The potential source of nitrous oxide in the pristine riparian marsh during freeze-thaw cycles, case study in Northeast China

Abstract

Soil Freeze-Thaw Cycles (FTCs) can provide large amounts of labile C and N to microorganisms to stimulate nitrous oxide (N2O) production and emission in the soil. To explore the effects of FTCs on N2O fluxes in the pristine riparian marsh, we used the static chamber-GC techniques to investigate N2O fluxes in the marsh meadow Calamagrostis angustifolia wetland (MMCW), Ecotone wetland (EW) and Carex Schmidtii Meinsh. marsh (CSMM) in Sanjiang Plain from March to April 2016. The results showed that the three marshes were potential sources of N2O during FTCS. The variations of N2O fluxes in the three marshes were significantly different (P < 0.001) during FTCS. Principal component analysis and regression analysis indicated that soil NH4+-N and NO3−-N content were the main driving factors of N2O fluxes in MMCW. Though significant correlations were observed between N2O fluxes and soil NH4+-N content in 0 to10 cm soil depth in EW (r = 0.98, P < 0.01) and in CSMM (r = 0.93, P < 0.05) respectively, the driving factors of N2O fluxes during FTCS in EW and CSMM were uncertain. In conclusion, soil FTCS might contribute to the emissions of N2O in the pristine riparian marshes.