The Study On The Impact Of Nitrogen Transformation Rates After Coastal Beach Reclamation

Nitrogen cycle system is an important part of the material recycling of ecosystem and plays an important role in the ecological balance and the sustainable development of the human environment. Tidal wetland is transitional zone between land and marine ecosystems and is the buffer responsing to the environmental change. Rich and diverse ecosystem landscape not only plays an important role in water conservation and purification, but also has an more important function in absorption, transformation and retention of nitrogen, phosphorus and other nutrients. However, with the recent rapid development of industry and agriculture, and the expanding coastal beach reclamation and.heavy use of nitrogen fertilizer, the tidal wetland ecosystem has been destroyed to some extent, resulting in a large number nitrogen of wetlands began to transfer to water bodies and atmosphere. It’s serious threat to the nitrogen cycle system and to the ecological balance. Therefore, it’s necessary to do some research in nitrogen transformation and conversion regulation after beach reclamation and that will provide important theoretical basis for the rational development of tidal wetlands and optimizing nitrogen management. Through the experimental measurement on the soil nitrogen transformation processes, the physical and chemical properties and the nitrogen forms of Jiangsu coastal beaches and wetlands before and after reclamation and under different cultivation ages, this study analyzed and researched the variation of the nitrogen cycle under different cultivation ages and the mutual influence and function among different nitrogen conversion indicators. In addition, the study also researched the environmental factors which control and influence the nitrogen transformation process.This study researched conclusions as follows:(1) After coastal beach reclamation, the content of total nitrogen, ammonium nitrogen, nitrate nitrogen and organic carbon show rising trend, while pH and conductivity are downtrend. With the ages increasing of cultivation after 30a, both of the indicators of nitrogen forms and physical and chemical properties are stabilized with the land use patterns stabilized; Both of the indicators of nitrogen forms and physical and chemical properties are showing significant differences in different cultivation age; In addition to ammonium, the other indicators of soil properties have a significant correlation with reclamation age.(2) After coastal beach reclamation, total mineralization rate, total nitrification rate, total ammonium assimilation rate, net mineralization rate and net nitrification rate show notably rising trend, while the nitrate assimilation rate changes slowly With the ages increasing of cultivation after 30a, both of the indicators are stabilized with the land use patterns stabilized; Both of the indicators of soil nitrogen transformation rates are showing significantly differences in different cultivation age; Both of the indicators of soil nitrogen transformation rates have significantly correlation with reclamation age. This indicates that this nitrogen activating indicators such as total mineralization rate, total nitrification rate, net nitrification rate, net mineralization rate and net nitrification rate will significantly accelerate after reclamation, while the nitrate assimilation rate conduciving nitrogen retention will slow down, this will accelerate the nitrogen loss in some extent.(3) After coastal beach reclamation, in addition to ammonium, total nitrogen, nitrate, pH and organic carbon have significantly correlation with nitrogen transformation rates. This indicates that the changes of soil properties after reclamation bring nitrogen transformation rates changes.