宁夏石嘴山河滨工业园区表层土壤重金属污染的时空特征

Spatial and Temporal Characteristics of Heavy Metal Concentration of Surface Soil in Hebin Industrial Park in Shizuishan Northwest China

为研究西北地区工业区土壤重金属空间分布及时间变化的区域特征,以宁夏石嘴山河滨工业园区西北端面积为1.74hm2的区域为研究区,采集表层土壤样品96个,利用原子吸收分光光度计测定Cu、Zn、Pb、Cr、Cd含量,SPSS 16.0软件做描述性统计和相关分析,资料对比法结合Google earth卫星地图分析含量的时空格局变化对应性.在GS+3.0软件理论拟合基础上,利用ArcGIS 9.0软件进行克里格插值,分析空间分布特征及可能的污染源.结果表明,Zn、Cu、Cr、Pb、Cd的平均含量分别为100.29、352.86、77.56、50.52、4.06 mg.kg-1,均高于宁夏土壤背景值.Zn、Cr、Pb为非污染,Cu、Cd属轻度污染和重度污染.Zn、Cu、Cr、Pb、Cd含量较1985年该地区水平增加明显,均从西北向东南增加并局部呈岛状空间分布.土壤中Cu、Cr、Zn、Pb、Cd的含量变化与2009年后该园区企业数量迅速增加及周边另一内蒙古高耗能工业园区的工业燃煤烟尘排放密切相关,空间格局主要由主导的西北强风控制、影响范围大,局地地形和企业分布格局是岛状分布的主要因素.

Concentrations of Zn,Cu,Cr,Pb and Cd in 96 topsoil samples collected from the northern Hebin Industrial Park were measured by the atomic absorption detector（AAD）.Spatial variability was identified by geostatistical analysis with the aid of GS＋3.0 and ArcGIS 9.0.Temporal variability of five heavy metals was contrasted to the concentration in 1985 of the Ningxia second soil census.Google earth maps in years of 2003,2004,2009 and 2011 have been analyzed to find the variation of the geographical distribution of factories in study Area.Result showed that mean concentrations of Zn,Cu,Cr,Pb and Cd were 100.29,352.86,77.56,50.52,4.06 mg·kg^-1,respectively,and were all higher than the background values.Using the second level of environmental quality standard for soils of China as the criterion,Zn,Cr,Pb were not risk,Cu,Cd were mild contamination and serious contamination.Spatial distribution of the concentration of the five heavy metals varies with prevailing wind direction,from the northwest to southeast,increasing gradually.Meanwhile,there were several hotspots.Google earth map analysis showed that in the northeast and southeast part appeared a large number of factories after 2009,which should be the main sources of the five heavy metals in soils.In the low-lying southwest part,although there was no factory,soils still have been polluted heavily because of another adjacent industrial area in Inner Mongolia Autonomous Region and the smoke dust was blocked by the Helan Mountain along its west.Conclusions： ①The number of the enterprise increased and trans-boundary pollution led to the high heavy metal concentration in surface soil of study area;②In northwest China,because of the strong wind,smoke dusts spread very long and distribution range was extensive,and low terrain area and enterprise distribution pattern lead to the island distribution.