Chemical Fraction of Heavy Metals in an Oasis Soil and Their Bioavailability to Cole Crops

Abstract

Heavy metals in soil arising from mining and wastewater irrigation have greatly threatened human health and the environment. This research used pot experiments to study the fraction and bioavailability of Cd, Pb, Zn, and Ni in irrigated desert soil from oasis regions of Northwest China. The accumulation of selected heavy metals in the tissues of cole crops (Brassica campestris L.) was studied, and the bioavailability of selected metals in soils to cole crops was analyzed by Pearson coefficients. The results show different levels of accumulation of the selected heavy metals in cole crop tissues, which are shown as follows: leaves have a higher content of Cd than roots; roots have a higher content of Pb and Ni than leaves; the contents of Zn in leaves and roots are almost the same. Cd and Zn mainly accumulate in the edible part of the cole crop in arid soil. The exchangeable fraction of Cd, Pb, Zn, and Ni, the carbonate bound fraction of Zn and Ni, were available to the cole crop. Health risk index values for selected heavy metals were less than 1 for both control soil and spiked soils in case of Cd in treatment No. 8. Cole crops grown on spiked soil can pose health risks because of a high concentration of Cd.