不同温度下2种不同pH值水稻土甲烷产生的比较

摘要

水稻土甲烷的产生受环境因子的影响。为了比较不同温度下不同pH值水稻土甲烷产生的差异，同时分析不同温度下产甲烷随时间的变化与理化因子变化的相关性，以酸性砂质水稻土（pH值4.67）和偏碱性粘质水稻土（pH值7.88）为研究对象，在15℃、25℃、37℃以及50℃4个温度下进行为期100 d的厌氧培养，定期测定培养过程中产甲烷累积量以及土壤理化因子pH值、氨氮以及有机碳的变化。结果表明，在15℃~37℃范围内初始有机碳含量以及氨氮浓度高的酸性砂质水稻土产甲烷大于偏碱性粘质水稻土；2种土壤产甲烷量以及产甲烷速率均随温度升高而增大，均在37℃时达到最大值；然而在50℃高温下，酸性砂质水稻土甲烷产量明显小于碱性粘质水稻土，且其产甲烷量以及产甲烷速率明显下降，甚至低于25℃，而碱性粘质土壤产甲烷量依然高于37℃，产甲烷速率与37℃相比没有明显下降，说明高温对酸性砂质水稻土的影响大于碱性粘质水稻土。在厌氧培养过程中，不同温度下氨氮浓度与产甲烷始终保持比较高的相关性，而有机碳含量的变化与产甲烷的相关性随温度升高而下降，说明高温下影响土壤产甲烷的因素较低温复杂得多。与碱性土壤相比，不同温度下酸性土壤pH值的变化对产甲烷的影响较大。%In order to study the impact of tempereture on methane production and analyse the correlation between methane emission and environment factors in different pH paddy soils, samples like an acidic sandy paddy soil (pH 4.67) and an alkaline clayey paddy soil (pH 7.88) were anaerobicly incubated at 15℃, 25℃, 37℃and 50℃for 100 days. During the incubation the changes of the cumu-lant of methane-production and soil characteristics such as pH, organic carbon and nitrogen of ammonium were measured. The results indicated that the cumulant and rate of methane production increased with the increasing temperatures in the range of 15℃-37℃and reached the maximum at 37℃in both of acidic sandy paddy soil and alkaline clayey paddy soil. We also found that the methan pro-duction of acidic sandy paddy soil which contained more carbon content and high concentration of ammonium nitrogen were always higher than those in alkaline clayey paddy soil whith the scope of 15℃-37℃, however, this phenomenon was reversed at 50℃. Under high temperature, the cumulant and rate of methane production in acidic sandy paddy soil dropped much more obviously and fell be-low 25℃, but the changes of methane production in alkaline soil were not significant. It indicated that the impact of high temperature was greater in sandy paddy soil. During the process of anaerobic culture, the correlation coefficients between the changes of ammoni-um concentration and methane production always maintained in a relatively high value under different temperatures. However the cor-relation coefficients between methane emission and carbon content decreased with increasing temperature, which indicated that there were much more complex factors influenced methane production in higher temperature. Compared with alkaline soil, the changes of pH in acidic soil at different temperatures had more significantly influence on the methane production.