| The groundwater pollution of nitrogen is popular all over the world and it has the trend of being serious. This has great harm to the ecological environment and the person's health. If people drink the polluted water by nitrogen for a long time, three nitrogen will accumulate in the body, nitrate will transform to harmful nitrite. Nitrite will react with the middle-amine and form nitrite amine, which can result cancer. The popularity and severity of nitrogen pollution arose the people's attention. Many scholars have begun to do the relative research and have the efficient treatment of nitrogen pollution. They always directly treat the polluted groundwater. But this is very expensive. To treat groundwater nitrogen pollution, first it should treat the nitrogen pollution in the soil and vadose. Treating nitrogen in vadose will in one hand eliminate the nitrogen pollution, in the other hand this can prevent groundwater from being polluted by nitrogen. Because the vadose is unsaturated zone, the environment condition is complex. It's difficult to eliminate the pollutant. There is localization in research of treating nitrogen in vadose.Guanzhong Basin is the area that is developing emphasized by the country. It is also the industrial base and produce area of food, cotton and oil. The shortage of water resource and the pollution of groundwater have become the serious problems in this area. This thesis aims at the nitrogen pollution status in vadose of Guanzhong Basin, discusses the transfer and transformation rules among three nitrogen and presents the measures to prevent groundwater from being polluted.Because the structure of Malan Loess is very special, it developed advanced vertically, using soil pillar in lab would break the natural structure of Malan Loess and influence the filter coefficient. It can't reflect the true condition. Based on this, it is decided to use the situ-experiment to simulate the transformation rules of three nitrogen in vadose under irrigation. Use certain content of ammonia to irrigate continuatively, taking samples in different depth, analyze the change of the nitrogen content then draw the conclusion of the transformation rules in Malan Loess under the natural condition. In Malan Loess, the three nitrogen transform by nitrification and denitrification. Nitrate was formed by ammonia through nitrification. Nitrate reduce by denitrification. In vadose of Malan Loess, 3.0m and 7.0m deep have obvious denitrification, nitrate decrease. In 5.0m, nitrate accumulates.Considered that the transformation of three nitrogen relates to microbes most. Aminate , nitrification , denitrification and nitrogen fixation will influence the transformation of three nitrogen. These functions are all the microbiological function. On the foundation of thesitu-experiment, develop the microbiological experiment. Detect the distribution rules of microbes related to the three nitrogen: aminate microbe, nitrification microbe, denitrification microbe and nitrogen fixation microbe. The distribution of microbes has a good relationship with three nitrogen. In 3.0m and 7.0m deep the denitrification microbes have great amount and nitrate decrease in these layer.Through the experiences it was found that 3.0m and 7.0m in vadose of Malan Loess are special soil layers. There are high content of organism , high content of water. It is in favor of the action of denitrification microbes. But in 3.0m deep, the oxygen content is high, it prevents the action of denitrification microbes. So there is an experiment of measuring denitrification intensity of 7.0m soil sample. The result shows that the Malan Loess has great ability to eliminate the nitrate in soil. Under the suitable condition, it can eliminate the content of nitrate within short time. So it can treat the nitrate pollution in vadose and prevent the groundwater from being polluted. This acknowledges has formed the base of treating the nitrate pollution in groundwater.This thesis lasted 16 months, has 456 soil samples, measure the issue of nitrate, nitrite... |
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