Growing season in situ uptake of atmospheric methane by desert soils in a semiarid region of northern China

Despite vast areas of desert soils distributed extensively in arid and semiarid regions of northern China, methane (CH4) uptake was sparsely observed in these soils. In this study, we selected a fenced sand land of the Xilin River basin in Inner Mongolia as a case to understand in situ CH4 uptake by desert soils. A set of measurements was made using a static chamber technique both to quantify temporal and spatial CH4 uptake and to examine the effect of environmental factors on the uptake. The CH4 uptake had large temporal and spatial variability during the growing seasons of both years 2009 and 2011, with a mean rate of -48.5 mu g m(2) h(-1). Vertical CH4 uptake coincided with the change in CH4 concentrations along various soil horizons, with the most active in the 5-30 cm soils. The dependence of CH4 uptake on soil temperature and moisture was well established in these desert soils. The CH4 uptake was temporarily enhanced over brief periods when desert soils were wetted. In order to more availably estimate in situ annual CH4 sink in arid and semiarid regions of northern China, it is suggested that year-round measurements should be centralized on the effect of soil temperature and moisture on the CH4 uptake. (C) 2012 Elsevier By. All rights reserved.