鄱阳湖丰水期不同底质类型下氮、磷含量分析

以2011年7月份(丰水期)鄱阳湖实测数据为基础,通过不同底质在遥感影像上的光谱特征,将鄱阳湖底质分为沙滩、泥滩和草洲3种类型,并就不同底质类型鄱阳湖水体和底泥总氮(TN)、总磷(TP)含量进行分析。结果表明:(1)底质类型不同时,鄱阳湖表层水体TN、TP含量以及底泥磷含量平均值:沙滩泥滩草洲。底泥TN含量平均值:草洲泥滩沙滩。(2)底质为沙滩的站点主要分布在饶河入湖口至都昌段、赣江北支入湖口至星子段和入江水道前段,饶河、赣江高含量氮、磷的输入,以及沿途陆源污染物的排放,可能是沙滩底质表层水体TN、TP含量较高的一个因素;泥滩底质的站点,有一部分分布在星子至湖口段,该区间陆源污染的影响是泥滩底质表层水体TN、TP含量居次原因之一;而底质为草洲时,草洲对水体中氮、磷的吸收使得草洲底质的站点表层水体TN、TP含量最低。

CONTENT ANALYSIS OF NITROGEN AND PHOSPHORUS ON DIFFERENT SEDIMENT TYPES DURING WET SEASON IN LAKE POYANG

Based on the measured concentration of total nitrogen (TN) and total phosphorus (TP) in Lake Poyang, in July,2011, firstly we classified the sediment of Lake Poyang into three categories according to the spectral signatures of different sediments on remote sensing images, which are sand, mudflat, and grassland. Then we analyzed the content characteristics of TN and TP in both water and sediment of different bottom sediment types. The results show as follows. (1) It has different TN and TP content in surface waters on different sediment types, representing a pattern of sand > mudflats > grass. TP content in bottom sediment has the same characteristics of TN and TP in surface water, and the characteristic of TN content in sediment is grass > mudflats > sand. (2) Stations on sandy sediment mainly distributed from Raohe River to Duchang, and from north branch of Ganjiag River to Duchang, and in the first section of upstream channels. It may result in high TN and TP content of station on sandy sediment from the high pollutants of nitrogen and phosphorus from Raohe River and Ganjiang River, and land sourced pollutants along the way. Part of the stations on muddy sediment distributed from Xingzi to Hukou, and land sourced pollutants is one reason that the surface water of station on grassy sediments has a relative high TN and TP content. And it has the lowest TN and TP content in surface water of stations on grassy sediments because of the absorption of nitrogen and phosphorous from water by grass in sediments