| The research focuses on some kinds of ecological restoration for inner lakeside belt located Zhudu gang port to West Shatang gang port in Zhushan Bay, Taihu Lake. Distribution, concentration and morphology of nitrogen, exchange flux of inorganic nitrogen were studied through the sediment-water interface, nitrification and denitrification intensity, urease activity in different ecological restoration project area sediments for a year. In order to reveal the impact of the construction of these types of the ecological restoration of the inner lakeside belt on sediment nitrogen transport and transformation. The results from analysis provided a scientific basis for further research in terms of the optimization and improvement of the Lake with ecological restoration. The conclusions are as follows:1. Total nitrogen content of the surface layer (0～10cm) sediment ranged from308.42to3546.98mg-kg-1, ammonia nitrogen content ranged from197.13～2964.23mg·kg-1. Compared to the past study results, the pollution load in this region has not been significantly changed. Vertical distribution of total nitrogen and ammonia nitrogen in sediment shows that the content in subsurface (5-10cm) is greater than the surface layer (0-5cm). With the depth increasing, the total nitrogen content is different, while the content of ammonia presents the decreasing trend. The results from an annual investigation showed that nitrogen pollution load in the region increased gradually, sediment performance of the role of nitrogen pollutants sunk, but the higher organic nitrogen content showed that the risk of changing to organic pollution might exist.2. studying on the exchange of inorganic nitrogen flux has shown that the exchange behavior of inorganic nitrogen flux through the water-sediment interface is complex, DIN average exchange flux was1.23mg-m-2·h-1. Light condition affects DIN exchange flux obviously.3.Nitrification and denitrification intensity are significantly different in the sediments of the different types of ecological restoration projects. Nitrification intensity in sediment of the type C was weaker than that of type A and B, while denitrification intensity was stronger, this phenomenon indicated that sediment environment of the type C is more conducive to remove the nitrogen pollution. The results of the experiment with different C/N ratio showed that, adding the carbon significantly enhanced the denitrification capacity in the sediment environment, but impact for Z1is not obvious.4. Intensity of urease activity in sediment in ecological restroration ranged from75.13to103.89NH3-N mg-kg-1·h-1, with the average of93.11NH3-N mg·kg-1·h-1. Urease activity in sediments and organic matter had a significant positive correlation. Intensity of urease activity in ecological restroration of type B and C with basement repair was significantly weaker than type A without basement repair. The basement repair could reduce the risk of endogenous contamination significantly.Overall, different types of ecological restoration affected the migration and transformation of sediment nitrogen significantly; Sediment environment in type C had better denitrification capacity and lower urease activity, so that type C had better performance of reducing the nitrogen pollution. |
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