南方河网地区鱼塘与河涌底泥重金属污染现状调查与评价

摘要

随着畜禽养殖业规模化发展,畜禽养殖废弃物排放大量增加给周边环境带来严重的污染问题.通过对南方河网地区典型养殖场周边鱼塘和河涌的底泥采样调查发现,河涌底泥含有较高的有机质(OM)、总氮(TN)、总磷(TP),且OM、TN、TP含量为鱼塘底泥的2~10倍.进一步分析发现,鱼塘和河涌底泥中As平均含量分别为70.06和73.21 mg/kg;Cr在底泥中呈现的垂直分布规律为0~10 cm>11~20 cm>21~30 cm>31~40 cm,河涌底泥Cr平均含量(133.66 mg/kg)是鱼塘底泥(54.36 mg/kg)的2.5倍.此外,河涌底泥中重金属的单项污染指数Pi和综合污染指数Pm均高于鱼塘底泥,其中单项污染指数最高的是As,多为重污染,其次是Cr,Cu、Pb、Zn多为轻污染.通过不同层级底泥中重金属含量与理化性质的相关性分析可知,底泥中Cu、Pb、Zn的污染主要受有机质(OM)、总氮(TN)、总磷(TP)的影响.可见,养殖场废物处置主要以鱼塘消纳为主,且鱼塘水每年外排导致周边河涌营养盐和重金属等污染问题.%The scaled development of livestock and poultry put substantial increasing wastes which brings serious pollution problems in the surrounding environment. The sediments of fish ponds and rivers were conducted to examine the environmental pollution in the Southern River Network region. This study showed that the concentration of organic matter (OM),total nitrogen (TN) and total phosphorus (TP) in the sediments of rivers were about 2.0-10.0 times that of fish ponds. In addition,the average value of arsenic (As) in the sediments of fish ponds and rivers were 70.06 mg/kg and 73.21 mg/kg,respectively. Furthermore,the vertical distribution pattern of Cr in the sediments was ranked in the order:0-10 cm>11-20 cm>21-30 cm>31-40 cm. And the average value of Cr in river sediments (133.66 mg/kg) was 2.5 times that of fish ponds (54.36 mg/kg). The single pollution index (Pi) and comprehensive pollution index (Pm) of heavy metals in river sediments were higher than fishponds. Furthermore,the order of Pi of fishpond and river sediments was As> Cr >Cu >Pb >Zn. Correlation analysis of heavy metal and physical-chemical properties in different layers of sediment indicated that Cu,Pb and Zn-contaminated in sediment is mainly affected by OM,TN,and Total P. Therefore,livestock waste disposal is mainly based on absorption of fish ponds which will cause pollution problems such as nutrient salt and heavy metals in surrounding rivers.