous decline trend since 1998, with a negative Sen's slope that is statistically significant. Specifically, BaP was reduced by 78% from 1998 to 2016, with a Sen's slope of -0.013 ng m^-3 year^-1. Correlations of BaP with RSP major species of high source specificity and PAH diagnostic ratios are employed to explore the source origins of PAHs. Our analysis reveals that PAHs mainly come from a combination of vehicular emissions and biomass/coal combustion. The decline trend of PAHs is further found in consistence with the declined particulate matter emissions from vehicular exhaust and biomass/coal combustion. This study fills the data vacancy in the long-term trends of ambient PAHs for the Pearl River Delta region, one of the economically more advanced regions in China.

Discerning effects of warming, sea level rise and nutrient management on long-term hypoxia trends in Chesapeake Bay

Analyses of dissolved oxygen concentration in Chesapeake Bay over the past three decades suggested seasonally-dependent changes in hypoxic volume and an earlier end of hypoxic conditions. While these studies hypothesized and evaluated multiple potential driving mechanisms, quantitative evidence for the relative effects of various drivers has yet to be presented. In this study, a coupled physical-biogeochemical model was used to conduct hindcast simulations between 1985 and 2016. Additional numerical experiments, in which the long-term trends in external drivers were removed, were analyzed to discern the separate effects of temperature increase, sea level rise and nutrient reduction. After the removal of seasonal and interannual variations, dissolved oxygen concentration in all regions of the estuary showed a statistically significant declining trend: ~0.1 mg/L per decade. Most of this decline occurred during winter and spring while May-August hypoxic volumes showed no changes and September hypoxic volume showed a slight decrease (~0.9 km³). Our simulations show that warming was the dominant driver of the long-term oxygen decline, overwhelming the effects of sea level rise and modest oxygen increases associated with nutrient reduction. There was no statistically significant trend in the initiation of hypoxia in spring, where the potential delay associated with nutrient reduction was offset by warming-induced oxygen declines, and both nutrient reduction and warming contributed to an earlier disintegration of hypoxia in the fall. These results suggest that recent warming has prevented oxygen improvements in Chesapeake Bay expected from nutrient input reductions and support the expectation that continued warming will serve to counter future nutrient management actions.

SES inequalities in cause-specific adult mortality: a study of the long-term trends using longitudinal individual data for Sweden (1813-2014)

Higher socioeconomic status (SES) is associated with lower mortality, and this correlation has been confirmed using different indicators across several geographical settings. Nevertheless, the timing of the emergence of the SES gradient remains unclear. We used individual-level longitudinal data for a regional population in southern Sweden covering the period between 1813 and 2014, and we applied a cause-specific proportional hazard model. We estimated SES differences in all-cause, nonpreventable, preventable, and cause-specific adult mortality in four subperiods (1813–1921, 1922–1967, 1968–1989, 1990–2014) by gender adjusting for birth year, place of residence, marital status, and migration status. The SES gradient in mortality present today for both genders emerged only around 1970, and with few exceptions, it emerged at approximately the same time for all causes of death. It emerged earlier for women than for men, particularly in infectious diseases. In the nineteenth and early twentieth centuries, we found a positive association between SES and mortality from circulatory diseases for men. SES has not always been a fundamental cause of mortality; it only emerged as such in the second half of the twentieth century. We argue that habits and behaviors embedded in the different social strata played a major role in the emergence of the SES gradient.

[Trend analysis and prediction of viral hepatitis incidence in China, 2009-2018]

Objective: To explore the time series characteristics of 5 types of viral hepatitis in China and predict their incidence through effective models. Methods: The monthly incidence data of 5 types of viral hepatitis (A, B, C, D and unspecified) in China from 2009 to 2018 were collected for descriptive and time series analyses, decomposition methods were used to explore the seasonality in the form of seasonal indices and the long-term trend in the form of a linear regression model. Autoregressive integrated moving average (ARIMA) models were established for each type of viral hepatitis. Results: From 2009 to 2018, a total of 14 856 990 cases of viral hepatitis were reported, the seasonal index range of 5 types of viral hepatitis were all lower than 1, the seasonality of hepatitis E was significant, and its incidence was unimodal, but no obvious seasonality characteristics were observed for other four types of viral hepatitis. The incidences of hepatitis A, hepatitis E and unspecified hepatitis remained at lower levels, showing slow declines. Although the cases of hepatitis B accounted for the highest proportion (79.59%, 11 824 262/14 856 990) among 5 types of viral hepatitis, the decline was fastest (-0.01/100 000). The incidence of hepatitis C was on rise, and the rate of increase remained stable (0.005/100 000). The predicted incidences of 5 types of viral hepatitis in China from January 2009 to December 2018 fitted by ARIMA model were consistent with the actual incidences, and the mean absolute error percentage (MAPE) ranged from 3.756 8 to 8.068 3. Conclusions: Time series analysis on surveillance data is useful for better understanding the incidence of the viral hepatitis. The ARIMA model has good application value in the short-term prediction of viral hepatitis incidence in China.

Contrast patterns and trends of lapse rates calculated from near-surface air and land surface temperatures in China from 1961 to 2014

The near-surface lapse rate reflects the atmospheric stability above the surface. Lapse rates calculated from land surface temperature (γ_Ts) and near-surface air temperature (γ_Ta) have been widely used. However, γ_Ts and γ_Ta have different sensitivity to local surface energy balance and large-scale energy transport and therefore they may have diverse spatial and temporal variability, which has not been clearly illustrated in existing studies. In this study, we calculated and compared γ_Ta and γ_Ts at ~ 2200 stations over China from 1961 to 2014. This study finds that γ_Ta and γ_Ts have a similar multiyear national average (0.53 °C/100 m) and seasonal cycle. Nevertheless, γ_Ts shows steeper multiyear average than γ_Ta at high latitudes, and γ_Ts in summer is steeper than γ_Ta, especially in Northwest China. The North China shows the shallowest γ_Ta and γ_Ts, then inhibiting the vertical diffusion of air pollutants and further reducing the lapse rates due to accumulation of pollutants. Moreover, the long-term trend signs for γ_Ta and γ_Ts are opposite in northern China. However, the trends in γ_Ta and γ_Ts are both negative in Southwest China and positive in Southeast China. Surface incident solar radiation, surface downward longwave radiation and precipitant frequency jointly can account for 80% and 75% of the long-term trends in γ_Ta and γ_Ts in China, respectively, which provides an explanation of trends of γ_Ta and γ_Ts from perspective of surface energy balance.

Spatiotemporal trends of PM2.5 concentrations in central China from 2003 to 2018 based on MAIAC-derived high-resolution data

Long-term PM_2.5 levels with high precision at fine spatiotemporal resolution are essential for quantitatively understanding the health risk of exposure to ambient fine particulate matter (PM_2.5) and making effective air pollution control policies. The emerging statistically derived PM_2.5 estimations from satellite remote sensing observations of aerosol optical depth (AOD) data are an effective alternative to reconstruct global, long-term, high spatiotemporal resolution PM_2.5 information. However, studies on PM_2.5 estimation and its application to exposure and health-related studies are limited in China due to the lack of historical in-situ measurements before 2013. In this study, we explored the long-term trends of PM_2.5 exposure in central China, a hotspot that has recently been experiencing severe particulate pollution, at the local scale. We first developed a spatiotemporal model incorporating periodical characteristics within the data to estimate daily concentrations of historical PM_2.5 at a fine scale of 1 km for 2003-2018. The linear effects of predictors including AOD, meteorological and land-use parameters and the non-linear interaction between AOD and meteorological parameters were considered in the modeling process. The most recently released high-resolution satellite aerosol product, Multi-Angle Implementation of Atmospheric Correction (MAIAC) was used to help to represent the fine-scale particle gradients. Our daily estimates correlated well with in-situ observations (cross-validation R² = 0.59), achieving precision comparable to previous statistical models. Through linking with gridded demographic data, the population-weighted PM_2.5 average during 2003 to 2018 was found to be high (62.23 μg/m³ for the whole domain) with obvious spatial variations and seasonality. An inverse U pattern was seen in the time series, with two inflection points around 2008 and 2015. Our model provides reliable particulate information with high spatial resolution and long-term temporal coverage, which can inform local-scale PM_2.5-related epidemiological studies and health-risk assessments for central China.

Yearly changes of the sulfate-nitrate-ammonium aerosols and the relationship with their precursors from 1999 to 2016 in Beijing

The change in particulate matter (PM)_2.5 composition in relation to precursors over recent decades has not been elucidated clearly in Beijing. Using ground-based measurements from the literature, this study investigated the yearly time series of PM_2.5 and its chemical composition over Beijing from 1999 to 2016 to identify the driving forces underlying these changes. The PM_2.5 concentration declined slightly, due to the organic carbon, elemental carbon, and dust rather than to either sulfate-nitrate-ammonium (SNA) aerosols. Before 2013, the trend of SNA aerosols was opposite to that of PM_2.5; however, subsequently, SNA aerosols have represented the major contribution to the reduction of PM_2.5, coinciding with a large decline of regional precursor gases. The yearly time series of SNA aerosols can be explained better by regional precursor gases than by local ones. Generally, precursor gases emissions over the region of North China Plain can be controlled if Beijing's air quality is to be improved.

Trends of outdoor air pollution and the impact on premature mortality in the Pearl River Delta region of southern China during 2006-2015

Severe air pollution in the Pearl River Delta (PRD) region of southern China has increased attention of both the scientific community and policy makers. Air quality data collected at the PRD Regional Air Quality Monitoring Network during 2006-2015 were analyzed for assessing the effectiveness of pollution control measures and for estimating the trends of premature mortality attributable to ambient PM_2.5 and O₃. Statistically significant decreasing trends were detected for PM_2.5 (-1.74 to -1.83 μg m^-3 yr^-1), PM₁₀ (-2.70 to -2.78 μg m^-3 yr^-1), NO (-0.61 to -0.74 μg m^-3 yr^-1), NO₂ (-1.20 to -1.22 μg m^-3 yr^-1), and SO₂ (-3.46 to -4.01 μg m^-3 yr^-1), while an increasing trend was found for O₃ (0.70-0.86 μg m^-3 yr^-1) during the study period. The findings demonstrate the effectiveness of control measures implemented in the last decade for primary pollutants and also indicate the challenges for controlling secondary pollutants. The PM_2.5-related premature deaths varied little, e.g., from 40.6 thousand deaths in 2006 to 40.4 thousand deaths in 2015, due to the two contrasting factors, i.e., the decreased PM_2.5 concentration and increased population. The increases in both O₃ concentration and exposed population resulted in a significant rising trend for the O₃-related premature deaths, which increased from 2.7 thousand deaths in 2006 to 4.5 thousand deaths in 2015, at a rate of 165 deaths yr^-1. Consistent with the spatial distribution of air pollution and population density, high levels of premature deaths from PM_2.5 and O₃ were located in the central PRD including Guangzhou, Foshan, Dongguan, and Shenzhen. Decreasing PM_2.5 concentration is the most effective way in reducing the regional mortality burden from air pollution in the near future. Besides controlling primary emissions of PM_2.5, reducing VOCs emissions is also important for limiting atmospheric oxidizing capacity and associated secondary PM_2.5 formation.

Long-term trend in vegetation gross primary production, phenology and their relationships inferred from the FLUXNET data

Climate-induced changes in plant phenology and physiology plays an important role in control of carbon exchange between terrestrial ecosystems and the atmosphere. Based on dataset during 1997-2014 from 41 flux tower sites (440 site-years) across the northern hemisphere, relationships between long-term trends in start of growing season (SOS), end of growing season (EOS), length of growing season (LOS), maximal gross primary production (GPP_max), and seasonal and annual gross primary production (GPP) were analyzed. Statistical Models of Integrated Phenology and Physiology (SMIPP) were built for predicting the long-term trends in annual GPP. Results showed that SOS advanced and EOS delayed for forest sites, while both SOS and EOS for grassland (GRA) sites delayed. Long-term trends in SOS and EOS of evergreen needle-leaf forests (ENF) sites were greater than those of deciduous broadleaf forests (DBF) sites. Seasonal and annual GPP for forest sites increased, among which long-term trend in annual GPP of ENF sites was the largest. Spring GPP of GRA sites decreased, but annual GPP increased. Strong relationships between long-term trends in phenological and physiological indicators and seasonal GPP were found. Long-term trend in GPP_max had the highest relationship with long-term trend in annual GPP for forest sites, but long-term trend in SOS was the most related to long-term trend in annual GPP for GRA sites. Increases in spring and autumn GPP due to a one-day advance in SOS and delay in EOS for DBF sites were greater than ENF sites. Delay in EOS resulted in more carbon sequestration than advance in SOS for forest sites, while advance in SOS significantly increased spring GPP for GRA sites. The SMIPP model driven by long-term trends in LOS and GPP_max had stronger explanatory power for predicting long-term trend in annual GPP than the SMIPP model driven by long-term trends in SOS, EOS, and GPP_max. Long-term trend in annual GPP was accurately predicted by using the SMIPP model, while long-term trend in annual GPP for GRA sites was more difficult to be captured than the forest sites. Drought and disturbance effects on phenology and physiology were major factors for model uncertainty. This study is helpful to understand changes in phenology and carbon uptake and their differences among different vegetation types and provides a potential way for predicting annual rate of change in carbon uptake through vegetation photosynthesis at a global scale.

A descriptive analysis of the Spatio-temporal distribution of intestinal infectious diseases in China

Background

Intestinal infectious diseases (IIDs) have caused numerous deaths worldwide, particularly among children. In China, eight IIDs are listed as notifiable infectious diseases, including cholera, poliomyelitis, dysentery, typhoid and paratyphoid (TAP), viral Hepatitis A, viral Hepatitis E, hand-foot-mouth disease (HFMD) and other infectious diarrhoeal diseases (OIDDs). The aim of the study is to analyse the spatio-temporal distribution of IIDs from 2006 to 2016.

Methods

Data on the incidence of IIDs from 2006 to 2016 were collected from the public health science data centre issued by the Chinese Center for Disease Control and Prevention. This study applied seasonal decomposition analysis, spatial autocorrelation analysis and space-time scan analysis. Plots and maps were constructed to visualize the spatio-temporal distribution of IIDs.

Results

Regarding temporal analysis, the incidence of HFMD and Hepatitis E showed a distinct increasing trend, while the incidence of TAP, dysentery, and Hepatitis A presented decreasing trends over the last decade. The incidence of OIID remained steady. Summer is the season with the greatest number of cases of different IIDs. Regarding the spatial distribution, approximately all p values for the global Moran’s I from 2006 to 2016 were less than 0.05, indicating that the incidences of the epidemics were unevenly distributed throughout the country. The high-risk areas for HFMD and OIDD were located in the Beijing-Tianjin-Tangshan (BTT) region and south China. The high-risk areas for TAP were located in some parts of southwest China. A higher incidence rates for dysentery and Hepatitis A were observed in the BTT region and some west provincial units. The high-risk areas for Hepatitis E were the BTT region and the Yangtze River Delta area.

Conclusions

Based on our temporal and spatial analysis of IIDs, we identified the high-risk periods and clusters of regions for the diseases. HFMD and OIDD exhibited high incidence rates, which reflected the negligence of Class C diseases by the government. At the same time, the incidence rate of Hepatitis E gradually surpassed Hepatitis A. The authorities should pay more attention to Class C diseases and Hepatitis E. Regardless of the various distribution patterns of IIDs, disease-specific, location-specific, and disease-combined interventions should be established.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4400-x) contains supplementary material, which is available to authorized users.

Concentration decline in response to source shift of trace metals in Elbe River, Germany: A long-term trend analysis during 1998-2016

Monitoring spatial and temporal chemical status of water bodies is crucial to assist environmental policy, identify the chemical fingerprints, and further reduce the source orientated pollutants. Elbe River is one of the major rivers affected by anthropogenic activities in vicinity countries. This study assessed the spatiotemporal changes in response to source shift of Cd, Cu, Ni, Pb, and Zn in the suspended particulate matter (SPM) at upstream, midstream, and downstream of the Elbe River reach in Saxony state, Germany. The average contents of trace metals in SPM was found in the order of Zn (676 mg/kg) » Pb (79 mg/kg) > Cu (74 mg/kg) > Ni (48 mg/kg) » Cd (3.2 mg/kg). According to the Mann-Kendall trend test, Cd, Cu, Pb, and Zn showed significant declines over 1998-2016. The results of source apportionment indicate industrial, urban, natural, and historical mining sources influencing the metal contents in the Elbe River of Saxony. The contributions of industrial and urban pollution decreased by 58.2% from 1998 to 2007 to 2008-2016. The contribution of the natural source was steady over the last two decades.

Trend analysis and modeling of nutrient concentrations in a preliminary eutrophic lake in China

Accurately measuring and estimating trends and variations in nutrient levels is a significant part of managing emerging eutrophic lakes in developing countries. This study developed an integrated approach containing Seasonal Trend Decomposition using Loess (STL) and a dynamic nonlinear autoregressive model with exogenous input (NARX) network to decompose and estimate the nutrient concentrations in Lake Erhai, a preliminary eutrophic lake in China. The STL decomposition results indicated that total nitrogen (TN) concentration of Lake Erhai progressively descended from 2006 to 2014, except for some agriculture area. The total phosphorus (TP) concentration showed an increasing trend from 2006 to 2013 and then decreased in 2014, but in the area near the tourist attractions, TP increased continuously from 2011 to 2014. Seasonal variations in TN and TP indicated that the lowest water quality of Lake Erhai occurred from July to October. Based on results obtained with STL, TP was selected as the sensitive parameter, as it showed a significant deterioration trend, and the area near the tourist attractions was selected as the sensitive area. Three variables (DO, pH, and water temperature) were selected as input parameters to estimate TP using the dynamic NARX model. The NARX modeling results demonstrated that it can accurately estimate TP concentrations with low root-mean-square error (0.0071 mg/L). The study establishes a new approach to better understand trends and variations in nutrient levels and to better refine estimates by identifying more easily accessible physical parameters in a preliminary eutrophic lake.

A decline in the concentration of PAHs in Elbe River suspended sediments in response to a source change

This study focuses on the analysis of the long-term trends and source apportionment of PAHs in the suspended sediments of the Elbe River in Saxony, Germany, from 2001 to 2016. The results of the Mann-Kendall trend test indicated that the concentrations of total and individual PAHs exhibited decreasing trends during the 16-year study period. According to the positive matrix factorization (PMF) receptor model, primary sources for every four-year period were identified as oil burning, biomass burning, and vehicular emissions from gasoline and diesel-powered engines. The changes in the sources were consistent with the trends in vehicle numbers and energy consumption during the last 16 years. Furthermore, the results of total toxic benzo[a]pyrene equivalent (TEQ) values indicated potential cancer risks. The results of the mean hazard quotient (MHQ) suggested that PAHs exhibited a 21% probability of being toxic to benthic organisms and to the aquatic environment.

Reconstructing Soil Recovery from Acid Rain in Beech (Fagus sylvatica) Stands of the Vienna Woods as Indicated by Removal of Stemflow and Dendrochemistry

Our goal was to reconstruct soil recovery from Acid Rain based upon removal of stemflow at beech (Fagus sylvatica) stands of known historic and recent soil status. Fourteen beech stands in the Vienna Woods were selected in 1984 and again in 2012 to study changes in soil and foliar chemistry over time. A part of those stands had been strip cut, and to assess reversibility of soil acidification, we analyzed soils around beech stumps from different years of felling, representing the years when acidic stemflow ceased to affect the soil. Furthermore, it was hypothesized that changes of soil chemistry are reflected in the stemwood of beech. Half-decadal samples of tree cores were analyzed for Ca, Mg, K, Mn, Fe, and Al. Soil analyses indicated recovery in the top soil of the stemflow area but recovery was delayed in the between trees areas and deeper soil horizons. Differences in soil pH between proximal and distal area from beech stumps were still detectable after 30 years indicating that soils may not recover fully from acidification or do so at a rather slow rate. Stemwood contents indicated mobilization of base cations during the early 80s followed by a steady decrease thereafter. Backward reconstructions of soil pH and soil nutrients, building on regressions between recent stemwood and soil chemistry, could not be verified by measured soil data in 1984, but matched with declining cation foliar contents from 1984 to 2012. Dendrochemical reconstructions showed highest values in the 1980s, but measured soil exchangeable cation contents were clearly lower in 1984. Hence, we conclude that our reconstructions mimicked soil solution rather than soil exchanger chemistry.

Long-term trends in NO2 columns related to economic developments and air quality policies from 1997 to 2016 in China

This study detected the long-term trends in NO₂ concentrations in China from 1997 to 2016 based on the NO₂ columns from GOME, SCIAMACHY, and GOME-2A. Both differences in the time-overlapped NO₂ columns from GOME vs. SCIAMACHAY and SCIAMACHAY vs. GOME-2A showed seasonal variations, and the annual NO₂ columns from GOME were 0.9% higher than those from SCIAMACHY, which exceeded that from GOME-2A by 14%. The long-term trends of the NO₂ columns on a provincial scale could be simulated by cubic models (0.60 < R² < 0.96, p < 0.05) and presented three shapes: first decreasing then increasing and decreasing again; first decreasing then increasing; and continuously decreasing. The peak years of NO₂ columns in 17 provinces occurred in 2011 and 2012. These trends in NO₂ columns were determined by the economic developments and enacted air quality policies in nearly all the provinces except for Xizang and Qinghai Provinces, where the trends were determined by natural NO_x emission sources. In detail, the panel data analysis showed that the simulated model had fixed effects, and the thermal power generation, consumption of diesel oil in agriculture, passenger traffic by highways, and freight traffic by highways significantly increased NO₂, while the air quality policies in the 12th five-year plan decreased NO₂ columns from 1997 to 2016. The benefits to decreasing NO₂ columns from the air quality policies issued in the 10th and 11th five-year plans were offset by the quickly increasing economies.

Assessment of the 11-year nationwide trend of out-of-hospital cardiac arrest cases among elderly patients in Japan (2005-2015)

OBJECTIVE

Japan has one of the most rapidly aging societies worldwide. This study aimed to assess the long-term nationwide trend of out-of-hospital cardiac arrest (OHCA) cases among elderly patients in Japan.

METHODS

This prospective, nationwide observational study in Japan included elderly patients aged ≥65 years who experienced OHCA from January 1, 2005 to December 31, 2015. The patients were classified into three groups: young-old, aged 65-74 years; old-old, aged 75-84 years; and oldest-old, aged ≥85 years. The primary outcome of this study was one-month survival with a favorable neurological outcome, which was defined as a cerebral performance category scale score of 1 or 2.

RESULTS

A total of 877,009 patients were included in our analysis. The number of elderly patients with OHCA increased from 65,968 in 2005 to 87,339 in 2015, and each age category showed a significantly increasing trend (p value <0.001 for each trend). The proportions of favorable neurological outcomes also increased from 1.2% in 2005 to 2.8% in 2015 in the young-old group; from 0.6% in 2005 to 1.1% in 2015 in the old-old group; and from 0.2% in 2005 to 0.5% in 2014 in the oldest-old group. Furthermore, this improving trend was notable for those with a shockable first documented rhythm.

CONCLUSIONS

Based on this long-term nationwide observational study in Japan, the number of elderly patients with OHCA increased annually, and a significant improvement in the patients' neurological outcomes was noted regardless of age category, particularly among those with an initially shockable rhythm.

MAIAC-based long-term spatiotemporal trends of PM2.5 in Beijing, China

Satellite-driven statistical models have been proven to be able to provide spatially resolved PM_2.5 estimates worldwide. The North China Plain has been suffering from severe PM_2.5 pollution in recent years. An accurate assessment of the spatiotemporal characteristics of PM_2.5 levels in this region is crucial to design effective air pollution control policy. Our objective is to estimate daily PM_2.5 concentrations at 1km spatial resolution from 2004 to 2014 in Beijing and its surrounding areas using the Multi-angle implementation of atmospheric correction (MAIAC) aerosol optical depth (AOD). A high-performance three-stage model was developed with AOD, meteorological, demographic and land use variables as predictors, which includes a custom-designed PM_2.5 gap-filling method. The 11-year average annual coverage increased from 177days to 279days and annual PM_2.5 prediction error decreased from 14.1μg/m³ to 8.3μg/m³ after gap-filling techniques were applied. Results show that the 11-year overall mean of predicted PM_2.5 was 67.1μg/m³ in our study domain. The cross-validation R² value of our model is 0.82 in 2013 and 0.79 in 2014. In addition, the models predicted historical PM_2.5 concentrations with relatively high accuracy at the seasonal and annual levels (R² ranged from 0.78 to 0.86). Our long-term PM_2.5 prediction filled the gaps left by ground monitors, which would be beneficial to PM_2.5 related epidemiological studies in Beijing.

Particulate matter levels in a South American megacity: the metropolitan area of Lima-Callao, Peru

The temporal and spatial trends in the variability of PM₁₀ and PM_2.5 from 2010 to 2015 in the metropolitan area of Lima-Callao, Peru, are studied and interpreted in this work. The mean annual concentrations of PM₁₀ and PM_2.5 have ranges (averages) of 133-45 μg m^-3 (84 μg m^-3) and 35-16 μg m^-3 (26 μg m^-3) for the monitoring sites under study. In general, the highest annual concentrations are observed in the eastern part of the city, which is a result of the pattern of persistent local winds entering from the coast in a south-southwest direction. Seasonal fluctuations in the particulate matter (PM) concentrations are observed; these can be explained by subsidence thermal inversion. There is also a daytime pattern that corresponds to the peak traffic of a total of 9 million trips a day. The PM_2.5 value is approximately 40% of the PM₁₀ value. This proportion can be explained by PM₁₀ re-suspension due to weather conditions. The long-term trends based on the Theil-Sen estimator reveal decreasing PM₁₀ concentrations on the order of -4.3 and -5.3% year^-1 at two stations. For the other stations, no significant trend is observed. The metropolitan area of Lima-Callao is ranked 12th and 16th in terms of PM₁₀ and PM_2.5, respectively, out of 39 megacities. The annual World Health Organization thresholds and national air quality standards are exceeded. A large fraction of the Lima population is exposed to PM concentrations that exceed protection thresholds. Hence, the development of pollution control and reduction measures is paramount.

Declining atmospheric deposition of heavy metals over the last three decades is reflected in soil and foliage of 97 beech (Fagus sylvatica) stands in the Vienna Woods

Rigorous studies on long-term changes of heavy metal distribution in forest soils since the implementation of emission controls are rare. Hence, we resampled 97 old-growth beech stands in the Vienna Woods. This study exploits an extensive data set of soil (infiltration zone of stemflow and between trees area) and foliar chemistry from three decades ago. It was hypothesized that declining deposition of heavy metals is reflected in soil and foliar total contents of Pb, Cu, Zn, Ni, Mn and Fe. Mean soil contents of Pb in the stemflow area declined at the highest rate from 223 to 50 mg kg^-1 within the last three decades. Soil contents of Pb and Ni decreased significantly both in the stemflow area and the between trees area down to 80-90 cm soil depth from 1984 to 2012. Top soil (0-5 cm) accumulation and simultaneous loss in the lower soil over time for the plant micro nutrients Cu and Zn are suggested to be caused by plant uptake from deep horizons. Reduced soil leaching, due to a mean soil pH (H₂O) increase from 4.3 to 4.9, and increased plant cycling are put forward to explain the significant increase of total Mn contents in the infiltration zone of beech stemflow. Top soil Pb contents in the stemflow area presently exceed the critical value at which toxicity symptoms may occur at numerous sites. Mean foliar contents of all six studied heavy metals decreased within the last three decades, but plant supply with the micro nutrients Cu, Zn, Mn and Fe is still in the optimum range for beech trees. It is concluded that heavy metal pollution is not critical for the studied beech stands any longer.

Long-term monitoring study of beached seabirds shows that chronic oil pollution in the southern North Sea has almost halted

Trends in oil rates of beached seabirds reflect temporal and spatial patterns in chronic oil pollution at sea. We analysed a long-term dataset of systematic beached bird surveys along the Belgian North Sea coast during 1962-2015, where extreme high oil contamination rates and consequently high mortality rates of seabirds during the 1960s used to coincide with intensive ship traffic. In the 1960s, >90% of all swimming seabirds that washed ashore were contaminated with oil and estimated oil-induced mortality of seabirds was probably several times higher than natural mortality. More than 50years later oil rates of seabirds have dropped to historically low levels while shipping is still very intense, indicating that chronic oil pollution has significantly declined. The declining trend is discussed in the light of a series of legislative measures that were enacted in the North Sea region to reduce oil pollution.

A slight recovery of soils from Acid Rain over the last three decades is not reflected in the macro nutrition of beech (Fagus sylvatica) at 97 forest stands of the Vienna Woods

Rigorous studies of recovery from soil acidification are rare. Hence, we resampled 97 old-growth beech stands in the Vienna Woods. This study exploits an extensive data set of soil (infiltration zone of stemflow and between trees area at different soil depths) and foliar chemistry from three decades ago. It was hypothesized that declining acidic deposition is reflected in soil and foliar chemistry. Top soil pH within the stemflow area increased significantly by 0.6 units in both H2O and KCl extracts from 1984 to 2012. Exchangeable Ca and Mg increased markedly in the stemflow area and to a lower extent in the top soil of the between trees area. Trends of declining base cations in the lower top soil were probably caused by mobilization of organic S and associated leaching with high amounts of sulfate. Contents of C, N and S decreased markedly in the stemflow area from 1984 to 2012, suggesting that mineralization rates of organic matter increased due to more favorable soil conditions. It is concluded that the top soil will continue to recover from acidic deposition. However, in the between trees areas and especially in deeper soil horizons recovery may be highly delayed. The beech trees of the Vienna Woods showed no sign of recovery from acidification although S deposition levels decreased. Release of historic S even increased foliar S contents. Base cation levels in the foliage declined but are still adequate for beech trees. Increasing N/nutrient ratios over time were considered not the result of marginally higher N foliar contents in 2012 but of diminishing nutrient uptake due to the decrease in ion concentration in soil solution. The mean foliar N/P ratio already increased to the alarming value of 31. Further nutritional imbalances will predispose trees to vitality loss.

Study of surveillance data for class B notifiable disease in China from 2005 to 2014

Background

The surveillance of infection is very important for public health management and disease control. It has been 10 years since China implemented its new web-based infection surveillance system, which covers the largest population in the world.

Methods

In this study, time series data were collected for 28 infectious diseases reported from 2005 to 2014 . Seasonality and long-term trends were explored using decomposition methods. Seasonality was expressed by calculating the seasonal indices. Long-term trends in the diseases were assessed using a linear regression model on the deseasonalized series.

Results

During the 10-year period, 38 982 567 cases and 126 372 deaths were reported in the system. The proportion of deaths caused by AIDS increased from 12% in 2005 to 78% in 2014. There were six diseases for which the seasonal index range was greater than 2: dengue fever, Japanese encephalitis, leptospirosis, anthrax, cerebrospinal meningitis, and measles . Among the 28 diseases, the incidence of syphilis increased fastest, with an average increase of 0.018626/100 000 every month after adjustment for seasonality.

Conclusions

Effective surveillance is helpful in gaining a better understanding of the infection behaviour of infectious diseases; this will greatly facilitate disease control and management.

Seasonal dynamics and long-term trend of hypoxia in the coastal zone of Emilia Romagna (NW Adriatic Sea, Italy)

Long-term series of meteorological, hydrological and oceanographic data were compared with hypoxia occurrence, in order to define characteristics and trends of this phenomenon in the Emilia Romagna Coastal Zone (ERCZ) in 1977-2008. During this period, hypoxia was recorded at all sampling stations, up to 20 km offshore. In winter, spring and late autumn, hypoxia appearance was matched to significant positive anomalies of air and surface seawater temperatures (up to +3.6 °C), whereas this effect was less pronounced in August-October. Hypoxia generally occurred with scarce precipitation (0-2 dm(3)m(2)d(-1)) and low wind velocity (0-2 ms(-1)), suggesting the importance of stable meteo-marine conditions for the onset of this phenomenon. Nevertheless, wind direction emerged as an indicator of hydrodynamic seasonal changes in the area and is thus a hypoxia regulator. In winter, spring and autumn, hypoxia was favored by large increases of biomass induced by river freshets. In contrast, summer hypoxia occurred during periods of low runoff, suggesting that pronounced stratification and weak circulation of coastal waters were more important in this season. Since the 1990s, a shift from widespread summer hypoxia to local hypoxia irregularly distributed across the year has occurred. This process was concomitant to long-term increases of air temperature (+0.14 °C yr(-1)), wind speed (+0.03 ms(-1) yr(-1)) and salinity (+0.09 yr(-1)), and decreases of Po River flow (-0.54 km(3) yr(-1)), oxygen saturation (-0.2% yr(-1)) and PO4(3-) (-0.004 μmol P L(-1) yr(-1)) and NH4(+) (-0.04 μmol N L(-1) yr(-1)) concentrations in surface coastal waters. Despite that several of these changes suggest an ERCZ trophic level positive reduction, similar to that reported for the N Adriatic, the concomitant climate warming might further exacerbate hypoxia in particularly shallow shelf locations. Therefore, in order to avoid hypoxia development a further mitigation of anthropogenic pressure is still needed in the area.

Rising prevalence of back pain in Austria: considering regional disparities

BACKGROUND

Back pain is the most common form of musculoskeletal conditions and leads to high health care costs. Information about geographic variations in highly prevalent diseases/disorders represents important implications for public health planning to face structural challenges. The present study aims to investigate regional trends in the prevalence of back pain and the role of obesity and social inequalities among Austrian adults.

METHODS

A secondary data analysis based on five nationally representative cross-sectional surveys (1973-2007) was carried out (N = 178,818). Back pain was measured as self-reported presence. Obesity (BMI ≥ 30 kg/m²) was adjusted for self-report bias. For the regional analyses, Austria was divided into Western, Central and Eastern Austria. A relative index of inequality (RII) was computed to quantify the extent of social inequality.

RESULTS

A continuous rise in back pain prevalence was observed in the three regions and among all investigated subgroups. In 2007 the age-standardised prevalence was similar in Central (36.9 %), Western (35.2 %) and Eastern Austria (34.3 %). The absolute change in back pain prevalence was highest among obese subjects in Central Austria (women: + 29.8 %, men: + 32.5 %). RIIs were unstable during the study period and in 2007 highest in Eastern Austria.

CONCLUSION

Variation and trends in back pain are not attributable to geographic variation in Austria: an assumed East-West gradient in Austria has not been confirmed. Nevertheless our study confirms that back pain dramatically increased in all Austrian regions and investigated subgroups. This worrying trend should be further monitored and public health interventions should be implemented increasingly, especially among obese women and men.

Joint modeling of cross-sectional health outcomes and longitudinal predictors via mixtures of means and variances

Joint modeling methods have become popular tools to link important features extracted from longitudinal data to a primary event. While most modeling strategies have focused on the association between the longitudinal mean trajectories and risk of an event, we consider joint models that incorporate information from both long-term trends and short-term variability in a longitudinal submodel. We also consider both shared random effect and latent class (LC) approaches in the primary-outcome model to predict a binary outcome of interest. We develop simulation studies to compare and contrast these two modeling strategies; in particular, we study in detail the effects of the primary-outcome model misspecification. Among other findings, we note that when we analyze data from a shared random-effect using a LC model while the information from the longitudinal data is weak, the LC approach is more sensitive to such a model misspecification. Under this setting, the LC model has a superior performance in within-sample prediction that cannot be duplicated when predicting new samples. This is a unique feature of the LC approach that is new as far as we know to the existing literature. Finally, we use the proposed models to study how follicle stimulating hormone (FSH) trajectories are related to the risk of developing severe hot flashes for participating women in the Penn Ovarian Aging Study.

Demonstration of long-term increases in tropospheric O3 levels: causes and potential impacts

Ground-level ozone (O3) is a well-known atmospheric pollutant with its adverse impacts on the environment and human health. Here, the tropospheric O3 concentrations monitored in seven major cities in Korea at monthly intervals over a 22-year period (1989-2010) are presented, and their long-term variability examined. The analysis of annual mean values of O3 (in nmolmol(-1), or ppb) showed a noticeable increase of 118±69% in all seven cities over the two decades (p<0.01). Changes in O3 levels are closely associated with both environmental (e.g., NOx (NO+NO2), SO2, CO, and total suspended particles (TSPs) (p<0.01), temperature, and sunshine hours) and common anthropogenic variables (e.g., population density and number of vehicles). Evidence collected in this study suggests that the atmospheric conditions in most major cities of Korea should be volatile organic compounds (VOCs) sensitive or NOx saturated with respect to O3 formation. As such, establishment of a proper management strategy seems a sensible approach to control tropospheric ozone concentrations in densely populated cities.