【作者】 普惠娟；

【导师】 张乃明；

【作者基本信息】 云南农业大学 ， 环境科学， 2009， 硕士

【摘要】 目前,水体富营养化已成为世界上最严重的水环境质量问题之一,氮是导致水体富营养化的主要因子,土壤氮素的累积会增加农田氮的流失风险,影响水环境质量。本文研究了宝象河流域不同土地利用类型,不同土壤层次土壤氮的累积与水体氮污染浓度特征,结果表明:（1）宝象河流域农田土壤pH值5.2～8.12之间,即整个研究区域内土壤pH值处于弱酸性和碱性之间;土壤有机质含量8.18～73.68g/kg,土壤有机质处于较高和一般含量水平之间。整个宝象河流域0～10cm土壤全氮含量为:0.40～3.60g/kg,平均值为:1.94g/kg。10～20cm土壤全氮含量为:0.40～3.41g/kg,平均值为:1.69g/kg,宝象河土壤的全氮含量显著高于全国和云南省的平均含量,全氮含量比较丰富。（2）整个宝象河流域0～10cm、10～20cm层次土壤全氮含量依次为:下游大棚土壤>中上游平地耕地>下游平耕地>中上游坡耕地>上游稀疏林地,结果表明0～20㎝下游大棚土壤氮素有累积明显,且总体趋势是近城区的土壤总氮平均累积水平高于上游和近滇池的平耕地。从分级情况上看,下游、中游土壤总氮和碱解氮含量主要处于高水平,上游的主要处于中级水平,整个流域氮素含量水平较高。（3）不同层次土壤全氮表现为0～10cm土层>10～20cm土层,不同层次土壤碱解氮除上游坡耕地外其余土壤利用类型均表现为0～10cm土层土壤>10～20cm土层土壤,且层次间差异不显著。不同土地利用类型土壤全氮含量表现为下游大棚土壤>中上游平地耕地>下游平耕地>中上游坡耕地>上游稀疏林地,下游大棚土壤的全氮与上游稀疏林地的全氮含量达到显著性差异;土壤碱解氮含量表现为下游大棚土壤>中上游平地耕地>中上游坡耕地>上游稀疏林地>下游平耕地,下游大棚土壤的碱解氮含量分别与上游稀疏林地和下游平耕地的碱解氮含量达到显著性差异。（4）宝象河不同河段农田沟渠水和河道水体氮素浓度有较大差异,总体趋势是沟渠水氮浓度高于河道水体氮浓度、河道水体和沟渠水体氮含量由上游到下游逐渐增加;硝态氮是水体氮素的主要形式,硝态氮占总氮比重大于氨态氮占总氮的比重。氮素浓度随时间（2008年6月～2008年11月）动态变化总体趋势是先升高后降低再升高;TN、NO₃^-- N和NH₄⁺ - N含量随时间呈现明显的动态变化。（5）对农田水体氮素污染特征的影响因素研究中发现:雨季降雨量的多少对沟渠水和河道水体中氮素含量具有一定的影响,沟渠周边表层土壤氮含量与沟渠水氮含量、沟渠沉积物氮含量与沟渠水氮含量间有显著的正相关性。对沟渠周边表层土壤和沟渠水体总氮含量进行相关性分析表明:7月沟渠旁表层土壤和沟渠水体总氮含量显著正相关,11月沟渠周边表层土壤和沟渠水体总氮含量相关,但是相关性不显著,这恰好说明降雨是氮素流失的一个主要因素。（6）在沟渠流动的条件下,当沟渠水浓度高于河道水浓度时,农田沟渠对河道氮素具有增负荷影响。降雨是氮素流失的重要影响因素,施肥后降雨能使沟渠水中总氮浓度升高,如果降雨强度大到能使沟渠流动,那么氮素极其容易随水流进入宝象河。更多还原

【Abstract】 At present, eutrophication has become the world’s most serious water quality problems, nitrogen is the main factor lead to eutrophication. The accumulation of soil nitrogen will increase the risk of nitrogen lossing in farmland, affecting the environment quality of water. This article studied the nitrogen accumulation of different soil use types and different soil layers, and water body nitrogen pollution characteristics, results showed that:（1） Baoxiang River basin soil pH value is between 5.2 and 8.12, that is, the entire study area soil pH value is between the weak acid and alkaline; soil organic matter content range from 8.18 to 73.68g/kg, the scope of a large area of soil organic matter at a higher level and middle level. Baoxiang River Basin 0 10cm of soil total nitrogen content: 0.40 3.60g/kg, average: 1.94g/kg. 10 20cm of soil total nitrogen content: 0.40 3.41g/kg, average: 1.69g/kg. The total nitrogen content in soil Baoxiang was significantly higher than the nitrogen content of national average levels and Yunnan Province average levels, nitrogen content is rich.（2） The total nitrogen levels of 0 10cm、10 20cm soil layer were: downstream greenhouse soil﹥upstream-middle flat farmland﹥downstream flat farmland﹥upstream-middle sloping land﹥upstream sparse woodland.The results showed that the nitrogen of 0 20 cm soil in downstream greenhouse have accumulated significantly, and the overall trend is close to urban areas the average accumulation of soil nitrogen level higher than the upstream and the flat land near the Dianchi Lake. From the classification point view, the soil total nitrogen and nitrogen content of downstream and middle stream main at a high level, the soil total nitrogen and alkaline nitrogen content of upstream mainly in the intermediate level, the entire basin nitrogen content is higher.（3） Different levels of soil nitrogen is 0¹0cm soil layer﹥10²0cm soil layer, at different levels of soil nitrogen in addition to the upstream slope of cultivated land use types other land use types are reflected 0¹0cm soil layer﹥10²0cm soil layer,but nitrogen of the difference soil layer is not significant. The soil total nitrogen content of different soil use types were: downstream greenhouse soil﹥upper-middle stream flat land﹥downstream flat farmland﹥upstream slope farmland﹥upstream sparse woodland,the total nitrogen of greenhouse soil downstream and upstream sparse woodland reach to significant difference. The performance of soil alkaline nitrogen content were: downstream greenhouse soil﹥upper-middle stream flat land﹥upstream slope farmland﹥upstream sparse woodland﹥downstream flat farmland.The alkaline nitrogen content of downstream greenhouse soil with upstream sparse woodland and downstream flat farmland nitrogen content significantly different.（4） Baoxiang river water and drains farmland water nitrogen concentration are differences, the overall regular is the ditch water nitrogen concentration is higher than the nitrogen concentration of river water.The river water and ditch water nitrogen gradually increase from upstream to downstream.Nitrate nitrogen in water bodies is the main form of N, accounted for the proportion of total nitrogen greater than ammonia-N accounted for the proportion of total nitrogen. The overall trend of nitrogen concentration with time （June in 2008 November in 2008） dynamic changes is the first rise after lower and then increased; TN, NO₃- N, NH₄ - N concentration over time shown clear signs dynamic changes.（5） In the study of nitrogen pollution characteristics factors of the farmland water body found: the number of rainfall during has a certain impact on the rainy season on the ditch water and nitrogen content of river.The nitrogen content of drains surrounding surface soil and ditches water nitrogen content,and ditches sediment nitrogen content and the drains between water have significant positive correlation.The drains and ditches surrounding the surface of the soil total nitrogen content of the water body correlation analysis showed that ditches and drains near the surface of the soil total nitrogen content of the water a significant positive correlation in July, and on the surrounding soil ditches and water drains associated total nitrogen content, but no significant correlation,this is just explain that rain is a major factor of nitrogen loss.（6）On the conditions of ditch flowing, when the ditch water concentration is higher than the concentration of river water, the ditches on farmland by the river with a load impact of nitrogen. Rainfall is an important nitrogen loss factors, rainfall after fertilizer application can increase the concentration of total nitrogen in the water drains, if the rainfall intensity to make the drains flow, then is very easy with nitrogen flow into the Dianchi Lake.更多还原