Methane (CH4) emission from a natural wetland of northern China.

This article focuses on the seasonal and spatial changes of CH4 emission from the natural reed marsh of Liaohe Delta, China. Field experiments showed that this natural wetland acts as a CH4 sink in spring (-30 approximately -1000 microg/m2 x h), a strong source in summer (400-3000 microg/m2 x h) and a weak source in autumn (< 400 microg/m2 x h). Reed plants play an important role in transportation and emission of methane produced in soil. According to our field measurement data, CH4 emission is positively related to temperature, and negatively related to Eh value and water depth. The activity of methanogenic bacteria is higher in the rhizosphere and surface layer, and thus contributes more in CH4 emission than other layers.