Abstract: The temperature sensitivity of soil carbon mineralization (Q₁₀) is an important index to evaluate the responses of ecosystem carbon cycling to climate change. We examined the effects of three electron acceptors [SO₄^2-, NO₃^- and Fe(Ⅲ)] addition on the Q₁₀ value of anaerobic carbon mineralization of Phragmites australis community soil (0-10 cm) in the Yellow River Estuary wetland with the closed culture-gas chromatography method. The results showed that the three electron acceptors addition inhibited the production of CO₂ and CH₄ during the 48-day culture period, with a decrease of 17.3%-20.8% for CO₂ and 29.2%-36.2% for CH₄. Generally, the CO₂ production differed with the concentrations of electron acceptors, while CH₄ production differed with the type of electron acceptors. The CO₂:CH₄ ratios were significantly different with temperature, indicating an obvious temperature dependence for the anaerobic carbon mineralization pathway. The Q₁₀ values of CO₂ and CH₄ production under three electron acceptor additions ranged from 1.08 to 1.11 and from 1.19 to 1.37, respectively, showing an increasing trend compared with the control. The type and concentration of electron acceptors affected the temperature dependence of CO₂ production, while electron acceptors affected that of CH₄ production. It is suggested that the input of reducing salts would retard the mineralization loss of organic carbon in estuary freshwater wetlands under the background of climate change, but enhance the sensitivity of carbon mineralization to increasing temperature.

Key words: Yellow River Estuary wetland, organic carbon, anaerobic mineralization, temperature sensitivity (Q₁₀), electron acceptor