Current situation of Pb and Zn pollution in farmland soil based on meta analysis

Farmland soil is the material basis of grain production, and its quality is related to the national economy and the people's livelihood. With the development of economy and society, the content of Pb and Zn in farmland soil is increasing day by day. At present, the research on the total amount and form distribution of Pb and Zn in farmland soil and their influencing factors is relatively scattered, and there is a lack of systematic arrangement and cognition on the mutual transformation mechanism and pollution status of different forms. In order to further clarify the pollution status of heavy metals in soil and the distribution and mutual transformation mechanism of different forms, this study analyzes the pollution level, form distribution and influencing factors of Pb and Zn in farmland soil in China through data integration, and evaluates the ecological risk of heavy metals based on principal component analysis and geological accumulation index. The results showed that the average contents of Pb and Zn were 4045 mg · kg-1 and 10699 mg · kg-1, respectively; the proportion of Pb residual state is the highest in Northwest China, and the proportion of exchangeable state is the highest in Southwest China, and the proportion of residual Zn exceeds 50%; through analysis, it is found that ph is the main factor affecting the speciation distribution of heavy metals; the comprehensive analysis results of geological accumulation index and potential ecological risk index RI show that Pb in the study site is higher than Zn, but both are of slight hazard level; the comprehensive analysis of soil environmental factors showed that the speciation distribution of heavy metals reached the equilibrium state of speciation transformation by the combined action of multiple factors