1
|
Yang N, Hu J, Yin D, He T, Tian X, Ran S, Zhou X. Mercury and methylmercury in Hg-contaminated paddy soil and their uptake in rice as regulated by DOM from different agricultural sources. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27712-9. [PMID: 37249779 DOI: 10.1007/s11356-023-27712-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/13/2023] [Indexed: 05/31/2023]
Abstract
In this study, from the perspectives of structural and compositional variations of soil-dissolved organic matter (DOM), we explored the effects of agricultural DOM inputs on methylmercury (MeHg) accumulation in the soil and mercury (Hg) bioaccumulation in rice grains. Pot experiments with the addition of DOMs from maize straw (MaS), rape straw (RaS), rice straw (RiS), composted rice straw (CRiS), cow dung (CD), and composted cow dung (CCD) were then conducted. Results showed that, relative to the control, the DOM amendment from each agricultural source elevated MeHg concentrations in the soil, with an increase of 18-227%, but only parts of DOMs elevated total dissolved Hg (DHg) and MeHg (DMeHg) concentrations in pore water. Among all DOM species, RiS, CRiS, and CCD significantly increased total Hg (THg) and MeHg contents in rice grains by 34-64% and 32-118%, respectively. Compared with RiS, THg and MeHg contents in rice grains in the CRiS treatment decreased slightly, which was consistent with the distributions of DHg and DMeHg concentrations in pore water and the aromaticity variation of soil DOM. In contrast, the CCD input significantly enhanced the enrichment of THg and MeHg in rice grains relative to CD because it significantly reduced the humification of soil DOM at all rice-growing stages while increasing the low-molecular-weight fractions in soil DOM. The THg and MeHg contents in the rice grains were significantly lower treated by RaS than those by MaS and RiS, which may be related to the higher sulfur-containing compounds such as sulfate and cysteine in rape straw or its DOM solution. Overall, DOM amendment from different agricultural sources resulted in significantly discriminative effects on the MeHg accumulation in soil and Hg enrichment in rice in the Hg-contaminated paddy field by shaping soil DOM properties.
Collapse
Affiliation(s)
- Ningla Yang
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Jie Hu
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China.
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China.
| | - Xiang Tian
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Shu Ran
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| |
Collapse
|
2
|
Hu J, Yang N, He T, Zhou X, Yin D, Wang Y, Zhou L. Elevated methylmercury production in mercury-contaminated paddy soil resulted from the favorable dissolved organic matter variation created by algal decomposition. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 324:121415. [PMID: 36893976 DOI: 10.1016/j.envpol.2023.121415] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/18/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Algae-derived organic matter (AOM) may considerably regulate methylmercury (MeHg) production and accumulation in the paddy fields by changing the soil-dissolved OM (SDOM) properties. In this study, a 25-day microcosm experiment was performed to compare the responding mechanisms of MeHg production in the Hg-contaminated paddy soil-water system to the input of algae-, rice-, and rape-derived OMs. Results showed that algal decomposition could release much more cysteine and sulfate than crop straws. Compared with crop straw-derived OMs, AOM input greatly increased the dissolved organic carbon concentrations in soil but resulted in a greater decrease in tryptophan-like fractions while accelerated the formation of high-molecular-weight fractions in soil DOM. Moreover, AOM input significantly increased MeHg concentrations in the pore water by 19.43%-3427.66% and 52.81%-5846.57% compared to rape- and rice-derived OMs, respectively (P < 0.05). And, a similar MeHg changing pattern was also observed in the overlying water (10-25 d) and the soil solid-phase particles (15-25 d) (P < 0.05). Correlation analysis revealed that MeHg concentrations in the AOM-added soil-water system had significantly negative and positive relationships with the tryptophan-like C4 fraction and molecular weight (E2/E3 ratio) of soil DOM, respectively (P < 0.01). These findings suggest that AOM has a higher capacity than crop straw-derived OMs to promote MeHg production and accumulation in the Hg-contaminated paddy soils by creating a favorable soil DOM variation and providing more microbial electron donors and receptors.
Collapse
Affiliation(s)
- Jie Hu
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Ningla Yang
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Xian Zhou
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China.
| | - Yan Wang
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Litao Zhou
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Cheng Z, He T, Yin D, Tian X, Ran S, Zhou X. Effects of Composted Agricultural Organic Materials on Mercury Methylation in Paddy Soil and Mercury Enrichment in Rice. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2023; 110:38. [PMID: 36607425 DOI: 10.1007/s00128-022-03671-8] [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: 10/17/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Many studies have shown that returning fresh straw to the field can promote mercury accumulation in crops; therefore, it is necessary to find an appropriate way to use agricultural organic materials in mercury-contaminated farmlands. In this study, pot experiments were conducted to study the effects of composted agricultural organic materials on mercury bioaccumulation in the paddy field ecosystem by adding fresh rice straw (RS), composted rice straw (CRS), cow dung (CD) and composted cow dung (CCD) to the soils. Compared with RS and CD, the CRS and CCD amendments reduced dissolved organic matter (DOM) contents in soil, but increased the aromaticity and small molecule proportion of DOM, and also increased the tartaric acid contents in soil, as well as the methylation and release of mercury in soil. However, the increased available mercury and methylmercury in the soils in the CRS and CCD treatments were not effectively absorbed by rice plants. Overall, compared with fresh organic materials, composted organic materials amendments could reduce mercury accumulation in rice to a certain extent.
Collapse
Affiliation(s)
- Zongfu Cheng
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, 550025, Guiyang, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, 550025, Guiyang, China.
- College of Resources and Environment, Guizhou University, 550025, Guiyang, China.
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, 550025, Guiyang, China
- College of Resources and Environment, Guizhou University, 550025, Guiyang, China
| | - Xiang Tian
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, 550025, Guiyang, China
| | - Shu Ran
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, 550025, Guiyang, China
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, 550025, Guiyang, China
| |
Collapse
|
5
|
Sun T, Xie Q, Li C, Huang J, Yue C, Zhao X, Wang D. Inorganic versus organic fertilizers: How do they lead to methylmercury accumulation in rice grains. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 314:120341. [PMID: 36202265 DOI: 10.1016/j.envpol.2022.120341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/11/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Both inorganic and organic fertilizers are widely used to increase rice yield. However, these fertilizers are also found to aggravate mercury methylation and methylmercury (MeHg) accumulation in paddy fields. The aim of this study was to reveal the mechanisms of inorganic and organic fertilizers on MeHg accumulation in rice grains, which are not yet well understood. Potting cultures were conducted in which different fertilizers were applied to a paddy soil. The results showed that both inorganic and organic fertilizers increased MeHg concentrations rather than biological accumulation factors (BAFs) of MeHg in mature rice grains. Inorganic fertilizers, especially nitrogen fertilizer, enhanced the bioavailability of mercury and the relative amount Hg-methylating microbes and therefore intensified mercury methylation in paddy soil and MeHg accumulation in rice grains. Unlike inorganic fertilizers, organic matter (OM) in organic fertilizers was the main reason for the increase of MeHg concentrations in rice grains, and it also could immobilize Hg in soil when it was deeply degraded. The enhancement of MeHg concentrations in rice grains induced by inorganic fertilizers (5.18-41.69%) was significantly (p < 0.05) lower than that induced by organic fertilizers (80.49-106.86%). Inorganic fertilizers led to a larger increase (50.39-99.28%) in thousand-kernel weight than MeHg concentrations (5.18-41.69%), resulting in a dilution of MeHg concentrations in mature rice grains. Given the improvement of soil properties by organic fertilizer, increasing the proportion of inorganic fertilizer application may be a better option to alleviate MeHg accumulation in rice grains and guarantee the rice yield in the agricultural production.
Collapse
Affiliation(s)
- Tao Sun
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China; Funiu Mountain Forest Ecosystem Observation and Research Station, Zhengzhou University, Zhengzhou, 450001, China
| | - Qing Xie
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Chuxian Li
- Department of Forest Ecology & Management, Swedish University of Agricultural Sciences, Umeå, 90136, Sweden
| | - Jinyong Huang
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China; Funiu Mountain Forest Ecosystem Observation and Research Station, Zhengzhou University, Zhengzhou, 450001, China
| | - Caipeng Yue
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Xuejie Zhao
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing, 400715, China.
| |
Collapse
|
6
|
Liang L, Wang D. Effects of Herbaceous Plants on Methylmercury Net Production and Release From Sediment After Flooding in the Water-Level Fluctuation Zone of the Jialing River. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 109:735-740. [PMID: 35920851 DOI: 10.1007/s00128-022-03591-7] [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: 01/12/2022] [Accepted: 07/19/2022] [Indexed: 06/15/2023]
Abstract
To explore the effects of herbaceous plants on mercury (Hg) behaviors after flooding in the water-level fluctuation zone (WLFZ) of Jialing River, three typical local plants (D. pyramidalis, A. philoxeroides and C. dactylon) and their in-situ sediments were collected for flooding experiments to study the Hg dynamics of water and sediment in different treatments. The results showed that flooding increased sediment MeHg concentrations and flooded plants (especially for the D. pyramidalis) promoted this process. Similarly, the highest dissolved MeHg level and proportion of MeHg to total Hg (%MeHg) were observed in plant-water treatments in the presence of D. pyramidalis, indicating the potential for the methylation of Hg in the water body influenced by the decay process of herbaceous plants. These results suggest that the herbaceous plant D. pyramidalis contributes more to Hg methylation and release in the WLFZ of the Jialing River than other plants studied.
Collapse
Affiliation(s)
- Li Liang
- Chongqing Industry Polytechnic College, 401120, Chongqing, P. R. China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, 400715, Chongqing, P. R. China.
| |
Collapse
|
7
|
Ran S, He T, Zhou X, Yin D. Effects of fulvic acid and humic acid from different sources on Hg methylation in soil and accumulation in rice. J Environ Sci (China) 2022; 119:93-105. [PMID: 35934469 DOI: 10.1016/j.jes.2022.02.023] [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: 12/31/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 06/15/2023]
Abstract
Humus is often used as an organic modifier to reduce the bioaccumulation of heavy metals in plants, but the effects of different humus components from different sources on the fate of mercury (Hg) in paddy fields are still unclear. Here, fulvic acid (FA) and humic acid (HA) extracted from composted straw (CS), composted cow dung (CCD), peat soil (PM) and lignite coal (LC) were used to understand their effects on the methylation and bioaccumulation of Hg in paddy soil by pot experiments. Amendments of both FA and HA largely increased the abundance of Hg-methylating microbes and low-molecular-weight organic matters (e.g, cysteine) in paddy soil. They were also found to change the aromaticity, molecular size and Chromophoric DOM concentration of DOM, and resulted in heterogeneous effects on migration and transformation of Hg. All the FA-amended treatments increased the mobility and methylation of Hg in soil and its absorption in roots. Nevertheless, FA from different sources have heterogeneous effects on transport of Hg between rice tissues. FA-CCD and FA-PM promoted the translocation of MeHg from roots to rice grains by 32.95% and 41.12%, while FA-CS and FA-LC significantly inhibited the translocation of inorganic Hg (IHg) by 52.65% and 66.06% and of MeHg by 46.65% and 36.23%, respectively. In contrast, all HA-amended treatments reduced the mobility of soil Hg, but promoted Hg methylation in soil. Among which, HA-CCD and HA-PM promoted the translocation of MeHg in rice tissues by 88.95% and 64.10%, while its accumulation in rice grains by 28.43% and 28.69%, respectively. In general, the application of some FA and HA as organic modifiers to reduce Hg bioaccumulation in rice is not feasible.
Collapse
Affiliation(s)
- Shu Ran
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China.
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China.
| |
Collapse
|
8
|
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.
Collapse
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.
| |
Collapse
|
9
|
Xu L, Dai H, Skuza L, Xu J, Shi J, Wei S. Co-high-efficiency washing agents for simultaneous removal of Cd, Pb and As from smelting soil with risk assessment. CHEMOSPHERE 2022; 300:134581. [PMID: 35436460 DOI: 10.1016/j.chemosphere.2022.134581] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 04/01/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Soil washing is considered a highly efficient technology due to its higher removal rate of multiple heavy metals from contaminated soil. However, previous studies on Cd, Pb and As washing agents for soils with complex contaminations did not consider the differences in As and Cd/Pb properties, resulting in the lack of effective washing compounds and washing conditions for soils with complex contaminations. Moreover, most traditional washing agents can cause secondary pollution. In this study, HEDTA and lactic acid (LA) treatments resulted in a higher Cd and Pb removal, while 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) was more effective in As removal. Most importantly, a new washing strategy was proposed with a new combined high-efficiency washing agents consisting of HEDP + LA + FeCl3 with a ratio of 6:3:1. Considering washing efficiency and consumption under optimal washing conditions, i.e. the soil/liquid (S/L) ratio of 1:20 and washing time of 48 h, the rates of Cd, Pb and As removal were 79.93%, 69.84% and 61.55%, respectively. In addition, washing process could influence the speciation of heavy metals, especially oxidizable and residual Cd and Pb fractions, as well as reducible As fraction. The washing process using the new washing agent can significantly reduce the pollution level and health risk of Cd, Pb and As contamination. The results of this study can provide an efficient washing agent for the remediation of heavy metal-contaminated soils at smelting sites, which will help protect human health.
Collapse
Affiliation(s)
- Lei Xu
- Key Laboratory of Pollution Ecology and Environment Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Huiping Dai
- College of Biological Science & Engineering, Shaanxi Province Key Laboratory of Bio-resources, Qinling-Bashan Mountains Bioresources Comprehensive Development C.I.C, State Key Laboratory of Biological Resources and Ecological Environment Jointly Built By Qinba Province and Ministry, Shaanxi University of Technology, Hanzhong, 723001, China.
| | - Lidia Skuza
- Institute of Biology, Centre for Molecular Biology and Biotechnology, University of Szczecin, Szczecin, 71-415, Poland
| | - Jianming Xu
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Jiachun Shi
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Shuhe Wei
- Key Laboratory of Pollution Ecology and Environment Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
| |
Collapse
|
10
|
Liu J, Zhao L, Kong K, Abdelhafiz MA, Tian S, Jiang T, Meng B, Feng X. Uncovering geochemical fractionation of the newly deposited Hg in paddy soil using a stable isotope tracer. JOURNAL OF HAZARDOUS MATERIALS 2022; 433:128752. [PMID: 35364530 DOI: 10.1016/j.jhazmat.2022.128752] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/08/2022] [Accepted: 03/19/2022] [Indexed: 06/14/2023]
Abstract
The newly deposited mercury (Hg) is more readily methylated to methylmercury (MeHg) than native Hg in paddy soil. However, the biogeochemical processes of the newly deposited Hg in soil are still unknown. Here, a field experimental plot together with a stable Hg isotope tracing technique was used to demonstrate the geochemical fractionation (partitioning and redistribution) of the newly deposited Hg in paddy soils during the rice-growing period. We showed that the majority of Hg tracer (200Hg, 115.09 ± 0.36 μg kg-1) was partitioned as organic matter bound 200Hg (84.6-89.4%), followed by residual 200Hg (7.6-8.1%), Fe/Mn oxides bound 200Hg (2.8-7.2%), soluble and exchangeable 200Hg (0.05-0.2%), and carbonates bound 200Hg (0.04-0.07%) in paddy soils. Correlation analysis and partial least squares path modeling revealed that the coupling of autochthonous dissolved organic matter and poorly crystalline Fe (oxyhydr)oxides played a predominant role in controlling the redistribution of the newly deposited Hg among geochemical fractions (i.e., fraction changes). The expected aging processes of the newly deposited Hg were absent, potentially explaining the high bioavailability of these Hg in paddy soil. This study implies that other Hg pools (e.g., organic matter bound Hg) should be considered instead of merely soluble Hg pools when evaluating the environmental risks of Hg from atmospheric depositions.
Collapse
Affiliation(s)
- Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Lei Zhao
- School of Management Science, Guizhou University of Finance and Economics, Guiyang 550025, China; Guizhou Key Laboratory of Big Data Statistical Analysis (No. [2019]5103), Guiyang 550025, China.
| | - Kun Kong
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mahmoud A Abdelhafiz
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China; Geology Department, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt
| | - Shanyi Tian
- Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Tao Jiang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing 400716, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| |
Collapse
|
11
|
Sun T, Wang Y, Li C, Huang J, Hua Y, Yue C, Chao H, Zhang D, Zhang Y, Wang D. Use smaller size of straw to alleviate mercury methylation and accumulation induced by straw incorporation in paddy field. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:127002. [PMID: 34474359 DOI: 10.1016/j.jhazmat.2021.127002] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/07/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
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.
Collapse
Affiliation(s)
- Tao Sun
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Chuxian Li
- Department of Forest Ecology & Management, Swedish University of Agricultural Sciences, Umeå 90136, Sweden
| | - Jinyong Huang
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China.
| | - Yingpeng Hua
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Caipeng Yue
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Hongbo Chao
- School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Dingxi Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yongjiang Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Department of Environment and Quality Test, Chongqing Chemical Industry Vocational College, Chongqing 401220, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China.
| |
Collapse
|
12
|
Mei K, Wu G, Liu J, Hong H, Lu H, Yan C. Dynamics of low-molecular-weight organic acids for the extraction and sequestration of arsenic species and heavy metals using mangrove sediments. CHEMOSPHERE 2022; 286:131820. [PMID: 34416592 DOI: 10.1016/j.chemosphere.2021.131820] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/15/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
Mangrove wetlands are subjected to pollution due to anthropogenic activities. Mangrove fitness is mainly determined by root exudates and microorganisms activities belowground, but the mechanisms are not yet well known. Rhizospheric interactions among mangrove sediments, microorganisms and root exudates were simulated. In particular, low-molecular-weight organic acids (LMWOA), were examined to explore the metal(loid)s rhizospheric dynamics via batch experiments. Using a combination of comparative sterilised and unsterilised sediments, LMWOA extracts and sediments constituents were examined. Factors such as the solution pH, dissolved organic carbon (DOC), arsenic and iron species and metal(loid)s in the aqueous phase were evaluated. The results show that on an average, the As decreased by 68.3 % and 42.1 % under citric and malic acid treatments, respectively, after sterilisation. In contrast, the As content increased by 29.6 % under oxalic acid treatment. Microorganisms probably facilitate sediment As release in the presence of citric and malic acids but suppress As mobilisation in the presence of oxalic acid. Fe, Mn and Al were significantly (p < 0.05) positively correlated with the trace metal(loid)s (Zn, Pb, Ni, Cu, Cr, Co, Ba, Cd and As). The solution pH was negatively correlated with the solution As. Both DOC and pH reach the peaks at the end of all treatments. The As absorption-desorption dynamics are closely linked to proton consumption, Fe-Mn-Al sedimentation of ageing performance and organic ligand complexation. The study provides an insight into the rhizospheric processes of microbial involvement and gives an enlightening understanding of the metal(loid)s redeployment for plant adaptation in mangrove wetlands.
Collapse
Affiliation(s)
- Kang Mei
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
| | - Guirong Wu
- College of Food and Biological Engineering, Hezhou University, Hezhou, 542899, China
| | - Jingchun Liu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China.
| | - Hualong Hong
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
| | - Haoliang Lu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China
| | - Chongling Yan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
| |
Collapse
|
13
|
Xu Y, He T, Wu P, Yin D, Ran S. Fulvic acid: A key factor governing mercury bioavailability in a polluted plateau wetland. WATER RESEARCH 2021; 205:117652. [PMID: 34583206 DOI: 10.1016/j.watres.2021.117652] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/01/2021] [Accepted: 09/04/2021] [Indexed: 06/13/2023]
Abstract
Fulvic acids (FAs) are known to regulate the fate of mercury (Hg) in sediments, but the key effects of their properties are still unclear. In this study, field investigations and simulation experiments were conducted in a heavy metal-polluted wetland to identify FA characteristics and their association with the production and bioaccumulation of methylmercury (MeHg). Compared to permanently inundated areas (PIA), seasonally inundated areas (SIAs) had lower total Hg levels in sediments, whereas higher MeHg levels in sediments (0.20 ± 0.09 ng g-1 vs. 0.55 ± 0.31 ng g-1) and benthos (0.25 ± 0.22 ng g-1 vs. 1.62 ± 1.78 ng g-1). Meanwhile, the THg and MeHg concentrations in the same macrophyte species between PIA and SIA also followed a similar rule with benthos. FA-bound Hg in the sediment was significantly correlated with MeHg in the sediment (p < 0.01), as well as THg and MeHg in benthos (p < 0.05), indicating that FAs have the capacity to promote MeHg production and bioaccumulation. Moreover, the FAs in the sediments of the SIA had lower fractions and alkyl C/O-alkyl C ratios, but higher molecular weights and THg/MeHg concentrations than those in the PIA, indicating that FAs in SIA have increased bioavailability and enhanced competition for Hg, favoring significantly elevated FA-bound Hg levels. Biological exposure testing further demonstrated that FAs extracted from SIA had a greater ability to increase the production and bioaccumulation of MeHg than those extracted from PIA. Overall, these results highlight that the molecular composition and sources of FAs, excluding their concentrations, are one of important factors responsible for the obvious spatial heterogeneity of MeHg in sediments and aquatic organisms in the wetland.
Collapse
Affiliation(s)
- Yiyuan Xu
- College of Resources and Environment Engineering, Guizhou University, Guiyang 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Resources and Environment Engineering, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China.
| | - Pan Wu
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Resources and Environment Engineering, Guizhou University, Guiyang 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Resources and Environment Engineering, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China.
| | - Shu Ran
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China
| |
Collapse
|
14
|
Xie Q, Wang Y, Li S, Zhang C, Tian X, Cheng N, Zhang Y, Wang D. 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 (BARKING, ESSEX : 1987) 2021; 282:117041. [PMID: 33838440 DOI: 10.1016/j.envpol.2021.117041] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/23/2021] [Accepted: 03/27/2021] [Indexed: 06/12/2023]
Abstract
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 mercury (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 total mercury (THg) and methylmercury (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%, respectively) 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.
Collapse
Affiliation(s)
- Qing Xie
- 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
| | - Shouying Li
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Cheng Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Xiaosong Tian
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Nan Cheng
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yongjiang Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China; Department of Environment and Quality Test, Chongqing Chemical Industry Vocational College, Chongqing, 401220, China
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400715, China.
| |
Collapse
|
15
|
Liang H, Lyu LN, Sun C, Ding H, Wurgaft E, Yang GP. Low-molecular-weight organic acids as important factors impacting seawater acidification: A case study in the Jiaozhou Bay, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 727:138458. [PMID: 32339827 DOI: 10.1016/j.scitotenv.2020.138458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 03/31/2020] [Accepted: 04/03/2020] [Indexed: 06/11/2023]
Abstract
Low-molecular-weight organic acids (LMWOAs) are ubiquitous water-soluble organic compounds with mass production worldwide, but their influence on coastal marine environments is still lack of consideration. In this study, we select a typical nearshore bay - the Jiaozhou Bay, which is surrounded by Qingdao - a city with modern manufacture, agriculture, aquaculture and service industry, as study area, to investigate the effect of LMWOAs on the nearshore marine environment, and their impact on seawater acidification in coastal areas. During Sep. 2016 to Aug. 2017, we identified three different LMWOAs - acetic acid (AA), formic acid (FA) and lactic acid (LA), with average concentrations of 46.7, 13.9 and 1.4 μmol·L-1 in the seawater of the bay, respectively. Due to the establishment of the Jiaozhou Bay Bridge, the seawater exchange capacity was weakened and thereby the concentration and stocks of AA and FA increased. As weak acids in seawater, the influence of LMWOAs on the seawater acidification of the Jiaozhou Bay was investigated. LMWOAs had significant impact on seawater pH and every 10 μmol·L-1 LMWOA caused an average of 0.02 pH unit decrease. From 2010 to 2017, pH value in the seawater of the bay decreased by about 0.103 and LMWOAs contributed about 83% of its decrease. Besides, two models were established to estimate the influence of LMWOAs on the seawater pH by applying the data set of dissolved inorganic carbon (DIC), total alkalinity (TA) and LMWOAs. The results showed that LMWOAs could enhance acidification of coastal seawater. Considering the importance of LMWOAs in seawater, it is necessary to evaluate their future changes in coastal marine environments. This study initiated a way to identify the source of LMWOAs in seawater and to evaluate their contribution to seawater acidification, and also provided a series of dataset for future study on LMWOAs in coastal environment.
Collapse
Affiliation(s)
- Haorui Liang
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Li-Na Lyu
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Chengjun Sun
- Marine Ecology Center, First Institute of Oceanography, Ministry of Natural Resource, Qingdao 266061, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Haibing Ding
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory of Marine Science and Technology, Qingdao 266023, China; Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, Qingdao 266100, China.
| | - Eyal Wurgaft
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole 02543, USA
| | - Gui-Peng Yang
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory of Marine Science and Technology, Qingdao 266023, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China; Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, Qingdao 266100, China.
| |
Collapse
|
16
|
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.
Collapse
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.
| |
Collapse
|
17
|
Yin D, Wang Y, Xiang Y, Xu Q, Xie Q, Zhang C, Liu J, Wang D. 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 2020; 381:120962. [PMID: 31442691 DOI: 10.1016/j.jhazmat.2019.120962] [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: 01/29/2019] [Revised: 06/29/2019] [Accepted: 08/02/2019] [Indexed: 06/10/2023]
Abstract
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.
Collapse
Affiliation(s)
- Deliang Yin
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yongmin Wang
- 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
| | - Qing Xie
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Jiang Liu
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China.
| |
Collapse
|
18
|
Huang D, Wang T, Zhu K, Zhao S, Shi Y, Ye M, Wang C, Jia H. Low-molecular-weight organic acids impede the degradation of naphthol in iron oxides/persulfate systems: Implications for research experiments in pure conditions. CHEMOSPHERE 2019; 225:1-8. [PMID: 30852260 DOI: 10.1016/j.chemosphere.2019.02.127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
Naphthols are industrial contaminants occurring widely in soils and waters. Remediation of organic pollutants can be done by chemical oxidation using persulfate. However, most research experiments testing degradation of organic pollutants have been done in ideal conditions, e.g. using a pure compound in pure water, and thus are weakly representative of real natural conditions where pollutants occur in complex mixtures of numerous organic compounds. Therefore we tested here the effect of the presence of small organic acids, as typical compounds occurring in natural media, on the degradation of 1-napthol with persulfate and iron oxides. Results show that organic acids decreased naphthol transformation by 3.7% for malic acid, 53.2% for tartaric acid, 72.3% for citric acid and 77% for oxalic acids, in a magnetite/persulfate system during 10 h. Meanwhile, the dissolved Fe species increased gradually with the reaction time; the highest concentration of Fe ions reached to ∼18 μM L-1 in aqueous phase. Electron paramagnetic resonance technique was applied to determine reactive oxygen species (ROS). The spin density of ·OH, detected as the main ROS, decreased initially, followed by gradually increase, suggesting that organic acids might inhibit the degradation of 1-naphthol by competing with ·OH. These findings disclose the high inhibition of the transformation by organic acids, and thus, more generally, imply that studies using only pure contaminants are weakly representative for remediation of real, natural samples.
Collapse
Affiliation(s)
- Dan Huang
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China of Ministry of Agriculture, College of Resources and Environment, Northwest A & F University, Yangling, 712100, China; Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
| | - Tiecheng Wang
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China of Ministry of Agriculture, College of Resources and Environment, Northwest A & F University, Yangling, 712100, China
| | - Kecheng Zhu
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China of Ministry of Agriculture, College of Resources and Environment, Northwest A & F University, Yangling, 712100, China.
| | - Song Zhao
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China of Ministry of Agriculture, College of Resources and Environment, Northwest A & F University, Yangling, 712100, China.
| | - Yafang Shi
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China of Ministry of Agriculture, College of Resources and Environment, Northwest A & F University, Yangling, 712100, China.
| | - Mao Ye
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
| | - Chuanyi Wang
- Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi, 830011, China.
| | - Hanzhong Jia
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China of Ministry of Agriculture, College of Resources and Environment, Northwest A & F University, Yangling, 712100, China.
| |
Collapse
|
19
|
Ji X, Liu C, Shi J, Pan G. Optimization of pretreatment procedure for MeHg determination in sediments and its applications. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:17707-17718. [PMID: 31028624 DOI: 10.1007/s11356-019-05179-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 04/12/2019] [Indexed: 06/09/2023]
Abstract
Methylmercury (MeHg) in sediment is difficult to be determined due to its low concentration and binding compounds like sulfide and organic matter. Moreover, wet sediment samples have been suggested to behave differently from certified reference materials in MeHg analysis. Optimal pretreatment procedure for MeHg determination in sediments has not been ascertained and whether the procedure could apply to sediment samples with complex matrix merits further research. This work firstly compared recovery results of five pretreatment procedures for MeHg determination using ERM-CC580. Using the optimal pretreatment procedure, recovery results were analyzed in different sediment samples after manipulation of moisture content, organic matter, and acid volatile sulfide. The procedure using CuSO4/HNO3 as leaching solutions and mechanical shaking as extraction method was proved to produce the most satisfactory recovery results (100.67 ± 6.75%, mean ± standard deviation). And when moisture content varied from 20 to 80%, average recovery results in sediment samples ranged from 100 to 125%. Furthermore, before and after the manipulation of organic matter or acid volatile sulfide, spiking recovery results varied little and were all within acceptable limit (85~105%). Therefore, the procedure of CuSO4/HNO3-mechanical is proposed as a universal pretreatment method for MeHg determination in sediment samples with various characteristics.
Collapse
Affiliation(s)
- Xiaonan Ji
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Chengbin Liu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Jianbo Shi
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
| | - Gang Pan
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China.
- University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
- Beijing Advanced Science and Innovation Center, Chinese Academy of Sciences, Beijing, 101407, People's Republic of China.
- Center of Integrated Water-Energy-Food studies (iWEF), School of Animal, Rural, and Environmental Sciences, Nottingham Trent University, Brackenhurst Campus, Nottingham, NG25 0QF, UK.
| |
Collapse
|
20
|
He M, Tian L, Braaten HFV, Wu Q, Luo J, Cai LM, Meng JH, Lin Y. Mercury-Organic Matter Interactions in Soils and Sediments: Angel or Devil? BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:621-627. [PMID: 30600387 DOI: 10.1007/s00128-018-2523-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
Many studies have suggested that organic matter (OM) substantially reduces the bioavailability and risks of mercury (Hg) in soils and sediments; however, recent reports have supported that OM greatly accelerates Hg methylation and increases the risks of Hg exposure. This study aims to summarize the interactions between Hg and OM in soils and sediments and improve our understanding of the effects of OM on Hg methylation. The results show that OM characteristics, promotion of the activity of Hg-methylating microbial communities, and the microbial availability of Hg accounted for the acceleration of Hg methylation which increases the risk of Hg exposure. These three key aspects were driven by multiple factors, including the types and content of OM, Hg speciation, desorption and dissolution kinetics and environmental conditions.
Collapse
Affiliation(s)
- Mei He
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Lei Tian
- School of Petroleum Engineering, Yangtze University, Wuhan, 430100, People's Republic of China
| | | | - Qingru Wu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Jie Luo
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Li-Mei Cai
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Jiang-Hui Meng
- Hubei Cooperative Innovation Center of Unconventional Oil and Gas, Yangtze University, Wuhan, 430100, People's Republic of China
| | - Yan Lin
- School of Resources and Environment, Yangtze University, Wuhan, 430100, People's Republic of China.
- Norwegian Institute for Water Research, 0349, Oslo, Norway.
| |
Collapse
|
21
|
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.
Collapse
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.
| |
Collapse
|
22
|
Cao Y, Zhang S, Zhong Q, Wang G, Xu X, Li T, Wang L, Jia Y, Li Y. Feasibility of nanoscale zero-valent iron to enhance the removal efficiencies of heavy metals from polluted soils by organic acids. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 162:464-473. [PMID: 30015193 DOI: 10.1016/j.ecoenv.2018.07.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/03/2018] [Accepted: 07/08/2018] [Indexed: 06/08/2023]
Abstract
Soil washing with natural chelators to remediate metal-contaminated soils has been gained attention by researchers. However, the abilities of the chelators to remediate the multiple metal polluted soils are less effective. This study employed zero-valent iron nanoparticle (nZVI) to enhance the removal efficiencies of citric (CA), tartaric (TA) and oxalic acids (OA), and evaluate their feasibility. Results showed that metal removal efficiencies increased with the increasing concentration of nZVI and soil-liquid ratio, decreased with the increasing solution pH. The kinetic simulation indicated that pseudo-first-order and pseudo-second-order models could be used for describing the washing processes. Additionally, metal removals were significantly improved by addition of nZVI (p < 0.05). The highest enhancements of soil Cd, Pb and Zn removals under solution pH of 4.0, soil-liquid ratio of 1:20 and washing time of 120 min reached 12.83% (OA- nZVI), 24.92% (CA-nZVI) and 11.64% (OA- nZVI) for mine soil, and 19.24% (TA- nZVI), 18.16% (CA-nZVI) and 8.93% (OA- nZVI) for farmland soil, respectively. After soil washing, the exchangeable forms and the environmental risks of residual metals were markedly diminished in soils. Therefore, the combinations of the organic acids and nZVI are the feasible practices to repair the soils contaminated by heavy metals.
Collapse
Affiliation(s)
- Yaru Cao
- College of Environmental Sciences, Sichuan Agricultural University, Wenjiang 611130, China
| | - Shirong Zhang
- College of Environmental Sciences, Sichuan Agricultural University, Wenjiang 611130, China.
| | - Qinmei Zhong
- College of Environmental Sciences, Sichuan Agricultural University, Wenjiang 611130, China
| | - Guiyin Wang
- College of Environmental Sciences, Sichuan Agricultural University, Wenjiang 611130, China
| | - Xiaoxun Xu
- College of Environmental Sciences, Sichuan Agricultural University, Wenjiang 611130, China
| | - Ting Li
- College of Resources, Sichuan Agricultural University, Wenjiang 611130, China
| | - Lilin Wang
- College of Environmental Sciences, Sichuan Agricultural University, Wenjiang 611130, China
| | - Yongxia Jia
- College of Resources, Sichuan Agricultural University, Wenjiang 611130, China
| | - Yun Li
- College of Resources, Sichuan Agricultural University, Wenjiang 611130, China
| |
Collapse
|