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Zhu S, Yang C, Chen H, Wang Y, Li J, Zhang R, Yang Y, Zhang C, Wang D. Organic Carbon Controls Mercury Distribution and Storage in the Surface Soils of the Water-Level-Fluctuation Zone in the Three Gorges Reservoir Region, China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:3681. [PMID: 36834375 PMCID: PMC9968128 DOI: 10.3390/ijerph20043681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
The particular condition of the water-level-fluctuation zone (WLFZ) in the Three Gorges Reservoir (TGR), the largest hydroelectric reservoir in China, raises great concerns about mercury (Hg) contamination and ecological risk. In addition, previous research found that soil organic carbon (SOC) plays an essential role in controlling Hg distribution and speciation. However, there is minimal information on the Hg storage distribution and their relationships with SOC in the WLFZ in TGR. This study investigated Hg distribution, storage, and their relationships with SOC in the surface soils in WLFZ. The results showed that the total Hg (THg) content in the surface soils ranged from 18.40 to 218.50 ng g-1, with an average value of 78.17 ± 41.92 ng g-1. About 89% of samples had THg content above the background value in Chongqing, showing specific enrichment of Hg in WLFZ due to contamination in the TGR. The surface soils have low SOC, with an average value of 8.10 ± 3.90 g kg-1. Moreover, THg content showed consistent distribution with the SOC in WLFZ, with a significantly positive correlation (R = 0.52, p < 0.01, n = 242). THg storage (201.82 ± 103.46 g ha-1) in the surface soils was also significantly positively correlated with the SOC storage (R = 0.47, p < 0.01, n = 242). The reduced SOC sequestration, due to the periodical alternative "flooding-draining" and frequent reclamation and utilization of WLFZ, decreased the Hg adsorption in soil. Those might result in the re-release of Hg into waters when WLFZ is flooded. Therefore, more attention should be directed towards Hg cycling and the consequent environmental risks in the TGR region.
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Affiliation(s)
- Sihua Zhu
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Caiyun Yang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Hong Chen
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Yongmin Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Jieqin Li
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Ruixi Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Yu Yang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Cheng Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Dingyong Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400716, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400716, China
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Feng P, Xiang Y, Cao D, Li H, Wang L, Wang M, Jiang T, Wang Y, Wang D, Shen H. Occurrence of methylmercury in aerobic environments: Evidence of mercury bacterial methylation based on simulation experiments. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129560. [PMID: 35999748 DOI: 10.1016/j.jhazmat.2022.129560] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/01/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Methylmercury (MeHg) is mainly produced by anaerobic δ-proteobacteria such as sulfate-reducing bacteria (SRB). However, mercury bio-methylation has also been found to occur in the aerobic soil of the Three Gorges Reservoir (TGR). Using γ-proteobacterial TGR bacteria (TGRB) and δ-proteobacterial Desulfomicrobium escambiense strains, the efficiency of mercury methylation and demethylation was evaluated using an isotope tracer technique. Kinetics simulation showed that the bacterial Hg methylation rate (km) of TGRB3 was 4.36 × 10-9 pg·cell-1·h-1, which was significantly lower than that of D. escambiense (170.74 ×10-9 pg·cell-1·h-1) under anaerobic conditions. Under facultative and/or aerobic conditions, D. escambiense could not survive, while the km of TGRB3 were 0.35 × 10-9 and 0.29 × 10-9 pg·cell-1·h-1, respectively. Furthermore, the bacterial MeHg tolerance threshold of TGRB3 was 3.47 × 10-9 pg·cell-1, which was 98.6-fold lower than that of D. escambiense under anaerobic conditions. However, the MeHg tolerance threshold of TGRB3 remained at 0.50-0.52 × 10-9 pg·cell-1 under facultative and/or aerobic conditions. Notably, bacterial Hg methylation rates (km) were higher than the corresponding bacterial MeHg demethylation rates (kd1). These results establish the contribution of some aerobic and/or facultative anaerobic bacteria to net environmental MeHg production in terrestrial ecosystems and provide a novel understanding of the biogeochemical cycle of MeHg. SYNOPSIS: Hg methylation of facultative and/or aerobic bacteria may contribute to the net production of environmental methylmercury in terrestrial ecosystems.
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Affiliation(s)
- Pengyu Feng
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dan Cao
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Hui Li
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Lanqing Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Mingxuan Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Tao Jiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China.
| | - Hong Shen
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China.
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Wang J, Xiang Y, Tian X, Zhang C, Gong G, Xue J, Jiang T, Wang D, Wang Y. Role of the rhizosphere of a flooding-tolerant herb in promoting mercury methylation in water-level fluctuation zones. J Environ Sci (China) 2022; 119:139-151. [PMID: 35934459 DOI: 10.1016/j.jes.2022.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/26/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
The water-level fluctuation zone (WLFZ) has been considered as a hotspot for mercury (Hg) methylation. Flooding-tolerant herbs are gradually acclimated to this water-land ecotone, tending to form substantial root systems for improving erosion resistance. Accompanying rhizosphere microzone plays crucial but unclear roles in methylmercury (MeHg) formation in the WLFZ. Thus, we conducted this study in the WLFZ of the Three Gorges Reservoir, to explore effects of the rhizosphere of a dominant flooding-tolerant herb (bermudagrass) on MeHg production. The elevated Hg and MeHg in rhizosphere soils suggest that the rhizosphere environment provides favorable conditions for Hg accumulation and methylation. The increased bioavailable Hg and microbial activity in the rhizosphere probably serve as important factors driving MeHg formation in the presence of bermudagrass. Simultaneously, the rhizosphere environments changed the richness, diversity, and distribution of hgcA-containing microorganisms. Here, a typical iron-reducing bacterium (Geobacteraceae) has been screened, however, the majority of hgcA genes detected in rhizosphere, near-, and non-rhizosphere soils of the WLFZ were unclassified. Collectively, these results provide new insights into the elevated MeHg production as related to microbial processes in the rhizosphere of perennial herbs in the WLFZ, with general implications for Hg cycling in other ecosystems with water-level fluctuations.
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Affiliation(s)
- Juan Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- Laboratory of Environmental Nanotechnology & Health Effect, Chinese Academy of Sciences, Research Center for Eco-Environmental Sciences, Beijing 100085, China
| | - Xiaosong Tian
- College of Resources and Safety, Chongqing Vocational Institute of Engineering, Chongqing 402260, China
| | - Cheng Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Guiqing Gong
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Jinping Xue
- Institut des Sciences Analytiques et des Physico-Chimie pour l'Environnement et les Matériaux (IPREM), UMR 5254, CNRS, Université de Pau et des Pays de l'Adour, Pau 64000, France
| | - Tao Jiang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China.
| | - Yongmin Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China.
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Dongmei Z, Xinyu L, Hang L, Yuqi W, Meijie Z, Xiaoxiao X. Changes of mercury and methylmercury content and mercury methylation in Suaeda salsa soil under different salinity. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2022; 44:1399-1407. [PMID: 34677730 DOI: 10.1007/s10653-021-01094-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
In this paper, we studied the changes of Hg and MeHg contents in Liaohe estuarine Suaeda salsa soils under anaerobic conditions by simulated indoor incubation at constant temperature and whether the changes of salinity (CK, 0.5%, 1.0%, 1.5%, 2.0%) affected SRB and dominated the formation of MeHg. The lowest Hg content is found in the subsurface Suaeda salsa soils at 2.0% salinity. The MeHg content in the soil also showed a general trend of increasing and then decreasing with increasing flooding salinity, and the MeHg content was higher at 0.5-1.0% flooding salinity. SRB was present in the soil under all salinity conditions and reached the maximum value at 15 days of incubation. The SRB content was higher under CK, S1 and S2 conditions, and the soil MeHg content showed a significant positive correlation with the number of SRB bacteria, indicating that the formation of MeHg was related to SRB which is of great significance to the study of estuarine wetlands.
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Affiliation(s)
- Zheng Dongmei
- Environmental College, Shenyang University, Shenyang, 110044, China.
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Ministry of Education, Shenyang, 110044, China.
| | - Li Xinyu
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Ministry of Education, Shenyang, 110044, China
| | - Li Hang
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Ministry of Education, Shenyang, 110044, China
| | - Wang Yuqi
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Ministry of Education, Shenyang, 110044, China
| | - Zheng Meijie
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Ministry of Education, Shenyang, 110044, China
| | - Xu Xiaoxiao
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Ministry of Education, Shenyang, 110044, China
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Cao D, Chen W, Xiang Y, Mi Q, Liu H, Feng P, Shen H, Zhang C, Wang Y, Wang D. The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 207:111538. [PMID: 33254400 DOI: 10.1016/j.ecoenv.2020.111538] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 06/12/2023]
Abstract
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.
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Affiliation(s)
- Dan Cao
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Weihong Chen
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Qianfen Mi
- Biological Science Research Center of Southwest University, Chongqing 400715, China
| | - Hang Liu
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - PengYu Feng
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Hong Shen
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China.
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China.
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Liu J, Wang D, Zhang J, Liem-Nguyen V, Huang R, Jiang T. Evaluation of Hg methylation in the water-level-fluctuation zone of the Three Gorges Reservoir region by using the MeHg/Hg T ratio. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110468. [PMID: 32200146 DOI: 10.1016/j.ecoenv.2020.110468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 06/10/2023]
Abstract
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.
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Affiliation(s)
- Jiang Liu
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China; Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
| | - Dingyong Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China.
| | - Jinzhong Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China.
| | - Van Liem-Nguyen
- Laboratory of Advanced Materials Chemistry, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam; Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
| | - Rong Huang
- College of Resources, Sichuan Agricultural University, Chengdu, 611130, China.
| | - Tao Jiang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China.
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Li H, Zheng D, Zhang X, Niu Z, Ma H, Zhang S, Wu C. Total and Methylmercury of Suaeda heteroptera Wetland Soil Response to a Salinity Gradient Under Wetting and Drying Conditions. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2020; 104:778-785. [PMID: 32430533 DOI: 10.1007/s00128-020-02874-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 05/06/2020] [Indexed: 06/11/2023]
Abstract
Mercury (Hg) methylation could occur in freshwater ecosystems with low or high salinity. However, few studies are available about the effects of salinity change on mercury(Hg) release and methylation. In-situ experiments using Suaeda heteroptera wetland soil column from the Liaohe estuary were performed to decipher how total mercury (THg) and methylmercury (MeHg) contents change under fluctuant salinity and wet and dry soil conditions. Salinity gradients were set to 0.50% (S1), 1.00% (S2), 1.50% (S3) and 1.80% (S4), and pure deionized water was used as a blank control (CK). Wet and dry soil conditions were set to full inundation condition (WD1) and naturally dried treatment (WD2). Results indicated that the highest THg and MeHg contents were found in surface and bottom soil when water salinity treatment was CK under WD1. THg and MeHg decreased with salinity under WD1. THg contents in overlying water varied from 0.854 to 1.243 µg L-1 under WD1 treatments and increased with salinity change. When under WD2 treatment, THg contents in both soil layers gradually decreased with rising salinity. Meanwhile, MeHg contents in both soil layers reached the lowest level at CK (1.666 μg kg-1and 2.520 μg kg-1) and increased gradually with the rising salinity. By comparison, THg content of the soil was much lower in WD1 than that in WD2. Under the WD1 condition, the MeHg contents and %MeHg decreased with rising salinity and showed significantly different in different salinity treatment, however, its showed an opposite trend with rising salinity under the WD2 condition.
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Affiliation(s)
- Hang Li
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China
| | - Dongmei Zheng
- Environmental College, Shenyang University, Shenyang, 110044, China.
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China.
| | - Xun Zhang
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China
| | - Zhixin Niu
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China
| | - Huanchi Ma
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China
| | - Shiwei Zhang
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China
| | - Chenghao Wu
- Environmental College, Shenyang University, Shenyang, 110044, China
- Key Laboratory of Eco-Restoration of Regional Contaminated Environment, Shenyang University, Shenyang, 110044, China
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Du H, Sun T, Wang D, Ming M. Bacterial and archaeal compositions and influencing factors in soils under different submergence time in a mercury-sensitive reservoir. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 191:110155. [PMID: 31972452 DOI: 10.1016/j.ecoenv.2019.110155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/27/2019] [Accepted: 12/30/2019] [Indexed: 06/10/2023]
Abstract
Soils in the water-level-fluctuating zone (WLFZ) of Three Gorges Reservoir (TGR) inundated by water for different periods of time are confirmed to have disparate characteristics to mercury (Hg), and thus it is of great significance to further investigate microbial compositions and influencing factors. The objective of this study was to compare bacterial and archaeal richness, α-diversities and compositions, as well as affecting variables, especially Hg concentrations, among soils under different submergence time-SI (inundated soil), SS (semi-inundated soil), SN(non-inundated soil) and SSe (sediment)-based on high throughput sequencing. Results showed that sediment had significantly higher bacterial and archaeal richness and α-diversities than the other soil types. Anaerolinea and Aeromonas, as well as Altiarchaeales, Nitrosoarchaeum, and Methanosarta were dominant in SSe, while sharply decreasing in the other soil types, with significant difference among groups. An unclassified genus in SCG critically predominating in SI, SS and SN, drastically reduced in SSe, with extremely significant difference among groups. Bathyarchaeota and Nitrososphaera, both dominating in SSe, decreased dramatically and almost vanished in SI and SN. All the variables except pH posed a significant positive effect on bacterial and archaeal compositions in SSe, while opposite effect in the other three soil types. MeHg and THg concentrations had relatively weaker effects on microbial compositions comparing to variables like NH4+, CEC, OM and SO42+.
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Affiliation(s)
- Hongxia Du
- College of Resources and Environment, Southwest University, Chongqing, 400715, China; Chongqing Key Laboratory of Bioresource for Bioenergy, Southwest University, Chongqing, 400715, China
| | - Tao Sun
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Ma Ming
- College of Resources and Environment, Southwest University, Chongqing, 400715, China; Chongqing Key Laboratory of Bioresource for Bioenergy, Southwest University, Chongqing, 400715, China.
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Wang Y, Chen Z, Wu Y, Zhong H. Comparison of methylmercury accumulation in wheat and rice grown in straw-amended paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 697:134143. [PMID: 31476499 DOI: 10.1016/j.scitotenv.2019.134143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/16/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Paddy soil is a key area of methylmercury (MeHg) production and is dominated by fluctuating redox conditions following rice plant growth or rice-wheat rotation planting in eastern and southern Asia. The role of organic matter in the formation of MeHg under these biogeochemical redox cycles remains poorly understood, especially in certain mercury (Hg)-contaminated paddy soils. Here, we provide a detailed understanding of the formation of MeHg and its accumulation in crops (i.e., wheat and rice) in rice-wheat rotation systems under straw return. Two series of experiments, pot and microcosm experiments, were performed using Hg-contaminated paddy soil with 1% (w/w) wheat or rice straw addition under aerobic or anoxic conditions. The results showed that straw amendments increased MeHg levels in wheat (by 225%) and rice (by 20%) grains, most likely due to the elevated soil MeHg following straw amendment. Microcosm experiments further confirmed that fresh straw-derived organic matter enhances MeHg net production in soil through an overall increase in the activity of sulfate-reducing bacteria (SRB), particularly under anoxic conditions. Our study clearly demonstrated that straw amendment enhanced MeHg accumulation in wheat and rice grains and highlighted that straw return in Hg-contaminated soils may increase the health risk of MeHg exposure to local residents via crop consumption. Thus, some guidance should be provided for crop residue return in rice-wheat rotation system farming practices.
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Affiliation(s)
- Yongjie Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China
| | - Zongya Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550002, PR China
| | - Yonggui Wu
- College of Resources and Environmental Engineering, Guizhou University, Guiyang 550002, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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10
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Wang Y, Yin D, Xiang Y, Xu Q, Zhang C, Xie Q, Wang D. A Review of Studies on the Biogeochemical Behaviors of Mercury in the Three Gorges Reservoir, China. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:686-694. [PMID: 30859245 DOI: 10.1007/s00128-019-02586-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 03/02/2019] [Indexed: 06/09/2023]
Abstract
The Three Gorges Reservoir (TGR) is a relatively large reservoir, and its water level management actions produce a widespread water level fluctuation zone (WLFZ), which has characteristics of both terrestrial and aquatic ecosystems. Here, an integrated overview of current knowledge on Hg behaviors in the TGR, especially the WLFZ, as well as exposure risk to local residents was presented. Hg levels in the TGR were comparable with other natural aquatic systems. WLFZ in the TGR was confirmed to be an environment favorable for Hg methylation by enhancing microbial activity, promoting sulfur cycling and increasing the level of low-molecular-weight organic matters. However, elevated fish Hg concentrations did not follow the impoundment of TGR, indicating no obvious reservoir effect, while it is still noteworthy that frequently consuming fish is likely to be a methylmercury (MeHg) exposure pathway for specific populations e.g. fishermen around the TGR.
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Affiliation(s)
- Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, 400715, Chongqing, China
| | - Deliang Yin
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Qinqin Xu
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
- Chongqing Key Laboratory of Agricultural Resources and Environment, 400715, Chongqing, China
| | - Qing Xie
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China.
- Chongqing Key Laboratory of Agricultural Resources and Environment, 400715, Chongqing, China.
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11
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Xing Z, Zhao T, Bai W, Yang X, Liu S, Zhang L. Temporal and spatial variation in the mechanisms used by microorganisms to form methylmercury in the water column of Changshou Lake. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 160:32-41. [PMID: 29783110 DOI: 10.1016/j.ecoenv.2018.05.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 04/17/2018] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
The microbiome in artificial lake water and its impact on mercury (Hg) methylation remain largely unknown. We selected the largest artificial lake in southeastern china, Changshou Lake (CSL), which has high background levels of Hg, for our investigation of Hg transformation microorganisms. Five different sections of the water column of CSL were sampled during four seasons. The water samples were subjected to analysis of geochemical parameters, various Hg species and microbiome information. High concentrations of total mercury (THg) were detected in CSL in comparison with those found in natural lakes. Significant differences in microbial community structure and Hg species abundance existed among seasons. High dissolved methyl mercury (DMeHg) formation and high bacterial richness and diversity occurred in the fall. The microbiome was dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Deinococcus-Thermus and many unclassified bacteria. Significant correlations were found between seasonal bacterial communities and Hg levels. Hg methylation was strongly linked to the abundance of Cyanobacteria. Methylators, including Syntrophus, Desulfovibrio and Desulfomonile species, were detected only in samples collected in the fall. The results of enzyme functional analyses revealed that many unknown types of bacteria could also be responsible for Hg transformation. This study was the first to investigate the impact of various Hg species on the microbiome of artificial lake water. The findings of this study illuminate the role of seasonal bacteria in Hg transformation.
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Affiliation(s)
- Zhilin Xing
- Faculty of Urban Construction and Environment Engineering, Chongqing University, Chongqing 400045, China; School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Tiantao Zhao
- Faculty of Urban Construction and Environment Engineering, Chongqing University, Chongqing 400045, China; School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China.
| | - Weiyang Bai
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Xu Yang
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Shuai Liu
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
| | - Lijie Zhang
- School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, China
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Liu J, Jiang T, Wang F, Zhang J, Wang D, Huang R, Yin D, Liu Z, Wang J. Inorganic sulfur and mercury speciation in the water level fluctuation zone of the Three Gorges Reservoir, China: The role of inorganic reduced sulfur on mercury methylation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 237:1112-1123. [PMID: 29153472 DOI: 10.1016/j.envpol.2017.11.045] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/06/2017] [Accepted: 11/11/2017] [Indexed: 06/07/2023]
Abstract
The water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) in China is a unique geomorphological unit that undergoes annual flooding and drying alternation cycle. The alternating redox conditions within the WLFZ are expected to result in dynamic cycling of reduced sulfur species, which could affect mercury (Hg) methylation due to the high affinity of reduced sulfur species to both inorganic divalent mercury (Hg(II)i) and methylmercury (MeHg). Variations of inorganic sulfur species (measured as acid volatile sulfide, chromium reductive sulfur, elemental sulfur, and water-soluble sulfate), total mercury (THg) and MeHg were studied at two typical WLFZ sites in the TGR from July 2015 to June 2016. Whereas the water-soluble sulfate contents stayed essentially constant, the reduced inorganic sulfur contents varied greatly as the water level changed. Compared with the control soils, the MeHg contents in the WLFZ soils increased, suggesting that water level fluctuations accelerated the methylation process of Hg(II)i. In situ Hg(II)i-methylation also appeared to occur in the sub-layer of the drained sediment during the draw-down season. The significant correlation between MeHg and elemental sulfur (S(0)) further suggests that polysulfides may have played a role in Hg(II)i-methylation by increasing the bioavailable Hg(II)i content in the WLFZ of the TGR.
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Affiliation(s)
- Jiang Liu
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg MB R3T 2N2, Canada
| | - Tao Jiang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden
| | - Feiyue Wang
- Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg MB R3T 2N2, Canada.
| | - Jinzhong Zhang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China.
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Rong Huang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Deliang Yin
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Zeyan Liu
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Jinzhu Wang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
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13
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Xiang Y, Wang Y, Zhang C, Shen H, Wang D. Water level fluctuations influence microbial communities and mercury methylation in soils in the Three Gorges Reservoir, China. J Environ Sci (China) 2018; 68:206-217. [PMID: 29908740 DOI: 10.1016/j.jes.2018.03.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/03/2018] [Accepted: 03/09/2018] [Indexed: 06/08/2023]
Abstract
Reservoirs tend to have enhanced methylmercury (MeHg) concentrations compared to natural lakes and rivers, and water level fluctuations can promote MeHg production. Until now, little research has been conducted on the effects of microorganisms in soils for the formation of MeHg during different drying and flooding alternating conditions in the Three Gorges Reservoir (TGR). This study aimed to understand how water level fluctuations affect soil microbial composition and mercury concentrations, and if such microbial variations are related to Hg methylation. The results showed that MeHg concentrations and the ratios of MeHg to THg (MeHg%) in soils were higher in the seasonally drying and flooding alternating areas (DFAs, 175-155m) than those in the non-inundated (NIAs, >175m) and inundated areas (IAs, <145m). However, MeHg% in all samples was less than 1%, indicating that the Hg methylation activity in the soils of the TGR was under a low level. 454 high-throughput sequencing of 16S rRNA gene amplicons showed that soil bacterial abundance and diversity were relatively higher in DFA compared to those in NIA and IA, and microbial community composition varied in these three areas. At the family level, those groups in Deltaproteobacteria and Methanomicrobia that might have many Hg methylators were also showed a higher relative abundance in DFA, which might be the reason for the higher MeHg production in these areas. Overall, our results suggested that seasonally water level fluctuations can enhance the microbial abundance and diversity, as well as MeHg production in the TGR.
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Affiliation(s)
- Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Hong Shen
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China.
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China.
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14
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Liu J, Jiang T, Huang R, Wang D, Zhang J, Qian S, Yin D, Chen H. A simulation study of inorganic sulfur cycling in the water level fluctuation zone of the Three Gorges Reservoir, China and the implications for mercury methylation. CHEMOSPHERE 2017; 166:31-40. [PMID: 27681258 DOI: 10.1016/j.chemosphere.2016.09.079] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 09/14/2016] [Accepted: 09/19/2016] [Indexed: 06/06/2023]
Abstract
The water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) in China experiences a drying and wetting rotation every year, and the water level induced redox variation may influence inorganic sulfur speciation and mercury methylation. In this work, a simulative flooding and drying experiment and a sulfate added flooding experiment were conducted to study this topic. The results showed that sulfate was reduced from the 10th d during the flooding period based on the detected sulfide in water and the increased elemental sulfur (S0) in sediment. Sulfate reduction and sulfide re-oxidation led to the increase of S0 contents with the maximal values of 1.86 and 0.46 mg kg-1 during the flooding and drying period, respectively. Methylmercury (MeHg) content in sediment displayed a rising trend (0.16-0.28 μg kg-1) in the first 40 d during the flooding period, and then declined from 0.28 to 0.15 μg kg-1. A positive correlation between MeHg content and S0 content in soil (r = 0.53, p < 0.05) was found during the flooding period, and a positive but not significant correlation between the percent of MeHg in THg (%MeHg) and S0 content (r = 0.85, p = 0.08). In sulfate added flooding simulation, MeHg content in sediment did not increase with the sulfate concentration increasing. The increased pyrite in high-sulfate treatment may fix mercury through adsorption process. This study demonstrated that inorganic sulfur species especially S0 and chromium reducible sulfur (CRS) play an important role on mercury methylation in the WLFZ of the TGR.
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Affiliation(s)
- Jiang Liu
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Tao Jiang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, PR China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden
| | - Rong Huang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, PR China
| | - Jinzhong Zhang
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, PR China.
| | - Sheng Qian
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Deliang Yin
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China
| | - Hong Chen
- College of Resources and Environment, Southwest University, Key Laboratory of Eco-environments in the Three Gorges Reservoir Region, Ministry of Education, Chongqing 400715, PR China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, PR China
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