| Heavy metal pollution is a concern of the public worldwide.The purpose of this study was to investigate the accumulation of heavy metals in wheat grains and its health risk in farmland near lead smelting facilities.Soil and wheat grain samples were collected near a large lead smelter for heavy metal concentration analysis,the risk of consumption such wheat grains were estimated.Additives were added into heavy metal polluted soils and the effect on heavy metal accumulation in wheat grains were assessed.Foliar intake of Cd by wheat was also investigated by a pot experiment.We found,1.Farm land soil,wheat grain and scalp hair samples were collected from three villages?named QD,GF and BS?with increasing distance from a large Pb smelter in Henan Province.Cadmium,Cu,Pb and Zn concentrations and distribution in soil,wheat,and the potential for human heavy metal accumulation were investigated.Wheat grain samples having Cd and Pb concentrations exceeding the safe levels 46%and 100%of the time,respectively.Soil and wheat grain Cd,Cu,Pb and Zn concentrations increased as distance to the smelter decreased.Similarly,greater Cd,Cu and Pb concentrations were present in human scalp hair for those residents living closest to the smelter.Decreasing trends existed for hair-to-wheat grain ratios for Cd and Pb as distance to the smelter increased.Results suggest that as distance to the smelter decreases,human heavy metal absorption via the consumption of metal contaminated food products?e.g.,wheat?increases.2.The wheat grains were pearled and whole wheat flour,bran and flour samples were prepared,Cd,Cu,Pb and Zn concentrations of these grain fractions were analyzed.Concentrations of these metals in whole wheat flour were 0.38,3.83,0.48 and 29.3 mg kg-1,respectively.The concentrations of flour were slightly lower than those of whole wheat flour.The ratio of non-carcinogenic daily average intake?ADD?of whole wheat flour to flour was1.06-3.76,and the ratio of Pb was the largest.Cd has the largest hazard quotient?HQ?,and the values of HQ of both wheat products are greater than one.The flour HQ value was less than that of whole wheat flour?p<0.05?,and the HQ values of Pb had the largest difference between these two wheat fractions.Compared with whole wheat flour consumption,wheat flour consumption reduces the carcinogenic risk for 5.40-15.6%.The overall results show that the consumption of flour can reduce the health risks of human intake of Pb,and the consumption of wheat products may lead to health problems of residents in areas polluted by heavy metals.3.Amendments were applied into farmland soils near a lead smelter,their effect on soil heavy metal availability and wheat grain Pb,Cd,Cu and Zn were investigated in field experiment.The amendments affected soil heavy metal availability and wheat grain metal concentration,but they did not result in significant variation of wheat grain yield?p>0.05?.In field No.1?more polluted?,the concentrations of DTPA-extractable heavy metals in lime-amended soil were significantly lower than the control?p<0.05?,while the concentrations of heavy metals in wheat grains decreased the most in phosphate+bentonite amended soil.In field No.2?less polluted?,compared with the control,the DTPA-extractable heavy metal concentrations in the higher-dose lime treatment were the lowest?p<0.05?,all amendments resulted in lower Pb and Cu concentration in wheat grains.Bentonite treatment had the lowest grain heavy metal concentrations,among which grain Cd concentration was 13.1%lower than the control?p<0.05?.Therefore,a combination of phosphate and bentonite was recommended for field No.1;however,it may be better to change the soil utilization,so residents will accumulate less heavy metal in their body via the food chain.Bentonite amendment was recommended for field No.2.4.Cadmium solution was sprayed to wheat shoot in the late stage of wheat growth in a pot experiment.Plant sample analyses after harvest indicated that both the biomass yield and grain yield were negatively affected by Cd application?p<0.05?;compared to controls,leaf and grain Cd concentrations increased 187-547%and 26.3-91.8%,respectively.However,grain Cd accumulation?concentration×yield?was not affected by Cd treatments?p>0.05?.Stem,leaf and glume Zn concentrations increased by less than 31%,while grain Zn concentrations were negatively affected by Cd treatments.The results of this work indicate that,i)lead smelting activities resulted in elevated levels of heavy metals in soil,wheat grain and the body of local residents,ii)distribution of heavy metals in wheat grains is uneven,whole wheat flour consumption can increase heavy metal intake of local residents,iii)lime and bentonite amendment of farmland soil reduced heavy metal concentrations of wheat grains in the study area,and iv)cadmium can be absorbed by aboveground part of wheat plants.Planting of non-edible plants in the contaminated farm fields is important for reducing heavy metals intake via the food chain for local residents. |
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