闽江口半咸水沼泽湿地土壤甲烷产生过程及硫酸盐还原对其抑制作用研究

Methane production and inhibition via sulfate reduction in a brackish marsh of the Min River estuary

甲烷产生和硫酸盐还原是湿地土壤有机物在厌氧条件下碳矿化的两个重要过程,硫酸盐还原对甲烷产生具有明显的抑制作用.本文以闽江口鳝鱼滩半咸水短叶茳芏沼泽湿地为研究对象,通过室内厌氧培养测定了土壤甲烷产生速率、硫酸盐还原对甲烷产生的抑制速率以及研究其抑制率的垂直分布和季节动态,并运用地统计方法量化了土壤甲烷产生速率、硫酸盐还原对甲烷产生的抑制速率的水平空间格局.短叶茳芏沼泽湿地100 cm深度土壤甲烷产生速率年均值为(0.67±0.33)μg·d-1·g-1(dry weight,dw)硫酸盐还原对甲烷产生的抑制速率均值为(0.87±0.55)μg·d-1·g-1(dw).年尺度上,土壤深度对于甲烷产生速率具有显著的影响(p=0.007),而硫酸盐还原抑制对甲烷产生的抑制速率在不同土壤深度则无显著差异(p=0.472),硫酸盐还原对甲烷产生的抑制率范围为62.6%~66.3%;在100 m2空间范围和1m2空间分辨率情景下,甲烷产生速率及硫酸盐还原对甲烷产生抑制速率的变异系数均超过100%,表现出极强的空间变异性;同时,甲烷产生速率、硫酸盐还原对甲烷产生的抑制速率的块金效应值分别为0.85和0.95,表明空间自相关性极弱.

Methanogenesis and dissimilatory sulfate reduction are two key processes of anaerobic decomposition of organic matter in wetland soils,and sulfate reduction shows an obvious inhibition on methane production. Using anoxic incubation method,vertical patterns and seasonal variations of methane production rates and inhibition rates of methane production via sulfate reduction were determined in the brackish Cyperus malaccensis Lam. var. brevifolius Bocklr marsh soils of the Min River estuary,and spatial variability of methane production rates,and inhibition rates of methane production via sulfate reduction were visualized using geostatistical analysis model. The averaged methane production rates and inhibition rates of methane production via sulfate reduction during four seasons was(0. 67 ± 0. 33) μg·d- 1·g- 1(dw) and(0. 87 ± 0. 55) μg·d- 1·g- 1(dw),respectively. Soil depth showed a significant effect on methane production rate(p = 0. 007),but insignificant effect on inhibition rate of methane production via sulfate reduction(p = 0.472) on annual scale. Inhibition percentage of methane production via sulfate reduction ranged between 62. 6% to 66. 3%,with no significant seasonal difference( p > 0. 05). Sampling was performed for an area of 10 m × 10 m to a depth of 5 cm using a grid of 1 m resolution. To illustrate the spatial variability,the simple inverse distance moving average weighted method was used to map the spatial interpolation of methane production rates and inhibition rates of methane production via sulfate reduction. Large differences in methane production rates and inhibition rates of methane production viasulfate reduction were detected between each grid; coefficients of variation often exceeded 100%,indicating very high spatial variability in the brackish C. malaccensis marsh. The values of nugget semivariance / sill ratio were 0. 85 and 0. 95 for methane production rates and inhibition rates of methane production via sulfate reduction,which indicated that there was very weak spatial autocorrelation.