灌溉和降雨条件下生态沟渠氮、磷输出特征研究

为了研究长沙县金井河流域农业源头生态沟渠氮和磷的输出特征，对灌溉和降雨条件下及不同季节生态沟渠水体氮、磷的变化特征进行监测研究。研究结果表明：灌溉和降雨期间，生态沟渠中总氮的输出最大值为270 mg/L，其输出的主要形态为氨态氮和硝态氮，总磷的最大值达032 mg/L。灌溉后，生态沟渠氮、磷的输出均呈单调递减变化，在灌溉初期均最高。降雨后，总氮、总磷沿程变化趋势均呈递减变化；生态沟渠对水体总氮、总磷去除率分别达64%、70%；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、氨态氮含量在雨后第3 d达到最高，总磷含量在雨后第2 d达到最高。在不同季节中水体氮、磷的变化以冬季总氮、氨态氮和磷浓度最高

STUDY ON THE CHARACTERISTICS OF NITROGEN AND PHOSPHORUS TRANSPORTATION THROUGH ECOLOGICAL DITCH DURING IRRIGATION AND RAINFALL

To study the transportation characteristics of nitrogen and phosphorus through agricultural headwater ecological ditch of Jinjin River Basin in Changsha County,the seasonal changes of nitrogen and phosphorus concentration in ecological ditches during irrigationand rain period were studied.The results showed that the highest concentration of total nitrogen exported was 270 mg/L,and ammonium and nitrate were the predominant forms; the highest concentration of total phosphorus was 032 mg/L.After irrigation,total nitrogen and total phosphorus concentration decreased gradually.After the rainfall,total nitrogen and total phosphorus also decreased gradually.The removal rates of total nitrogen and total phosphorus in ecological ditches were 64% and 70%,respectively.The concentration of total nitrogen and total phosphorus increased first and then declined with time; total nitrogen,ammonium were at their highest in 3 d after the rainfall,and total phosphorus were at their highest in 2 d after the rainfall.The highest concentration of total nitrogen,ammonium and total phosphorus were found in winter