干旱区生态环境知识资源中心

Methane (CH4) is one of the most abundant organic gases in the atmosphere. Recently the importance of CH4 as a greenhouse gas has been recognized and studies have been carried out to assess its contribution to global warming. Although the rate of increase has slowed down in the last decade (Steel et al. 1992; Rudolph 1994), the results from some of these studies have shown that the atmospheric concentration of CH4 is increasing at a rate estimated to be approximately 1% per year (Rowland 1991; Blake and Rowland 1988; Bolle et al. 1986; Graedel and McRae 1980), Clearly it is important to identify sources and sinks of CH4, in both terrestrial and oceanic ecosystems, in order to estimate global methane budgets (Cicerone and Oremland 1988).

It has been generally recognized for sometime that soils play a significant role in the estimation of CH4 budgets. Although the majority of studies to date have been centered on soils as sources, soils can however also act as methane sinks. Since Seller et al. (1984) first demonstrated the uptake of CH4 by soil in the tropics, methane consumption has been measured in humisol (Megraw and Knowles 1987), moss-derived peat soils (Yavitt et al. 1990), tundra soils (Whalen and Reeburgh 1990), temperate forest soils (Steudler et al. 1989; Born et al. 1990), grasslands (Mosier et al. 1991; Minami et al. 1993), desert soils (Striegl et al. 1992), and fertilized soils (Hutsch et al. 1993). However, there is no information about the uptake of CH4 by paddy soils.

We describe the influence of soil temperature and atmospheric CH4 concentration on CH, uptake in three Japanese paddy soils unflooded under laboratory conditions.