Amino acids as indicators of seasonal variations in organic matter degradation in surface sediments from a shallow lake

Degradation of organic matter (OM) in sediments is a key link in nutrient cycling and sedimentation processes in lakes. The aim of this study was to explore the degradation of OM in surface sediments of a shallow lake (Baiyangdian Lake, China) under seasonal temperature variations. For this, we used the amino acid-based degradation index (DI) and the spatiotemporal distribution characteristics and sources of OM. Sediment OM in the lake mainly originated from freshwater aquatic plants and terrestrial C4 plants. The sediment at some sampling sites was affected by surrounding crops. The organic carbon and total nitrogen contents, and the total hydrolyzed amino acid concentrations in the sediments were highest in summer and lowest in winter. The lowest DI occurred in spring, which indicated that the OM in the surface sediment at this time was highly degraded and relatively stable, and the highest DI occurred in winter, which showed that the sediment was fresh. The water temperature was positively correlated with the organic carbon content (p < 0.01) and total hydrolyzed amino acids concentration (p < 0.05). Seasonal variations in the overlying water temperature had a large effect on OM degradation in the lake sediments. Our results will facilitate the management and restoration of lake sediments that suffer from endogenous release of OM in a warming climate.

Shifts in the bacterial community caused by combined pollutant loads in the North Canal River, China

A typical anthropogenically disturbed urban river polluted by a combination of conventional pollutants (nitrogen and phosphorus pollution) and heavy metals was investigated along a 238 km stretch. Changes in the bacterial community were evaluated using high-throughput sequencing, and the relationships between bacteria, heavy metals, and conventional pollutants were investigated. There was large spatial heterogeneity in the bacterial community along the river, and bacterial diversity in the upstream and midstream sections was much higher than in the downstream section. Heavy metals and conventional pollutants both exhibited close correlations with bacterial diversity and composition. For instance, potential fecal indicator bacteria, sewage indicator bacteria and pathogenic bacteria, such as Ruminococcus and Pseudomonas, were closely associated with Cu, Zn, and NH₄⁺-N. Rather than conventional pollutants, heavy metals were the main driving factors of the microbial community characteristics. These results confirm that bacterial communities play a crucial role in biogeochemical cycles. Therefore, heavy metals could be used as biomarkers of complex pollution to indicate the pollution status of riverine ecosystems and contribute to the restoration of habitats in anthropogenically disturbed urban rivers.

Variations in dissolved oxygen and aquatic biological responses in China's coastal seas

Coastal areas can represent an ecological transition zone with the function of biodiversity conservation, and good water quality is fundamental to maintaining this function. In this study, we analyzed data from 2011 to 2020 to reveal the variation in dissolved oxygen (DO) and the aquatic biological response in China's coastal seas. Results showed that DO in coastal waters exhibited an upward trend from 2011 to 2020 because of reduction in terrestrial anthropogenic pollutant (TAP) input. In comparison with DO in other seas, the DO content in the East China Sea was lower owing to higher TAP input, i.e., the proportion of DO of <5 mg L^-1 accounted for approximately 60% of the total. Species numbers, density, and the species diversity index of phytoplankton, zooplankton, and macrobenthos were different in the different sea areas because phytoplankton, zooplankton, and macrobenthos have different responses to changes in DO. In comparison with the species numbers of zooplankton and macrobenthos, the species numbers of phytoplankton were more significantly related to DO, and showed a negative linear relationship with a better DO environment (DO ≥ 5 mg L^-1; r² = 0.39, p < 0.01) and positive correlation with a poor DO environment (DO < 3 mg L^-1; r² = 0.52, p < 0.01). A better DO environment is conducive to increased density of macrobenthos. Studies have shown that a good DO environment contributes to coastal ecosystem health, and continuous control of TAP input is an effective means of ensuring DO recovery.

Evidence of temperature-controlled dissolved inorganic nitrogen distribution in a shallow lake

Dissolved inorganic nitrogen (DIN) plays an important role in aquatic ecosystems as an available source of nitrogen (N). Despite recent advances in our understanding of the effects of climate change on DIN in coastal waters, shallow high-latitude lakes exposed to large seasonal temperature differences have received limited research attention. Therefore, in the present study, Baiyangdian Lake (BYDL) was selected as the study area, as a typical high latitude shallow lake in North China. Based on water and sediment samples collected in spring, summer and winter seasons, DIN accumulation in sedimentary pore water and DIN diffusion fluxes at the sediment-water interface were quantified under different temperature conditions. Correlation analysis was used to establish the effects of temperature on DIN concentration and diffusion in different media. Results show that the diffusion of DIN at the lake sediment-water interface exhibited a strongly positive relationship with temperature, suggesting that high temperature conditions lead to greater DIN release from sediments. Cold temperatures cause DIN accumulation in sedimentary pore water, providing sufficient substrate for N-related bacteria in the sediment under cold temperature conditions. Temperature controls the vertical distribution of DIN by affecting its migratory diffusion and transformation at the sediment-water interface. These findings are valuable for understanding the impact of climate change on the distribution of N in inland shallow lakes, especially in high latitude shallow lakes subjected to large seasonal temperature differences throughout the year.

Evaluation of water quality at national scale from 2011 to 2021: Advances and challenges

More environmental policies and larger investments in protecting the aquatic environment in China have been made in the last decade than previously. It is important to assess how this will affect river water quality. Here, changes in water quality in China between 2011 and 2021 are assessed. Water bodies meeting class III or better defined in the Chinese Environmental Quality Standards for Surface Water (GB3838-2002) were labeled WQI, water bodies meeting class V or better but below class III were labeled WQII, and water bodies below class V were labeled WQIII. The percentage of WQI water bodies increased from 66.1 % in 2011 to 81.0 % in 2021, and the percentages of WQII and WQIII water bodies decreased between 2011 and 2021. The percentage of WQI water bodies increased more quickly and the percentage WQIII water bodies decreased more quickly after 2017 than between 2011 and 2016. The percentages of WQI water bodies in the Northwest River Basin (RB), Pearl RB, Southeast RB, Southwest RB, and Yangtze RB were >80 %, and were higher than the percentages of WQI water bodies in the other five RBs. The percentages of WQI and WQII water bodies increased but the percentage of WQIII water bodies decreased in the Hai RB. The percentage of WQI water bodies increased but the percentages of WQII and WQIII water bodies decreased in the Huai RB, Liao RB, Yangtze RB, and Yellow RB. The river monitoring capacity increased and pollution sources, particularly point sources, became more controlled, and this improved river water quality. River management in China has passed the first stage of controlling pollution sources after 10 years of centralized management. The next stage should be focused on strengthening control of non-point sources of pollution and rehabilitating ecological systems to improve river health.

Heavy metal distribution, fractionation, and biotoxicity in sediments around villages in Baiyangdian Lake in North China

The effects of human activities on heavy metal distributions and fractionation in sediments from villages around Baiyangdian Lake (BYDL), North China, were assessed. The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in sediments from five villages were determined, and the potential ecological risk index, risk assessment code, and Chironomus sp. larvae toxicity assay were used to assess the bioavailabilities and toxicities of the metals. The contribution of Cd to the potential ecological risk was 45.13-89.53%, the highest among the heavy metals investigated. The contributions of Cd, Pb, and Zn in the non-residual fractions to the total concentrations were 66.23-90.57%, 18.31-96.28%, and 8.89-76.84%, respectively, which indicated that these metals had important anthropogenic sources and were very bioavailable. The mean risk assessment codes decreased in the order of Cd (49.82%) > Zn (20.95%) > Cu (9.35%) > Pb (6.88%) > Ni (4.85%) > Cr (0.30%), and the toxicity of Cd and Zn to biota around BYDL is of concern. The mean survival rate of Chironomus sp. larvae in sediments from Dizhuang village was 44.02%, which indicated that there was a high degree of heavy metal toxicity, particularly in waterways around the village. Carboxylesterase and superoxide dismutase analysis results indicated that heavy metals could markedly increase or decrease enzyme activities in Chironomus sp. larvae. Overall, the results indicated that heavy metal pollution in villages around BYDL should be taken into consideration for its ecological management.

Accumulation and potential ecological risks of Heavy Metals in sediments from Rivers in the Beijing-Tianjin Area

Human activities can introduce heavy metals to water bodies, where they are then deposited in sediments. The risks, spatial distributions, and toxicities of heavy metals in sediment were investigated along the North Canal in the densely Beijing-Tianjin area. The average geoaccumulation index ranged from 0.2 to 2.91 and the highest value was obtained for Cd. All the pollution load indexes were greater than one, indicating that the heavy metals originated from anthropogenic sources. The risk indexes at three sampling points were greater than 300, indicating high potential ecological risk. Two probable effect concentration quotient values greater than 0.5, suggesting potential toxicity to certain sediment-dwelling organisms. Identification and evalution heavy metals could assist in improvement of the water quality, and support management strategies to restore the environment.

Evidence of improvements in the water quality of coastal areas around China

Coastal areas are huge carbon stores and hotspots for marine carbon fixation. Changes in the water quality of coastal areas are closely linked to their carbon fixation function. In this study, monitoring data were analyzed to identify how the water quality in China's coastal areas changed from 2001 to 2020. The results showed that the water quality in the coastal areas had improved gradually since 2001. The proportion of water quality in Class II and above gradually increased from 41.4% in 2001 to 77.4% in 2020, meanwhile, the proportion of water quality less than Class II, decreased from 58.6% to 22.6%, respectively. Of the four sea areas, the water quality was best in the Yellow Sea, and was poor in the East China Sea. The water quality varied between the different coastal provinces and cities and was good in coastal areas of Hainan, Guangxi, Shandong, and other provinces and cities, but was poor in Shanghai, Zhejiang, and Tianjin. Terrestrial anthropogenic pollutants were the main influence on the water quality in the coastal areas. As a hotspot for fixing blue carbon, the continuous improvement of the water quality of coastal areas laid a foundation for the health of the blue carbon ecosystems.

Risk assessment of heavy metals in suspended particulate matter in a typical urban river

Suspended particulate matter (SPM) is a major source of contamination in urban rivers as it serves as a carrier for pollutants, such as heavy metals. In this study, the Beiyun River, northern China, was used as a case study to determine the characteristics of SPM-associated heavy metal spatial distribution, to evaluate the potential ecological risks and identify heavy metal sources. The concentrations of seven heavy metals and other associated indicators (TC, TN, TP, and OM) were measured at 12 sites and analyzed by Pearson correlation (PC) and principal component analyses (PCA). The average concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb were 70.72, 27.88, 31.35, 115.70, 27.77, 0.23, and 29.62 mg/kg, respectively, with significant spatial differences occurring between some elements. Igeo values established the ranked order of heavy metal pollutant concentrations in SPM as As > Cd > Zn > Cu > Pb > Cr > Ni. [Formula: see text] analysis demonstrated that the ranked order of potential ecological risk from the seven metals was Cd > As > Cu > Pb > Ni > Cr > Zn. Potential ecological risk index (RI) results confirmed the high potential ecological risk in the study area. Among the measured heavy metals, Cd represented the highest pollution risk, as shown by its highest [Formula: see text] value. Correlation analysis (CA) showed that Zn had a strong correlation with Cu and Pb. Significant positive correlations were found between TC, TN, TP, and Cu. Three element pairs, Zn-Cd, Cr-Cu, and Cr-Ni, were also found to have strong correlations. Zn, Cu, and Ni were mainly introduced by human activities including urban industrial sewage discharge (such as metallurgy and electroplating industrial wastewater), agricultural drainage, and landfill wastewater, while Cr mainly originated from natural processes like mineral weathering and atmospheric precipitation. This information on the concentration, risk, and sources of SPM in Beiyun River provides an important reference for the reduction of heavy metal pollution in SPM in a typical river in the Haihe River Basin (China).

Effects of organic matter on polycyclic aromatic hydrocarbons in riverine sediments affected by human activities

Organic matter (OM) is an important component of riverine environments and a major factor in the migration and transformation of hydrophobic organic substances, such as polycyclic aromatic hydrocarbons (PAHs), to sediments. We studied the distributions, sources, and correlations between PAHs and OM in sediments from the Duliujian and the Beiyun rivers in North China. Sixteen PAHs were detected in the surface sediments at total concentrations ranging from 356 to 4652 ng·g^-1 dry weight, which caused a moderate to high level of pollution. The PAH distributions were significantly and positively correlated with OM (p < 0.01) and higher concentrations were detected downstream of areas affected by human activity. Petroleum, coal, and wood combustion were the main sources of PAHs in riverine sediments, and the sources of OM in sediment included terrestrial and aquatic higher plants, soil, and sewage discharge. The OM accumulated and aged along the river, with increases in the degree of aromaticity and condensation, which led to stronger adsorption of PAHs. Our results will help to promote the management and restoration of contaminated riverine sediments.

A new solution 31P NMR sample extraction scheme for freshwater ecosystem sediments

A new approach for the extraction of organic phosphorus (Po) from freshwater sediments, which can be used in solution ³¹P nuclear magnetic resonance spectroscopy (³¹P NMR), has been developed and optimized. This approach addresses three important factors for sediment extraction: pH, organic matter (OM), and paramagnetic ions. We classified the sediments according to the pH, OM, and paramagnetic ions (acidic: pH < 7, alkaline: pH > 7; low OM: OM < 100 g·kg^-1, high OM: OM > 100 g·kg^-1; non-calcareous: Ca/(Fe + Al) < 0.5, calcareous: Ca/(Fe + Al) > 0.5). The 0.25 and 0.5 mol·L^-1 NaOH were optimum concentration for acidic and alkaline sediment extracted, respectively. The ratio of sediment to extraction remains at 1:10 (w:v) which exhibited higher extraction efficiency compared with 1:5 and 1:20 for both low and high OM sediments. Use of 25 mmol·L^-1 and 50 mmol·L^-1 ethylenediaminetetraacetic acid (EDTA) was optimal for Po extraction from non-calcareous and calcareous sediments, respectively. A useful extraction ratio table was developed through systematic orthogonal experiment. This new approach will allow ³¹P NMR to be more efficiently used for freshwater Po analysis and will help answer questions regarding to the fate and function of Po in freshwater sediments.

Dissolved oxygen variation in the North China Plain river network region over 2011-2020 and the influencing factors

The 2011-2020 data of dissolved oxygen (DO) and nutrients-total phosphorus (TP), solution reactive phosphorus (SRP), total nitrogen (TN), ammoniacal nitrogen (NH₃-N), and chemical oxygen demand (COD_Cr)-in the North China Plain river network region were analyzed. Moreover, the DO variation trend and the influencing factors were investigated. The results showed that between 2011 and 2020, the DO concentration steadily increased from <3 mg L^-1 to >5 mg L^-1. Negative relationships were observed between the DO and COD_Cr (R = -0.34, p < 0.01), TN (R = -0.41, p < 0.01), NH₃-N(R = -0.40, p < 0.01), TP (R = -0.28, p < 0.01), and SRP (R = -0.19, p < 0.01), indicating that a reduction in the nutrient input promoted the increase in the DO concentration in the past decade. The DO concentration in the rainy season was lower than that in the dry season, which suggests that nonpoint-source pollution caused by heavy storm runoff was the main factor affecting the water quality. The average DO concentration in the suburban rivers (4.88 mg L^-1) was higher than that in urban rivers (3.41 mg L^-1). Furthermore, comprehensive analysis indicated that the loss of riparian buffer, river solidification, pollutant input, and sluice dam operations are the main factors affecting DO concentration decrease and water quality deterioration. Finally, measures for water improvement and DO recovery in the river network region, namely pollutant input control, reduction in the impact of water conservancy projects, and river ecological restoration, were examined. Overall, this study shows that water quality has improved over the past decade. The study results provide a reference for the continuous improvement of water quality and the continuous recovery of DO in river network regions.

Evaluating the biotoxicity of surface water in a grassy lake in North China

The biological toxicity of aquatic ecosystems should be considered when assessing the effects of toxicity on the water environment. The aim of this study was to identify the main pollutants in the Baiyangdian (BYD) and the factors that contribute to biological toxicity. We determined various physical and chemical indicators in the surface water of the BYD, including nutrients and heavy metals, and the biological toxicity. We also explored the sources of the main pollutants and how the pollutants contributed to toxicity in the lake, using correlation analysis and an index of the biological toxicity. The results showed that total nitrogen (TN), ammoniacal nitrogen (NH₄⁺-N), chromium (Cr), and zinc (Zn) were the main pollutants in the BYD surface water. The average concentration of Cr was 2.3 times greater than the Class V threshold, and the concentrations at about 65% of the sampling points, mainly those in the southern part of the BYD, exceeded the threshold standard. The average concentration of Zn was 1.25 times higher than the Class V threshold, with the concentrations of about 35% of the samples greater than the threshold concentration. The integrated toxicity of the surface water to luminescent bacteria ranged from 0.51% to 58%, and averaged 24.07%, which was within the range of moderate toxicity. The inhibition rates were high near Diantou (59%) and Duan (51.6%). The pollutant levels in the BYD tend to be related to the population density, with pollution mainly caused by sewage and domestic garbage, with little influence from local industries. Cr and TN were strongly correlated, but the biological toxicity was not correlated with any of the individual environmental indicators, which suggests that the toxicity in the surface water of the BYD reflected the combined effects of the environmental factors, rather than a single factor. The information from this study, about the main pollutants and the relationships between the physical and chemical properties of the surface water in the BYD, can be used to support plans for restoring the BYD.

Determining cadmium bioavailability in sediment profiles using diffusive gradients in thin films

Cadmium (Cd) uptake by plants or benthic organisms largely depends on its bioavailability in sediments, so it is necessary to understand Cd bioavailability for determining its ecological risks in riverine sediments. Pore water is easily disturbed during sample collection, indicating that there was a shortage of traditional methods for investigating Cd bioavailability. Here, sediment cores were collected from rivers, after which sequential extraction and diffusive gradients in thin films (DGT) method were employed to determine Cd potential bioavailability in the sediments and pore water. We found that Cd concentrations measured by DGT were lower than that in pore water profiles, and Cd distribution in various fractions changed remarkably. Pearson correlation analysis showed significant positive correlations between Cd concentrations measured by DGT and total Cd concentrations (r² = 0.76), exchangeable and weak acid soluble fraction (r² = 0.68), ferromanganese fraction (r² = 0.72) and bound organic matter or oxidizable fraction (r² = 0.54). However, the correlation was relatively low between Cd concentrations measured by DGT and that in pore water profiles (r² = 0.26). These results demonstrated that DGT method could provide more accurate information of Cd bioavailability in sediment profiles than traditional methods.

Mercury pollution of riverine sediments in a typical irrigation area in the Beijing-Tianjin-Hebei region

The Beijing-Tianjin-Hebei region is China's cultural and political center. Rapid social and economic development has led to serious water pollution in this region. A comprehensive investigation of mercury (Hg) pollution in riverine sediments was carried out in a typical irrigation area in this region. The results show that the total Hg levels in the surface sediments of the Duliujian River Network (DRN) ranged from 0.169 to 1.391 mg kg^-1, with an average of 0.528 mg kg^-1. The Hg levels at most of the sample points were higher than the background. The Hg fractions were categorized as exchangeable (B1), reducible (B2), oxidizable (B3), and residual (B4). The Hg was mainly present in the B4 fraction (0.439 mg kg^-1, on average). The order of the average percentage of different fractions of Hg was B4 > B3 > B2 > B1. A risk assessment using total Hg showed that the potential ecological risk in each section of the DRN ranged from 80.4 to 662 (average = 263). A risk assessment using Hg speciation showed that the average risk for B1 was 3.28%. Because the potential ecological risk is very high, more attention should be given to this risk in the management of the river. This research also provides theoretical support for the study of Hg in the developed area of the agricultural irrigation canal. The information obtained in this study could be used to develop effective management strategies to control Hg pollution in the DRN.

Distribution of nitrogen and phosphorus and estimation of nutrient fluxes in the water and sediments of Liangzi Lake, China

Water samples and sediments from Liangzi Lake were taken and used to study the vertical distribution characteristics of nitrogen (N) and phosphorus (P) in both the overlying and pore water. Fluxes of ammonia (NH₄⁺-N) and phosphate (PO₄^3--P) were calculated using a one-dimensional transport-reaction model based on Fick's First Law. The results showed that the mean NH₄⁺-N and NO₃^--N concentrations in the overlying water of Liangzi Lake were 2.59 and 0.46 mg L^-1, respectively. The mean PO₄^3--P concentrations were lower than the detection limit. Both N and P displayed peaks at the sediment-water interface. For example, the mean concentration of ammonia in pore water in the surficial layer (0-5 cm) was 4.29 ± 2.74 mg·L^-1, which was twice than that of the overlying water. Two PO₄^3--P vertical profile regimes were identified; one had a gradually increasing trend, while the other first increased and then decreased. The mean orthophosphate concentration in the pore water of the surface layer (0-5 cm) was 0.01 ± 0.01 mg·L^-1. The spatial distribution of ammonia flux values was highly heterogeneous. Using these data, the annual load contribution of autochthonous ammonia was calculated to be 481 t a^-1. Studying N and P pollution and fluxes in the lakes of urban drinking water sources facilitates the provision of protection measures.

MicroRNA-577 promotes the sensitivity of chronic myeloid leukemia cells to imatinib by targeting NUP160

OBJECTIVE

To explore the effect of microRNA-577 on the drug sensitivity of chronic myeloid leukemia (CML) and the underlying mechanism.

PATIENTS AND METHODS

Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect the expression of microRNA-577 in peripheral blood of patients with chronic myeloid leukemia. Meanwhile, the expression of microRNA-577 was detected in CML cell line after imatinib treatment. Cell counting kit-8 (CCK-8) and flow cytometry assay were applied to verify the effect of microRNA-577 on cell proliferation and cycle. NUP160 was identified as a target gene of microRNA-577 by dual-luciferase reporter gene assay. Cell reverse test was performed to figure out whether microRNA-577 can enhance the sensitivity of CML to imatinib.

RESULTS

QRT-PCR results revealed that microRNA-577 level was notably decreased in peripheral blood of patients with CML, and microRNA-577 could inhibit the proliferation and cycle of CML cells. In addition, the result of dual-luciferase reporting assay indicated that microRNA-577 had a binding relationship with NUP160, and up-regulation of microRNA-577 in CML cell lines reduced the expression of NUP160, and vice versa. Lastly, cell reverse experiments confirmed that microRNA-577 can alleviate the resistance of CML to imatinib.

CONCLUSIONS

We found that microRNA-577 promotes the sensitivity of chronic myeloid leukemia cells to imatinib by down-regulating the expression of NUP160.

Effects of the pyrolysis temperature on the biotoxicity of Phyllostachys pubescens biochar in the aquatic environment

The use of biochar as an adsorbent for environmental remediation has been attracting increasing interest. However, biochar can contain contaminants such as polycyclic aromatic hydrocarbons (PAHs) and metals (e.g., Cu, Pb, and Zn). We prepared Phyllostachys pubescens biochars at temperatures between 400 and 700 °C. The biochars were used in bioassays using Vibrio qinghaiensis Q67, Daphnia magna, Pseudokirchneriella subcapitata, and Limnodrilus hoffmeisteri to characterize the toxicities and effects of the biochars. The PAH, Cu, Pb, and Zn contents of the biochars were 8.59-14.67, 1.82-3.26, 1.17-3.53, and 8.76-16.47 mg/kg, respectively. The biochars gave maximum P. subcapitata, D. magna, and V. qinghaiensis Q67 inhibition rates of 6.47%, 6.70%, and 29.87%, respectively. The biochars produced at high pyrolysis temperatures (≥600 °C) had low acute biotoxicities to L. hoffmeisteri and barely affected L. hoffmeisteri biomass, reproduction, and lipid content. The biochars may therefore be suitable for sediment remediation.

The effects of urbanization and rainfall on the distribution of, and risks from, phenolic environmental estrogens in river sediment

There is increasing concern about phenolic environmental estrogens (PEEs) in river systems, especially in economically developed regions, because of their potential to impact ecological systems. We studied the distribution of, ecological risks from, and factors that influenced PEEs in the sediments from the Duliujian River in the Beijing-Tianjin-Hebei Urban Agglomeration and the Pearl River in Guangdong Province in China. The three target PEEs, nonyl phenol (4-NP), octyl phenol (4-t-OP), and bisphenol A (BPA), were detected in the sediments at concentrations ranging from 204.4 to 12604.3, 32.6 to 297.3, and from 12.8 to 298.4 ng g^-1 in the Pearl River, and from 153.5 to 3614.9, 90.7 to 990.0, and 83.5-913.3 ng g^-1 in the Duliujian River, respectively. The PEE concentrations were significantly and positively correlated with total organic carbon in the river sediments (p < 0.1). Urbanization influenced the distribution of PEEs and applications and discharges of PEEs were associated with large populations and industries. Rainfall and wastewater discharge patterns also influenced how PEEs were distributed in river sediments. The potential ecological risks from 4-NP, 4-t-OP, and BPA in these two rivers were high. Measures should be put in place to control the transport and storage of these compounds in river systems.

Identifying sediment-associated toxicity in rivers affected by multiple pollutants from the contaminant bioavailability

In this study, we estimated the toxicity risks from river sediments that were affected by multiple pollutants in the Haihe River Basin. We used a range of methods to determine the concentrations, bioavailability, and toxicity of a range of metals and contaminants in sediments and sediment porewater and then assessed the ecological risks and toxicity using various multivariate statistical approaches. We found that more than 70% of the samples were toxic. The concentrations of non-ionic ammonia (0.168-9.295 mg L^-1) were generally high in the sediment porewater, while the concentrations of bioavailable chromium (Cr) and polycyclic aromatic hydrocarbons (PAHs) were also high in the porewater samples from NW01 and NW02, respectively. We used the toxic unit (TU) approach, based on the bioavailable pollutant concentrations, to determine the toxicity of PAHs, heavy metals, and non-ionic ammonia in river sediments and sediment porewater. We found that non-ionic ammonia was the main source of toxicity for Daphnia magna, and that Cr and zinc were toxic for Pseudokirchneriella subcapitata and Chironomus dilutus. By combining various indexes, we identified the main contributors to the toxicity in sediments collected from rivers affected by multiple pollutants.

Genome-wide identification and comparison of mRNAs, lncRNAs and circRNAs in porcine intramuscular, subcutaneous, retroperitoneal and mesenteric adipose tissues

Many types of RNAs, including messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), play crucial roles in regulating fat cell differentiation and tissue development. However, the expression profiles of these RNAs in different adipose tissues are still largely unknown. To shed light on this issue, we performed a transcriptome analysis of mRNAs, lncRNAs and circRNAs obtained from intramuscular adipose tissue, subcutaneous adipose tissue, retroperitoneal adipose tissue and mesenteric adipose tissue of Chinese Erhualian pigs. A number of differentially expressed mRNAs, lncRNAs and circRNAs were identified among the four adipose tissues. Tissue-specific analysis indicated that circRNAs exhibited the highest tissue specificity among mRNAs, lncRNAs and circRNAs, whereas intramuscular adipose tissue had the most tissue-specific genes among the four adipose tissues. Gene Ontology analysis showed that differentially expressed mRNAs among groups were involved mainly in lipid metabolism and immune inflammatory response processes. Furthermore, the co-expression network construction of mRNAs-lncRNAs revealed that several important lncRNAs, such as MSTRG.426159 and MSTRG.604206, might associate with lipid metabolic process. Taken together, these data provide a genome-wide resource of mRNAs, lncRNAs and circRNAs potentially involved in porcine fat metabolism, thus improving understanding of their function in diverse adipose tissues.

Comprehensive analysis of nitrogen distributions and ammonia nitrogen release fluxes in the sediments of Baiyangdian Lake, China

The condition of Baiyangdian Lake (BYDL) will improve as the Xiongan New Area evolves and fulfills its role of easing overcrowding and supporting economic growth. Water and sediment samples from BYDL were analyzed to provide information on nitrogen (N) contamination in BYDL. The mean ammonium N (NH₄⁺-N), nitrate N, and total N concentrations in the water samples were 0.36, 0.12, and 2.22 mg/L, respectively, and the ranges were 0.003-8.38, 0.06-0.30, and 1.25-10.34 mg/L, respectively. The N concentrations in water gradually increased from the north to the south of BYDL. Sediment at 90% of the sampling sites was in or above the moderately contaminated class (1000-2000 mg/kg) defined in US Environmental Protection Agency total N pollution standards. Positive NH₄⁺-N fluxes were found for 28 of the 34 sediment core samples, so the potential for NH₄⁺-N being released from sediment was relatively high. The NH₄⁺-N fluxes were 5.35-48.76 mg/m²/day, and the mean and maximum fluxes were 8.71 and 48.76 mg/m²/day, respectively. Benthic organisms will be affected more by NH₄⁺-N and NH₃·H₂O in the surface sediment pore water (mean concentrations 4.93 and 0.13 mg/L, respectively) than by the other forms of N.

Using biochar capping to reduce nitrogen release from sediments in eutrophic lakes

The effects of reduced nitrogen release from sediments were studied using biochar (BC) capping in simulated water-sediment systems. Dried solid waste of Phyllostachys pubescens was used to produce BC, which was then pyrolyzed at 500 °C. Subsequently, 14 sediment cores were collected, including the sediment-water interface and some overlying water, from two sites in Baiyangdian Lake (China). The sediment cores were split into two batches (A and B), and then two each were capped with soil, BC or a BC/soil mixture, and incubated for 30 days. In the BC capped cores, the ammonia nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N) and total nitrogen (TN) concentrations decreased from 0.90 mg·L^-1 to 0.05 mg·L^-1, 0.88 mg·L^-1 to 0.18 mg·L^-1, 6.93 mg·L^-1 to 2.81 mg·L^-1, respectively, in batch A and 3.51 mg·L^-1 to 0.11 mg·L^-1, 0.92 mg·L^-1 to 0.61 mg·L^-1, 8.88 mg·L^-1 to 3.32 mg·L^-1, respectively, in batch B. The sediments to water fluxes of NH₄⁺-N, NO₃^--N and TN were greatly reduced or reversed. Compared with other cappings, the BC layer was shown to absorb more NH₄⁺-N from the pore water, thereby breaking the diffusion gradient of NH₄⁺-N at the sediment-water interface, and has a good inhibitory effect on the endogenous release of NH₄⁺-N from the sediments. Additionally, in the BC capped cores, the redox potential remarkably increased and dissolved oxygen was comparatively high. This study suggests that BC capping can reduce the amount of nitrogen released from polluted sediments because the diffusion of nitrogen to the overlying water is chemically blocked by the cap.

MAGE-A is frequently expressed in triple negative breast cancer and associated with epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a crucial step in tumor metastasis. Triple negative (TN) breast cancer, a high metastasis phenotype, has been verified to be associated with EMT. Melanoma associated antigen-A (MAGE-A) is exclusively expressed in cancers with high aggressiveness as well as unfavorable prognosis and likely to be associated with EMT of triple negative breast cancer (TNBC). The aim of the study is to analyze the expression profile of MAGE-A in breast cancer and the correlation between MAGE-A and EMT of TNBC. Immunohistochemistry (IHC) was performed to assess the prevalence of MAGE-A, vimentin, E-cadherin and β-catenin in breast cancer tissues and correlate them with clinical pathological parameters. The association between MAGE-A and EMT markers was also evaluated. Scratch assay and transwell invasion assay were carried out to evaluate the impact of MAGE-A down-regulation on migration and invasion of the breast cancer cells. Real-time PCR was also conducted to evaluate alterations in EMT markers with decrease in MAGE-A. The results showed that MAGE-A was absent in normal tissue but expressed in tumor samples with the incidence of 49.17% (P=0.008). MAGE-A staining was higher in TNBC (76.47%, 13/17), followed by HER-2(+) (53.85%, 7/13) and Luminal set (43.33%, 39/90), and it was significantly correlated with ER (-), PR (-), HER-2 (-), lymph nodes involvement and higher histological grade (P<0.05). E-cadherin-positivity was frequent in Luminal set (94.44%, 85/90) and linked to ER (+), negative lymph nodes and lower histological grade (P<0.05). Vimentin expression was often observed in TNBC (70.56%, 12/17) and ER (-), PR (-), lymph nodes (+) groups (P<0.05). Expression of β-catenin was prevalent in Luminal set (93.33%, 84/90) and correlated with ER (+), PR (+) and lower histological grade (P<0.05). MAGE-A was inversely associated with E-cadherin (P=0.011) and β-catenin (P=0.048) but expressed in the same trend with vimentin (P=0.000). Migration and invasion of MDA-MB-231 were inhibited when MAGE-A decreased. Increase in epithelial markers and decline in mesenchymal indicators were also seen with MAGE-A reduction. Snail, Slug, ZEB1 and ZEB2 were also down-regulated. In conclusion, MAGE-A may be responsible for high aggressiveness and EMT of TNBC and can be a new choice for targeted therapy.

Spatial and temporal variations of nutrition in representative river networks in Southwest China

To control pollutants in rivers, we need to have an understanding of the spatial and temporal variations on nutrients and environmental processes in complex river networks. In this study, 177 sampling sites were located in Jinjiang River in 2017, 15 monitoring stations in Jinjiang River from 2011 to 2016 were also collected. According to the data from the monitoring station, the total phosphorus (TP) and total nitrogen (TN) were the dominant contaminants. By analyzing historical water quality data and up-to-date information about the nutrient concentrations, the secondary canals of the Jinjiang River system, most of which were black and odorous, were much more seriously polluted than the main channel and tributaries. Correlation analysis indicated that the NH₃, CODcr, TN, and TP had similar sources (R²_NH3-CODcr = 0.572, R²_NH3-TN = 0.543, R²_NH3-TP = 0.537, p < 0.01). The vertical banks of urban rivers and the inadequate and poorly maintained pipe network systems promote deterioration of water quality in these secondary canals. Overall, our results suggest that the river water quality could be improved if the municipal pipe network systems were better maintained and if the vertical banks were transformed into vegetated buffer strips. This study will support initiatives to improve the water quality and function of the river network ecosystem.

Remediation effectiveness of Phyllostachys pubescens biochar in reducing the bioavailability and bioaccumulation of metals in sediments

Biochar has potential for application for in situ metal-contaminated sediment remediation, mainly because of its cost-effectiveness. In this study, the effectiveness of Phyllostachys pubescens (PP) biochar for immobilization of cadmium (Cd) chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) by decreasing the bioavailable fraction was investigated using a series of laboratory sediment remediation microcosms. The results demonstrated that biochar could significantly reduce the bioavailable fraction of metals (except for Cr) by diffusive gradients in thin film (DGT) measurement in porewater. Additionally, amended sediment treated with 15% w/w biochar resulted in 79.71%, 73.20%, 54.86%, 49.75%, 31.16% and 0.99% reductions in the acid-soluble fraction for Cu, Pb, Ni, Zn, Cd, and Cr, respectively. Similarly, bioaccumulation of metals (except for Cr) by Limnodrilus hoffmeisteri was reduced by 18.45%-59.15% in biochar amended sediment. PP biochar at 15% could also reduce the inhibition or lethality rate by 37.5%, 18.1% and 36.3% for Chlorella vulgaris, Daphnia magna and luminescent bacteria Vibrio qinghaiensis, respectively. Overall, these results demonstrate the potential for biochar application for in situ sediment remediation.

Contribution of particulate matter in storm runoff to organic phosphorus loads in urban rivers

To help us control pollution caused by urban runoff, we need to understand how particulate matter in storm runoff contributes to the total pollutant load. In this study, we collected samples from ten sites along on the banks of an urban river during five rainfall events. We determined the grain size and phosphorus (P) forms in the particulate matter to assess how much P there was in storm runoff. The results showed that the particles were mostly medium-sized, and particles with a diameter of less than 850 μm but greater than 150 μm accounted for 50% of the total particulate matter. The average particulate P concentration, at 298.7 mg/kg, was high and was mostly organic P (Po), which had an average concentration of 134.64 mg/kg. The concentrations of the different P forms varied with particle size. The main fraction in the large-sized grains was acid-extractable inorganic P (Pi), while Po and alkalinity-extractable Pi dominated in medium- and small-sized particles. Overall, our results illustrate that, by enhancing the control of particulate matter in storm runoff, P, and in particular Po, inputs to urban rivers can be reduced.

The effect of anthropogenic activities on the phosphorus-buffering intensity of the two contrasting rivers in northern China

The phosphorus (P)-buffering ability of suspended particulate matter (SPM) from the Ziya River Mainstream (ZRM) and the Luanhe River (LR) of northern China was investigated in this study. Forty samples of SPM from the ZRM and LR were collected in October and November of 2016. The ZRM has slow flow and poor water quality, while the LR has fast flow and reasonably good water quality. Under a scanning electron microscope, the SPM from the ZRM had a more complex microstructure than that from the LR, perhaps because of the slower flow and heavier pollution in the ZRM. P fractions in both SPM and water samples were determined using standard measurement and testing program methods. The equilibrium P concentration was used to determine the influence of SPM on soluble reactive P (SRP) concentrations. These SRP fractions were used to evaluate the P-buffering intensity of the two rivers. Differences in SPM microstructure resulted in the SPM from ZRM having a stronger P-buffering ability than the LR, making SPM an effective vector for SRP. Anthropogenic activities likely contributed to the differences in both microstructures of the SPM and P-buffering intensity of the rivers. A conceptual model was developed to show how anthropogenic activities influence the P-buffering intensity of the two rivers. As far as we know, this is the first time that the P-buffering intensity has been compared between two rivers that have been severely impacted by anthropogenic activities. Our findings provide an important reference for similar rivers worldwide.

Relationship of bioaccessibility and fractionation of cadmium in long-term spiked soils for health risk assessment based on four in vitro gastrointestinal simulation models

The bioavailability and bioaccessibility of heavy metals mainly depend on their speciation in soils; however, the relationship between bioaccessibility and its speciation as determined as fractionation remains to be better characterized. Therefore, Cd fractionations in three types of long-term Cd-spiked soils were determined using a modified BCR method, and compared with Cd bioaccessibility data obtained from four in vitro gastrointestinal simulation assays including the IVG, PBET, SBRC, and UBM. The results shows that the majority of Cd were found in the exchangeable/acid soluble (B1) and reducible (B2) fractions (total percentage>97%) after being spiked and aged for three years, indicating high Cd bioavailability; the bioaccessibility of Cd ranged from 57.7±1.8% to 99.3±2.8% in the gastric phase, and from 5.8±2.0% to 35.9±1.8% in the intestinal phase, respectively. Among the four assays, the strongest positive correlation was observed between Cd bioaccessibility based on the PBET assay and its B1 fraction in the spiked soils (r² gastric: 0.62 and intestinal: 0.52), suggesting that the PBET assay maybe more suitable for determining Cd bioaccessibility in aged contaminated soils.

Characteristics of suspended particulate matter in a typical slow-moving river of northern China: Insight into its structure and motion behavior

To investigate the characteristics of suspended particulate matter (SPM) in rivers of northern China, SPM was collected from 20 sampling sites within the severely polluted slow-moving Ziya River Mainstream (ZRM) and from 20 sampling sites within the less-polluted fast-moving Luanhe River (LR) between October and November of 2016. Physical and chemical attributes of river water from the ZRM and LR were measured; the microstructure, specific surface area and particle size of the SPM were also determined. The SPM had thicker organic coated layers on inorganic particles within the ZRM, compared with the LR, indicating strong interaction of the SPM with the water column. Along the ZRM length, these organic coated layers evolved, first plugging particle pores and then increasing in volume, causing the specific surface area to decrease at first and then increase. The presence of organic coated layers on inorganic particles greatly changed their particle size, density and inducing changes in their motion behavior. Such changes in SPM microstructure were most apparent in the slow-moving polluted ZRM. Given that SPM can adsorb contaminants, such as phosphorus and heavy metals, onto its surfaces and transport them downstream, these changes could have a profound impact on both sediment transport and river ecosystem function. Our results suggest we need to reevaluate our previous river management measures for slow-moving polluted rivers.

Evaluating the diffusive gradients in thin films technique for the prediction of metal bioaccumulation in plants grown in river sediments

The diffusive gradients in thin films (DGT) technique is a useful tool for assessing metal bioavailability in sediments. However, the DGT technique has not been used to predict metal bioaccumulation in plants grown in sediments in river systems. In this study, the DGT technique was evaluated for predicting metal bioaccumulation in Phragmites australis growing in contaminated sediments. In sediments with high levels of contamination, release of DGT-labile Cr, Zn, Cu, and Cd occurred, which resulted in high bioaccumulation of these metals in P. australis. Bioaccumulation of Cr, Cu, Zn, and Cd was strongly correlated with the metal concentrations in the sediments measured by the DGT technique. By contrast, the correlation between sediment content and bioaccumulation for As was weak. There were significant negative correlations between the content of Ni in the plant tissues and the contents of the other metals. Overall, the DGT technique provided predictions of metal bioaccumulation similar to those obtained using total metal measurements in multiple polluted sediment samples. Therefore, DGT analysis could be used for assessing heavy metal bioavailability, and metal bioaccumulation in P. australis was not all significantly correlated with the bioavailability concentrations of metals in river sediments.

Data collected in an integrated ecological survey of rotifer communities and corresponding environmental variables in the highly polluted Haihe River Basin, China

Here we presented two datasets (biological and environmental datasets) collected in a comprehensive large geographical scale (approximately 1.1×10⁵ km²) survey of rivers/streams in the Haihe River Basin (HRB), which has become the most polluted river basin in past two decades in China. The survey selected a total of 94 representative sampling sites in the plain region of HRB, where environmental pollution is more severe than the mountain region. The biological dataset contains the information on the identified rotifer species and their abundance, while the environmental dataset provides the measured environmental variables at each sampling site. Based on this ecological survey, we identified a total of 91 rotifer species and their abundance, as well as abundance of two crucial taxonomic groups on rotifers’ food webs (i.e., protozoans and crustaceans), and also presented seven environmental variables, particularly those associated with nitrogen and phosphorus pollution.

Assessment of potential bioavailability of heavy metals in the sediments of land-freshwater interfaces by diffusive gradients in thin films

It is important to understand the potential bioavailability of heavy metals in the sediments of land-freshwater interfaces (between terrestrial and aquatic ecosystems). Therefore, we evaluated the pollution of Cr, Ni, Cu, Zn, As, and Cd in land-freshwater interface sediments/soils according to total concentrations, and used sequential extraction method to measure different fractions of Cd. Then, the diffusive gradients in thin films (DGT) technique was employed to study the potential bioavailability of metals. Results showed that the concentrations of exchangeable and weak acid soluble fraction and oxidizable fraction were higher in ecotone area, and the values of reducible fraction and residual fraction were higher in deep water area. There existed significant positive correlations between [Cd]-DGT (concentration of Cd measured by DGT) and EXC-Cd (exchangeable and weak acid soluble fraction of Cd) (r² = 0.65), but the significant negative correlation was found between [Cd]-DGT and RES-Cd (Residual fraction of Cd) (r² = 0.52). DGT technique is a feasible method to measure potential bioavailability of heavy metals for risk assessment in the sediments/soils of land-freshwater interfaces.

Overestimation of orthophosphate monoesters in lake sediment by solution 31P-NMR analysis

Solution ³¹P nuclear magnetic resonance spectroscopy (³¹P-NMR) is a useful method for analyzing organic phosphorus (P_o). Unfortunately, the extraction conditions, which are highly alkaline and require long extraction times, make this analysis less effective. In this research, according to the lability of orthophosphate monoesters (mono-P_o) and orthophosphate diesters (diesters-P_o), we verified the hypothesized overestimation of mono-P_o in lake sediment using solution ³¹P-NMR. We set three scenes to redistribute the mono-P_o and diesters-P_o. Six components, including eight mono-P_o species, were detected in the NaOH-EDTA extracts of sediment samples using ³¹P-NMR. The results showed that mono-P_o (212.7 mg kg^-1) was the dominant P_o in the surface sediment. In the three scenes, mono-P_o decreased from 212.7 to 112.0 mg kg^-1, and diesters-P_o increased from 31.9 to 132.7 mg kg^-1. The ratio of mono-P_o to diesters-P_o increased from 6.7 to 0.8. Therefore, we deduced that the concentration of mono-P_o was overestimated, while that of diesters-P_o was underestimated, in most research because of the high pH and long extraction process. Diesters-P_o might be an important labile P source during the P "exhausted" period.

A scheme to scientifically and accurately assess cadmium pollution of river sediments, through consideration of bioavailability when assessing ecological risk

Evaluating heavy metal pollution status and ecological risk in river sediments is a complex task, requiring consideration of contaminant pollution levels, as well as effects of biological processes within the river system. There are currently no simple or low-cost approaches to heavy metal assessment in river sediments. Here, we introduce a system of assessment for pollution status of heavy metals in river sediments, using measurements of Cd in the Shaocun River sediments as a case study. This system can be used to identify high-risk zones of the river that should be given more attention. First, we evaluated the pollution status of Cd in the river sediments based on their total Cd content, and calculated a risk assessment, using local geochemical background values at various sites along the river. Using both acetic acid and ethylenediaminetetraacetic acid to extracted the fractions of Cd in sediments, and used DGT to evaluate the bioavailability of Cd. Thus, DGT provided a measure of potentially bioavailable concentrations of Cd concentrations in the sediments. Last, we measured Cd contents in plant tissue collected at the same site to compare with our other measures. A Pearson's correlation analysis showed that Cd-Plant correlated significantly with Cd-HAc, (r = 0.788, P < 0.01), Cd-EDTA (r = 0.925, P < 0.01), Cd-DGT (r = 0.976, P < 0.01), and Cd-Total (r = 0.635, P < 0.05). We demonstrate that this system of assessment is a useful means of assessing heavy metal pollution status and ecological risk in river sediments.

Comprehensive analysis of mercury pollution in the surface riverine sediments in the Haihe Basin, China

The Haihe Basin extends over 318,000 km² or 3.3% of the total area of China, has a population of over 120 million, and is one of China's most polluted river basins. We investigated the pollution and risks from mercury (Hg) in surface riverine sediments of this basin and found that total Hg concentrations in surface sediments ranged from 0.001 to 1.05 mg/kg and averaged 0.054 mg/kg. Using the modified European Community Bureau of Reference standard method, we found that the exchangeable/acid-soluble, reducible, oxidizable, and residual fractions of Hg accounted for 9.86, 6.54, 11.0, and 72.6% of total Hg, respectively. The riverine sediments in the Da Qing He watershed had the highest anthropogenic enrichment of Hg (enrichment factor >1.5). There was a high potential ecological risk from Hg in the riverine sediments in the upper reaches of the Bei San He and Da Qing He watersheds, the middle reaches of the Luan He and Hei Long Gang watersheds, and the lower reaches of the Zi Ya He watershed. Comparison with risk assessment code showed that the riverine sediments in the Da Qing He, Luan He, and Tu-Hai Ma-Xia He watersheds represented a medium risk, with 16.6, 11.9, and 11.8% of Hg in the exchangeable/acid-soluble fraction, respectively.

Assessment of the sediment quality of freshwater ecosystems in eastern China based on spatial and temporal variation of nutrients

Comprehensively characterizing and assessing the sediment quality in freshwater ecosystems based on the condition of the nutrients in eastern China was urgent. The distribution and concentration of nutrients were investigated; meanwhile, sediment quality guidelines (SQGs), organic pollution index (OPI), and organic nitrogen index (ONI) were used to assess the sediment quality. Total phosphorus (TP), total nitrogen (TN), and total sulfur (TS) concentrations in sediment samples were 48.4, 72.5, and 89.5% higher than the soil background value, respectively. In terms of the Ontario SQGs, 41.8 and 74.7% of sediment samples were severely polluted by TP and TN, respectively. The Haihe, Yangtze, and Pearl River Basins were much more severely contaminated than other basins. TN pollution was much more severe than TP pollution in all basins. The Haihe, Huaihe, and Pearl River Basins were seriously contaminated according to the OPI and ONI. On temporal scale, the TP and TN significantly increased since 1980s because of the social and economic development in eastern China. For most severely contaminated basins, TN contamination was higher than TP contamination, and concentrations of TN and TP continuously increased from 2007 to 2016, which ranged from 2.06 to 2.51 g/kg, and 1.02 to 1.22 g/kg, respectively, in the Haihe River Basin. This trend will continue without effective control. The freshwater sediment quality in eastern China revealed urgent attention.

Comparison of cadmium and lead sorption by Phyllostachys pubescens biochar produced under a low-oxygen pyrolysis atmosphere

Phyllostachys pubescens (PP) biochars produced under a low oxygen pyrolysis atmosphere (oxygen content 1-4%) were prepared as sorbents for investigating the mechanisms of cadmium and lead sorption. A low-oxygen pyrolysis atmosphere increased biochar ash and specific surface area, promoting heavy metal precipitation and complexation. The maximum sorption capacity (Q_m) of Pb²⁺ obtained from the Langmuir model was 67.4mg·g^-1, while Q_m of Cd²⁺ was 14.7mg·g^-1. The contribution of each mechanism varied with increasing oxygen content at a low pyrolysis temperature. Mineral precipitation with Pb²⁺ was the predominant mechanism for Pb²⁺ removal and the contribution proportion significantly increased from 17.2% to 71.7% as pyrolysis oxygen atmosphere increased from 0% to 4%. The results showed that cadmium sorption primarily involved coordination with π electrons, at 54.1-82.6% of the total adsorption capacity. The PP biochar shows potential for application in removing heavy metal contaminants, especially Pb²⁺.

Alleviation of enterotoxigenic Escherichia coli challenge by recombinant Lactobacillus plantarum expressing a FaeG- and DC-targeting peptide fusion protein

FaeG is the major subunit of K88 fimbriae. These cell surface attachments are considered to be the major virulence factor of enterotoxigenic Escherichia coli (ETEC), which causes diarrhoea in piglets. The use of dendritic cell-targeting peptide (DCpep) has been demonstrated to be an effective approach to enhance the immunity of vaccines. Lactobacillus plantarum is an attractive candidate for oral vaccination owing to its beneficial effects and safety. In this study, L. plantarum was employed to deliver a FaeG-DCpep fusion antigen, and the immune response in mice was evaluated. The synthesis of FaeG-DCpep dramatically increased the adhesion of recombinant L. plantarum (RLP) to IPEC-J2 cell surfaces, resulting in direct competition between L. plantarum and ETEC during adhesion assays. Significantly higher levels of body weight gain, sera immunoglobulin G and intestinal immunoglobulin A were observed in BALB/c mice immunised with RLP. In addition, the number of CD19+ B cells and CD11c+DC cells and the expression levels of several cytokines in the spleen and lymph nodes increased significantly compared to non-immunised mice. The oral administration of RLP also alleviated the symptoms of ETEC challenge, as shown by haematoxylin-eosin staining, indicating that RLP may be an efficient vaccine candidate.

Using Chironomus dilutus to identify toxicants and evaluate the ecotoxicity of sediments in the Haihe River Basin

To effectively manage a watershed and successfully restore a river system, it is very important to assess the toxicity of sediments and identify the substances causing the toxicity. Seventy-six sediments collected in the Haihe River Basin (HRB) in China were screened for acute toxicity using Chironomus dilutus. We found that sediments from more than 32% of sampling sites, distributed mainly in the Ziya tributary and along the estuary, were acutely toxic to midges. A toxicity identification evaluation showed that the toxicity of the sediment samples was mainly from ammonia nitrogen, metals, and organics. Calculations of the toxic unit (TU) showed that ammonia and metals contributed more to sediment toxicity than organics, and that PAHs may have contributed in other tributaries. A modified three-step sequential extraction procedure to assess the bioavailability of the metals indicated that the toxicity from metals was mainly from Cd and Zn. This is one of the first studies in which this type of approach has been applied to directly connect contaminants with ecological effects in the HRB.

Pollution, toxicity, and ecological risk of heavy metals in surface river sediments of a large basin undergoing rapid economic development

A comprehensive and detailed investigation of heavy metal pollution, toxicity, and ecological risk assessment was conducted for the surface river sediments of the Haihe Basin in China based on 220 sampling sites selected in 2013. The average concentrations of Cr, Cu, Ni, Pb, and Zn in the sediments were 129 mg/kg, 63.4 mg/kg, 36.6 mg/kg, 50.0 mg/kg, and 202 mg/kg, respectively. As indicated by the geoaccumulation and pollution load indices, most surface river sediments of the Haihe Basin were contaminated with the investigated metals, especially in the junction region of the Zi Ya He and Hei Long Gang watersheds. The 5 heavy metals in the sediments all had anthropogenic sources, and the enrichment degrees followed the order Cu > Pb > Zn > Cr > Ni, with mean enrichment factors of 3.27, 2.77, 2.58, 1.81, and 1.44, respectively. According to the mean index of comprehensive potential ecological risk (38.9), the studied sediments of the Haihe Basin showed low potential ecological risk, but the sediments were potentially biologically toxic based on the mean probable effect concentration quotient (0.547), which may be the result of speciation of the 5 metals in the sediments. The results indicate that heavy metal pollution should be considered during the development of ecological restoration strategies in the Haihe Basin. Environ Toxicol Chem 2017;36:1149-1155. © 2016 SETAC.