Spatial distribution charicteristics of soil heavy metals in vegetable growing area based on GIS in Shouguang city, Shandong province

Through the mathematical statistics and geo-statistical spatial analysis method, the soil heavy metal content and its characteristics of spatial distribution in vegetable growing area in Shouguang city were researched, and the spatial distribution map of heavy metals based on the geography information system (GIS) was plotted. The results showed that the average contents of the heavy metals in surface soil in Shouguang city were lower than those in farmland environmental quality evaluation standards for edible agricultural products (HJ332-2006). Five heavy metals (Cu, Cd, Cr, Hg, Nr) followed a positively skewed distribution, except for Zn, Pb and As, and the vertexes of all heavy metals in frequency plots exceeded those of the normal distribution plots. The results of spatial analysis showed that there were middle relations of all eight heavy metals in surface soil in Shouguang city. The distribution of heavy metals was higher in middle, south and east-south soil but lower in north, east-north and west-south soil in Shouguang city. The heavy metal content in the surface soil in Shouguang city was affected by the natural and artificial factors.