Research Center for Marine Ecology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, PR China; Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, PR China; Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
Research Center for Marine Ecology, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, PR China; Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, PR China.
Sci Total Environ. 2022 Sep 15;839:156266. doi: 10.1016/j.scitotenv.2022.156266. Epub 2022 May 27.
Silicon (Si) plays an essential role in the biogeochemistry of rivers. This study explored how damming, eutrophication and climate change alters the abundance and flux of DSi in the Changjiang (Yangtze) River based on long-term observations. The results showed that Three Gorges Reservoir (TGR) could enhance DSi transfer only during low-flow time period, and a downstream DSi retention effect by the TGR was found between the Yichang and Jianli stations in the Changjiang River. This resulted in a DSi loss during March and April in the mainstream from Three Gorges Dam (TGD) to Jianli but a DSi addition during July and October along the main channel of the Changjiang River. Long-term data showed a sharp decrease in DSi abundance at the Cuntan, Hankou and Datong stations between the 1960s and 1980s, but a slight increase in DSi between the 1990s and 2010s at these stations. The decrease in DSi during the 1960s -1980s was primarily the result of a decrease trend of silicate weathering, while a slight DSi increase compared to the temperature/DSi relation after the 1990s was largely due to increased DSi retention in the basin by damming and eutrophication. Eutrophication and damming increase DSi trapping in both the river channel and reservoir systems in the low-flow period and thus enhance the nutrient distortion in the coastal ocean.
硅（Si）在河流的生物地球化学中起着至关重要的作用。本研究通过长期观测，探讨了筑坝、富营养化和气候变化如何改变长江（Yangtze River）中溶解硅（DSi）的丰度和通量。结果表明，三峡水库（TGR）仅在低流量时期增强 DSi 的转移，并且在宜昌和监利站之间的长江流域发现了 TGR 的下游 DSi 保留效应。这导致了从三峡大坝（TGD）到监利的主流在 3 月和 4 月期间 DSi 损失，但在 7 月和 10 月期间长江干流沿线 DSi 增加。长期数据显示，在 20 世纪 60 年代至 80 年代期间，在寸滩、汉口和大通站的 DSi 丰度急剧下降，但在 20 世纪 90 年代至 21 世纪 10 年代期间，这些站的 DSi 略有增加。20 世纪 60 年代至 80 年代期间 DSi 的减少主要是由于硅酸盐风化的减少趋势，而与 90 年代以后的温度/DSi 关系相比，DSi 的轻微增加主要是由于筑坝和富营养化导致流域内 DSi 截留的增加。富营养化和筑坝在低流量期增加了河道和水库系统中 DSi 的截留，从而增强了近岸海域的养分扭曲。
