Effects of nitrogen and sulfur deposition on CH4 and N2O fluxes in high-altitude peatland soil under different water tables in the Tibetan Plateau

Abstract

The effects of nitrogen (N) and sulfur (S) deposition on methane (CH4) and nitrous oxide (N2O) emissions under low (10 cm below soil surface) and high (at soil surface) water tables were investigated in the laboratory. Undisturbed soil columns from the alpine peatland of the Tibetan Plateau were analyzed. CH4 emission was higher and N2O emission was lower at the high water table than those at the low water table regardless of nutrient application. Addition of N (NH4NO3 (ammonium nitrate), 5 g N m−2) decreased CH4 emission up to 57% and 50% at low and high water tables, respectively, but correspondingly increased N2O emission by 2.5 and 10.4 times. Addition of S (Na2SO4 (sodium sulfate), 2.5 g S m−2) decreased CH4 and N2O emission by 64% and 79% at the low water table, respectively, but had a slightly positive effect at the high water table. These results indicated that the responses of CH4 and N2O emissions to the S deposition depend on the water table condition in the high-altitude peatland.