盐城海岸带土壤重金属潜在生态风险控制优先格局

采用GS+软件,分析了盐城海岸带106个土壤采样点的表层土壤样品中Cr、Cu、Ni、Zn、Cd共5种重金属元素的地统计特征,计算了重金属元素的Hakanson潜在生态风险指数并采用ArcGIS软件对其进行空间插值,结合NDVI及距离海岸带主要干扰源的欧氏距离分析,以及土地利用分析,研究了盐城海岸带区域的生态热点地区,分析了海岸带具有不同生态风险水平的生态热点区域,并以此对盐城海岸带的重金属生态风险控制提出了空间策略.结果表明:Cr、Cu、Cd的空间相关性强,Ni的空间相关性为中,Zn不具有空间相关性；半方差函数模型模拟分析表明,指数模型可以很好的模拟Cr、Ni的空间分布,而Cu、Cd的较优模拟模型是球状模型；插值的结果表明,Hakanson指数的空间分布异质性较强,南部靠近大丰麋鹿自然保护区和梁垛河闸、中部大丰港和四卯酉闸之间,以及北部射阳港以北几个区域的HRI值较低,而射阳港周边、射阳盐场周边的HRI值较高.通过计算,给出了一个优先的具有较高生态价值并具有中度和低度重金属生态风险的生态保护格局.

The Priority Pattern for Managing the Potential Ecological Risks Associated with Heavy Metals of the Top Soil on Yancheng Coast

The spatial geostatistical characteristics of the 5 heavy metals (Cr, Cu, Ni, Zn and Cd) of the top 106 soil samples on Yancheng coast, were studied with the aid of GS + software. With ARCGIS 9.2, the Hakanson risks index (HRI), which was a synthetic reflection of the potential ecological risks of heavy metals, was interpolated. A computational approach, including NDVI, determining Euclidean Distance to the main anthropogenic impact sources, and land use reclassification, was proposed to detect the ecological hotspots, with clarification of different levels of potential ecological risks through integrating the Hakanson index computing. The conclusions can be drawn as follows. Metals (Cr, Cu and Cd) had strong spatial autocorrelations, while Ni had modest spatial autocorrelations, and the spatial autocorrelation of Zn could not be modeled. Through the semivariogram functions analysis, the exponential model could best model the spatial autocorrelations of Cr and Ni, while spherical model could best model Cu and Cd. There was a high heterogeneity of HRI, and areas including the Dafeng Natural Reserve areas, near the Liangduo River Gate, the areas between Dafeng Habour and Simaoyou Gate, and areas north to the Sheyang Habour, had a relatively low HRI, while areas including areas neighboring Sheyang Habour and Sheyang Salt Field had a high HRI. The priority ecological hotspots with medium and low heavy metal ecological risks were finally proposed.