Chen TongBin;Struwe S;Kjoller A;Chen TB

;Station for Agroecology and Environmental Technology, Institute of Geography, Chinese Academy of Science, Beijing 100101, China.

gases nitrous oxide;carbon dioxide;acetylene replacement incubation soil emission anaerobic conditions

The effect of C2H2 and change of headspace gas on N2O emission, denitrification, as well as CO2 emission was studied by anaerobically incubating slurries of an agricultural soil for 7 days at 25 degC. Both N2O reduction and CO2 emissions were inhibited by the addition of 100 ml/litre of C2H2. However, the inhibition to CO2 emission was alleviated by the replacement of headspace gas, and the N2O emission was enhanced by the replacement. Acetylene disappeared from the soil slurries during the incubation. Results obtained from the traditional C2H2 blocking technique for determination of denitrification rate, especially in a long-time incubation, should be treated with care because of the side-effect existing in the incubation environments without change of headspace gas. To reduce the possible side-effect on the processes other than denitrification, it is suggested that headspace gas should be replaced several times during a long-time incubation.