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Influence of phosphate amendment and zinc foliar application on heavy metal accumulation in wheat and on soil extractability impacted by a lead-smelter near Jiyuan, China
Citation:
Xing, W., E. Cao, K. Scheckel, X. Bai, AND L. Li. Influence of phosphate amendment and zinc foliar application on heavy metal accumulation in wheat and on soil extractability impacted by a lead-smelter near Jiyuan, China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH. Ecomed Verlagsgesellschaft AG, Landsberg, Germany, 25(31):31396-31406, (2018). https://doi.org/10.1007/s11356-018-3126-4
Impact/Purpose:
Heavy metals are the most widespread pollutants in the environment, and can be readily absorbed by plants and animals, allowing entry into the food chain and exerting negative effects on human health. Nonferrous metal mining and smelting are major sources of heavy metal contamination in the environment. During the mining and smelting process of nonferrous metals, heavy metals enter the environment through the weathering and leaching of solid wastes, emission of polluted water, or the atmospheric decomposition of particles from stacks of the smelters. China is the biggest lead (Pb) producer in the world at present. Lead mining and smelting have resulted in accumulation of lead and cadmium (Cd) in soils in many areas of some provinces, such as Henan, Hunan and Guangdong. Heavy metal pollution near smelting facilities has resulted in elevated concentrations of Pb and Cd in crop grains, bearing negative impacts on the health of local residents from the heavy metals. Jiyuan City in Henan Province in northern China produces about 800,000 tonnes of Pb annually, which is about 10% of the world annual Pb output. High blood lead levels have been found for children living near the smelters. Ingestion of heavy metal polluted food and water is one of the dominant pathways for accumulation in humans living near polluted areas. This field study was conducted in a smelter impacted area in Jiyuan, China to investigate, i) the effect of whole and split application of phosphate amendments on Pb and Cd availability in soil and the accumulation of Pb and Cd in wheat grains; and ii) the effect of foliar application of Zn to wheat plants on the accumulation of Cd in wheat grains.
Description:
Higher concentrations of Pb and Cd in wheat grains harvested in several lead-smelting-polluted areas in northern China have been reported. This field experiment was conducted to investigate the effect of phosphate amendment and Zn foliar application on the accumulation of Pb and Cd in wheat grains grown in a lead-smelting impacted area in Jiyuan in northern China. The soil (total Pb and Cd are 261 and 2.65 mg kg−1, respectively) was amended with superphosphate at P:Pb ratios (mol:mol) of 1.90 or 2.57 either during wheat (Triticum aestivum L.) planting or a split of 60% of the phosphate applied at planting, with remaining 40% applied at the jointing stage. Zn was sprayed on the canopy of the wheat plants at the jointing stage. The phosphate amendment resulted in lower DTPA (diethylene triamine pentaacetic acid)-extractable Pb (1.39–10.7% lower than the control) and Cd (0.040–7.12%) in the soil. No significant effect of split application of phosphate was found on Pb and Cd availability in soil; however, higher rates of P resulted in lower Pb and Cd availabilities in the soil. Grain Pb (5.41–21.5% lower than the control), Cd (3.62–6.76%), and Zn (4.29–9.02%) concentrations were negatively affected by the phosphate application, with higher rates of phosphate resulting in lower grain heavy metal concentrations. Foliar application had no statistically significant influence on Pb and Cd concentrations in the grain (p > 0.05). Although Pb and Cd concentrations in wheat grains were reduced by the phosphate application, their concentrations were still much higher than the maximum permissible concentrations for wheat in the national standards of China. The results suggest that it is feasible to reduce wheat grain concentrations of Pb and Cd in Pb-smelting-polluted areas in northern China by soil application of superphosphate; however, the split application of the phosphate and the foliar application of Zn compounds do not have substantial impact on reducing accumulation of Pb and Cd in the wheat grains.
URLs/Downloads:
DOI: Influence of phosphate amendment and zinc foliar application on heavy metal accumulation in wheat and on soil extractability impacted by a lead-smelter near Jiyuan, China
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