苏北某市垃圾填埋场周围地下水氮污染及其形态研究

通过对垃圾填埋场地下水氮污染状况的监测,分析了垃圾填埋场渗滤液的水质特征及其对地下水氮污染的影响。结果表明:垃圾渗滤液含有高浓度的NH4+-N,渗滤液进入土壤后,大量共存离子的竞争吸附减弱了土壤胶体对NH4+-N的吸附能力;土壤中有机质增加后,土壤胶体对NH4+-N的吸附性降低,吸附量减少;且高浓度NH4+-N的存在抑制了硝化作用,从而使大量的NH4+-N未能被土壤胶体吸附转化就随渗滤液继续迁移至地下水中,导致地下水的氮污染主要以NH4+-N为主。

Study on Nitrogen Contamination and Its Main Form in Groundwater around the Refuse Landfills of a City in North Jiangsu Province

Nitrogen contamination of groundwater in refuse landfills has been monitored and evaluated by analyzing the characteristics of refuse landfill leachate and assessing the potential effects of nitrogen contamination on groundwater.The results showed that there were large amounts of NH+4-N in refuse landfill leaehate,when some metal ions and NH+4-N in the leachate found their way into soil along with the leachate,soil colloids prone to adsorb coexistent ions rather than NH+4-N.After these ions were adsorbed,the NH+4-N adsorption ability of soil would be reduced.Moreover,the organic matter contents in the soil around a refuse landfill were higher than those in unpolluted soil by leachate.A complex function of organic matter and soil minerals reduced the exchange sites for NH+4-N.Therefore,when large amounts of organic matter and metal ions coexisted with NH+4-N in the soil,the ability of soil to adsorb NH+4-N could be decreased.In addition,the high concentrations of NH+4-N in the leachate could help the soil inhibiting nitrifying microorganisms in the soil and reduce the transformation speed from NH+4-N to NO-3-N,resulting in that the nitration of soil has been restrained.Accordingly,a great deal of NH+4-N moved along with waste leachate into the groundwater before they had been adsorbed or conversed,which made the contamination of NH+4-N being the major form of pollution in groundwater around refuse landfills.