| Taking PeiYan river of Xuzhou as the research object, using the method of literature, field monitoring and track monitoring, laboratory research and model simulation, and getting a total of nearly 3,300 data from nearly 3 tons of soil samples and about 520 water samples, this paper analyzed the spatial-temporal dynamic changes of water quality of PeiYan river and the migration of non-point source pollution from the agricultural field, created the estimation model of non-point source pollution load of PeiYan river, and studied interception and treatment technology of agricultural non-point source pollution. The major conclusions were listed as follows:(1)Water quality monitoring showed that PeiYan river pollution mainly contained organic pollution and nutrient pollution, the main pollution factors were NH3-N, COD, TP and CODMn, and water quality of Pei Yan river has been improved since 2004, but water quality of Li ji bridge state-controlled section still can not reachâ…¢standard set by the state. Water quality of Pei Yan river was poorer during the rainy season than during other periods. During the rainy season, especially heavy rain or rainstorms (6-9 month)made non-point source pollutants to PeiYan river, which made water quality far beyond the standard.(2) Nitrogen and phosphorus release of different types of soil before and after fertilization showed that: The release of nitrogen and phosphorus from soil to upper water is an adsorption - desorption process, which can be expressed in first-order kinetics model. The release of nitrogen and phosphorus was affected by different types of land, among them phosphorus release of paddy land was slower than other soils, but that of orchard land was reversed. Fertilization improved markedly the release of soil nitrogen and phosphorus. Increasing the number of changing water times nitrogen and phosphorus release intensity decreased, and the release intensity after fertilization on the first 3 days was significantly higher than the latter.(3) Under different rainfall intensity, different types of soil, different land cover and fertilization, migration of nitrogen, phosphorus, ammonia nitrogen and CODMn in the farmland runoff was studied by taking the indoor simulated rainfall experiment. The results showed that: a. The runoff and sediment concentration in runoff changed as different physical and chemical properties of different types of soil .Under 40mm / h and 80mm / h , the order of the size of farmland surface runoff was paddy land.> forest land > orchard land and that of erosion sediment transport was orchard land> paddy land> forest land. There was a positive correlation between rainfall intensity and soil erosion. b.TP, TN, CODMn and ammonia concentration in surface runoff decreased with duration of rainfall, and then tended to be stable. And TP, TN, CODMn and ammonia concentration in surface runoff increased with the increasing of rainfall intensity. The proportion of PN and PP of total nitrogen and total phosphorus was greater than that of DN and DP, and the proportion of PN and PP significantly increased with the increasing of rainfall intensity, especially PP, which showed that granule state was the main form of nitrogen and phosphorus loss in rainfall runoff. The relationship between the cumulative amount of nitrogen and phosphorus loss (Y) and the cumulative amount of runoff (Q) was Y = aQb, in which a and b were constants and they were affected by rainfall intensity and characteristics of soil surface. c. Nitrogen and phosphorus concentration in runoff significantly increased after fertilizer, especially ammonia nitrogen concentration increased more than 10 times. Fertilization had a significant influence on the concentration of different forms of nitrogen and phosphorus in runoff, among them, DN and DP concentration were significantly increased, which showed that fertilizer applied to soil was not easy to be absorbed and fixed in a short time, so farm fertilization should avoid rainfall time to reduce nitrogen and phosphorus loss. d. Crop cover made nitrogen, phosphorus and ammonia nitrogen concentration in soil runoff decrease significantly, and farmland surface cover could significantly reduce soil erosion and nitrogen and phosphorus loss. Under 40mm/h rainfall intensity, TN and TP loss dropped 27.1% and 33.3% respectively in covered soil than bare area in runoff; Under 80mm/h rainfall intensity, TN and TP loss dropped 51.4% and 43.8% respectively .However, cover crop immersion also increased CODMn concentration.(4)The runoff curve of SCS model and USLE models were modified according to the characteristics of the PeiYan river region. The coefficient of nitrogen and phosphorus in water distribution was calculated based on the experiment results, correcting the traditional calculation ways reasonably. Screening comparing with the measured and simulated values by a single storm event four times, the accuracy of model was fine overall. Appling to the model to accout the non-point source pollution load of farmland along the PeiYan river region in 2009, we got the total nitrogen, total phosphorus, total sediment load and time distribution law. The results show that the pollution load was positively a direct proportion correlated with precipitation, while sediment, the pollution load of total nitrogen and total phosphorus were concentrated in May, June and July (accounting for more than 80% of the annual total pollution load). The three months were not only the main period of farming fertilization, but the main focus rainfall months, and the runoff generated from rainfall became a key driver of transport of pollutants.(5)Through the purificatory experimental study on the ecosystem dam, artificial wetland and submersed plants, combining the characteristics of PeiYan river regional, the engineering measures such as the artificial vein ecological river settlement which was composed of ecosystem dam system, undercurrents of artificial wetland system , biological floating bed purification system and the diversion of integrated system and the coastwise buffer zone settlement , the integrated management measures of agricultural non-point source pollution control have been put forward.
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