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Non-point Nitrogen Pollution in Urban Agricultural Region

Author: HuangHaiBo
Tutor: ZhangJinZhong;ZhouPei
School: Southwestern University
Course: Environmental Engineering
Keywords: Urban Agriculture Non- point source pollution Nitrogen Water Environment Protection
CLC: X52
Type: Master's thesis
Year: 2011
Downloads: 85
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Abstract


Urban agriculture is the dominant direction of the agricultural development of the suburbs of Shanghai. In the course of its development, the farmers in order to improve product yield, the blind application of large amounts of fertilizer, not only a waste of resources, soil nitrogen utilization rate is low and a huge loss, but also makes the surface water and groundwater pollution by nitrogen. Study of urban agriculture Village is a non-point source nitrogen pollution characteristics, provide a theoretical basis for the sustainable development of urban agriculture, the prevention and control of non-point source nitrogen pollution and the protection of the water environment. In this paper, urban agriculture the typical villages domain - Shanghai Nanhui new town Orchard Village for the study, the study of nitrogen in the soil and water environment through the nitrogen content in the soil, surface water and groundwater monitoring under different land use types, space distribution characteristics analyzed the nitrogen the migration output characteristics typical rainfall events, and the use of the the rainfall flow-weighted average concentration hydrological sub-models (EMC) and hydrological sub-model (SCS), the estimated typical rainfall conditions orchard soil nitrogen the output load, the key findings are as follows: 1. primary form of nitrogen pollutants in surface water and groundwater nitrate; total nitrogen (TN), nitrate (NO3 - N) and ammonium the average content of nitrogen (NH4-N) in groundwater showed the spatial distribution pattern. Specific performance of the river next to the groundwater TN highest average concentration of nitrogen pollution is the most serious, lightest and residential area groundwater TN lowest average concentration of nitrogen pollution; NO3 - N the spatial distribution characteristics consistent with TN; neighborhood The average groundwater NH4-N was significantly higher than the canal and next to the orchard groundwater; nitrite (NO2 - N), the average concentration of the randomness in the spatial distribution no significant spatial distribution characteristics; groundwater TN, NO3 - N and NH4-N, NO2 - N the average content change over time. Overall, more rainfall season, the average concentration of nitrogen in groundwater is relatively high, and in a period of very little rainfall is relatively low. Channel in the orchard, the ring channel and river TN, NO3 - N and NH4-N average levels of differences in surface water TN, NO3 - N and NH4-N the average content changes over time. (2) the use of classical statistics and geostatistics to study the characteristics of the village main land use types - orchard farming layer spatial variability of soil nitrogen. The results show that the TN and NO3 - N degree of variation in the orchard soil, is a strong variability; variability of NH4-N to a lesser extent, is a moderate variability. TN, NO3 - N and NH4-N the best fit of the variogram models are linear models, have a weak spatial correlation. NO3 - N and NH4-N content of the spatial distribution of patchy; TN content of the spatial distribution in spots. Particulate nitrogen storm events cause the main form of nitrogen loss, soluble nitrogen the main form of nitrogen loss caused by heavy rain event. NO3 - N is the main form of soil soluble nitrogen loss caused by the two rainfall events: nitrogen form and intensity of rainfall, rainfall will affect the changes in the nitrogen concentration process line. Two rainfall events, NH4-N concentration process line changed little, while the other forms of nitrogen concentration process line changes significantly in response to the flow process line to control the loss of soil nitrogen load; storm events particulate nitrogen, control the loss of soil nitrogen load in the event of heavy rain in soluble nitrogen. (4) in the conventional fertilization group NO3 - N is the main form of soil nitrogen leaching. 20cm and 60cm soil nitrogen leaching loss in the control group in the main morphological basically NO3 - N, the main form of the loss of nitrogen leaching in a 40cm layer of organic nitrogen; the conventional fertilization leachate TN , NO3 - N, NH4-N and nitrite (NO2 - N) concentration was significantly higher than the corresponding soil leachate concentration; fertilization, rainfall and soil nitrogen accumulation volume affect soil nitrogen leaching concentration.

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