Study on Influencing Factors of Farmland Soil Heavy Metals in Central Yunnan Province

[Objective] This study aimed to explore the relationship between contents of heavy metals with soil type,altitude distribution as well as physical and chemical properties.[Method] Based on determination of contents of soil heavy metals and soil physical and chemical properties from agricultural land in Central Yunnan Province,the relationship between soil heavy metals with soil type,altitude distribution and soil physical and chemical properties were analyzed.[Result] The average contents of all heavy metals in farmland of Central Yunnan didn't extend their limits of Grade Ⅱ in the National Soil Environmental Quality Standard(GB15618-1995).and the heavy metals content in red soil was higher than that in other types.Soil Cd content changes slightly with the altitude,while contents of other heavy metals were greatly affected by altitude.There were extremely significant positive correlation between heavy metals and clay particle content,that is,soil with heavier texture has more heavy metals.There was positive correlation between pH and each heavy metal content;there were positive correlation between Mn with Pb,Cd,Hg and Hg;exchangeable Ca and Mg contents in soil show negative correlations with most heavy metals.[Conclusion] This study has provided scientific bases for the heavy metal management in Central Yunnan area.