Use of silicone tubes as a simple method to measure in situ soil gas N_2O concentrations and fluxes
Chamber method,which was used as a regular way to measure N_2O fluxes from soils,has the disadvantages on sampling in situ soil-derived N_2O with high concentration,monitoring N_2O fluxes under all weather conditions and studying the behaviors of N_2O in soil profile.The possibility of using silicone tubes to sample in situ soil gas Was tested by measuring the diffusivity of standard N_2O gas through the silicone tube walls.Field plots were under treatments of NH_4~+、NO_3~- and NO_3~- plus glucose,with four randomly arranged replicates.Silicone tubes and sampling chambers were buried under soil surface with different depths.In situ collection of soil N_2O with hish concentration and the efficiency of monitoting the concentration and fluxes of N_2O were compared,as the silicone tube and traditional chamber had different sensitivity to N_2O variation in soil.Results revealed that it took only 2.9 hours for N_2O in the silicone inner space to reach95% equilibrium with the surrounding atmosphere,which was fast enough to satisfy regular sampling interval.The silicone tubes method had the advantage over chamber method in collection of soil-derived N_2O with high concentration and the collected sample showed clear trends concerning N_2O concentration over time.The temporal variation of N_2O emissions calculated by different methods showed significantly positive correlations,while the silicone tube method gave lowervalues.The agreement of two data sets depended on the matching of the site of sampling and N_2O production.It is recommended to bury horizontal silicone tube at surface soil layer for N_2O flux monitoring or at different soil depths to investigate the spatial and temporal variation of N_2O behavior in soil profile.
silicone gas probeN_2O emissionN_2O diffusionsoil-derived N_2O with high concentrationdynamic monitor
国家科技期刊平台
NSTL
万方数据
维普
