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根据在１９９７和１９９８年内对长江干流大通站河水的３次采样分析，结合该站１９６２～１９９０年的水质资料，对长江下游Ｎ、Ｐ含量变化及其输送量进行研究．总氮、总磷的平均含量分别为１．６～２．２ｍ ｇ·Ｌ－ １和０．１１～０．１５ｍ ｇ·Ｌ－ １，Ｎ 以ＮＯ－３ －Ｎ 为主，约占７６％ ，其余主要为溶解有机氮和颗粒氮；Ｐ以颗粒态为主，占９５％ 以上．从５、６月到８月，ＮＯ－３ －Ｎ含量是逐渐降低的，ＤＯＮ含量有较大幅度的上升，ＰＮ、ＰＰ及ＴＰ含量也有所增高．与历史资料相比，长江大通站溶解无机氮（ＤＩＮ）和ＰＯ３－４ －Ｐ含量还在不断上升，Ｎ、Ｐ含量的上升与流域化肥施用量变化趋势一致．１９９８年夏季洪水期间，约有７９．９５万ｔＮ和８．３６万ｔＰ从大通站向下游输送，其中ＤＩＮ与生物有效磷（ＢＡＰ）比值远高于浮游植物生长的Ｐ限制值
According to the three sampling and analysis of the river water of the Changjiang River mainstream station in 1997 and 1998, and the water quality data of the station from 1962 to 1990, the content of N and P in the lower reaches of the Yangtze River and its transportation were studied. The average contents of total nitrogen and total phosphorus were 1.6 ~ 2.2m g · L -1 and 0.11 ~ 0.15m g · L -1, while N was mainly NO-3-N, accounting for 76% , The rest are mainly dissolved organic nitrogen and particulate nitrogen; P to the particulate state, accounting for more than 95%. From May to June and August, the content of NO-3-N decreased gradually, the content of DON increased greatly, and the contents of PN, PP and TP also increased. Compared with the historical data, the content of dissolved inorganic nitrogen (DIN) and PO3-4-P in the Changtong Station of the Changjiang River is still rising. The increase of the N and P contents is consistent with the change of the chemical fertilizer application rate in the basin. During the summer 1998 floods, about 799,500 tN and 83,600 tP were transported downstream from Datong Station, where the ratio of DIN to bioavailable phosphorus (BAP) was much higher than the P limit for phytoplankton growth