黑土漫川漫岗区冻融-融雪-径流耦合形成农业非点源机理研究

It is the background that moderate-depth of seasonal frozen ground,black soil zones, national commodity grain base, State Key improvement water pollution control area， ecologically fragile area，and eco-security zone. It attempts to apply to the methods combination of that field monitoring experiment, laboratory simulation experiments, analysis of physical and chemical experiments and numerical simulation.The freeze-thaw-snowmelt-runoff coupled to the formation of agricultural non-point source pollution mechanism has become a favorite topic in the black soil hills of gentle slope farmland. The main content is the formation ofthe substance of non-point source nitrogen(N) and phosphorus(P) in the freezing and thawing of soil, ground surface snowmelt runoff leaching, runoff carrying three migration processes, conduct the following studies: at first, the black soil hills of gentle slope farmland freezing and thawing of non-point source substances N and P transport to the surface aggregation process; secondly, the black soil surface non-point source substances in situ loss law, including snow-melting the process of production flow and non-point source substances runoff leaching in situ loss;thirdly, snowmelt runoff carrying non-point source substances spatial transport processes; last, dynamic programming to the time axis to clarify the real mechanism of the black soil hills of gentle slope farmland freeze-thaw-snowmelt-runoff coupled to the formation of agricultural non-point source. The purpose is to exposit that black soil freezing and thawing of water-hot-salt transport law, snowmelt runoff the formation of the critical conditions, nonpoint source N and P spatial transport law, black soil gentle slope farmland freeze-thaw cycle snowmelt erosion of the formation of agricultural non-point source pollution in the state transition law. It is significance that to provide the basis for the theoretical basis for black soil hills of gentle slope farmland area of agricultural non-point source pollution control and soil and water resources protection.

本项目以中-深季节冻土区、黑土区、国家商品粮基地、国家重点治理的水污染控制区、生态脆弱区以及生态安全保障区为大背景。通过野外监测实验、室内模拟实验和物理化学分析实验与数值模拟相结合进行黑土漫川漫岗区冻融-融雪-径流耦合形成农业非点源机理研究。以形成非点源物质氮磷在冻融土壤中、地表面融雪径流淋洗、径流携带三个运移过程为主线，开展以下研究：黑土漫川漫岗区冻融非点源物质氮磷运移向表层聚集过程，地表非点源物质原位流失规律，包括积雪-融化-产流和非点源物质径流淋洗原位流失过程，融雪径流携带非点源物质空间运移过程，运用动态规划以时间为轴阐明黑土漫川漫岗区冻融-融雪-径流耦合形成农业非点源污染机理。揭示：黑土冻融水-热-盐运移规律，融雪径流形成的临界条件，非点源氮磷空间运移规律，黑土坡耕地冻融循环融雪侵蚀形成农业非点源污染的状态转移规律。为黑土漫川漫岗区农业非点源污染防治和水土资源保护提供基础理论依据。

东北黑土区大部分处于中-深度（-2±1m）季节性冻土区，且东北黑土区的漫川漫岗坡耕地占耕地面积的60%，多数为3°～10°坡.东北黑土区为中国重要的商品粮生产基地和粮食安全保障基地。在中度-深度季节性冻土区的中国东北黑土区，伴随商品粮产量的增加的同时，在秋收后黑土耕层土壤中化肥残留量逐年增多。黑龙江省耕地总面积保持2000年至2009年不变，氮肥、磷肥的纯氮、纯磷施用量从2000年到2009年分别增加了37.8％和53％(黑龙江省统计年鉴 2001-2010)，黑土耕地的氮、磷含量也逐年提高。在中度-深度季节性冻土区、中国东北黑土坡耕地上，利用黑龙江省哈尔滨市郊黑龙江省水利科学研究院水利试验研究中心的综合实验观测场的野外微地貌模型, 及以中国黑龙江省巴彦县龙泉镇一块黑土坡耕地为实验观测点。 项目在整个冬季冻融循环期的实测黑土耕层剖面黑土土壤温度、湿度、土壤有效磷含量、氨氮含量等数据。对典型中-深季节冻土区黑土耕层土壤湿度与冻结融化期土壤温度变化进行研究，研究东北黑土区黑土耕层土壤的冻融状况及水分运移情况，及研究黑土漫川漫岗型坡耕地冻融循环过程中土壤的氮、磷的分布变化情况。在试验中心微地貌模型研究发现黑土耕层土壤冻结融化过程分为5个阶段，经过整个冻结融化期后，阴、阳坡黑土耕层各层土壤含水量均大于冻结前，阳坡15 cm、10 cm、5 cm及1 cm深度黑土耕层土壤湿度随冻结融化期土壤温度变化的线性相关。在野外黑土坡耕地坡长为168m、坡度为1.3°、距坡底10m、50m、100m和150m处分别分层取样测试分析，黑土坡耕地冻融期土壤水、氨氮、有效磷的垂向分布研究结果表明：黑土耕层同一位置处0~1cm/1cm~5cm/5cm~10cm不同深度处，土壤水含量随时间从冻结前、冻结中、冻融循环前期、冻融循环中期、冻融循环后期及融化后均呈Guass型分布；土壤有效磷含量随时间从冻结前、冻结中、冻融循环前期、冻融循环中期、冻融循环后期及融化后均呈正弦曲线型分布；土壤氨氮与土壤有效磷相似随冻融循环的时间呈正弦曲线型分布。 0~1cm/1cm~5cm/5cm~10cm不同深度处土壤经冻融循环后，有效磷含量在各层均略有增加，1cm~5cm、5cm~10cm土壤含水量均增加。项目研究对中-深度季节性冻土区黑土耕层土壤有效利用水资源、保护水土资源、保障商品粮食产量安全有重要意义。