【摘要】 为研究降水径流过程中非点源污染物氮、磷浓度的变化特征,分析降水作用下长沙县金井河小流域农业源头沟渠水中氮、磷的流失特征与生态拦截效应。结果表明:在降水初期非点源污染物氮、磷浓度与降水径流量的变化均呈逐渐递增趋势,雨后均呈递减变化;降水作用下沟渠系统总氮输出的最大值为4.67 mg/L,总磷输出的最大值为0.38 mg/L,其氮素输出的主要形态为氨态氮和硝态氮;雨后各断面氮、磷的输出随着时间的增加呈先增加后降低的趋势,其中总氮与总磷含量分别在雨后第3天和第2天达到最高;菖蒲–茭白段的生态拦截效果明显高于自然段的自然净化效果,表明植物拦截和吸收是植被段氮、磷去除的重要途径,菖蒲、茭白在6月吸收氮、磷分别达26.90、2.34 g/m~2。更多还原

【Abstract】 An agricultural ditch in headwater of Jinjin River, located at a small watershed in Changsha county, was selected as the study area, changes and losses of nitrogen, phosphorus in ditches and effects of ecological interception from rainfall runoff were analyzed. The results showed that the pollutants concentration and rainfall runoff increased gradually at their highest in preliminary stage of rainfall,however, they decreased gradually after the rainfall.The highest total nitrogen and total phosphorus content reached up to 4.67 mg/L and 0.38 mg/L during raining time respectively, ammonium and nitrate were the predominant forms. The transportation content of total nitrogen and total phosphorus increased at first, and then declined by time, the total nitrogen and total phosphorus content appeared to their maximum at the third days and the second days after the rainfall respectively, and they gradually decreased by time. The ecological interception capacity in ditches of Acorus calamus L. and Zizania latifolia was obviously higher than that of natural purification sections, which indicated that plant interception and assimilation were vital to decrease the nitrogen and phosphorus. The total assimilated nitrogen and phosphorus amounts were 26.90 and 2.34 g/m~2 respectively during the rainy season(between April and June) in ditches.The results could provide references for agricultural non point pollution control at river basin scale.更多还原