The Accumulation Level Of Heavy Metals And Health Risk Assessment To Local Inhabitants In Agricultural Area, Baiyin Gansu

Baiyin was a major industrial city based on non-ferrous metals mining and smelting, and produced amount of metal-rich contaminants during production activity. The wastewater containing high heavy metals was discharged into the Yellow River through Xidagou and Dongdagou. The agricultural area in Baiyin was mainly situated along Xidagou basin and Dongdagou basin with a long history of wastewater irrigation, the irrigation water used presently from the Yellow River may contain high heavy metals due to the immission of industrial sewage and domestic wastewater. Thus, besides of the traditional agricultural activities (use of fertilizer and pesticide), wastewater irrigation could also increase the input of heavy metals in the area. Moreover, the residents mainly feed on local food crops, they may suffer health risk due to dietary intake of heavy metals through daily food and drink.The present study determined the heavy metals concentration of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd) in selected samples (irrigation water, soil, the edible parts of vegetables, wheat, drinking water) colleted from the agricultural area in Baiyin. The ecological risk of each part was assessed compared with the corresponding limits in environmental quality standard, and the source of the contaminants were also investigated. The study analyzed the potential health risk to local residents according to the data of dietary survey and health risk assessment model, the results were showed as follow:1. The soil in studied area suffered pollution of Cd, while the concentration of Cu, Zn and Pb were inside the safe interval; Cd concentration in determined irrigation water surpassed the limit and the wastewater irrigation was a major reason for the high heavy metals contamination in soil.2. Pb and Cd concentrations in the wheat grains planted in this area exceeded the permissible thresholds, it was referred according to the correlation analysis that the high level of Cd was accumulated through soil, while Pb was mainly from the deposition on the surface of the wheat discharged from traffic activity.3. In the11vegetables universally planted in studied area, the concentration of Cu, Zn and Cd in all vegetable samples were inside the safe interval, but Pb concentration in Vigna unguiculata, Solanum lycopersicum, Raphanus sativus, Solanum tuberosum and Brassica pekinensis surpassed the permissible limit, it was because the vegetable field in the studied area mainly located near the rural road, Pb discharged from traffic activity was absorbed by vegetables leading to the Pb pollution of theses vegetables.4. The results of health risk showed that the risk of the four heavy metals followed the sequence of:HIPb> HICd>HICu>HIZn>1, suggesting that every heavy metal had produced adverse effect to local inhabitants, and the impacts of Pb and Cd were much severer than the others. The potential health risk due to the three dietary intake paths followed the sequence of:HI wheat>1>HI vegetables> HI drinking water, suggesting that heavy metals had produced significant adverse effects to residents from wheat intake rather than drinking water intake nor vegetables intake because of the relatively large quantities of daily wheat ingestion and high concentrations of Pb and Cd in wheat.Based on the above results, the paper suggested that the soil, food crops and drinking water in the studied area were contaminated by heavy metals in different degrees, and the heavy metals had produced adverse health risk to residents through food chain. According to the present research, we suggested that the amount of wastewater discharged directly into the Yellow River should be limited, also, the purification of irrigation and drinking water was needed urgently. Besides, the residents should adjust the distribution of agriculture cropping pattern, and food crops should not be planted near the rural road. Further more, the government should pay more attention to the safety of the agricultural ecological system, crop production and the health of local inhabitants while performing urbanization, industrialization and increasing economic benefits.