Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
Environ Pollut. 2020 Jan;256:113376. doi: 10.1016/j.envpol.2019.113376. Epub 2019 Oct 12.
River-sea transition plays a key role in global geochemical cycles. The Yangtze River Estuary of China was selected as the research area, and the Section-Segmented Method was applied to determine the nutrient discharge from the Yangtze River to the East China Sea. A 3-D numerical model for the estuary was established and validated against the field investigated data. By numerical experiments the dynamics of hydrology and nutrient from 1950 to 2016 were simulated under four varied schemes. The individual and combined impacts on the nutrient flux induced by the Three-Gorges Dam (TGD) and the South-to-North Water Transfer Project (SNWTP) were explored. The following results were observed: (1) During the Pre-TGD period, the Yangtze River delivered the loads of 1.32 Tg/yr and 0.08 Tg/yr for TN and TP, respectively. July and Feb. were characterized by the highest and lowest monthly flux, respectively. (2) TGD played a significant role in regulating the temporal nutrient deliveries. After the closing of TGD, the discharges of TN and TP in the dry season respectively went up to 0.55 Tg and 0.032 Tg, with a mean increase of 28.3%. (3) SNWTP reduced the nutrient transport at a relatively stable level, and the total loads of 40.66 Gg and 2.4 Gg were reduced per year for TN and TP, respectively. (4) The combined impacts of TGD and SNWTP varied with seasons. October was characterized by the greatest cumulative effects. In dry seasons, the reduction caused by SNWTP was leveled by TGD-induced increase, limiting the flux variation linked to project operations.
江河湖海的转化在全球地球化学循环中起着关键作用。中国长江口被选为研究区域，并采用分段法确定长江向东海的营养物质排放量。建立了河口的三维数值模型，并通过野外调查数据进行了验证。通过数值实验，模拟了 1950 年至 2016 年在四种不同方案下的水文学和营养动力学。探讨了三峡大坝（TGD）和南水北调工程（SNWTP）对营养通量的单独和综合影响。结果表明：（1）在 TGD 前，长江输送的 TN 和 TP 负荷分别为 1.32Tg/yr 和 0.08Tg/yr。7 月和 2 月分别是月通量最高和最低的月份。（2）TGD 在调节营养物质的时间输送方面发挥了重要作用。TGD 关闭后，枯水季 TN 和 TP 的排放量分别上升到 0.55Tg 和 0.032Tg，平均增加 28.3%。（3）SNWTP 以相对稳定的水平减少了营养物质的输送，TN 和 TP 的总负荷分别减少了 40.66Gg 和 2.4Gg/yr。（4）TGD 和 SNWTP 的综合影响随季节而变化。10 月的累积效应最大。在枯水季节，SNWTP 减少的通量被 TGD 增加的通量所抵消，限制了与项目运行相关的通量变化。
