Effect of electron acceptor addition on the temperature sensitivity of soil anaerobic carbon mineralization in the Yellow River Estuary wetland, China.

The temperature sensitivity of soil carbon mineralization () is an important index to evaluate the responses of ecosystem carbon cycling to climate change. We examined the effects of three electron acceptors [SO, NO and Fe(Ⅲ)] addition on the value of anaerobic carbon mineralization of 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 CO and CH during the 48-day culture period, with a decrease of 17.3%-20.8% for CO and 29.2%-36.2% for CH. Generally, the CO production differed with the concentrations of electron acceptors, while CH production differed with the type of electron acceptors. The CO:CH ratios were significantly different with temperature, indicating an obvious temperature dependence for the anaerobic carbon mineralization pathway. The values of CO and CH 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 CO production, while electron acceptors affected that of CH 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.