白洋淀表层沉积物元素的空间特征、风险评价及来源分析

对白洋淀流域表层沉积物中营养元素(N和P)、重金属(Pb、Cu、Zn、Cd、Cr、Co、Ni及Sn)及粒度进行研究,分析元素的空间变化并进行污染和风险评价,在此基础上结合河流的沉积特征,利用多元统计方法分析淀内沉积物元素的来源及其变化规律.结果表明,白洋淀和河流表层沉积物重金属平均含量均高于背景值,淀内空间上呈现营养元素"西北高东南低",重金属"中部高南北低"的特征;表层沉积物中元素综合污染指数(I)大小顺序为:Cd Pb Cr Cu=Zn Ni Sn Co,其中Cd为重度污染,其它重金属为中度污染,枣林庄地区Cr为重度污染;潜在生态危害系数(Eri)大小顺序为:Cd Pb Cu Cr Ni Zn,其中Cd除采蒲台地区具有强潜在生态风险,其他元素具有轻度潜在生态风险.淀内沉积物质地差异较小,流域河流入淀后的面源污染是影响白洋淀表层沉积物元素空间变化的主要原因,但淀内村庄的点源污染也不容忽视,尤其是元素N、P、Pb及Cr.

Spatial Characteristics, Risk Assessment, and Source Analysis of Elements in Surface Sediments from the Baiyangdian Lake

In this paper, nutrient elements (N and P), heavy metals (Pb, Cu, Zn, Cd, Cr, Co, Ni, and Sn), and grain size in surface sediments of Baiyangdian Lake, northern China, are studied. We also analyze the spatial variation in elemental characteristics and undertaken a pollution risk assessment. By combining data with information on the river sediment characteristics, we use multivariate statistical methods to reveal the sources and variation of elements in sediments. The results showed that the average contents of heavy metals in surface sediments from the lake and associated rivers were higher than background values. Within the area of the lake, nutrient elements are relatively high in the northwest region but low in the southeast region, and heavy metals are relatively high in the middle of the lake but low in the southern and northern areas. The sequence of comprehensive pollution index (I) in sediments was Cd > Pb > Cr > Cu=Zn > Ni > Sn > Co, with Cd being assessed as severe pollution and other elements as moderate pollution, although severe pollution of Cr was found in the Zaolinzhuang area. The order of potential ecological risk coefficients (E_rⁱ) was determined as Cd > Pb > Cu > Cr > Ni > Zn, whereby Cd was associated with a strong potential ecological risk (except in the Caiputai area) and other elements were associated with a slight potential ecological risk. Differences in the lake sediment texture were found to be slight. Non-point source pollution after rivers flow into the lake was determined as the main reason for the spatial variation of elements in the surface sediments of Baiyangdian Lake, although point source pollution in the villages surrounding the lake should not be ignored, especially with respect to N, P, Pb, and Cr.