青弋江芜湖市段无机氮的分布特征

Inorganic Nitrogen Characteristics in Wuhu Section of Qingyi River

通过实地监测,系统分析青弋江芜湖市段三态无机氮的分布特征,研究表明:(1)青弋江芜湖市段无机氮无论是枯水期还是丰水期,NO3-N和NH4-N浓度从上游到下游不断上升,总体体现了NO2-N,NH4-N不断转化为NO3-N的过程。(2)无机氮分布具有明显的季节变化,总体枯水期含量较高,丰水期较低,说明氮污染物主要来源于市区点源排放,丰水期流量大,对污染物起到稀释的作用。(3)三态无机氮含量随叶绿素a的增加而减少,呈负相关。(4)青弋江芜湖市段DO含量较高,不会成为氮硝化反应的限制因素,有利于三氮之间的相互转化。

The distributional characteristics of inorganic nitrogen in Wuhu of Qingyi River were analyzed by field monitoring. The results showed that： （1） From upper reaches to lower reaches in the section of Qingyi River,the concentrations of NO3 --N and NH4 --N rise gradually both in low water period and high water period, presenting a transformation process from NO2- N and NH4- N to NO3- N which representing the main existence form. （2） The distributions of inorganic nitrogen are higher in low water period whereas lower in high water period. It revealed that pollutants were main from point source discharge in urban area and were diluted by the help of larger flux in high water period. （3） Contents of inorganic nitrogen were negatively related with that of chlorophyll a. （4） The high content of DO in the section of Qingyi River would not be a limiting factor for nitration but a promoter for intertransform among the nitrogens.