广西钦州湾-防城港潮间带表层沉积物重金属生态风险评价

对广西钦州湾-防城港潮间带表层沉积物中的重金属元素Hg,Cd,As,Pb,Cu,Cr和Zn的质量分数和空间分布特征及其潜在生态危害进行了分析和评价。钦州湾潮间带表层沉积物中的重金属元素的质量分数相对较低,均在国家一级标准之内。空间分布上,从防城港-企沙-鸡墩头-三娘湾-沙角,重金属元素含量有逐渐增加的趋势,尤其在企沙QZ-07、三娘湾QZ-09和沙角地区的QZ-08剖面的质量分数最高。其中Cd,Cu和Zn的最高值出现在沙角地区QZ-08剖面,其平均质量分数分别达到了0.14,29.15和64.56μg/g;Hg,As,Cr和Pb的最高值出现在企沙地区QZ-07剖面,其平均质量分数分别达到了0.11,11.29,88.23和26.47μg/g。选用Hakanson的潜在生态风险指数法对沉积物的环境质量进行了评价。结果表明,钦州湾潮间带表层沉积物重金属元素的潜在生态风险参数均小于40,而风险指数均小于150,显示其潜在生态风险为低风险级别。但部分调查剖面如沙角QZ-08剖面的生态危害风险指数接近临界值140,所以该污染的风险是存在的。在空间分布上,从防城港-企沙-鸡墩头-三娘湾-沙角,重金属元素的污染生态危害指数有逐渐增加的趋势,尤其在企沙QZ-07、三娘湾QZ-09和沙角地区的QZ-08剖面的危害指数最高。

Ecological Risk Assessment of Heavy Metals in Sediments of the Intertidal Zone From the Qinzhou Bay to the Fangcheng Port of Guangxi Province

Distribution analysis and potential ecological risk assessment were made of heavy metal elements such as Hg,Cd,As,Pb,Cu,Cr and Zn in the surface sediments of the intertidal zone from the Qinzhou Bay to the Fangcheng Port of Guangxi Province.The contents of heavy metals in the intertidal zone of the Qinzhou Bay are relatively low,with all being within the National Standard Level 1.From the point of spatial distribution,the contents of heavy metals tend to increase gradually in the zone from the Fangcheng Port via Qisha,Jiduntou and Sanniangwan to Shajiao,particularly at the sections of Qisha QZ-07,Sanniangwan QZ-09 and Shajiao QZ-08,where the contents of heavy metals are the highest.The peak values of Hg、Cu and Zn occur at the section of Shajiao QZ-08,and those of Cd、As、Cr and Pb at the section of Qisha QZ-07.The environmental quality assessment of the sediments was performed by means of Potential Ecological Risk Index proposed by Hakanson.The results show that the potential ecological risk of heavy metals in the surface sediments in the intertidal zone studied is generally in a low level,but at some sections of the zone such as at Shajiao QZ-08,the ecological risk index reaches nearly to the critical value of 140,indicating the possible presence of pollution risk.In general,the ecological risk index tends to increase gradually from the Fangcheng Port via Qisha,Jiduntou and Sanniangwan to Shajiao,especially at the sections of Qisha QZ-07,Sanniangwan QZ-09 and Shajiao QZ-08,where the ecological risk index reaches to the maximum.