| In the case of the current water shortage, sewage irrigation is of great significance on China’s agriculture. Taiyuan sewage irrigation area is one of the most typical sewage irrigation areas in the northern region, it has a wastewater irrgation history of nearly30years, nearly40million mu sewage irrigation farmland, mainly distributed in Xiaodian, Jinyuan District, and Qingxu County. Long-term sewage irrigation, will lead to harmful substances in the sewage, such as a variety of organic compounds, heavy metals and others enrichment in soil, or polluted groundwater through seepage, or further enriched by the crop, and then enter in the body via the food chain and has harmful on health.In order to study Cd and Pb pollution status of soil-crop systems in sewage irrigation area, research ecological toxicity effects of Cd and Pb, and then provide the basic data for soil pollution control and food safety evaluation. Choosing Xiaodian sewage irrigation as the research object, studying the heavy metals Cd and Pb pollution station of sewage irrigated farmland, crops and vegetables, moreover, the effects of sewage and Cd combined treatment on the growth and quality of spinach is studied with greenhouse pot culture, the impact of sewage and Pb combined treatment on corn seed germination and seedling growth is investigated through indoor culture experiments. The main conclusions are as follows:1. The Cd, Pb contents of the Xiaodian surface (0-20cm), and layered soil samples (0～20,20～40,40～60,60～80,80～100cm) were analyzed, the results show that the Cd, Pb content of all surface soil samples are more than Taiyuan soil heavy metal background values; the Pb content of50%of surface soil samples exceeds the soil heavy metals lead background value, suggesting that Cd and Pb in surface soil have significantly enrichded. The analysis results of layered soil samples show that the Cd content in underlying soil decreased and stabilized, the Pb in the soil vertical migration trend is not obvious. 2. The Cd, Pb content determination results of corn and22kinds of vegetables in sewage irrigation, show that Cd and Pb concentrations of corn exceeds the prescribed environmental quality standard for foods, and Pb content’s superstandard multiples is much larger than Cd content’s; Cd content in59%of vegetables is more than the standard, Pb content in64%of vegetables is also more than the standard; the heavy metal content of vegetables classification results show that Cd content in root vegetables is the highest, Pb content in leafy vegetables is the highest.3. The result of sewage and Cd combined treatment on the spinach show that the effect on the spinach plant height, leaf area, leaf number, stem diameter exhibits a regular pattern, low concentration of stimulation and high concentration of inhibition. Compared with the water and Cd group, the content of Vc and chlorophyll decreased, the content of protein, soluble sugar and nitrite in spinach treated by sewage increased significantly; the content of chlorophyll, Vc, protein and soluble sugar decreased and the content of nitrite and Cd increased with the rise in concentration of Cd214. The result of sewage and Pb compbined treatment on corn growth indicate that, compared with the separate sewage treatment, sewage and Pb combined treatment has no significant effect on seed germination, germination rate of each group is more than94%; with the increasing of Pb-concentrations, the change situation of corn plant height, root length, fresh weight show that the low concentration of stimulation, high concentration of inhibition,200mg/L of Pb2+concentration is the effect of turning point. Corn Pb content is increasing with the increase of Pb2+concentration. |
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