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Typhoon-induced increases in porewater nutrient concentrations and CO2 and CH4 emissions associated with salinity and carbon intrusion in a subtropical tidal wetland in China: A mesocosm study
Geoderma ( IF 5.6 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.geoderma.2020.114800 Chun Wang , Jordi Sardans , Chuan Tong , Josep Peñuelas , Weiqi Wang
Geoderma ( IF 5.6 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.geoderma.2020.114800 Chun Wang , Jordi Sardans , Chuan Tong , Josep Peñuelas , Weiqi Wang
Abstract Typhoons can alter carbon cycling by increasing carbon inputs and by the oceanic water intrusion at low latitudes. Our understanding of how typhoons impacts C and N cycles by reflecting combine and separate effects of elevated salinity and carbon enrichment is poor. We conducted a mesocosm experiment simulating the effect of a salinity of 10‰ and dissolved organic carbon (DOC) enrichment of the surface water with acetate as DOC source on the dynamics of porewater nutrients and the emissions of carbonaceous greenhouse gases using plants and soil system from a Cyperus malaccensis freshwater wetland in the Min River estuary, southeastern China. The concentrations of NH4+-N and NO3−-N in porewater rose under elevated salinity but decreased with DOC enrichment, salinity and DOC in combination acted antagonistically such that there was no effect compared to the control. A 10‰ increase in salinity increased the cumulative CO2 emissions (+29%) and decreased the cumulative CH4 emissions (−61%) during the growing season. In response to DOC, The cumulative emissions of CO2 and CH4 increased by 79% and 84%, respectively. In response to the combined elevated salinity and DOC enrichment, the cumulative emissions of CO2 increased by 69% and cumulative methane emissions increased by 44%. Elevated salinity plus DOC enrichment decreased the activity of the N-cycling enzyme β-1,4-N-acetylglucosaminidase, but increased the activities of two C-cycling enzymes (β-1,4-glucosidase and 1,4-β-cellobiosidase) and the P-cycling enzyme acid phosphatase, indicating a higher demand for C and P relative to N. The combination of increased C as CO2 in all cases, increased CH4 only in the case of DOC addition, and rising inorganic N fluxes only in the case of salt suggeated that elevated salinity and DOC enrichment induced by typhoons may thus accelerate the release of C but have little influence on N release from tidal freshwater wetland ecosystems.
更新日期：2021-02-01
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