State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, People's Republic of China.
Environ Sci Pollut Res Int. 2013 Dec;20(12):8871-80. doi: 10.1007/s11356-013-1859-7. Epub 2013 Jun 8.
Excessive inputs of nitrogen and phosphorus (N and P) degrade surface water quality worldwide. Impoundment of reservoirs alters the N and P balance of a basin. In this study, riverine nutrient loads from the upper Yangtze River basin (YRB) at the Yichang station were estimated using Load Estimator (LOADEST). Long-term load trends and monthly variabilities during three sub-periods based on the construction phases of the Three Gorges Dam (TGD) were analyzed statistically. The dissolved inorganic nitrogen (DIN) loads from the upper YRB for the period from 1990 to 2009 ranged from 30.47 × 10(4) to 78.14 × 10(4) t, while the total phosphorus (TP) loads ranged from 2.54 × 10(4) to 7.85 × 10(4) t. DIN increased rapidly from 1995 to 2002 mainly as a result of increased fertilizer use. Statistics of fertilizer use in the upper YRB agreed on this point. However, the trend of the TP loads reflected the combined effect of removal by sedimentation in reservoirs and increased anthropogenic inputs. After the TGD impoundment in 2003, decreasing trends in both DIN and TP loads were found. The reduction in DIN was mainly caused by ammonium consumption and transference. From an analysis of monthly loads, it was found that DIN had a high correlation to discharges. For TP loads, an average decrease of 4.91 % in October was found when the TGD impoundment occurred, but an increase of 4.23 % also occurred in July, corresponding to the washout from sediment deposited in the reservoir before July. Results of this study revealed the TGD had affected nutrient loads in the basin, and it had played a role in nutrient reduction after its operation.
过量的氮（N）和磷（P）输入会导致全球地表水水质恶化。水库的蓄水会改变流域的 N 和 P 平衡。本研究采用 LOADEST 模型估算了长江上游宜昌站的河流营养物负荷。基于三峡大坝（TGD）的建设阶段，统计分析了三个子时段的长期负荷趋势和月变异性。1990 年至 2009 年期间，来自长江上游流域的溶解无机氮（DIN）负荷范围为 30.47×10(4)78.14×10(4)t，总磷（TP）负荷范围为 2.54×10(4)7.85×10(4)t。1995 年至 2002 年，DIN 迅速增加，主要是由于化肥用量增加。上游流域化肥使用量的统计数据也证实了这一点。然而，TP 负荷的趋势反映了水库沉降去除和人为输入增加的综合影响。2003 年 TGD 蓄水后，DIN 和 TP 负荷都呈下降趋势。DIN 的减少主要是由于铵盐的消耗和转移。从月负荷分析来看，DIN 与流量有很高的相关性。对于 TP 负荷，当 TGD 蓄水时，10 月平均下降 4.91%，但 7 月也出现了 4.23%的增长，这与 7 月前水库中沉积的泥沙冲刷有关。本研究结果表明，TGD 已经影响了流域的营养物负荷，并且在其运行后发挥了减少营养物的作用。
