Historical trend of nitrogen and phosphorus loads from the upper Yangtze River basin and their responses to the Three Gorges Dam
Historical trend of nitrogen and phosphorus loads from the upper Yangtze River basin and their responses to the Three Gorges Dam
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DOI：
10.1007/s11356-013-1859-7
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发表时间：
2013-06
影响因子：
5.8
通讯作者：
Cheng Sun;Zhenyao Shen;Ruimin Liu;M. Xiong;F. Ma;O. Zhang;Yangyang Li;Lei Chen
中科院分区：
文献类型：
--
作者：
Cheng Sun;Zhenyao Shen;Ruimin Liu;M. Xiong;F. Ma;O. Zhang;Yangyang Li;Lei Chen
氮和磷（N和P）的过量输入会降低全球地表水质量。水库蓄水改变了流域的氮磷平衡。采用负荷估算法（LOADEST）对长江上游宜昌站的营养盐负荷进行了估算。统计分析了三峡大坝各施工阶段负荷的长期变化趋势和3个子时段的月变化。1990 - 2009年，长江上游溶解无机氮（DIN）负荷变化范围为30.47 × 104 ~ 78.14 × 104 t，总磷（TP）负荷变化范围为2.54 × 104 ~ 7.85 × 104 t。从1995年到2002年，DIN迅速增加，主要是由于化肥使用量增加。YRB上游的化肥使用统计数据也同意这一点。然而，TP负荷的趋势反映了在水库中的沉积和人为输入增加的去除的综合影响。2003年三峡工程蓄水后，DIN和TP负荷均呈下降趋势，DIN的下降主要是由于氨氮的消耗和迁移。通过对月负荷的分析，发现DIN与流量有很高的相关性。对于TP负荷，TGD蓄水后10月平均下降4.91%，但7月也出现了4.23%的增加，这与7月前水库沉积物的冲刷相对应。研究结果表明，TGD影响了流域的营养盐负荷，并在运行后起到了削减营养盐的作用。
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 × 104to 78.14 × 104t, while the total phosphorus (TP) loads ranged from 2.54 × 104to 7.85 × 104t. 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.