青藏高原多年冻土区沼泽草甸土壤CH_4产生速率研究

Study of Soil Methane Production Rate from Marsh Meadow in Permafrost Regions on Tibetan Plateau

用实验室培养法对青藏高原多年冻土区沼泽草甸土壤不同温度条件下的CH4产生速率进行了研究.结果表明:CH4产生速率与温度之间呈现显著的指数关系,整个土壤剖面平均CH4生成速率和CH4生成速率初始值随温度的变化具有显著的相似性,都表现出随温度的升高而增加规律,0℃、5℃、18℃时的CH4生成速率分别是-18℃时的5.7、171.4倍和3 257倍.0℃、5℃、18℃件下,CH4产生速率在各土层间呈现"U"型分布特征;-18℃条件下,CH4产生速率在各土层间分布没有明显的规律.0℃、5℃、18℃条件下,各深度平均的CH4产生速率与时间呈现极显著的线性正相关关系;-18℃条件下,各深度平均的CH4产生速率与时间的也有线性正相关关系.但在不同温度条件下,1～72 h培养时间内,CH4产生速率变化范围存在明显差异,-18℃、5℃、18℃时,各土层平均CH4产生速率变化范围分别为:0.005～0.008、0.93～1.49 ng.g-1.h-1和16.4～30.7 ng.g-1.h-1;0℃条件下的CH4产生速率变异性最大,为0.02～0.06 ng.g-1.h-1.4种温度条件下.CH4产生速率与土壤有机碳含量没有相关性,但在正温条件下,与土壤pH存在负相关关系.

Soil methane production rate from marsh meadow in permafrost regions on the Tibetan Plateau at various temperatures were determined using an anaerobic incubation technique.The results show that there is a significant exponential correlation between methane production rate and temperature and the methane production rate averaged over all soil layers and the initial methane production rate have pronounced comparability（n=4,p0.05）,increasing with temperature.The methane production rate at 0 ℃,5 ℃,18 ℃ is 5.7,171.4 and 3 257 time more than that at-18 ℃.At 0 ℃,5 ℃,18 ℃,the vertical profile of methane production rates has ＂U＂ shape,with the higher rate at the ranges of 0～20 cm and 20～80 cm,and the lowest rate at the range of 20～80 cm.But at-18 ℃ there is no obvious changing tendency.The average methane production rates of various depths significantly correlate with incubation time at the incubation temperatures of-18 ℃,0 ℃,5 ℃,18 ℃（n=9,R＋2=0.55;n=9,R＋2=0.99;n=9,R＋2=0.96;n=9,R＋2=0.96）.However,the ranges of the average methane production rates of various soil layers have obvious difference for all incubation temperatures with incubation time of 1～72 hour,for example,0.005～0.008,0.93～1.49 and 16.4～30.7 ng·g＋-15h＋-1 at-18 ℃,5 ℃,18 ℃,with the variation rate of 160%,160% and 187%.At 0 ℃ the range of methane production rate was 0.02～0.06 ng·g-15h-1,equivalent to a variation rate of 300%,which is the maximum.It is found that the methane production rate has no significant correlation with soil organic carbon,but the methane production rate of various soil layers has significant correlation with soil pH value at the incubation temperature of 0 ℃,5 ℃,18 ℃.At the same time,it is revealed that the methane production rate has significant correlation with soil mechanical composition.