Effects of nitrogen and sulfur deposition on CH₄and 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 (CH 4 ) and nitrous oxide (N 2 O) 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. CH 4 emission was higher and N 2 O emission was lower at the high water table than those at the low water table regardless of nutrient application. Addition of N (NH 4 NO 3 (ammonium nitrate), 5 g N m −2 ) decreased CH 4 emission up to 57% and 50% at low and high water tables, respectively, but correspondingly increased N 2 O emission by 2.5 and 10.4 times. Addition of S (Na 2 SO 4 (sodium sulfate), 2.5 g S m −2 ) decreased CH 4 and N 2 O 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 CH 4 and N 2 O emissions to the S deposition depend on the water table condition in the high-altitude peatland.

Release of Carbon and Nitrogen from Alpine Soils During Thawing Periods in the Eastern Qinghai-Tibet Plateau

“…The eastern Qinghai-Tibet Plateau has the world's largest extent of alpine peatlands, where alpine peatland soils and alpine meadow soils contain large amounts of organic C and N, and thus have a significant potential to influence the whole plateau atmospheric budget of greenhouse gases (Gao et al 2014;Wu et al 2010). Alpine peatland soils are usually sources of CO 2 , CH 4 , and N 2 O (Chen et al 2011(Chen et al , 2012Wang et al 2005), while alpine meadow soils are sources of CO 2 and N 2 O, but a sink of CH 4 (Jiang et al 2010).…”

“…Nevertheless, studies on the ecological processes of the Qinghai-Tibet Plateau have traditionally focused on the growing season, while ecological processes during winter are often ignored. In this study, soils were obtained from alpine meadow and alpine peatland ecosystems in the eastern region of the Qinghai-Tibet Plateau, an area that contains world's largest extent of high-altitude peatlands (Gao et al 2014), to simulate freezing and thawing under laboratory conditions. The purposes of this study were to determine the release rates of CO 2 , CH 4 , and N 2 O during the thawing of frozen soils from different alpine ecosystems, to determine the availability of DOC, DON, NO 3 − -N, NH 4 + -N, and NO 2 − -N, and to compare the effects of different freezing temperatures.…”

Molecular mechanisms of water table lowering and nitrogen deposition in affecting greenhouse gas emissions from a Tibetan alpine wetland

“…a). This is supported by the results of an experiment using soil columns in a peatland of the eastern Tibetan Plateau (Gao et al ., ) showing that N addition inhibits CH 4 emissions. The indirect influence was caused by the increased plant ANPP, which benefits CH 4 emissions (Hirota et al ., ).…”

Effects of the addition of nitrogen and sulfate on CH4 and CO2 emissions, soil, and pore water chemistry in a high marsh of the Min River estuary in southeastern China

“…This value is well above the SO 4 2saturation concentrations of 300-3000 μmol•L -1 , reported for SRB (Vile et al, 2003), which suggests that the SO 4 2concentration in the high marsh in Min River estuary was at saturation, with the effect of SO 4 2on sulfate reduction being minor. The situation is different compared to studies on natural peatland and freshwater wetlands, where an increase in SO 4 2availability in low SO 4 2environments can significantly stimulate SRB, which then consume more substrate and inhibit methanogens (Gao et al, 2014). Vile et al (2003) speculated that if methanogens and SRB dominate different vertical depths of the soil, with the SRB community showing more superficial distribution relative to the methanogens, the methanogens might not be exposed to exogenous SO 4 2-, thus not being competitively inhibited.…”