The influencing factors of N2O emission and denitrification in the soil of water-level-fluctuation zone in the Three Gorges Reservoir area
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Abstract:
In order to study the influences of water filled pore space (WFPS), temperature, the addition of nitrate (NO -3) and carbon source on N2O emission and denitrification in the soil of water-level-fluctuation zone in the Three Gorges Reservoir area, C2H2 in hibition incubation experiments are applied. Results from experiments in laboratory and in situ field are analyzed. Results show that the WFPS is a main factor determining N2O emission and denitrification. Denitrification rate increases while the WFPS increases, and the maximum denitrification rate and the maximum N2O emission rate appear when the WFPS is 100% and 60%, respectively. In addition, while the temperature is between 10 ℃ and 40 ℃, the increase of temperature contributes to the increase of the N2O emission and denitrification rates. Furthermore, it is found that the N2O emission and denitrification rates are significantly and positively correlated with temperature. The addition of carbon source could increase denitrification performance in soil. However, the addition of nitrate has a negative impact on the denitrification performance, because nitrogen source is not the main factor determining denitrification performance and excessive nitrate could inhibit the denitrification in these experiments. The addition of glucose, which is a carbon source easily be utilized by denitrifying bacteria, could significantly increase the denitrification rate in soil, and the maximum denitrification rate takes place while the carbon content in per kilogram soil is 240 mg.
