北京低山区森林土壤中CH_4排放通量的研究

CH_4 Emission Flux of Forest Soils in Lower Mountain Area, Beijing

CH4是大气中一种重要的温室气体，与土壤圈有着频繁的交换过程。用静态箱式技术原位测定了北京西山低山区油松人工林地土壤中CH4的排放通量，结果显示北京西山森林土壤为大气CH4重要的汇。年平均吸收值为20.47 g(m-2(h-1，变动范围0～44.8 g(m-2(h-1。 吸收值有一定的季节变化规律， 冬季的吸收值最小，几乎为0，春秋季较高，夏季最高。影响吸收的外界环境因素主要有地表下5 cm处的土壤温度。原状土壤氧化CH4的模拟实验表明吸收过程为纯生物化学过程，吸收作用主要发生在0～5 cm的矿质土层，而枯落物层和20 cm以下的层次基本无吸收反应。CH4的氧化速率在开始的12 h内可用一级反应动力学方程 C =C 0e-kt很好地模拟 。

：CH4 is a main kind of greenhouse gases, and has a frequent exchange process with soil biosphere. The static chamber technique was used to study CH4 emission flux at the forest soils under Chinese Pine woodland in lower mountain area, Beijing. The annual CH4 emission flux ranges from 0 to 44.8 (g.m-2.h-1 with mean of 20.47 (g.m-2.h-1. CH4 absorption has a seasonal variation with a sequence of summer>spring>autumn >winter, and it is affected mainly by soil temperature on 5 cm layer. The simulated experiments in a soil core at laboratory shows that the oxidization of CH4 in forest soils is a real biochemical process. It appears mainly occurred in 0～5 cm mineral topsoil. There is almost no absorption in O layer and below 20 cm-layer soil. The CH4 concentration reduced can be modeled with an equation C = Co e-kt in the first 12 hours.