| Eutrophication has recently become the main issue of water pollution in China. Under the condition of bad eutrophication, algae blooms outbreak frequently. One of the essential factors of eutrophication is nitrogen input. A large number of scientific researches showed that nitrogen content in water is related to socio-economic development and land use change. The socio-economic development is also related to land use change.It has a big significance to study the water pollution of Qingpu District in Shanghai. First, the data analysis shows that the nitrogen content of Qingpu District has similar temporal and spatial tendency with socio-economic and land use indexes. Which means the study of nitrogen pollution of Qingpu District could reveal the relationship between water and socio-economic, land use change. Second, Qingpu District located on the head of Huangpu River water protection zone. It has a large significance to study the water quality of Qingpu District for the safety of drinking water of Shanghai. Third, Qingpu District belongs to Taihu Lake Basin, it can provide some references for the study of water pollution of Taihu Lake Basin. Fourth, Qingpu District belongs to low-lying and plain region of eastern China, it also could provide some informations for other Plain River Area.Qingpu District has numerous rivers and lakes, and they connect with each other. There has carried out many studies about lakes, such as Dianshan Lake. But the researches about rivers are little. The rivers can be divided into four levels: city, district, town and village. The urban-town rivers run through outside, and the village rivers are closed in Qingpu District. The indexes related to eutrophication include ammonia, nitrate, nitrite, organic nitrogen, total nitrogen and so on. Therefore, this thesis chooses rivers as the study object. First, it studied the temporal and spatial tendency of river water nitrogen content. Second, it studied whether the socio-economic development and land use are the driving factors of nitrogen content changes or not.First, this thesis used two ways to reveal the spatial distribution of nitrogen content: Applied ArcGIS to make map of spatial distribution; Compared the nitrogen content of different river levels, water tablets, administrative regions and Huangpu River branches. The results showed that the river water nitrogen content of Qingpu District has obvious spatial distribution: The ammonia nitrogen and nitrite nitrogen content in the eastern part are much higher than the western part. But the nitrate nitrogen content in the eastern part is a bit lower than the western part.Second, this thesis used the river water quality monitoring data of Qingpu District from 1997 to 2007 to reveal the temporal tendency of nitrogen content. It found that there was a little difference between different river levels. The nitrogen content of urban-town rivers has been rising year after year, but the nitrogen content of village river had a large peak in 2000. In addition, both the urban-town and village river's TN:TP ratio has significant seasonal changes: lowest in summer, highest in winter, middle in spring and autumn.Third, this thesis analyzed the main driving factors of nitrogen content change of urban-town rivers and village rivers respectively from two aspects: socio-economic development and land use changes. The socio-economic data came from statistical yearbook of Qingpu District. This thesis adopted supervised and non-supervised classification methods to interpret the Landsat5 TM remote sensing image from 1986 to 2007. It gained the area of six land use type, such as cropland, vegetable land, residential and industrial land, water, forest and barren land. The analysis of main driving factors adopted two methods: gray cognate analysis and buffer zone analysis. The results showed: the main socio-economic driving factors of ammonia content changes in urban-town rivers was total households, and the number of corporations in village rivers. The main land use driving factors were residential and industrial land area and barren land area in both river levels. The main socio-economic driving factors of nitrate content changes in urban-town rivers was gross output of fishery. The land use had little effect on nitrate content. The main socio-economic driving factors of nitrate content changes in urban-town rivers was the number of corporations. The main LUCC driving factors were residential and industrial land area and water area in both river levels. The main land use driving factors of TN of both river levels were the same as nitrate content.Above all, the change of nitrogen content in Qingpu District was effected by three aspects: first, socio-economic development drives nitrogen content change. Second, land use drives nitrogen content change. Third, socio-economic development drives land use, and then drives nitrogen change indirectly. |
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