Enrichment, contamination, ecological and health risks of toxic metals in agricultural soils of an industrial city, northwestern China

Abstract

BackgroundThe impacts of rapid urbanization and industrialization often cause toxic metal contamination in agricultural soils, which has been a global environmental issue. MethodsAgricultural soil samples were obtained from Lanzhou city, a typical industrial city in northwestern China. The levels of six toxic metals (i.e., Cd, Cr, Cu, Pb, Sb, and Zn) were determined in soil samples using Inductively Coupled Plasma Optical Emission Spectrometer. Afterwards, enrichment, contamination, ecological and health risks of them were comprehensively evaluated. ResultsThe average concentrations of toxic metals were 0.30, 79.7, 21.6, 26.7, 0.97, and 69.0 mg kg−1 for Cd, Cr, Cu, Pb, Sb, and Zn, respectively in soils. Cd was moderately enrichment while other metals were minimally enriched in soils of Lanzhou. The agricultural soils were characterized by moderate to considerable contamination of Cd and low contamination of other metals. Moreover, Cd might cause noticeable ecological risks at most sites. In addition, the average target hazard quotient (THQ) for children was 0.727, almost ten times higher than that for adults. Cr, Pb, and Sb were the most sensitive factors affecting the health risk assessment and contributed over 99% to the THQ. ConclusionLithogenic source, industrial and mining activities, and phosphorus fertilizer usage were the three main factors affecting the concentrations of Cd, Cr, Cu, Pb, Sb, and Zn in agricultural soils of Lanzhou, which should be taken into consideration in future supervision and management. Health risks of these metals, especially Cd, Cr, and Sb, for children should receive considerable attention due to their health hazard.