Effect of long-term fertilization on element contamination (Pb, Cd, Cu, Zn, Ni and Cr) and environment risk assessment in the Meadow Black Soil in China

To identify the effect of fertilization on the heavy metal concentration and assess the soil environmental quality, Meadow Black Soil (MBS) samples were collected from Long-term location fertilization base located in the Changchun City, Jilin Province of China. Subsequently, MBS samples were analyzed to determine the total concentrations of specific elements (Pb, Cd, Cu, Zn, Ni and Cr), for which data were available for 1984, 1989 and 2012. Under long-term location fertilization conditions, this investigation revealed that the mean concentrations of Pb, Cd, Cu, Zn, Ni and Cr exceeded their corresponding background values and the accumulations of Pb and Cd were readily apparent in the MBS and were beyond of the second grade of China soil standards. Pb and Cd were accounted for mainly by chemical fertilizers. In addition, the accumulations of Cu, Zn, Ni and Cr did not appear to reach pollution levels, and no obvious pollution was observed in the MBS. Significant correlations were observed between Pb and Cd, Cu and Ni, Cu and Cr, Ni and Cr, suggesting that they might originate from a common source. However, Pb and Ni, Cu and Zn showed negative correlations, suggesting a different source. The quality of the soil environment and the heavy metal pollution were evaluated by the Single-Pollution Index and Nemerow-Pollution Index method. Each treatment soil sample had a low or slight pollution index (PI) of Cu, Zn, Ni and Cr, whereas the PI values of Pb and Cd were high, and samples were classified as being moderately or heavily contaminated by Pb and Cd. Although practically uncontaminated by Cu, Zn, Ni and Cr, a potential danger may emerge in the future depending on the agricultural activities in this region. The results of heavy metal assessment in the MBS will be helpful for the formulation of strategic sustainable agriculture in Jilin Province and improvement of corn quality and safety.