| Eutrophication is an important problem for water resource development and utilization at present. Research results about eutrophication showed that excessive nutrient elements in the water body caused directly the eutrophication features such as the harmful algaes' overgrowing . Therefore, traditionally there were two corresponding control measures of eutrophication: one was external recuction and the other was internal adjustment. ShanZi reservoir in the paper was a eutrophicated drinking water resource, Fujian province government had released the decree 《management measures for protecting the drinking water resources in Aojiang river》, and local governments took a series strictly response actions to reduce the nutrients' eternal inputs. After that, the water quality got a good change in a short time, but the water returned to the original state of eutrophication again because of ignoring the study of the nutrients' internal release. So the paper took the reservoir sediment nitrogen element release ( also named internal nitrogen's pollution) as the main research subject. Firstly, the vertical distribution of nitrogen from surface to bottom in water and sediment had been investigated and chemically analyzed, then a laboratory simulation experiment scheme about nitrogen's release and adsorption was designed and practiced, the experiment revealed how the different environmental factors influenced the nitrogen releasing level from sediment to water. According to the research results, the paper proposed that the internal pollution should be controlled by biotechnical restoration with sediment dredging engineering as a affiliated measure. The paper got the following conclusions: (1) The vertical distribution features of nitrogen in water and sedimentTN in water body increased gradually from the surface to the bottom, while oppositely in sediment reduced from the surface to the bottom. Of all selected sample locations, RiXi's TN and soluble nitrogen both in water and in sediment was highest, which was caused by relatively more pollution sources and pollution product there. However BaQian's TN and soluble nitrogen in sediment was lowest, for there was fewer pollution sources there. It showed that nutrients both in water and in sediment were directly related with the number of local pollution sources.(2) Results of anaerobic simulating experiment on NH/-N adsorption from water to sedimentTemperature, NH/-N content in water and the sediment particles had an important impacts on the NH4+-N adsorption from water to sediment. The adsorption ability got weaker with the high temperature; High NH4+-N content in water led to the high adsorption of the sediment; Solution with Large sediment particles could be balanced in a short time.(3) Results of anaerobic simulating experiment on NH/-N release from sediment to waterThe amount of NH/-N release from sediment to water increased with the time increasing. And after 15 days ,it reached the maxmuim (about 1.2mg), then it would get a trend of balance .The temperature of release reaction and the sediment particles had a obvious effect on the release of NH4+-N. Furthermore, the high temperature improved the release rate of NH4+-N, while NH4+-N in large sediment particles was not liable to being solved. (4) Conclusion By analyzing the present external control measurements of ShanZi reservoir,it proposed that the reservoir's internal pollution should not be ignored. Biological restoration engineering was suggested as the major measure for reducing internal pollution with the sediment dredging as the affiliated method. As for the place where the reservoir was polluted seriously and the depth of water body was shallow, planting some erecting vegitations and breeding some kinds of fish such as silver carp(Hypophthalmichthys molirix), bighead carp(Aristichthys nobilis) could be recommended for the aim of capturing the plankton of water body and reducing nutrient.
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