Yu Chenghao, Lin Huiming, Guo Junming, Peng Mao, Liu Maodian, Tong Yindong, Lu Yifan, Wang Xuejun, Pan Xiangliang
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.
Ministry of Education Key Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Environ Int. 2023 Oct;180:108216. doi: 10.1016/j.envint.2023.108216. Epub 2023 Sep 19.
Rivers are important sources of Hg for adjacent seas, and seafood from nearshore waters is a major source of Hg exposure for humans. There is thus a key scientific concern regarding how much riverine Hg inputs influence Hg loads in nearshore waters as well as how far the impact range can extend from the river to the open sea. In addition, it is important to understand the influence of anthropogenic hydro-facilities and activities on Hg levels in downstream seas. Because of the concise mass exchange pattern between the seas and the previously demonstrated intensive Hg inputs under anthropogenic regulation from the Yellow River, the Bohai and Yellow Seas, which are key fishery and marine breeding areas for China, are an ideal research area for exploring the impacts of riverine Hg on nearshore and adjacent open seas. Field surveys were conducted in eight major rivers and two seas, and 433 water samples were collected. The main Hg input and output terms (rivers, ocean currents, underground discharge, sewage, coastal erosion, atmospheric deposition, surface evasion, sedimentation, and fisheries) were quantified in the Bohai and Yellow Seas. Owing to the high inputs from the Yellow and Yalu Rivers, elevated THg concentrations were found. Apart from direct MeHg discharge, riverine nutrients may also seemingly affect nearshore MeHg. Using mass balance models, we found that the Yellow River (9.8 t) was the dominant Hg source in the Bohai Sea, which accounted for more than half of all contributions, and the Bohai Sea played the role of a secondary source of Hg to the Yellow Sea, with a flux of 3.3 t. Anthropogenic hydro-activities in large rivers could significantly influence Hg outputs and loads in the nearshore and even open seas. This study provides useful information for water resource management applications to reduce potential MeHg risks.
河流是邻近海域汞的重要来源，近岸水域的海鲜是人类汞暴露的主要来源。因此，一个关键的科学问题是河流汞输入对近岸水域汞负荷有多大影响，以及影响范围能从河流延伸到公海多远。此外，了解人为水利设施和活动对下游海域汞含量的影响也很重要。由于海洋之间简洁的物质交换模式，以及先前已证明的在人为调控下黄河向渤海和黄海大量输入汞的情况，渤海和黄海作为中国重要的渔业和海洋养殖区，是探索河流汞对近岸和邻近公海影响的理想研究区域。在八条主要河流和两个海域进行了实地调查，共采集了433个水样。对渤海和黄海的主要汞输入和输出项（河流、洋流、地下排放、污水、海岸侵蚀、大气沉降、表面逸出、沉积和渔业）进行了量化。由于黄河和鸭绿江的高输入量，发现总汞浓度升高。除了直接排放甲基汞外，河流中的养分似乎也会影响近岸甲基汞。通过质量平衡模型，我们发现黄河（9.8吨）是渤海汞的主要来源，占所有贡献的一半以上，渤海对黄海起到了汞的次要来源作用，通量为3.3吨。大型河流中的人为水利活动会显著影响近岸甚至公海的汞输出和负荷。本研究为水资源管理应用提供了有用信息，以降低潜在的甲基汞风险。
