Effects of different exogenous electron acceptors and salt import on methane production potential of estuarine marsh soil
不同电子受体及盐分输入对河口湿地土壤甲烷产生潜力的影响

Methane is an important greenhouse gas with high warming potential, most of methane emit from various wetlands. Some studies on methane emission in wetlands were done, however, few studies were reported in China, especially on tidal marsh. Production of methane is the basis of methane emission, and is also the first step of methane emission influencing greatly the emission process.Hence, research on the fields is necessary. The Minjiang River Estuary wetland was one of the tidal wetlands, which is situated on the southeast seashore of China influenced by tide,the concentrations of soil water content, salinity and electron acceptors were changed, and the effects of variation of soil physiochemical properties on methane production were unknown. Phragmites australis was one of the main species in Minjiang River Estuary wetland, distributed on the intertidal belt, so our study took Phragmites australis marsh which is typical and representative as the study areas. The methane production potential from the Phragmites australis marsh soil of the Minjing River Estuary after the import of electron acceptors and salt was determined using an anaerobic incubation technique. The range of methane production potential in different soil layers was 0.0202-0.0871μg · g-1 · d-1, the average value was 0.0378 μg · g-1 · d-1, and the highest methane production potential occurred in the surface soil, differing significantly from other soil depths(P<0.05). Methane production potential was inhibited by electron receptors import. When the concentrations of three kinds of electron acceptors increased from 4 to 12 mmol/L, methane production potential all dropped gradually.The methane production potential after adding nitrate and ferric was significantly different from that of controlling soils(P<0.05), but there was no significant difference when adding sulfate. There was no significant difference when the different concentration levels of the three types 08 electron receptors were applied(P>0.05). The inhibited effect of the three electron receptors on methane production potential was nitrate>ferric>sulfate; and methane production potential was partly inhibited by salt. The methane production potential dropped when the concentration increased from 4 to 12 mmol/L. The difference was not significant between the methane production potential after adding salt and controlling soil, and also the three concentration levels salt import(P>0.05).