Spatial Distribution Of Heavy Metals In Soil Of Fulin Farm Based On GIS And Ecological Risk Assessment

The green ecological agriculture and ecological village are constructed based on the background of sustainable development. In this paper, By using GIS and geo-statistics technology and combining with single factor pollution index, Nemerow composite index, the sampling, investigations and determination were carried out in order to clarify the spatial variability, distribution characteristics and heavy metal pollution status of six kinds of heavy metals (As, Cd, Cr, Cu, Pb and Zn) which were collected from the Fulin technology ecological village in Yangzhou city. Taking heavy metal toxicity factor into consideration, we analysis their potential ecological risks and giving some management recommendations, The main conclusions can be divided as follows:(1) According to the correlationship between the six heavy metals in soil, analysis shows that:As and Cd, Cr, Zn, Pb element at the0.01level have a significant positive correlation, indicating that they may come from the same or similar sources; Cu and Zn, Pb element has a significant negative correlation at the0.05level, but not with As, Cd, Cr, indicating that they come from different sources; Pb and each element has a relevance, while As has the highest correlation index reached0.572.(2) The using of geo-statistics to study the spatial variability of six kinds of soil heavy metals, Gaussian model is the best choice for As, Cd, Cr and Pb elements, while Cu and Zn fit exponential model better. As Cu has a larger range value, so that it has a spatial autocorrelation in the relatively large range of sampling steps, and it can be appropriately increased distance to improve the efficiency, other elements from the process variable are greater than the average length of the sampling step distance, so the sample points are reasonable and representative.(3) Choosing the best semi-variogram, using ordinary Kriging method to measure the concentration of heavy metals in soil, shows the spatial distribution within eco-village, As, Cd and Cr elements with similar properties, are decreased gradually from the south side to the north side, and in the forest near the village banks and two neighborhoods have a higher concentration enrichment; while the spatial distribution of Cu is significantly different compared to the previous three ones, farmland located in the northeast area has a high density; The spatial distribution of Pb and Zn extend from south to north in the general trend, According to the study the highest value of Pb is located in the southwest corner of the region, while the distribution of Zn with higher concentration located in the middle zone of the two neighborhoods.(4) The assessment of heavy metal pollution shows that:Cd, Cu polluted all the farmland using single-factor evaluation method, but different regions with the different degrees of contamination; As, Pb made parts of the farmland affected, with still clean farmland in the northern for As, still clean area is located in the northeastern portion of the farm for Pb; Cr, Zn did not cause the pollution within the scope of the whole region. Most of the areas were light polluted by using comprehensive evaluation to study the entire farm pollution range, Farmland near the village have been polluted heavily, human activities played a leading role on the soil pollution.(5) Using Hankanson method to research the potential ecological risk of heavy metals in the soil, the result indicates that:the region’s ecological risk is mainly concentrated in a few areas in southern and northeastern part with the higher ecological risk index near the neighborhoods, The index in the central and western regions is small, the level of potential ecological risk among the whole zone is weak.