Relations between soil properties and selected heavy metal concentrations in spring wheat (Triticum aestivum L.) grown in contaminated soils

Spring wheat was grown in soils near a non-ferrous metals mining and smelting base in Baiyin city, Gansu province, P.R. China. The area studied is 501 km(2). Some of the croplands had been contaminated by heavy metals mainly through wastewater irrigation or aerial deposition. The soil samples were analyzed for pH, organic matter and available phosphorous (P); also for total cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) contents. Spring wheat grains were also analyzed for heavy metals. The results were interpreted using multiple linear correlation and stepwise regression analyses. The increment of total soil contents of selected heavy metals could enhance grain Cd accumulation, and the increment of total Zn content of soil could lower the grain Pb accumulation. The correlations were markedly increased by including other soil properties for grain Cd and Pb. Stepwise regression analyses indicated that the effect of soil pH and available P on the uptake of grain Cd were greater than that of the other total soil contents of heavy metals. Grain Cd and Pb could be reliably predicted by the total soil contents of Cd and Pb while the uptake of grain Zn and Cu were not satisfactorily predicted.