The Research Of Soil Nitrogen Mineralization Dynamic Of Wetland In Taihu Lake

The research of soil nitrogen mineralization of wetland is very important to understand the balance of nitrogen in wetland system to global change and environmental quality of water. And we applied lab incubation method to incubate primary soil samples and the method of collecting and analyzing soil samples to study soil nitrogen mineralization and dynamics of soil mineralized nitrogen, respectively. The purposes were to understand the potential influence caused by the global warming of the soil net N mineralization amount and N mineralization rates and the relevance in various factors along a soil moisture gradient in a riparian area in Taihu lake. The results showed:(1)In the condition of laboratory, the soil samples were put in PVC tube and incubated at 5, 15,25, and 35℃for 30 days. The results showed that the soil mineralized nitrogen amount, net N nitrification rate and N mineralization rates increased significantly with increasing temperature. At the same temperature, the soil mineralized nitrogen amount, net N nitrification rate and N mineralization rates increased with distance from the water body.(2)The Q10 value of soil N mineralization fluctuated between 1.16 and 1.55. There was no obvious regularity of the Q10 value of soil N mineralization with distance from the water body. The Q10 from 5℃to 15℃was higher than that from 15℃to 25℃and from 25℃to 35℃near the water body. The Q10 from 25℃to 35℃was higher than that from 5℃to 15℃and from 15℃to 25℃for the further distance from the water body.(3)The research of soil nitrogen mineralization dynamic in each season for different moisture gradient showed that, the amount of soil NH4+-N, NO3--N, TMN in different moisture gradient decreased with distance from the water body, and the amount reached maximum at summer.(4) In the summer, the soil near the water nitrification rate reached maximum, and the soil in the middle of water area nitrification rate reached minimum. But the soil nitrification rate increased with distance from the water body in others seasons. The N mineralization rates increased with distance from the water body and the amount reached maximum at summer along a soil moisture gradient.(5)The amount of soil WSON and SMBN along a soil moisture gradient changed very consistent in different seasons, and showed that:Summer>Spring>Autumn>Winter, and the amount increased with distance from the water body.(6)The soil temperature and humidity have significant correlation with the soil NH4+-N and the mineralized total nitrogen(p<0.05). The soil TN, TOC and pH have very significant correlation with the soil NH4+-N and the mineralized total nitrogen(p<0.01), but there were no significant correlation between them and the soil NO3--N (p>0.05). The soil NH4+-N and the mineralized total nitrogen have very significant correlation(p<0.01).