Transport of mercury in a regulated high-sediment river and its input to marginal seas

Chenghao Yu; Maodian Liu; Junming Guo; Huiming Lin; Yunyun Yan; Qianru Zhang; Menghan Cheng; Yifan Lu; Xuejun Sun; Xuejun Wang; Xiangliang Pan

doi:10.1016/j.watres.2022.118211

Transport of mercury in a regulated high-sediment river and its input to marginal seas

Water Res. 2022 May 1:214:118211. doi: 10.1016/j.watres.2022.118211. Epub 2022 Feb 21.

Authors

Chenghao Yu¹, Maodian Liu², Junming Guo³, Huiming Lin⁴, Yunyun Yan⁴, Qianru Zhang⁴, Menghan Cheng⁵, Yifan Lu⁶, Xuejun Sun⁷, Xuejun Wang⁸, Xiangliang Pan⁹

Affiliations

¹ Ministry of Education Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China; Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
² Ministry of Education Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China; School of the Environment, Yale University, New Haven, CT 06511, United States.
³ State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China.
⁴ Ministry of Education Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
⁵ Ministry of Education Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China; Pinggu District Bureau of Ecology and Environment of Beijing Municipality, Beijing 101200, China.
⁶ Zhejiang Construction Investment Environment Engineering Co., Ltd., Hangzhou 310014, China.
⁷ Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China.
⁸ Ministry of Education Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China. Electronic address: xjwang@urban.pku.edu.cn.
⁹ Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China. Electronic address: panxl@zjut.edu.cn.

PMID: 35220063
DOI: 10.1016/j.watres.2022.118211

Abstract

Seafood is a major source of Hg exposure for humans, and rivers are an important source of Hg for adjacent seas. The Yellow River is an extremely high-sediment river that is heavily influenced by anthropogenic water facilities, especially sediment regulations, which might result in significant intra- and inter- year flux variations on pollutants. Overestimations of Hg flux were found in previous studies on high-sediment rivers, and a comprehensive study of Hg transport along such a river has not yet been attempted. In this study, we quantified the fates of Hg and methylmercury (MeHg) in the Yellow River and its main branches, as well as the impacts of anthropogenic activities, including deposition of contaminants in the reservoirs, diversion in the downstream, and sediment regulation, by sampling in 2017 and 2018,and comparing the two typical years with and without sediment regulation. The total Hg (THg) and MeHg concentrations in the Yellow River and its tributaries were high, and extremely high MeHg/THg ratios were found in the three sampled reservoirs. The river discharges substantial amounts of THg and MeHg into the Bohai Sea, and particulate Hg in the humid period accounts for a large proportion. A significant increase in Hg flux into the ocean was found in 2018 compared with that in 2017, which was primarily attributed to the altered hydrology caused by sediment regulation. Substantial amounts of Hg were impounded in the reservoirs, and only a small fraction was discharged downstream of the reservoir in the non-regulation years. Moreover, Hg fluxes to the coastal ocean were impacted by downstream water diversion in non-regulation years, whereas the contributions of diversions in regulation years were small. In conclusion, models showed that in recent 15 years, sediment regulation can enhance the Hg burden and risk to coastal ecosystem of Bohai Sea.

Keywords: High-sediment river; Mercury; Methylmercury; Sediment regulation; Yellow river.