| The towns in the southern of Jiangsu province are undergoing a rapid process of industrialization and urbanization,and the heavy metal pollution develop a hotspot.The spatial pattern of cultivated land is easily affected by human activities,through small-scale research based on villages and towns,it can more accurately grasp the impact of landscape pattern on soil heavy metal pollution and implement more targeted control measures.Based on Geostatistic method and GIS,it carried out a series of studies on a town in the southern of Jiangsu.It expresses the result by visualization.It also exaumined the relationship between of the spatial pattern of cultivated land and soil heavy metal concentrations in the buffers of soil samples and analyzed the impacts between spatial pattern of cultivated land and comprehensive pollution index of soil heavy metals.It shows:(1)The spatial distribution characteristics of heavy metals were quantitatively described using geostatistical methods.The coefficients of variation of Pb?Cr?Cu?Zn were less than 10%,which had a low variability;the coefficients of variation of As?Ni?Hg?Cd had moderate variation.The nugget constant of As?Pb?Ni?Hg?Cd?Cu?Zn were lessthan 25%,which showed that these elements were affected by other factors;the nugget constant of Cr has moderate variability,which mainly caused by stochastic factors(2)There is significant distribution characteristics in the spatial distribution,in which As?Pb?Ni?Hg?Cr?Cu?Zn showed a increasing trend from south to north and Cd showed a decreasing trend from south to north.The contents of As,Pb,Hg,Cu and Zn were relatively high in the western region,and relatively low in the central region.The high value area of heavy metal Cd is mainly concentrated in the south and southwest,and the low value areas are mainly concentrated in the east and the north.In general,the trend is decreasing gradually from southwest to northeast.(3)The study explained that the serious pollution was Cd,the average single pollution index was 0.64,belonging to mild pollution.The average value of comprehensive pollution index was less than 0.7.Pollution Load Index showed that Cd,Zn and Cu contributed the most to the regional pollution load,more than 85%of them belonged to moderate pollution,and the regional pollution load index was 1.02,which existed a certain accumulation of man-made pollution.Potential Ecological Risk Index showed that Hg and Cd were the most important factors contributing to ecological risk,among which Cd was highly toxic and had a high degree of risk.The distributions of pollution were obtained by interpolating the results of comprehensive evaluation,it found that the distributions were similar.The low value areas were mainly in the southeast and south and the high value areas were mainly concentrated in the central west region.It showed that human activities have a certain impact on the ecological environment of cultivated land in the study area.(4)By analyzing the relationship between spatial pattern of cultivated land and heavy metal content,it showed that:the contents of heavy metals are only significantly correlated with a small number of landscape pattern index in the buffers,PD negatively correlated with As levels(p<0.05),but positively correlated with Ni levels(p<0.05),SHAPE-AM and FRAC-AM negatively correlated with Ni levels(p<0.05),ED negatively correlated with Pb?Hg levels(p<0.05),AI negatively correlated with Cd?Zn levels(p<0.05).But landscape-level structural and Cr?Cu levels didn't have a significantly positive correlation;landscape-level structural complexity and aggregation can explain the comprehensive pollution degree of heavy metals of cultivated lands in each administrative village better,especially the connectivity/aggregation and comprehensive pollution index of heavy metals have a significantly positive correlation(p<0.05).The connectivity/aggregation degree is higher,the soil heavy metal pollution of cultivated land in administrative villages is more serious. |
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