Organic matter content, source, and composition varying with seasons and anthropogenic activities regulate methylmercury dynamics in the Yellow River

IF 7.6 2区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES

Environmental Pollution Pub Date : 2025-03-12 DOI:10.1016/j.envpol.2025.126042

Xiaoquan Liu , Yingjun Wang , Xiaomeng Ji , Qingzhe Zhang , Yue Song , Yanbin Li , Yongguang Yin , Yong Cai

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Abstract

Organic matter (OM) in rivers, influenced by natural and anthropogenic events, plays a critical role in regulating methylmercury (MeHg) dynamics. This study investigated the spatial-temporal patterns of MeHg and OM in the Yellow River, through collecting water and sediment samples within the dry and wet seasons and human-induced water-sediment regulation scheme (WSRS) event. During the wet season, the river water was characterized by terrigenous OM, high unfiltered MeHg (UMeHg) concentration (206 ± 83.6 pg/L), and a low UMeHg percentage in unfiltered total Hg (UTHg) (UMeHg/UTHg = 0.37 ± 0.18 %). These findings may suggest that MeHg in the wet season was likely produced in the catchment and imported into the river. In contrast, autochthonous OM predominated during the dry season, probably enhancing in situ MeHg production (UMeHg/UTHg = 1.01 ± 0.50 %), although UMeHg concentration was lower (81.8 ± 25.5 pg/L) due to obviously reduced external inputs. The WSRS dramatically increased water MeHg contents (589 ± 116 pg/L) and UMeHg/UTHg ratios (0.78 ± 0.16 %) probably through direct inputs of upstream reservoirs’ MeHg and resuspension of downstream sediments. Exploring the effects of OM on sediment MeHg sources suggested that MeHg in the wet season primarily originated from watershed soil inputs, while in the dry season, it mainly resulted from in situ Hg methylation. However, extremely low total Hg (THg) and MeHg/THg (0.02–0.35 %) indicated that sediment MeHg production may be of minor importance in the Yellow River.

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来源期刊

Environmental Pollution 环境科学-环境科学

CiteScore

16.00

自引率

6.70%

发文量

2082

审稿时长

2.9 months

期刊介绍： Environmental Pollution is an international peer-reviewed journal that publishes high-quality research papers and review articles covering all aspects of environmental pollution and its impacts on ecosystems and human health. Subject areas include, but are not limited to: • Sources and occurrences of pollutants that are clearly defined and measured in environmental compartments, food and food-related items, and human bodies; • Interlinks between contaminant exposure and biological, ecological, and human health effects, including those of climate change; • Contaminants of emerging concerns (including but not limited to antibiotic resistant microorganisms or genes, microplastics/nanoplastics, electronic wastes, light, and noise) and/or their biological, ecological, or human health effects; • Laboratory and field studies on the remediation/mitigation of environmental pollution via new techniques and with clear links to biological, ecological, or human health effects; • Modeling of pollution processes, patterns, or trends that is of clear environmental and/or human health interest; • New techniques that measure and examine environmental occurrences, transport, behavior, and effects of pollutants within the environment or the laboratory, provided that they can be clearly used to address problems within regional or global environmental compartments.