电子受体添加对黄河口湿地土壤厌氧碳矿化温度敏感性的影响

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

土壤碳矿化的温度敏感性(Q_(10))是研究生态系统碳循环响应气候变化的重要指标。以黄河口湿地芦苇群落表层土壤(0~10 cm)为对象,采用室内密闭培养-气相色谱法,研究不同温度和浓度下3种电子受体[SO_(4)^(2-)、NO_(3)^(-)和Fe(Ⅲ)]添加对湿地土壤厌氧碳矿化Q_(10)的影响。结果表明:48 d的培养期内,电子受体添加对厌氧生成CO_(2)和CH_(4)具有不同程度的抑制作用;SO_(4)^(2-)、NO_(3)^(-)和Fe(Ⅲ)添加使得CO_(2)和CH_(4)生成量分别下降17.3%~20.8%和29.2%~36.2%;总体上,CO_(2)生成因电子受体浓度而异,CH_(4)生成因电子受体类型而异。CO_(2)∶CH_(4)值在不同温度条件下差异明显,表明厌氧碳矿化途径具有明显的温度依赖性。不同处理中CO_(2)和CH_(4)的Q_(10)值分别在1.08~1.11和1.19~1.37,与对照相比有升高趋势;总体上,CO_(2)的温度敏感性因电子受体类型和浓度而异,CH_(4)的温度敏感性因电子受体类型而异。气候变化背景下,还原性盐离子的输入将在一定程度上减缓河口淡水湿地有机碳的矿化损失,但会增强碳矿化对升温的敏感性。

The temperature sensitivity of soil carbon mineralization(Q_(10))is an important index to evaluate the responses of ecosystem carbon cycling to climate change.We examined the effects of three electron acceptors[SO_(4)^(2-),NO_(3)^(-) and Fe(Ⅲ)]addition on the Q_(10)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 CO_(2)and CH_(4)during the 48-day culture period,with a decrease of 17.3%-20.8%for CO_(2)and 29.2%-36.2%for CH_4.Generally,the CO_(2)production differed with the concentrations of electron acceptors,while CH_(4)production differed with the type of electron acceptors.The CO_(2):CH_(4)ratios were significantly different with temperature,indicating an obvious temperature dependence for the anaerobic carbon mineralization pathway.The Q_(10)values of CO_(2)and CH_(4)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_(2)production,while electron acceptors affected that of CH_(4)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.