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酸性矿山废水(acid mine drainage,AMD)对周边农田的污染是煤等含硫矿产资源开采过程中普遍存在的问题。通过模拟实验,研究了AMD对稻田上覆水pH、EC(电导率)和Eh(氧化还原电位)等理化特征和对其中氮形态转化的影响。结果表明,AMD持续污染对稻田上覆水pH、EC和Eh等综合理化指标、重金属含量以及稻田上覆水中的总氮、氨氮、可溶性有机氮、亚硝酸盐氮含量产生了极显著影响(p<0.01)。AMD污染后上覆水总氮、可溶性有机氮、亚硝酸盐氮和硝酸盐氮含量分别从3.92、3.27、0.005 0、0.33 mg/L变为9.33、8.67、0.017、0.18 mg/L;同时AMD的灭菌处理实验表明,AMD中的铁硫杆菌等微生物具有影响稻田上覆水中氮转化的作用,灭菌后的AMD可显著降低稻田土壤氮的损失,有效降低稻田上覆水总氮(比对照降低42.01%)、可溶性有机氮(比对照降低73.34%)以及亚硝态氮(比对照降低70.59%)含量,提高土壤上覆水硝态氮浓度(比对照提高93.71%)。说明,AMD持续污染可通过对稻田水环境特征产生显著的直接影响,继而直接或间接地影响着稻田上覆水中可溶性有机氮、氨氮、硝态氮、亚硝态氮形态及总氮的数量变化,同时AMD及稻田中的微生物在其中发挥着重要作用。
Acid mine drainage (AMD) pollution of the surrounding farmland is a common problem in the mining of sulfur-bearing minerals such as coal. Through simulation experiments, the effects of AMD on the physicochemical properties such as pH, EC (conductivity) and Eh (redox potential) of paddy field and the transformation of nitrogen forms were studied. The results showed that the persistent pollution of AMD had a very significant effect on the comprehensive physical and chemical indexes such as pH, EC and Eh, heavy metal content and total nitrogen, ammonia nitrogen, soluble organic nitrogen and nitrite nitrogen in overlying paddy water (p < 0.01). The contents of total nitrogen, soluble organic nitrogen, nitrite nitrogen and nitrate nitrogen in overlying water after AMD pollution were changed from 3.92,3.27,0.005 0,0.33 mg / L to 9.33,8.67,0.017,0.18 mg / L, respectively. Meanwhile, AMD Sterilization experiments showed that microorganisms such as Thiobacillus ferrooxidans in AMD had an effect on nitrogen transformation in overlying water of paddy field. After sterilized AMD, the loss of soil nitrogen in paddy soil was significantly reduced, and the total nitrogen in overlying water in paddy field was effectively reduced 42.01%), soluble organic nitrogen (73.34% lower than the control) and nitrite nitrogen (70.59% lower than the control), and increased the concentration of nitrate nitrogen on the overlying water in the soil (93.71% higher than the control). This indicates that continuous AMD pollution can directly or indirectly affect the changes of the forms of soluble organic nitrogen, ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and total nitrogen in the overlying water of paddy field by having a significant direct impact on the water environment characteristics of the paddy field , While micro-organisms in AMD and paddy fields play an important role.