Effects of freeze-thaw cycles on soil N2O concentration and flux in the permafrost regions of the Qinghai-Tibetan Plateau

摘要

Nitrous oxide (N2O) is one of the most important greenhouse gases in the atmosphere; freeze-thaw cycles (FTCs) might strongly influence the emission of soil N2O on the Qinghai-Tibetan Plateau(QTP).However,there is a lack of in situ re-search on the characteristics of soil N2O concentration and flux in response to variations in soil properties caused by FTCs. Here, we report the effect of FTC-induced changes in soil properties on the soil N2O concentration and flux in the perma-frost region of the higher reaches of the Shule River Basin on the northeastern margin of the QTP. We measured chemical properties of the topsoil, activities of soil microorganisms, and air temperature (AT), as well as soil N2O concentration and flux, over an annual cycle from July 31, 2011, to July 30, 2012. The results showed that soil N2O concentration was signi-ficantly affected by soil temperature (ST), soil moisture (SM), soil salinity (SS), soil polyphenol oxidase (SPO), soil al-kaline phosphatase (SAP), and soil culturable actinomycetes (SCA), ranked as SM>SS>ST>SPO>SAP>SCA, whereas ST significantly increased soil N2O flux, compared with SS. Overall, our study indicated that the soil N2O concentration and flux in permafrost zone FTCs were strongly affected by soil properties, especially soil moisture, soil salinity, and soil temperature.