江苏盐城原生盐沼湿地大型底栖动物重金属含量及生物质量评价

摘要

The core area in Jiangsu Yancheng National Nature Reserve belongs to one of the last original salt marshes, with perfect succession of Phragmite ausralis wetland, Suaeda glauca wetland , Spartina alterniflora wetland , Bullacta exarata wetland and Mactra veneriformis Reeve wetland from the land to the sea. The macrobenthos ( Nereis, Bullacta and Mactra veneriformis) samples was collected from Suaeda glauca wetland, Spartina alterniflora wetland and non-vegetated wetland respectively. The concentrations of different heavy metals ( Hg, As, Cd, Cr, Cu , Pb, Zn and Ni ) within the macrobenthos was measured and analyzed with metal pollution index(MPI),single factor pollution index ( P;) and biota-sediment accumulation factors( BSAF) . The results show that heavy metals are distributed differently in various macrobenthos. Cd is enriched most in Mactra veneriformis from non-vegetated wetland, Zn is enriched most in Nereis from Spartina alterniflora wetland, while all other heavy metals ( Hg, As, Cr, Cu, Pb and Ni)are enriched most in Bullactal from non-vegetated wetland. The MPI value of Nereis from Suaeda glauca wetland, Nereis from Spartina alterniflora wetland, Bullactal and Mactra veneriformis from non-vegetated wetland reached 1.984, 2. 085,4. 320 and 1. 618 respectively. Furthermore, Bullactal is polluted most severely, twice more than Nereis and Mactra veneriformis. In addition, the concentration of Zn in Nereis and Mactra veneriformis is higher than the sediment,so are the concentrations of As and Cu in Bullactal. Biological quality evaluation was conducted according to the first category indicators of Marine shellfish biological quality standard, Bullacta was polluted most seriously in this study area, the content of Cr, Cu and Pb all exceeded the criteria, especially the excess Pb is most significant, with the value of Pi as high as 7. 628. Mactra veneriformis has a generally good biological quality,with all elements within the range but Cd and Cr a little superfluous. Their contents were 1.812 times and 1. 408 times that of Marine shellfish biological quality standard. Variance analysis suggests that there was a significant difference in the metal enrichment capabilities among different Macrobenthic species. In addition, biological species had more effects on the heavy metal accumulation than environment background. Compared with other studies,the heavy metal contents in Nereis and Mactra veneriformis from our study area are lower than the same type of benthos in other districts.%以江苏盐城国家级自然保护区核心区为研究区域,分别于盐蒿滩、互花米草滩、光滩采集大型底栖动物沙蚕、泥螺和四角蛤蜊样品,测定其体内重金属Hg,As,Cd,Cr,Cu,Pb,Zn和Ni含量,并运用统计分析、金属污染指数(MPI)、单因子污染指数(Pi)、生物-沉积物累积因子(BSAF)进行分析.结果表明,重金属元素在各类底栖动物体内的含量分布不同,Cd在光滩四角蛤蜊中富集最多,Zn在互花米草滩沙蚕中富集最多,Hg,As,Cr,Cu,Pb和Ni均在光滩泥螺体内富集最多.盐蒿沙蚕、米草沙蚕、光滩泥螺和光滩蛤蜊MPI值分别为1.984,2.085,4.320和1.618.泥螺受污染程度最重,超出沙蚕和四角蛤蜊的2倍.沙蚕、四角蛤蜊体内Zn的积累量、泥螺体内As和Cu的积累量均高于沉积物.按照海洋贝类生物质量标准中的第一类指标对样品进行生物质量评价,发现研究区泥螺体内Cr,Cu和Pb含量均超过此标准,尤以Pb超标最为严重,污染指数Pi值达7.628.四角蛤蜊生物质量总体良好,除Cd和Cr超标,分别为海洋贝类质量标准的1.812倍和1.408倍外,其余元素均未超过标准.方差分析显示不同大型底栖动物种类对重金属的富集能力差别较大.生物类型比环境背景对重金属在生物体内的富集影响更大.研究区泥螺和四角蛤蜊体内的多数重金属元素含量低于国内其他区域的同种底栖动物.