喀斯特山区不同农作方式下土壤质量变化对浅层地下水质量的影响

Effects of Farming Behaviors on Quality of Shallow Groundwater in Small Karst Basin

选择贵州中部喀斯特山区普定县猫洞小流域,对长期受不同农作行为影响的区域(低复种旱作区、高复种旱作区、高复种复合农作区)土壤和浅层地下水进行采样和分析。结果表明,不同农作区浅层地下水化学组分明显不同,从低复种指数的旱作区、高复种指数的旱作区到高复种指数的复合农作区,浅层地下水中的NO3-、NH4+、PO34-、高锰酸钾指数和SO24-的含量依次增大,呈显著上升趋势,在高复种指数农作区浅层地下水中氮磷含量更高;在浅层地下水中,NO3-含量受土壤有机质、腐植酸、全氮和碱解氮的影响最大,PO34-含量受土壤全磷、碱解氮、CEC的直接影响大;Cl-对浅层地下水影响不明显。不同农作方式对地下水的NO3-、NH4+、高锰酸钾指数的贡献存在差异,可见喀斯特特殊的双重水文结构使水环境质量易受土壤质量等环境因素影响,特别是浅层地下水更易受到污染。

Shallow groundwater and soil were analyzed by samples collected from three type of agricultural areas in small karst basin. Results showed that the chemical composition of shallow groundwater was distinctly varied in different farming regions. The permanganate index and the content of SO4^2-、 NO3^-、NH4^＋、PO4^3- in shallow groundwater increased by the order of dry farming areas of lower index with planting crops,complex agriculture areas with higher index planting crops. The content of nitrogen and phosphorus was higher in higher complex index planting crops farming areas. The content of NO3^- in shallow grounderwater was obviously influenced by organic matter,total nitrogen,available nitrogen; The content of PO4^3- in shallow grounderwater was mainly influenced by total phosphorus,available nitrogen and CEC; The tested 13 water chemistry components were hardly influenced by Cl^-in shallow groundwater. The different content of NO3^-,NH4^＋ and permanganate index in shallow grounderwater resulted from different agricultural practices. The special double hydrographic structures in Karst made the aquatic environment quality were easily influenced by some environmental factors such as land quality,especially the shallow groundwater was more likely prone to be polluted.