不同土壤类型及降雨强度下面源污染中氮元素去向特征规律研究

发布时间：2017-12-31 21:29

本文关键词：不同土壤类型及降雨强度下面源污染中氮元素去向特征规律研究　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：上世纪80年代以来,中国在短短几十年的时间内实现了农业的化学化。化肥的大量使用对粮食增产、保障我国的粮食安全发挥了重要作用,但是由于化肥使用过量以及施用技术落后,导致化肥的有效利用率普遍偏低,过量的养分造成了严重的农业面源污染。四川是我国农业大省,同时,四川省也是我国长江上游重要的生态屏障,是长江重要的水源涵养区和补给区,四川农业面源污染的防治对改善我国的水环境质量、促进我国农业经济的良性发展有着重要意义。通过搭建"雨水喷淋系统+蔬菜土地种植+地表径流及地下渗水收集装置"实验平台,研究不同土壤类型及不同降雨强度下,地表径流和地下渗水中氮元素的流失特征,以期为四川省的农业面源污染治理提供因地制宜、因时制宜的决策参考。一是针对四川地区常见的水稻土、紫色土和黄壤3种不同类型的土壤,分析不同土壤类型对氮元素流失的影响。通过实验研究发现,在降雨强度均为中雨的条件下,紫色土中氮元素流失率最高,达到3.67%,且流失速度快,因此可以推测在人为增加施肥的情况下,紫色土中氮元素极易流失;水稻土的氮元素保持能力最强,氮元素流失率为1.73%,流失速度慢;而黄壤的氮元素流失率虽然较低,为1.49%,但是由于黄壤本身全氮含量较高,因此氮元素流失量最大。二是针对四川多变的气象条件,分析小雨、中雨和大雨3种不同降雨强度对氮元素流失的影响。通过实验研究发现,在实验土壤均为水稻土条件下,小、中、大降雨强度下氮元素流失率分别为0.93%、1.79%和2.37%。氮元素的流失随着降雨强度的增大而急剧增加。流失量受降雨强度影响最大的是氨氮,大雨强度下氨氮流失量为685.10mg,占所施用化肥含氨量的35.13%,而小雨强度下这一数值仅为8.19%。实验中发现在不同类型土壤农地中以及不同降雨强度下,通过地下渗水流失是氮元素流失的主要途径。地表径流中氨氮是氮元素流失的主要形式,而在地下渗水中,硝态氮是氮元素流失的主要形式。
[Abstract]:Since -20s, China has realized the chemization of agriculture in a short time of several ten years. The large use of chemical fertilizers has played an important role in increasing grain production and ensuring the food security of our country. However, due to excessive use of chemical fertilizer and backward application technology, chemical fertilizer utilization efficiency is generally low, excessive nutrients caused serious agricultural non-point source pollution. Sichuan is a big agricultural province in China, at the same time. Sichuan Province is also an important ecological barrier in the upper reaches of the Yangtze River and an important water conservation and supply area of the Yangtze River. The prevention and control of agricultural non-point source pollution in Sichuan Province can improve the quality of water environment in China. It is of great significance to promote the benign development of agricultural economy in China. The experimental platform of "surface runoff and underground seepage collection device for vegetable land cultivation in Rain Water sprinkler system" was built. To study the characteristics of nitrogen loss in surface runoff and underground seepage under different soil types and rainfall intensity in order to provide appropriate measures for agricultural non-point source pollution control in Sichuan Province. The first is to analyze the effects of different soil types on nitrogen loss of paddy soil, purple soil and yellow soil, which are common in Sichuan. Under the condition that the rainfall intensity is moderate rain, the nitrogen loss rate in purple soil is the highest (3.67%), and the rate of loss is fast, so it can be speculated that in the case of artificial fertilization. Nitrogen is easily lost in purple soil. The nitrogen retention capacity of paddy soil was the strongest, the nitrogen loss rate was 1.73, and the loss rate was slow. Although the loss rate of nitrogen in yellow soil is low, it is 1.49, but because the total nitrogen content of yellow soil is high, the loss of nitrogen is the largest. The second is to analyze the light rain according to the changeable meteorological conditions in Sichuan. Effects of three different rainfall intensities on nitrogen loss in moderate rain and heavy rain. The experimental results showed that the experimental soil was small and medium under the condition of paddy soil. The nitrogen loss rate was 0.93% under heavy rainfall intensity. 1.79% and 2.37.The loss of nitrogen increased sharply with the increase of rainfall intensity. The amount of ammonia nitrogen was the most affected by rainfall intensity, and the loss of ammonia nitrogen was 685.10mg under the intensity of heavy rain. It accounts for 35.13% of the ammonia content of the fertilizer applied, but the value is only 8.19 under the light rain intensity. It is found in the experiment in different types of soil farmland and under different rainfall intensity. Ammonia nitrogen is the main form of nitrogen loss in surface runoff and nitrate nitrogen is the main form of nitrogen loss in underground water seepage.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52;X71

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