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The heavy metal accumulation in the Tibet Plateau (TP) poses a serious ecologic risk to the health of human and the other biota. Given the TP far away from the large anthropogenic emission sources, the rapid development of traffic activities during last several decades possibly leads to the elevated heavy metal concentration in the roadside soils. Therefore, we comprehensively assessed the heavy metal distribution in the 0–5 cm and 15–20 cm depth soils located at 5 m, 50 m, and 100 m distance to the edge of two major roads among the different vegetation covers and climatic conditions in the TP to verify this hypothesis. Results show that most of heavy metal concentrations in soils of different distance to the major road display an insignificant difference. The Nemero Synthesis indexes which represent the risk of pollution for these regions almost range 1 to 2 (low pollution risk), except 12.7 (extreme pollution risk) at one site. These indicate the limited impacts from the traffic activities for the whole region, but at some specific sites with the elevated traffic pollution. The forest cover at the altitude of 3700–4100 m has the highest mercury accumulation due to the vegetation and climatic factors induced the higher atmospheric depositions and stronger complexation with the organic matters. The statistical analysis finally suggests the geogenic weathering processes, climate, terrain and vegetation play an important role in shaping heavy metal distribution along the roadside of the TP.
Siwei An; Nantao Liu; Xianming Li; Shufang Zeng; Xun Wang; Dingyong Wang. Understanding heavy metal accumulation in roadside soils along major roads in the Tibet Plateau. Science of The Total Environment 2021, 802, 149865 .
AMA StyleSiwei An, Nantao Liu, Xianming Li, Shufang Zeng, Xun Wang, Dingyong Wang. Understanding heavy metal accumulation in roadside soils along major roads in the Tibet Plateau. Science of The Total Environment. 2021; 802 ():149865.
Chicago/Turabian StyleSiwei An; Nantao Liu; Xianming Li; Shufang Zeng; Xun Wang; Dingyong Wang. 2021. "Understanding heavy metal accumulation in roadside soils along major roads in the Tibet Plateau." Science of The Total Environment 802, no. : 149865.
Straw sizes were found to affect the methylmercury (MeHg) accumulation in rice grains induced by straw incorporation. The mechanism behind, however, still remains unclear. Here, we incorporated rice straw in different sizes (powder, 2 cm and 5 cm) into a Hg-contaminated paddy soil. Our results showed that straw sizes regulated the release of different fractions of organic matter (OM) in straw residues and further Hg methylation in paddy soil. The easily degradable OM (EDOM) was a key driving factor that facilitated net Hg methylation, though it only occupied a small fraction (1.12–3.12%) of the soil OM. Powdered straw reduced the duration of net Hg methylation by 74.39% compared to 5 cm straw, resulting in a strong and rapid net Hg methylation in paddy soil before the rice flowering. After the release of EDOM, the humified OM dominated in paddy soil and bound to MeHg, leading to less MeHg being transported to rice grains during the grain filling. Powdered straw decreased MeHg accumulation by 25.32% in the mature rice grains compared with 5 cm straw. Our study suggests that straw powdering before incorporation provides a feasible pathway for reducing MeHg accumulation in rice grains induced by straw incorporation.
Tao Sun; Yongmin Wang; Chuxian Li; Jinyong Huang; Yingpeng Hua; Caipeng Yue; Hongbo Chao; Dingxi Zhang; Yongjiang Zhang; Dingyong Wang. Use smaller size of straw to alleviate mercury methylation and accumulation induced by straw incorporation in paddy field. Journal of Hazardous Materials 2021, 423, 127002 .
AMA StyleTao Sun, Yongmin Wang, Chuxian Li, Jinyong Huang, Yingpeng Hua, Caipeng Yue, Hongbo Chao, Dingxi Zhang, Yongjiang Zhang, Dingyong Wang. Use smaller size of straw to alleviate mercury methylation and accumulation induced by straw incorporation in paddy field. Journal of Hazardous Materials. 2021; 423 ():127002.
Chicago/Turabian StyleTao Sun; Yongmin Wang; Chuxian Li; Jinyong Huang; Yingpeng Hua; Caipeng Yue; Hongbo Chao; Dingxi Zhang; Yongjiang Zhang; Dingyong Wang. 2021. "Use smaller size of straw to alleviate mercury methylation and accumulation induced by straw incorporation in paddy field." Journal of Hazardous Materials 423, no. : 127002.
Mercury (Hg), a highly toxic element, poses severe risks to human health worldwide. Potential health risks have been reported to be resulted from elemental, inorganic, and organic Hg (e.g., methylmercury, MeHg) exposure, and these forms of Hg primarily originate from gold or Hg mining, Hg-related industries, and Hg-contaminated food (e.g., fish and rice). The analysis of Hg in human hair serves as a reliable tool for investigating potential Hg exposure to human body and thus for revolving health concerns. This review builds on the dataset of Hg in hair from a vast array of existing studies conducted in 88 regions of 44 countries across the globe. In essence, it focuses on different pathways of Hg exposure, levels of Hg exposure of different exposure populations in different regions, and Hg speciation in hair and its corresponding sources.
Yongmin Wang; Linjun Li; Cong Yao; Xiaosong Tian; Yurong Wu; Qing Xie; Dingyong Wang. Mercury in human hair and its implications for health investigation. Current Opinion in Environmental Science & Health 2021, 22, 100271 .
AMA StyleYongmin Wang, Linjun Li, Cong Yao, Xiaosong Tian, Yurong Wu, Qing Xie, Dingyong Wang. Mercury in human hair and its implications for health investigation. Current Opinion in Environmental Science & Health. 2021; 22 ():100271.
Chicago/Turabian StyleYongmin Wang; Linjun Li; Cong Yao; Xiaosong Tian; Yurong Wu; Qing Xie; Dingyong Wang. 2021. "Mercury in human hair and its implications for health investigation." Current Opinion in Environmental Science & Health 22, no. : 100271.
Three Gorges Dam (TGD) is the largest hydroelectric construction in the world, and its potential impacts on the ecological environment and human health risks have invoked considerable global concern. However, as a Hg sensitive system, limited work was conducted on the Hg exposure level of local residents around the Three Gorges Reservoir (TGR). Thus, 540 human hair samples and 22 species of local food samples were collected to assess the Hg exposure and human health risk to the residents located in the Three Gorges Reservoir Region (TGRR) and to investigate their dietary exposure to Hg. The results showed that the geometric mean concentrations of THg and MeHg in hair were 0.42 ± 0.43 μg g-1 and 0.23 ± 0.32 μg g-1, respectively, lower than the reference level (1.0 μg g-1) recommended by the United States Environmental Protection Agency (US EPA), indicating a low level Hg exposure for residents around the TGR. No significant difference in the accumulation of Hg in hair between the gender subgroups was observed, whereas age difference, smoking and alcohol drinking behavior, and fish consumption frequency were significant predictors of hair Hg level. Besides, THg and MeHg of all the investigated food samples did not exceed the corresponding Chinese national standard. The average probable daily intakes (PDIs) of THg and MeHg were 0.032 μg kg-1 day-1 and 0.007 μg kg-1 day-1, which were obviously below the recommended values of 0.57 μg kg-1 day-1 and 0.1 μg kg-1 day-1, respectively. The cereal (mainly rice) contribution of THg (76.0%) and MeHg (74.4%) intakes to the local residents around the TGR was much higher than that of fish (10.7% and 22.9%) due to the considerable rice consumption. Overall, residents around the TGR were at a low Hg exposure and rice consumption was the major pathway for Hg exposure.
Qing Xie; Yongmin Wang; Shouying Li; Cheng Zhang; Xiaosong Tian; Nan Cheng; Yongjiang Zhang; Dingyong Wang. Total mercury and methylmercury in human hair and food: Implications for the exposure and health risk to residents in the Three Gorges Reservoir Region, China. Environmental Pollution 2021, 282, 117041 .
AMA StyleQing Xie, Yongmin Wang, Shouying Li, Cheng Zhang, Xiaosong Tian, Nan Cheng, Yongjiang Zhang, Dingyong Wang. Total mercury and methylmercury in human hair and food: Implications for the exposure and health risk to residents in the Three Gorges Reservoir Region, China. Environmental Pollution. 2021; 282 ():117041.
Chicago/Turabian StyleQing Xie; Yongmin Wang; Shouying Li; Cheng Zhang; Xiaosong Tian; Nan Cheng; Yongjiang Zhang; Dingyong Wang. 2021. "Total mercury and methylmercury in human hair and food: Implications for the exposure and health risk to residents in the Three Gorges Reservoir Region, China." Environmental Pollution 282, no. : 117041.
The effects of long-term applications of fertilizer form and rate on methylmercury concentration in rice grain have been previously reported. However, there remains a large gap in understanding fertilizer treatments affect the transformation of mercury (Hg) in paddy soils and the translocation of Methylmercury (MeHg) in rice plants. Thus, we investigated the effects of four fertilizer treatments (NK, nitrogen and potassium; NPK, nitrogen, phosphorus and potassium; NPKM, nitrogen, phosphorus, potassium and swine manure; and NPKS, nitrogen, phosphorus, potassium and rice straw) on mercury (Hg) methylation in paddy soils and on MeHg translocation in rice plants after a 24-year period; specifically, we investigated differences in MeHg production in paddy soils and MeHg mass flow in rice plants. The results showed that Geobacteracea and Methanosarcinacea were the major Hg-methylating microorganisms and their relative abundances were significantly promoted by rice straw return, which led to the significantly higher MeHg concentration both in paddy soils and in the rice grain of NPKS treatment compared with control. In addition, the phosphate and organic fertilizers increased MeHg translocation from the roots to the leaves and grain more than the nitrogen and potassium fertilizers did. In detail, compared with the control, NK increased MeHg concentrations in the rice grain by approximately 1-fold; NPK and NPKM, by approximately 3-fold; and NPKS, by approximately 8-fold. Last, we suggest that policy-makers worldwide should comprehensively assess the high potential risk of MeHg in rice grain in large production areas where rice straw is returned.
Zhenya Tang; Fangling Fan; Xun Wang; Xiaojun Shi; Dingyong Wang. Understanding the effects of long-term different fertilizer applications on methylmercury accumulation in rice (Oryza sativa L.) plants. Science of The Total Environment 2021, 777, 146125 .
AMA StyleZhenya Tang, Fangling Fan, Xun Wang, Xiaojun Shi, Dingyong Wang. Understanding the effects of long-term different fertilizer applications on methylmercury accumulation in rice (Oryza sativa L.) plants. Science of The Total Environment. 2021; 777 ():146125.
Chicago/Turabian StyleZhenya Tang; Fangling Fan; Xun Wang; Xiaojun Shi; Dingyong Wang. 2021. "Understanding the effects of long-term different fertilizer applications on methylmercury accumulation in rice (Oryza sativa L.) plants." Science of The Total Environment 777, no. : 146125.
Limited information is available about the bio-methylation of inorganic mercury (iHg) under aerobic conditions. In this study, two γ-proteobacteria strains (P. fluorescens TGR-B2 and P. putida TGR-B4) were obtained from the soil of The Three Gorges Reservoir (TGR), demonstrating effective aerobic transformation capacities of iHg into methylmercury (MeHg). Based on periodical changes in soil oxygen content of the TGR, a culture system was established, in which 300 ng Hg (II) L–1 and O2 were set at 7%, 14%, and 21%, respectively. Results indicated that the two strains differed significantly in bacterial growth rate and MeHg production. The kinetic model of MeHg showed typical characteristics of a “two-staged” process: The first stage was dominated by bio-methylation, which was shown by increasing of net MeHg content. Moreover, the second stage was dominated by bio-demethylation, which decreased net MeHg content. Thus, we hypothesized that the mechanism of aerobic bacterial iHg bio-methylation: (1) should inefficiency compared to anaerobic bacteria i.e.SRB, which were regulated by hgcA/B gene clusters, (2) might be regarded as a passive stress response and depended on the bacterial iHg intoxication threshold and MeHg tolerance threshold.
Dan Cao; Weihong Chen; Yuping Xiang; Qianfen Mi; Hang Liu; Pengyu Feng; Hong Shen; Cheng Zhang; Yongmin Wang; Dingyong Wang. The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations. Ecotoxicology and Environmental Safety 2020, 207, 111538 .
AMA StyleDan Cao, Weihong Chen, Yuping Xiang, Qianfen Mi, Hang Liu, Pengyu Feng, Hong Shen, Cheng Zhang, Yongmin Wang, Dingyong Wang. The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations. Ecotoxicology and Environmental Safety. 2020; 207 ():111538.
Chicago/Turabian StyleDan Cao; Weihong Chen; Yuping Xiang; Qianfen Mi; Hang Liu; Pengyu Feng; Hong Shen; Cheng Zhang; Yongmin Wang; Dingyong Wang. 2020. "The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations." Ecotoxicology and Environmental Safety 207, no. : 111538.
Water and sediment samples were collected from a tributary (Ruxi River) of the Three Gorges Reservoir (TGR) to analyze the concentrations of seven heavy metals (HMs) and their fractions for better understanding the migration, bioavailability and potential environmental risk of HMs. The results indicated that the concentrations of HMs in water were lower than the Environmental Quality Standards for Surface Water Class I standards, except for Ni. Cd in sediment was found to be more sensitive to environmental changes, as the acid-soluble fraction of Cd accounted for about 40% of total Cd, and the sediment–water partition coefficient of Cd was the smallest among all the HMs. Meanwhile, multiple risk assessment methods of HMs indicated that sediment Cd in most sampling sites, significantly influenced by human activities, exhibited heavy pollution, suggesting that the Cd pollution should be attached great importance in the Ruxi River.
Zhiqing Fang; Yongmin Wang; Deti Xie; Dingyong Wang. Potential Ecological Risk of Heavy Metals in a Typical Tributary of the Three Gorges Reservoir. Bulletin of Environmental Contamination and Toxicology 2020, 106, 18 -23.
AMA StyleZhiqing Fang, Yongmin Wang, Deti Xie, Dingyong Wang. Potential Ecological Risk of Heavy Metals in a Typical Tributary of the Three Gorges Reservoir. Bulletin of Environmental Contamination and Toxicology. 2020; 106 (1):18-23.
Chicago/Turabian StyleZhiqing Fang; Yongmin Wang; Deti Xie; Dingyong Wang. 2020. "Potential Ecological Risk of Heavy Metals in a Typical Tributary of the Three Gorges Reservoir." Bulletin of Environmental Contamination and Toxicology 106, no. 1: 18-23.
Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.
Zhenya Tang; Fangling Fan; Shiping Deng; Dingyong Wang. Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review. Ecotoxicology and Environmental Safety 2020, 202, 110950 .
AMA StyleZhenya Tang, Fangling Fan, Shiping Deng, Dingyong Wang. Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review. Ecotoxicology and Environmental Safety. 2020; 202 ():110950.
Chicago/Turabian StyleZhenya Tang; Fangling Fan; Shiping Deng; Dingyong Wang. 2020. "Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review." Ecotoxicology and Environmental Safety 202, no. : 110950.
In the recent decade, the hydroelectric reservoir is identified as a methylmercury (MeHg) hotspot and gained much attention. The artificial water level management in the Three Gorges Reservoir (TGR) in China formed a water-level-fluctuation zone (WLFZ) undergoing flooding drying rotations annually. However, the mercury (Hg) methylation and major geochemical driving factors at different elevations in the WLFZ remain unclear. Here we use total Hg (HgT) normalized MeHg (MeHg/HgT ratio) to evaluate Hg methylation degree in a one-year field study at 155, 165 m elevations in the WLFZ and with >175 m elevation as the reference. Results demonstrate that MeHg/HgT ratio at the WLFZ could reach 4.1% in soils, and both 155 and 165 m elevations have a higher Hg methylation degree than the >175 m elevation. However, the differences in MeHg/HgT ratios both in soils and waters between 155 and 165 m elevations are not significant. This indicates the influence of different submerging periods on the MeHg/HgT at the WLFZ elevations is not observed. The significant correlation between the MeHg/HgT ratio and soil organic carbon (SOC) content implies a MeHg retention in re-exposed soils after flooding. Decoupling of MeHg/HgT ratios between submerged soil and overlying water are found at both elevations and therefore make MeHg/HgT in waters alone cannot be used to evaluate Hg methylation degree in this study. The calculation of HgT and MeHg partitioning coefficient (Kd) found an immobilization of MeHg by submerged soils at the WLFZ during the flooding period. Major geochemical factors, determined through principal component analysis (PCA), in affecting Hg methylation are the redox cycling of sulfur and the distribution of organic matters in the WLFZ.
Jiang Liu; Dingyong Wang; Jinzhong Zhang; Van Liem-Nguyen; Rong Huang; Tao Jiang. Evaluation of Hg methylation in the water-level-fluctuation zone of the Three Gorges Reservoir region by using the MeHg/HgT ratio. Ecotoxicology and Environmental Safety 2020, 195, 110468 .
AMA StyleJiang Liu, Dingyong Wang, Jinzhong Zhang, Van Liem-Nguyen, Rong Huang, Tao Jiang. Evaluation of Hg methylation in the water-level-fluctuation zone of the Three Gorges Reservoir region by using the MeHg/HgT ratio. Ecotoxicology and Environmental Safety. 2020; 195 ():110468.
Chicago/Turabian StyleJiang Liu; Dingyong Wang; Jinzhong Zhang; Van Liem-Nguyen; Rong Huang; Tao Jiang. 2020. "Evaluation of Hg methylation in the water-level-fluctuation zone of the Three Gorges Reservoir region by using the MeHg/HgT ratio." Ecotoxicology and Environmental Safety 195, no. : 110468.
Fish cage farming has been generally banned in some regions since there is growing concern about adverse environmental issue caused by cage culture practices. This paper presents the long-term effects of past cage culture activities on heavy metal accumulation in sediment and fish in one historical cage culture lake (Changshou reservoir, Chongqing, China). Although cages were removed for over one decade in this studied lake, the average concentrations of heavy metals in sediments were still above 2 times higher than their background values, posing a moderate ecological risk. Higher levels of heavy metals appeared in demersal fish who is more susceptible to heavy metals exposure in sediment. Fish consumption would not lead to a significant health risk of most heavy metals. Hg levels in catfish posed a health risk to vulnerable group (children) and specific group (fishermen), whereas the presence of Se decreased Hg toxicity to a safety level. Therefore, it can be speculated that the cage culture activities could influence the heavy metal accumulation in sediment in the long term, however, consumption of current farmed fish in one lake used to carry out cage-culture is safe for local residents.
Qing Xie; Lishan Qian; Shanyi Liu; Yongmin Wang; Yongjiang Zhang; Dingyong Wang. Assessment of long-term effects from cage culture practices on heavy metal accumulation in sediment and fish. Ecotoxicology and Environmental Safety 2020, 194, 110433 .
AMA StyleQing Xie, Lishan Qian, Shanyi Liu, Yongmin Wang, Yongjiang Zhang, Dingyong Wang. Assessment of long-term effects from cage culture practices on heavy metal accumulation in sediment and fish. Ecotoxicology and Environmental Safety. 2020; 194 ():110433.
Chicago/Turabian StyleQing Xie; Lishan Qian; Shanyi Liu; Yongmin Wang; Yongjiang Zhang; Dingyong Wang. 2020. "Assessment of long-term effects from cage culture practices on heavy metal accumulation in sediment and fish." Ecotoxicology and Environmental Safety 194, no. : 110433.
Soil dissolved organic matter (DOM) plays an essential role in the Three Gorges Reservoir (TGR) as a linkage between terrestrial and aquatic systems. In particular, the reducing capacities of soil DOM influence the geochemistry of contaminants such as mercury (Hg). However, few studies have investigated the molecular information of soil DOM and its relationship with relevant geochemical reactivities, including redox properties. We collected samples from eight sites in the TGR areas and studied the link between the molecular characteristics of DOM and their electron donation capacities (EDCs) toward Hg(II). The average kinetic rate and EDC of soil DOM in TGR areas were (0.004 ± 0.001) hr−1 and (2.88 ± 1.39) nmol e−/mg DOMbulk, respectively. Results suggest that higher EDCs and relatively rapid kinetics were related to the greater electron donating components of lignin-derived and perhaps pyrogenic DOM, which are the aromatic constituents that influenced the reducing capacities of DOM in the present study. Molecular details revealed that even the typical autochthonous markers are important for the EDCs of DOM as well, in contrast to what is generally assumed. More studies identifying specific DOM molecular components involved in the abiotic reduction of Hg(II) are required to further understand the relations between DOM sources and their redox roles in the environmental fate of contaminants.
Tao Jiang; Joeri Kaal; Jiang Liu; Jian Liang; Yaoling Zhang; Dingyong Wang. Linking the electron donation capacity to the molecular composition of soil dissolved organic matter from the Three Gorges Reservoir areas, China. Journal of Environmental Sciences 2019, 90, 146 -156.
AMA StyleTao Jiang, Joeri Kaal, Jiang Liu, Jian Liang, Yaoling Zhang, Dingyong Wang. Linking the electron donation capacity to the molecular composition of soil dissolved organic matter from the Three Gorges Reservoir areas, China. Journal of Environmental Sciences. 2019; 90 ():146-156.
Chicago/Turabian StyleTao Jiang; Joeri Kaal; Jiang Liu; Jian Liang; Yaoling Zhang; Dingyong Wang. 2019. "Linking the electron donation capacity to the molecular composition of soil dissolved organic matter from the Three Gorges Reservoir areas, China." Journal of Environmental Sciences 90, no. : 146-156.
The reducing capacity (RC) of natural organic matter plays an important role in the carbon cycle and biogeochemical fates of environmental contaminants in the aquatic system. However, the electron donation potentials of dissolved organic matter (DOM) from high-latitude lakes are still uncertain. In this study, we collected DOM samples from high-latitude lakes across the Arctic and boreal regions in Sweden and Norway to investigate the effects of the DOM concentration and characteristics on its ambient reducing capacity (ARC). Mercury (Hg(II)) abiotic reduction in darkness was used to determine the ARC. The results showed that the DOM in Arctic lakes is less terrestrial-dominant than in reference sites (i.e., forest lakes). Between the two categories of Arctic lakes, tundra lakes are more terrestrial-influenced compared to mountain lakes. Additionally, terrestrial-originated DOM is a main controlling factor for enhancing the ambient reducing capacity, whereas the DOM concentration, i.e., dissolved organic carbon (DOC), resulted in variations in the Hg/DOC ratios that also cause the variations of the observed ARC values. Thus, comparisons of the ARC values can be conducted while oxidant/DOC ratios are kept the same and reported through the method using heavy metals as a chemical probe. After correction for Hg/DOC ratio interference, the ambient reducing capacity of DOM followed the order: boreal forest lakes > Arctic tundra lakes > Arctic mountain lakes. This study highlights that the DOM concentration should also be considered when estimating the ARC as compared to the previous that mainly focusing on the properties of DOM such as its origins. As climate change is projected to be severe in high latitudes, this study demonstrates a significant connection between aquatic DOM geochemical reactivity and terrestrial inputs, which is crucial for a better prediction of the role of DOM in high-latitude lakes in the context of climate change.
Tao Jiang; Dingyong Wang; Bo Meng; Jinshu Chi; Hjalmar Laudon; Jiang Liu. The concentrations and characteristics of dissolved organic matter in high-latitude lakes determine its ambient reducing capacity. Water Research 2019, 169, 115217 .
AMA StyleTao Jiang, Dingyong Wang, Bo Meng, Jinshu Chi, Hjalmar Laudon, Jiang Liu. The concentrations and characteristics of dissolved organic matter in high-latitude lakes determine its ambient reducing capacity. Water Research. 2019; 169 ():115217.
Chicago/Turabian StyleTao Jiang; Dingyong Wang; Bo Meng; Jinshu Chi; Hjalmar Laudon; Jiang Liu. 2019. "The concentrations and characteristics of dissolved organic matter in high-latitude lakes determine its ambient reducing capacity." Water Research 169, no. : 115217.
Rice (Oryza sativa) paddy is the hotspot of mercury (Hg) methylation. Given distinct influences of rotation systems on the physicochemical properties of paddy soils, we hypothesized different rotation systems in rice paddies inducing a large difference in Hg methylation. Here, we investigated Hg species distribution, dissolved organic matter (DOM) features, and Hg methylation in five rotation systems (Other farmland newly reclaim into paddy field, i.e., NR-R; Drain the water in winter, i.e., DW-R; Flooding in winter, i.e., FW-R; Rape-Rice rotation, i.e., Ra-R; Wheat-Rice rotation, i.e., Wh-R) of paddy fields to identify such hypothesis. Results shown that FW-R had the strongest Hg methylation, followed by Ra-R and Wh-R, then DW-R, and finally NR-R. We further found that much higher soil organic matter (SOM) and organo-chelated Hg (Hg-o) from straw residues and root exudates were the main cause for the greater Hg methylation in FW-R, Ra-R and Wh-R. This was because the protein-like fraction of SOM facilitated the net production of methyl Hg (MeHg), meanwhile the humin-like fraction had a strong affinity to MeHg in paddy soils. Therefore, it can be concluded that paddy soil under DW-R was the optimum pattern in order to reduce the occurrence of Hg methylation. However, paddy soils under Ra-R and Wh-R were the recommendable patterns if the productivity of paddy fields was considered.
Tao Sun; Ming Ma; Hongxia Du; Xun Wang; Yongjiang Zhang; Yongmin Wang; Dingyong Wang. Effect of different rotation systems on mercury methylation in paddy fields. Ecotoxicology and Environmental Safety 2019, 182, 109403 .
AMA StyleTao Sun, Ming Ma, Hongxia Du, Xun Wang, Yongjiang Zhang, Yongmin Wang, Dingyong Wang. Effect of different rotation systems on mercury methylation in paddy fields. Ecotoxicology and Environmental Safety. 2019; 182 ():109403.
Chicago/Turabian StyleTao Sun; Ming Ma; Hongxia Du; Xun Wang; Yongjiang Zhang; Yongmin Wang; Dingyong Wang. 2019. "Effect of different rotation systems on mercury methylation in paddy fields." Ecotoxicology and Environmental Safety 182, no. : 109403.
Forest ecosystem has long been suggested as a vital component in the global mercury (Hg) biogeochemical cycling. However, there remains large uncertainties in understanding total Hg (THg) and methylmercury (MeHg) variations and their controlling factors during the whole hydrological processes in forest ecosystems. Here, we quantified Hg mass flow along hydrological processes of wet deposition, throughfall, stemflow, litter leachate, soil leachate, surface runoff, and stream, and litterfall Hg deposition, and air-forest floor Hg0 exchange flux to set up a Hg mass balance in a subtropical forest of China. Results showed that THg concentration in stream was lower than that in wet deposition, while an opposite characteristic for MeHg concentration, and both THg and MeHg fluxes of stream were lower than those of wet deposition. Variations of THg and MeHg in throughfall and litter leachate had strong direct and indirect effects on controlling variations of THg and MeHg in surface runoff, soil leachate and stream, respectively. Especially, the net Hg methylation was suggested in the forest canopy and forest floor layers, and significant particulate bound Hg (PBM) filtration was observed in soil layers. The Hg mass balance showed that the litterfall Hg deposition was the main Hg input for forest floor Hg, and the elemental Hg vapor (Hg0) re-emission from forest floor was the dominant Hg output. Overall, we estimated the net THg input flux of 13.8 μg m−2 yr−1 and net MeHg input flux of 0.6 μg m−2 yr−1 within the forest ecosystem. Our results highlighted the important roles of forest canopy and forest floor to shape Hg in output flow, and the forest floor is a distinct sink of MeHg.
Tao Sun; Ming Ma; Xun Wang; Yongmin Wang; Hongxia Du; Yuping Xiang; Qinqin Xu; Qing Xie; Dingyong Wang. Mercury transport, transformation and mass balance on a perspective of hydrological processes in a subtropical forest of China. Environmental Pollution 2019, 254, 113065 .
AMA StyleTao Sun, Ming Ma, Xun Wang, Yongmin Wang, Hongxia Du, Yuping Xiang, Qinqin Xu, Qing Xie, Dingyong Wang. Mercury transport, transformation and mass balance on a perspective of hydrological processes in a subtropical forest of China. Environmental Pollution. 2019; 254 ():113065.
Chicago/Turabian StyleTao Sun; Ming Ma; Xun Wang; Yongmin Wang; Hongxia Du; Yuping Xiang; Qinqin Xu; Qing Xie; Dingyong Wang. 2019. "Mercury transport, transformation and mass balance on a perspective of hydrological processes in a subtropical forest of China." Environmental Pollution 254, no. : 113065.
Water-level-fluctuating zone (WLFZ) is a prevalent water-land ecotone favorable for mercury (Hg) methylation. The succession of flooding tolerance plants in WLFZ gradually changes the landscape, and also brings a new question worth understanding whether these plants would enhance methylmercury (MeHg) production in WLFZ and increase risks to the aquatic environment. Given bermudagrass (Cynodon dactylon (L). Pers) as the dominant perennial herb with high flooding-tolerance in WLFZ of the Three Gorges Reservoir (TGR), we conducted a comprehensive study to investigate its roles in the production and migration of MeHg in WLFZ by field observations and stable isotope tracer experiments. Results showed that both elevated MeHg levels and Hg methylation rates appeared in soil/sediment in bermudagrass growing area, implying that the growth of bermudagrass could significantly enhance MeHg production. However, MeHg migration from sediment to water was restricted during the flooding period of the TGR, as obviously higher partitioning coefficients of MeHg between the sediment and porewater (p < 0.05) and lower MeHg release fluxes were observed in vegetated area, indicating that the presence of bermudagrass instead probably decreased the water MeHg level. Whereas, it is noteworthy that elevated MeHg in soil/sediment induced by the bermudagrass could pose potential risks to the benthos and further to the TGR food chain.
Deliang Yin; Yongmin Wang; Yuping Xiang; Qinqin Xu; Qing Xie; Cheng Zhang; Jiang Liu; Dingyong Wang. Production and migration of methylmercury in water-level-fluctuating zone of the Three Gorges Reservoir, China: Dual roles of flooding-tolerant perennial herb. Journal of Hazardous Materials 2019, 381, 120962 .
AMA StyleDeliang Yin, Yongmin Wang, Yuping Xiang, Qinqin Xu, Qing Xie, Cheng Zhang, Jiang Liu, Dingyong Wang. Production and migration of methylmercury in water-level-fluctuating zone of the Three Gorges Reservoir, China: Dual roles of flooding-tolerant perennial herb. Journal of Hazardous Materials. 2019; 381 ():120962.
Chicago/Turabian StyleDeliang Yin; Yongmin Wang; Yuping Xiang; Qinqin Xu; Qing Xie; Cheng Zhang; Jiang Liu; Dingyong Wang. 2019. "Production and migration of methylmercury in water-level-fluctuating zone of the Three Gorges Reservoir, China: Dual roles of flooding-tolerant perennial herb." Journal of Hazardous Materials 381, no. : 120962.
Mercury (Hg) methylation is mainly a microbial process mediated by anaerobes. The continued study of Pseudomonas putida (P. putida) strain TGRB4 genome was inspired by the fact that it can transform Hg into the highly toxic methylmercury (MeHg) under aerobic conditions. P. putida strain TGRB4 is a Gram-negative rod-shaped Gamma-proteobacterium (γ-proteobacterium), isolated from the soil in a typical water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR), which suffered from seasonally water level alternations every year. Draft genome assembly of P. putida strain TGRB4 is presented here, which was sequenced using Illumina Hiseq and PacBio single-molecule real-time (SMRT) platforms. Its genome harbors a total of 5504 genes and a G + C content of 62.6%. We further identified the enzymes related to Hg methylation, and found two well-known methyltransferase, including 5-methyl-tetrahydrofolate (5-methyl-THF) and S-adenosylmethionine (AdoMet), were annotated in the genome of P. putida strain TGRB4. This genome information could be treated as a research material to further study the Hg methylation mechanisms under aerobic environment.
Yuping Xiang; Yongmin Wang; Hong Shen; Dingyong Wang. The Draft Genome Sequence of Pseudomonas putida Strain TGRB4, an Aerobic Bacterium Capable of Producing Methylmercury. Current Microbiology 2019, 77, 522 -527.
AMA StyleYuping Xiang, Yongmin Wang, Hong Shen, Dingyong Wang. The Draft Genome Sequence of Pseudomonas putida Strain TGRB4, an Aerobic Bacterium Capable of Producing Methylmercury. Current Microbiology. 2019; 77 (4):522-527.
Chicago/Turabian StyleYuping Xiang; Yongmin Wang; Hong Shen; Dingyong Wang. 2019. "The Draft Genome Sequence of Pseudomonas putida Strain TGRB4, an Aerobic Bacterium Capable of Producing Methylmercury." Current Microbiology 77, no. 4: 522-527.
Although mercury (Hg) is toxic at all valence states, organic Hg, especially monomethylmercury (MeHg, CH3Hg+, methylmercury), is more toxic than inorganic Hg (Hg(II), Hg2+). As Hg is predominately methylated via bio-methylation, studies on the mechanism of Hg bio-methylation by microorganisms are particularly important. It is widely accepted that MeHg is mainly produced by anaerobic microorganisms in the environment, and the Hg-methylating process is a cellular reaction. Hence, the production rate of MeHg is not only related to the presence and activities of Hg-methylating anaerobic microorganisms, but also the transport of Hg(II) into microbial cells and the biochemical reactions for forming MeHg in the cells. Therefore, this review described the current state of knowledge on: 1) what kind of microorganisms can methylate Hg; 2) what pathways are the Hg(II) take to enter into the microbial cells; 3) what kind of biochemical reactions happen in the cells; and 4) biogeochemical factors affecting Hg methylation, which are critical to elucidate the regulating mechanisms of Hg methylation by microorganisms. Simultaneously, the existing issues or controversies on biotic Hg methylation were also discussed.
Ming Ma; Hongxia Du; Dingyong Wang. Mercury methylation by anaerobic microorganisms: A review. Critical Reviews in Environmental Science and Technology 2019, 49, 1893 -1936.
AMA StyleMing Ma, Hongxia Du, Dingyong Wang. Mercury methylation by anaerobic microorganisms: A review. Critical Reviews in Environmental Science and Technology. 2019; 49 (20):1893-1936.
Chicago/Turabian StyleMing Ma; Hongxia Du; Dingyong Wang. 2019. "Mercury methylation by anaerobic microorganisms: A review." Critical Reviews in Environmental Science and Technology 49, no. 20: 1893-1936.
: In the present study, the accumulation and degradation of testosterone by Chlorella vulgaris were studied. The results showed that C. vulgaris has a significant ability to eliminate testosterone by bioaccumulation and biodegradation, and during the 96 h experimental period, the data demonstrated that the accumulation of testosterone followed a sigmoidal accumulation pattern. At the end of the experiment, the bioconcentration percentages of testosterone by C. vulgaris in the high-concentration group and the low-concentration group were 11.49 ± 2.78% and 40.10 ± 1.98%, respectively, and the biodegradation percentages of testosterone were 69.64 ± 4.33% and 42.48 ± 1.92%, respectively. The rate of biodegradation of testosterone by C. vulgaris mainly depended on the relative initial concentration of testosterone. When the relative initial concentration of testosterone increases, the degradation may gradually change from zero-order kinetics to second-order kinetics.
Mei Fu; Bixiang Deng; Hongjian Lü; Weizhi Yao; Shengqi Su; Dingyong Wang. The Bioaccumulation and Biodegradation of Testosterone by Chlorella vulgaris. International Journal of Environmental Research and Public Health 2019, 16, 1253 .
AMA StyleMei Fu, Bixiang Deng, Hongjian Lü, Weizhi Yao, Shengqi Su, Dingyong Wang. The Bioaccumulation and Biodegradation of Testosterone by Chlorella vulgaris. International Journal of Environmental Research and Public Health. 2019; 16 (7):1253.
Chicago/Turabian StyleMei Fu; Bixiang Deng; Hongjian Lü; Weizhi Yao; Shengqi Su; Dingyong Wang. 2019. "The Bioaccumulation and Biodegradation of Testosterone by Chlorella vulgaris." International Journal of Environmental Research and Public Health 16, no. 7: 1253.
As a global toxic pollutant, mercury (Hg) bioaccumulation within food chain could be influenced by human disturbance. Ten typical fish species were collected from Changshou Lake, an artificial lake used to carry out cage fish culture, to investigate the C/N isotopic compositions and Hg bioaccumulation in fish. The results showed that the total Hg (THg) and methylmercury (MeHg) levels in fish muscles ((56.03 ± 43.96) and (32.35 ± 29.57) ng/g, wet weight), comparable with those in most studies in China, were significantly lower than the international marketing limit (0.5 mg/kg). Past human input for cage culture in this lake led to abnormal 15N enrichment in food chain, as the quantitative trophic levels based on δ15N were different with that classified by feeding behaviors. This phenomenon subsequently demonstrated that it should be considered thoughtfully with respect to the application of the traditional method for understanding Hg bioaccumulation power by the slope of log10[Hg] with δ15N regression in specific water body (i.e., Changshou Lake). In addition, no significant linear correlation between Hg and body weight or length of some fish species was observed, suggesting that the fish growth in the eutrophic environment was disproportionate with Hg bioaccumulation, and fish length or weight was not the main factor affecting Hg transfer with food web. The occurrence of human disturbance in aquatic system presents a challenge to a better understanding of the Hg bioaccumulation and biomagnification within the food chain.
Yongmin Wang; Qing Xie; Qinqin Xu; Jinping Xue; Cheng Zhang; Dingyong Wang. Mercury bioaccumulation in fish in an artificial lake used to carry out cage culture. Journal of Environmental Sciences 2019, 78, 352 -359.
AMA StyleYongmin Wang, Qing Xie, Qinqin Xu, Jinping Xue, Cheng Zhang, Dingyong Wang. Mercury bioaccumulation in fish in an artificial lake used to carry out cage culture. Journal of Environmental Sciences. 2019; 78 ():352-359.
Chicago/Turabian StyleYongmin Wang; Qing Xie; Qinqin Xu; Jinping Xue; Cheng Zhang; Dingyong Wang. 2019. "Mercury bioaccumulation in fish in an artificial lake used to carry out cage culture." Journal of Environmental Sciences 78, no. : 352-359.
Mercury (Hg) is one of the most toxic heavy metal pollutants, which can be easily transmitted and enriched through the food chain, posing severe threat to human beings. Forest ecosystems are one of the most active environments for biogeochemical cycles of Hg. It is essential to research on Hg cycling in the forest ecosystem, which contributes to a comprehensive understanding of global biogeochemical cycle of Hg. However, there is still a lack of consensus on whether the forest ecosystem is a "source" or "sink" of Hg in the global Hg cycle so far. Therefore, it is necessary to elucidate the current state of knowledge on Hg deposition, transformation and fate in the forest ecosystem, especially the existing puzzles or issues encountered by scientists worldwide. This review highlights the complexity and uncertainties of Hg cycling in forest ecosystems. It is proposed that a new perspective is required to further understand the role of forest ecosystems in global Hg cycle based on a sufficient understanding of Hg exchange fluxes at the interface of air-soil and air-plant, Hg deposition flux through litterfall, and accurate construction of Hg mass balance system.
Ming Ma; Hongxia Du; Dingyong Wang. A New Perspective is Required to Understand the Role of Forest Ecosystems in Global Mercury Cycle: A Review. Bulletin of Environmental Contamination and Toxicology 2019, 102, 650 -656.
AMA StyleMing Ma, Hongxia Du, Dingyong Wang. A New Perspective is Required to Understand the Role of Forest Ecosystems in Global Mercury Cycle: A Review. Bulletin of Environmental Contamination and Toxicology. 2019; 102 (5):650-656.
Chicago/Turabian StyleMing Ma; Hongxia Du; Dingyong Wang. 2019. "A New Perspective is Required to Understand the Role of Forest Ecosystems in Global Mercury Cycle: A Review." Bulletin of Environmental Contamination and Toxicology 102, no. 5: 650-656.