江苏盐城原生湿地表层沉积物中的重金属污染评价

通过对江苏盐城盐沼湿地表层沉积物中的Hg、As、Cd、Cr、Cu、Pb、Zn、Ni等8种重金属元素的分析得出,所测样品指标的平均值除Hg、As和Zn与背景值较接近外,其余重金属元素在沉积物中的含量都高于背景值,Cu的含量为背景值的6倍,属超Ⅱ类沉积物。其次是Cd,以偏中污染为主。运用地累积指数法对8种重金属的污染评价结果为CuCdCrNiPbAsZnHg,且以Cu的污染最为严重。同时,结合粒度分析可知,沉积物在空间分布上的累积强度与粒径大小密切相关,粒径越大,污染程度越小。有植被覆盖的潮滩对重金属的吸附能力明显要高于无植被覆盖的光滩。与近年来的背景值相比,重金属在沉积物中的增加可能与核心区外围经济活动有关。

Pollution Assessment of Heavy Metals in Coastal Surface Sediments in Original Salt Marshes in Yancheng, Jiangsu Province, China

According to the analysis of heavy metals of Hg,As, Cd, Cr, Cu,Pb,Zn,Ni in the core area in Jiangsu Yancheng National Nature Reserve, the average contents of Hg,As,Zn are closer to the background values, while the contents of other heavy metals＇ contents in sediments are higher than the background values. The average contents of Cu are far more 6 times of its background value which belongs to II sediments. The average contents of Cd belongs to partial medium pollution. The results of Geoaccumulation Index Assessment showes that the pollution classification is Cu〉 Cd〉 Cr〉 Ni〉 Pb〉 As〉 Zn〉 Hg, in which Cu ba~ much concentration in some area with lit- tle heavy pollution calling for much attention. At the same time, the contents of heavy metals show positive relationship with sand size of sediments based on spatial distribution. The absorption capacity of heavy metals in vegetated wetlands with reed, Suaeda glauca and Sparti- na alterniflora was higher than that in non - vegetated wetlands with high density of macrobenthos, especially Bullacta exarata and Mactra veneriformis Reeve. Comparing with the background value of recent years, the contents of heavy metals should have close relationship with economic development.