罗时江河口湿地沉积物磷的空间分布及污染风险评价

Spatial distribution and pollution risk assessment of phosphorus in sediments at estuarine wetland of Luoshijiang River

以云南洱海罗时江入湖河口湿地为典型对象,利用柱状底泥分层采样器采集罗时江河口湿地沉积物样品,0-10 cm为表层,10-30 cm为中层,30-60 cm为底层,分析了3层沉积物的总磷含量。研究结果表明,（1）从水平方向看,罗时江河口湿地各层（表层、中层、底层）沉积物总磷分布均呈现出沿2条主水道（水道Ⅰ和水道Ⅱ）向岸边递减,并在入水口处出现峰值的规律;垂直方向上看,总磷含量随着沉积深度增加而减少,表层富集明显。表层、中层和底层沉积物总磷平均含量分别为1.09、1.03和0.99 g/kg。（2）运用单因子污染指数评价法对沉积物总磷进行了评价,3层沉积物总磷总体属于中度污染,局部出现重度污染。各层污染程度从大到小依次为表层（1.81）〉中层（1.72）〉底层（1.65）,重度污染主要集中在水道Ⅰ上。

The estuarine wetland of Luoshijiang River,which flowed into Erhai Lake in Yunnan Province,is regarded as the typical research object. Sediment samples in Luoshijiang River were collected by the cylindrical sediment sampler and each sample was divided into 3 layers from the top to the bottom as the following rules： 0-10 cm as the surface layer,10—30 cm as the middle layer,and 30—60 cm as the bottom layer. The total phosphorus concentrations of each sample were analyzed. The research results showed that：（ 1） Horizontally,along with the main watercourse（ I and II）,the total phosphorus concentrations decreased from the center of the watercourse to the bank of the river,and the highest concentrations were found around the lake inlet and the islands.Vertically,the total phosphorus concentrations decreased with the increasing depth of the sediments,and the surface layer exhibited significant accumulation of phosphorus. The average total phosphorus concentrations in the surface,middle and bottom layer of the sediment were 1. 09 g / kg,1. 03 g / kg and 0. 99 g / kg,respectively.（ 2） Single factor pollution index assessment was used to evaluate the contamination level of the total phosphorus of the sediments. In general,the contamination level of the three layers＇ sediment was medium,while some parts of the research area was intense. The contamination level of each layer followed the sequence： surface layer（ 1. 81） middle layer（ 1. 72） bottom layer（ 1. 65）,the heavy contamination was mainly found around watercourse I.