Investigation and Evaluation of Heavy Metal Pollution in Soil from Zhengzhou City

The heavy metal contents of 1014 surface soil samples from a geochemical survey (1:100000) in Zhengzhou city and its surrounding areas has been determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Atomic Fluorescence Spectrometry (AFS). The single-factor index method and Nemerow index method were also used to evaluate the content level and morphological characteristics of heavy metals, and the distribution of their pollution. Analytical results show that the average contents of eight types of heavy metals are below the critical value of soil category I in the environmental quality standard for soils and the content of heavy metals decreases from the surface to the deep soil. In the 1000 km² testing area, first-class, second-class and third-class soils account for 89.6%, 9.4%, and 1.0%, respectively, indicating good soil quality. In a few moderately and strongly polluted areas, heavy metals exist in the forms of a residual, ferri-manganese oxidation state, which were hard to migrate or use by plants and thus are not harmful to people and the environment.