| Yanghe reservoir is an important water source in Qinhuangdao Town Hebei Province. But recent years, the pollution which results in industrial, domestic and agricultural non-point source surrounding the reservoir has pricked up day by day. The reservoir water showed a cloud-type algae eutrophication, it became an important environmental issue that could not be ignored. Therefore, the thesis investigated phosphorus forms of sediments and the potential release capacity of nitrogen and phosphorus had great help to understand the current polluting situation of Yanghe reservoir. Through investigating the agricultural non-point source pollution loads had help to master the pollution characteristics of the pollution loads, so as to provide a theoretical basis which could contribute to control eutrophication.Firstly, Total phosphorus (TP), inorganic-phosphorus (IP), organic phosphorus (OP), Fe/Al-bound phosphorus (Fe/Al-P) and Ca-bound phosphorus (Ca-P) in sediments of Yanghe Reservoir and in soil of its basin were measured using the standard measurement and test (SMT) procedure. The results showed that the general mean content variation trends of total phosphorus (TP), total nitrogen (TN) and organic matter (OM) in the soil and sediments were stream sediments>reservoir sediments>soil, while the TP mean content changed little during the migration process. Nutrients enter Yanghe Reservoir not only by soil runoff and stream migration, but also the role of sediment release is obvious. The nutrients contents in surface sediment were high according the results of the column sediments, and the contents of TP, TN and OM decreased with the increase of sediment depth from the surface to 16cm, and then held on line below 16cm, which indicated that nitrogen and phosphorus pollution in the sediments was primarily on the surface. The IP was the major phosphorus species in the soil and sediments, which accounted for 46%～79% of the TP; and the Ca-P was the major phosphorus species in the study area, and accounted for 22%～68% of TP, which related to the geological-geochemical characteristics of the Yanghe Reservoir. The TP in the soil was original mainly from Ca-P, which relate to the geological background in this region. The TP in sediment from the stream was original mainly from Fe/Al-P, which relate to the industrial and human pollution in this basin. The TP in sediment from Yanghe Reservoir was original mainly from the OP, which indicate that the eutrophication of Yanghe reservoir relates to the industrial, domestic pollution and agricultural non-point pollution in this basin.Secondly, the release potential capacity of nitrogen and phosphorus in sediments of Yanghe reservoir was studied in this thesis, using infinite dilution measurement, the potential release capacity of different forms of nitrogen (total nitrogen, ammonia nitrogen, nitrate nitrogen, dissolved organic nitrogen) and different forms of phosphorus (total phosphorus, SRP, dissolved organic phosphorus) were analyzed. In addition, the four points'sediments of other three different types of lakes (Erhai Lake, Taihu Lake and Wuhan East Lake) were selected in this thesis, and the nitrogen and phosphorus release potential capacity were compared with Yanghe reservoir sediments'. The results showed that the total variety was increasing with the increscent of water sediment ratio. The potential release capacity of nitrogen presented good regularity with the variability of different water and sediment ratios, the sediments potential release capacity of nitrogen of Yanghe reservoir was less than Erhai Lake, and higher than Wuhan East lake and Taihu lake. The regularity of phosphorus potential release capacity was not better than nitrogen. The phosphorus potential release capacity of Yanghe reservoir was higher than other lakes'. The results showed that the potential release risks of Yang Reservoir sediments was higher and should be better controlled.Thirdly, agricultural non-point source pollution load of Yanghe reservoir basin for three consecutive years—2007, 2008, 2009 were estimated using SWAT model, the results showed that the non-point source pollution loads were different in different years and months with different rainfall. The rainfall and non-point source pollution load had direct ratio. And nitrogen pollution dominated the entire basin.
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