Characteristics of Heavy Metal Pollution in Farmland Soil along the Lancang River in Lincang, Yunnan

Abstract

Taking the farmland soil along the Lancang River in Lincang as the research object, through soil sampling test and analysis, using single factor evaluation method, Nemeiro comprehensive pollution index method and relative pollution index method, the heavy metals As, Cd, Pb and Zn pollution characteristics and causes in farmland along the Lancang River were analyzed. The results show that according to the national soil environmental quality standards, the Cd in the farmland along the Lancang River in Lincang seriously exceeded the standard on a large scale, followed by Pb and Zn, while As did not exceed the standard; the soil single factor pollution index is Cd>Zn>Pb>As. It shows that the relative pollution indexes of As, Cd, Pb and Zn in farmland soil all exceed the standard, and the exceeding rate is Pb>Zn>Cd>As. The pollution of heavy metals in the soil of the farmland along the Lancang River in Lincang is not only caused by mine development, but also related to its high background value. The pollution of heavy metals in farmland soil along the north river from upstream to downstream has changed significantly. The correlation between the pollution of As, Cd, Pb and Zn in the farmland along the Lancang River in Lincang is significant, the probability of homology is very high, and there is a danger of combined pollution of four heavy metals.