千岛湖流域不同土地利用方式对氮和磷流失的影响

Influence of different land use patterns upon nitrogen and phosphorus loss in the Qiandaohu drainage area

从流域尺度研究氮、磷随地表径流的流失是国内外研究的热点。通过研究千岛湖流域降雨径流中总氮(TN)、总磷(TP)、可溶氮(DN)和可溶磷(DP)浓度变化,探讨不同土地利用方式对氮素、磷素流失的影响,结果表明:不同土地利用方式下日降雨量与径流水中的总氮、可溶氮、总磷和可溶磷浓度均呈显著正相关;不同土地利用方式下土壤中降雨径流中总氮和总磷浓度变异较大。红薯地和园地等有人工耕种的坡地氮磷流失浓度最大,草地和林地等受人工影响干扰少的土地利用方式氮磷流失浓度相对较少。高坡林地降雨径流中氮磷流失浓度大于缓坡林地,平均DN/TN值和DP/TP值变化较小,分别为0.45和0.22左右。

Nitrogen and phosphorus loss with surface runoff at the drainage scale has been one of the hot subjects of study at home and abroad. The influence of different ways of land use on nitrogen and phosphorus loss was studied by monitoring the changes of the concentrations of the total nitrogen (TN), total phosphorus (TP), soluble nitrogen (DN) and soluble phosphorus (DP) in surface runoff in the Qiandaohu drainage. There is a pronounced positive correlation between daily rainfalls and the TN, TP and DP concentrations in different ways of land use. The concentrations of TP and TN in soils in surface runoff vary greatly. Cultivated slope land such as sweet potato land and orchards suffer heavier nitrogen and phosphorus loss than grassland and forestland, because the latter suffers less artificial disturbance. The loss of nitrogen and phosphorus in higher slope forestland is heavier than gentle slope forestland. There is no appreciable variation in average ratios of DN/DP and DP/TP, which are 0.45 and 0.22 respectively.