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.