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侵蚀性风化花岗岩坡地壤中流携氮磷流失动态模拟
张丽萍1, 杨洁2, 范晓娟1, 邓龙洲1, 邬燕虹1
1.浙江大学 土水资源与环境研究所 浙江省农业资源与环境重点实验室, 浙江 杭州 310058;2.江西省水土保持科学研究院 江西省土壤侵蚀与防治重点实验室, 江西 南昌 330029
摘要:
[目的] 探究侵蚀环境下,风化花岗岩残积坡地土壤氮磷流失特征以及坡面径流和壤中流携带氮磷流失的强度和贡献率,为不同侵蚀环境及生态环境脆弱条件下,坡地氮磷流失规律的试验研究及防治提供理论依据。[方法] 采用原状土搬迁,室内人工模拟降雨的方法,设计2个坡度(8°和25°),5个降雨强度(30,60,90,120,150 mm/min),通过坡度与雨强的多重组合试验,在测试浓度与径流量分析的基础上,研究氮磷流失强度及在坡面径流和壤中流中的分配。[结果] ①在强烈侵蚀的坡地,土壤结构性较差,漏水漏肥现象严重,壤中流随携带的氮磷流失比重很大,壤中流携带的TN流失量均占到总流失量的90%以上,TP稍次之;②TN随径流的流失量远大于TP的流失量,径流中TN与TP总流失量的比值最高能达到160倍; ③雨强对氮磷流失量的影响大于坡度的影响,径流量的影响大于浓度的影响。④雨强对氮磷流失的影响存在2个转折,在60 mm/min附近存在一个蓄满产流和超渗产流的雨强分界,在90 mm/min左右,出现一个侵蚀性雨强的转折。[结论] 强烈的侵蚀影响土壤养分的流失方式及流失通道的比配,壤中流所携带氮磷流失所占比重很大,进而会影响到地下水的污染问题,加强残积土母质坡地土壤的侵蚀防治,是地表水和地下水面源污染控制及土壤养分流失减少的根本。
关键词:  强烈侵蚀  红壤坡地  模拟降雨  流失浓度  动态分析
DOI:10.13961/j.cnki.stbctb.2018.06.024
分类号:
基金项目:江西省土壤侵蚀与防治重点实验室开放基金项目“红壤坡地不同降雨情况下壤中流水流动态及携氮磷流失特征研究”(JXSB201502);国家自然科学基金项目“风化花岗岩侵蚀坡地表层流水流动态及携氮磷流失特征研究”(41471221)
Dynamic Simulation of Nitrogen and Phosphorus Losses in Erosive Weathered Granite Slope
ZHANG Liping1, YANG Jie2, FAN Xiaojuan1, DENG Longzhou1, WU Yanhong1
1.Institute of Soil and Water and Environmental Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, College of Environment and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China;2.Jiangxi Provincial Key Laboratory of Soil Erosion and Prevention, Jiangxi Institute of Soil and Water Conservation, Nanchang, Jiangxi 330029, China
Abstract:
[Objective] The objective is to investigate the losses of nitrogen and phosphorus in typical weathered granite parent material soil under erosive environment, and to discuss the contribution rates of nitrogen and phosphorus losses in slope runoff and interflow.[Methods] Slope gradients(8°, 25°) and rainfall intensities (30,60, 90, 120,150 mm/h) were selected as the variable factors for artificially simulated rainfall experiments, the study revealed the distributions of nitrogen and phosphorus losses in slope runoff and interflow based on mass concentration and runoff volume analyses.[Results] ① In the heavily eroded sloping fields, soil structure was instable; the soil was highly permeable, so the proportion of nitrogen and phosphorus loss in interflow was very large. The amount of TN loss in the interflow accounted for more than 90% of the total loss, and TP loss was slightly lower. ② The loss of TN with runoff was much greater than the loss of TP. TN in the slope runoff can reach 160 times higher than the total loss of TP. ③ The effect of rainfall intensities on the losses of nitrogen and phosphorus were greater than that of slope gradients; and the effect of runoff volume was greater than that of mass concentration. ④ There were two transitions in the effect of rainfall intensity on nitrogen and phosphorus loss, the first one was near 60 mm/h rainfall intensity, at which full-stored Horton runoff begin tranited to one dunne, and the second was 90 mm/min, from that on, the rain intensity became erosive.[Conclusion] Strong erosion affects both the loss of soil nutrients and the ratio of loss pathways. The losses of nitrogen and phosphorus in the interflow contribute a large proportion to the total ones, which inveitablly affects the quality of groundwater. Strengthening the prevention and control of soil erosion on sloping fields in rock formations soil is the basis for the control of non-point source pollution of surface water and groundwater, and it is essential to reduce soil nutrient loss.
Key words:  strong erosion  red soil slope  simulated rainfall  loss concentration  dynamic analysis