School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Guangdong Province Academic of Environmental Science, Guangzhou, 510045, China; Guangdong Key Laboratories on Geological Process and Mineral Resources Exploration, Guangzhou, 510275, China.
School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, 510632, China.
Environ Pollut. 2018 Apr;235:710-719. doi: 10.1016/j.envpol.2017.12.106. Epub 2018 Jan 12.
Soil-bound heavy metals are of great concern for human health due to the potential exposure via food chain transfer. In the present study, the occurrence, the bioavailability and the soil-to-crop transfer of heavy metals in farmland soils were investigated based on data from two agricultural areas, i.e. Sihui and Shunde in South China. Six heavy metals (As, Cu, Hg, Mn, Ni and Pb) were quantified in the farmland soils. The mean single pollution level indices (PI) were all lower than 1 except for Hg in soils from Shunde (PI = 1.51 ± 0.46), suggesting the farmland soils were within clean and slightly polluted by heavy metals. As, Cu, Ni and Pb were found to be mostly present in the non-bioavailable form. The majority of Hg was considered potentially bioavailable, and Mn was found to be largely bioavailable. Soil pH was an important factor influencing bioavailability of soil-bound heavy metals. The concentrations of heavy metals in vegetables from Sihui and Shunde were within the food hygiene standards, while the rice grain from Sihui was polluted by Pb (PI = 10.3 ± 23.4). Total soil concentrations of heavy metals were not correlated to their corresponding crop concentrations, instead, significant correlations were observed for bioavailable concentrations in soil. The results supported the notion that the bioavailability of the investigated heavy metals in the soil was largely responsible for their crop uptake. The soil-to-crop transfer factors based on bioavailable concentrations suggested that Cu, As and Hg in soils of the study area had greater tendency to be accumulated in the vegetables than other heavy metals, calling for further human health assessment by consuming the contaminated crops.
由于通过食物链转移而潜在暴露的可能性，土壤结合态重金属对人类健康非常关注。在本研究中，基于华南地区的两个农业区（四会和顺德）的数据，调查了农田土壤中重金属的发生、生物有效性和向作物的转移。对农田土壤中的六种重金属（As、Cu、Hg、Mn、Ni 和 Pb）进行了定量分析。除了顺德土壤中的 Hg（PI=1.51±0.46）外，所有单一污染水平指数（PI）的平均值均低于 1，表明农田土壤处于清洁和轻微重金属污染状态。As、Cu、Ni 和 Pb 主要以非生物有效形式存在。大多数 Hg 被认为具有潜在的生物可利用性，而 Mn 则具有较大的生物可利用性。土壤 pH 值是影响土壤结合态重金属生物有效性的重要因素。四会和顺德蔬菜中的重金属浓度均在食品卫生标准范围内，而四会大米中的 Pb 则受到污染（PI=10.3±23.4）。重金属在土壤中的总浓度与相应作物浓度之间没有相关性，而是在土壤中观察到生物有效浓度的显著相关性。研究结果支持了这样一种观点，即所研究土壤中重金属的生物有效性在很大程度上决定了它们对作物的吸收。基于生物有效浓度的土壤向作物的转移系数表明，研究区域土壤中的 Cu、As 和 Hg 比其他重金属更倾向于在蔬菜中积累，这需要通过食用受污染的作物对其进行进一步的人类健康评估。
