广西茅尾海入海河口表层沉积物重金属分布及风险评价

Assessing the distribution and ecological risks of heavy metals in surface sediments of the Maowei Sea estuary,Guangxi

为揭示茅尾海入海河口表层沉积物中重金属分布特征及生态风险,在茅岭江、大榄江、钦江入海河口采集13件表层沉积物样品进行重金属分析。研究结果表明,茅尾海沉积物中重金属As、Cd、Cr、Cu、Hg、Pb、Zn含量平均值分别为7.78×10^(-6)、0.14×10^(-6)、37.6×10^(-6)、18.9×10^(-6)、0.0048×10^(-6)、22.5×10^(-6)、54.7×10^(-6),均低于GB 18668—2002的一类标准。沉积物中重金属空间分布差异较大,茅尾海东部工业区和西部茅岭江附近具有较高的重金属含量。重金属污染分析表明,大部分重金属元素显示为无污染—轻度污染水平,Cr具有中等污染水平;生态风险分析显示,重金属总体处于较低潜在风险,东部工业区Hg、Cd显示出中等生态风险。通过相关性分析、聚类分析、主成分分析探讨重金属污染物来源,结果显示重金属污染主要受河流控制,Hg、As、Cd还受到临港工业区废水排放的影响。综合研究表明,茅尾海生态环境总体较好,但建议重点关注东部工业区重金属排污状况。

A total of 13 surface sediment samples were collected from estuaries of the Maoling,Dalan,and Qinjiang rivers for heavy metal analysis,aiming to study the distribution characteristics and ecological risk of heavy metals in the surface sediments of the Maowei Sea estuary.The results are as follows.The average contents of heavy metals As,Cd,Cr,Cu,Hg,Pb,and Zn in Maowei Sea sediments were 7.78×10^(-6),0.14×10^(-6),37.6×10^(-6),18.9×10^(-6),0.0048×10^(-6),22.5×10^(-6),and 54.7×10^(-6),respectively.They are all lower than the class-I standard specified in GB18668—2002.The heavy metals in the sediments show quite different spatial distribution,with high content of heavy metals concentrating in the industrial zone to the east of the Maowei Sea and near the Maoling River to the west of the Maowei Sea.The analysis of heavy metal pollution shows that most elements are at levels of no pollution to moderate pollution,and Cr is at a medium pollution level.As indicated by the ecological risk analysis,the heavy metals generally show potentially low potential risks,and Hg and Cd in the industrial zone to the east show moderate ecological risks.The sources of heavy metal pollutants were explored through correlation analysis,cluster analysis,and principal component analysis.The results show that heavy metal pollution is mainly controlled by rivers,and Hg,As and Cd are also affected by wastewater discharged from the port industrial zone.This comprehensive study shows that the Maowei Sea has a good ecological environment overall,but it is recommended to focus on the drainage of heavy metal pollution in the industrial zone to the west of the Maowei Sea.