Geochemical behavior of heavy metals Pb and Hg in the farmland soil of Hebei plain

The geochemical behavior of heavy metal elements in soil is a hot research topic. Studies show that the geochemical behavior of heavy metal elements is related not only to soil texture, but also to the physical and chemical properties of soil. In this paper, the authors chose the farmland of Hebei plain as the study area, collected 325 soil samples, made effective state analysis of soil Pb, Hg heavy metals, and discussed the factors affecting the geochemical behavior of heavy metals. Some conclusions have been reached:(1) Pb, Hg water soluble ions and exchanged values show a significant negative correlation with soil pH values, and soil acidification results in increase of Pb, Hg effective fraction, which leads directly to increase of Pb, Hg in the crops; and hence maintaining soil pH in weak acid and weak alkaline range and preventing soil acidification and salinization can reduce the harm of heavy metals. (2) The values of organic matter and Pb, Hg exhibit significant positive correlation in soil, the increase of the soil organic matter can significantly reduce water soluble and exchangeable content of Pb, Hg elements. (3) With the increase of clay soil, Pb, Hg in water solution state and ion exchangeable state decrease, indicating that the clay can absorb a certain amount of heavy metal ions, and heavy metal elements Pb and Hg show certain relationship in geochemical behavior. The pH value, organic matter, and viscosity of soil seem to be important factors controlling the geochemical behavior of the heavy metals Pb, Hg.