山东省典型污灌区土壤-小麦重金属健康风险评估

为探讨污灌区农田土壤-小麦体系中重金属的富集特征和潜在健康风险，选取山东省龙口市北部平原为典型区，系统采集了小麦籽粒和对应点表层土壤样品各63个，测定Cr、 Cu、 Ni、 Pb、 Zn、 As、 Cd和Hg的含量，对土壤和小麦籽粒的重金属含量水平、富集能力和健康风险进行研究.结果表明，土壤中8种重金属的含量均值超出山东省东部元素背景值，由Cd元素造成的土壤污染比较明显.小麦籽粒中Ni和Pb元素的样品超标率偏高，分别为100%和96.8%.小麦籽粒与土壤重金属含量间的相关性并不显著，总体上小麦籽粒对Zn、 Hg、 Cd和Cu的富集能力较强.以本地小麦面粉为食源时，健康风险评价结果显示，在当前食用量下，成人和儿童摄入的Ni元素分别占日允许摄入量的28.278%和131.980%,潜在威胁性较大.As和Pb的风险指数(HQ)超过1,是威胁研究区成人和儿童健康的主要物质，约占总风险的80%. 8种重金属的HQ总和虽低于安全值，但儿童的总风险值为成人的1.245倍，儿童的食品安全问题应引起足够重视.从空间分布来看，研究区南部的健康风险高于北部，今后应加强对南部地区的重金属污染防治工作力度.

Health Risk Assessment of Heavy Metals in Soil and Wheat Grain in the Typical Sewage Irrigated Area of Shandong Province

Sewage irrigation is a common alternative to make up for the shortage of agricultural irrigation in intensive agricultural areas. Abundant organic matter and nutrients in sewage can improve soil fertility and crop yield, but hazardous materials, such as heavy metals, will damage the soil environmental quality and threaten human health. To better understand the characteristics of heavy metal enrichment and potential health risk in a sewage irrigated soil-wheat system, a total of sixty-three pairs of topsoil and wheat grain samples were collected from the sewage irrigated area of Longkou City in Shandong Province. The contents of Cr, Cu, Ni, Pb, Zn, As, Cd, and Hg were determined to analyze heavy metal contamination and calculate bio-accumulation factor (BAF), estimated daily absorption (EDA), as well as hazard quotient (HQ). The results showed that the average contents of the eight heavy metals were 61.647, 30.439, 29.769, 36.538, 63.716, 8.058, 0.328, and 0.028 mg·kg^-1, respectively, which all exceeded the background values of corresponding heavy metals in the eastern Shandong Province. Especially, the average content of Cd was higher than the current standard value of soil environmental quality of agricultural land soil pollution risk control, indicating the apparent soil contamination. However, the correlations between the heavy metal contents in soil and wheat grains were not significant, suggesting that it is difficult to conclude the enrichment degree of heavy metals in wheat grains merely by the heavy metal contents in soil. The results of BAF showed that the high enrichment capacity of wheat grain was primarily obtained with Zn, Hg, Cd, and Cu. According to the national food safety limit standard, the over-limit ratios of Ni (100%) and Pb (96.8%) in wheat grains were the most serious. As a result, under the current consumption of local wheat flour, the EDAs of Ni and Pb were high, accounting for 28.278% and 1.955% of the acceptable daily intakes (ADI) for adults and 131.980% and 9.124% of the ADIs for children. The results of the health risk assessment exhibited that As and Pb were the main sources causing health risks, accounting for approximately 80% of the total risk. Although the sums of the HQ of the eight heavy metals for adults and children were below 10, the total HQ of children was 1.245 times higher than that of adults. The food safety of children should receive more attention. When considering spatial characteristics, the health risk in the southern study area was higher than that in the northern part of the study area. The prevention and control of heavy metal contamination in the southern area should be strengthened in the future.