The farmland irrigation with the sewage is a common and better pathway to save the resource of groundwater in Northern China. The investigation was conducted in the farmland along the Fuhe River to explore characteristics of heavy metals in soils and grains of wheat and maize from a long-term sewage-irrigated area of Baoding region. The results showed that the topsoil with long-term sewage irrigation accumulated more Cd, Pb, and Hg compared with that of soil irrigated with groundwater and their corresponding natural background values. Cd concentrations in 48% of sewage-irrigated soil samples exceeded the Chinese safety limitation at 0.6 mg/kg, but less Cd accumulated in crop grains and did not pose the potential health risk. On the contrary, Pb levels in soils irrigated with sewage were lower than the safety limitation but Pb concentrations in 24% of wheat grain samples exceeded the Chinese national safety limit. Long-term sewage irrigation did not increase As, Cr, and Ni concentrations in soils or crop grains. The target hazard quotient (THQ) of heavy metals in edible grains of crops was selected to assess their risk to human health. Total THQ values were higher than 1.0 for the wheat samples from sewage-irrigated area and both sewage-irrigated and smelter-impacted areas, and As is the main contributor to the total THQ and posed the potential risk to human health. Therefore, the accumulation of Cd, Pb, Hg, and As in soils and crops in sewage-irrigated area should be monitored continuously to ensure food safety and security.
微生物在重金属污染治理中具有重要作用.采用微生物纯培养技术从镉污染土壤中分离获得一株在液体培养基和固体培养基中能够分别耐受45 mmol·L~(-1)和50 mmol·L~(-1)Cd~(2+)的细菌,通过形态学、生理生化及分子鉴定,初步鉴定该菌株属于链霉菌(Streptomyces sp.),命名为Streptomyces sp.strain Cd TB01.进一步实验结果表明,耐镉链霉菌Streptomyces sp.strain Cd TB01的优化培养条件为:马铃薯蔗糖培养基,在250m L的三角瓶中装液量为90 m L,培养温度30℃,初始pH=6.0,接种量6.0%,NaCl质量分数0%;湿菌体吸附Cd~(2+)的优化条件为:温度30℃,pH=8.0,NaCl质量分数1.0%,Cd~(2+)浓度500 mg·L~(-1),吸附率为44.78%;干菌粉吸附Cd~(2+)的优化条件为:温度30℃,pH=9.0,NaCl质量分数0%,Cd~(2+)浓度100 mg·L~(-1),吸附率达到70.45%.说明链霉菌Streptomyces sp.strain Cd TB01在重金属污水处理中具有广阔的应用前景. 相似文献