Zhuo Hai-Hua, Qiu Guang-Sheng, Zhai Wan-Ying, Liu Yun-Bing, Lan Jing
Yangtze Valley Water Environment Monitoring Center, Wuhan 430010, China.
Water Resources Protection Bureau of the Yangtze River Basin, Wuhan 430010, China.
Huan Jing Ke Xue. 2017 Dec 8;38(12):5020-5031. doi: 10.13227/j.hjkx.201705127.
With the construction of the Three Gorges Dam, the river flow pattern and sediment dynamics are expected to be affected. As a consequence, the sediment traits could be impacted by these changes. The temporal and spatial variation characteristics of the nutrient content from 2000 to 2015 in surface sediment were analyzed in the main stream from Jiangjin to the dam site section of the Yangtze River and in the estuaries of the representative input tributaries of the Three Gorges Reservoir, such as the Jialing River, Yulin River, Wujiang River, Xiaojiang River, Daning River, and Xiangxi River. Then, the state of the pollution was assessed. Results revealed that the average concentrations of total phosphorus (TP) in the surface sediments of the main stream ranged from 678.2 to 928.6 mg·kg, the average contents of total nitrogen (TN) ranged from 0.203% to 0.362%, the average contents of potassium ranged from 1.74% to 2.37%, and the average contents of organic matter ranged from 0.94% to 1.54%. The average concentrations of TP in the estuaries of the representative input tributaries ranged from 490.1 to 832.3 mg·kg, the average contents of TN ranged from 0.257% to 0.495%, the average contents of potassium ranged from 1.69% to 2.32%, and the average contents of organic matter ranged from 1.21% to 2.27%. The concentrations of TP and potassium in the study sections were generally within background concentration ranges, while the concentrations of TN were obviously above background levels, and the concentrations of organic matter were obviously below background levels. The nutrient contents in the surface sediment did not display significant differences among the study sites; however, the distributions of different nutrient contents along the river varied widely. Although the nutrient contents in the surface sediments fluctuated somewhat during different flow periods, they were seemingly unaffected by the impoundment, since no obvious enrichment was observed throughout the impoundment. The evaluation of organic index indicated a clean state for the surface sediments in the majority of the study area, while there was a moderately polluted state in some local sections. The evaluation of nitrogen pollution indicated a polluted state for most sections. Overall, the nutrients in the surface sediments of the Three Gorges Reservoir showed moderate ecological risks, possibly caused by TP and TN.
随着三峡大坝的建设，预计河流的水流形态和泥沙动态将受到影响。因此，这些变化可能会影响泥沙特性。分析了2000年至2015年长江江津至坝址段干流以及三峡水库代表性输入支流河口（如嘉陵江、御临河、乌江、小江、大宁河和香溪河）表层沉积物中营养物质含量的时空变化特征。然后，对污染状况进行了评估。结果表明，干流表层沉积物中总磷（TP）的平均浓度在678.2至928.6mg·kg之间，总氮（TN）的平均含量在0.203%至0.362%之间，钾的平均含量在1.74%至2.37%之间，有机质的平均含量在0.94%至1.54%之间。代表性输入支流河口TP的平均浓度在490.1至832.3mg·kg之间，TN的平均含量在0.257%至0.495%之间，钾的平均含量在1.69%至2.32%之间，有机质的平均含量在1.21%至2.27%之间。研究断面TP和钾的浓度总体在背景浓度范围内，而TN的浓度明显高于背景水平，有机质的浓度明显低于背景水平。表层沉积物中的营养物质含量在各研究地点之间没有显著差异；然而，不同营养物质含量沿河流的分布差异很大。尽管表层沉积物中的营养物质含量在不同流量期有所波动，但它们似乎不受蓄水的影响，因为在整个蓄水过程中没有观察到明显的富集现象。有机指数评价表明，研究区域大部分表层沉积物处于清洁状态，而一些局部断面处于中度污染状态。氮污染评价表明，大部分断面处于污染状态。总体而言，三峡水库表层沉积物中的营养物质显示出中等程度的生态风险，可能是由TP和TN造成的。
