Automated sampling system for long-term monitoring of nitrous oxide and methane fluxes from soils

We describe an automated gas sampling system for monitoring trace gas fluxes from soils. The sampling system allows automated collection of gas samples in glass vials using a syringe pump connected to an automated static chamber installed in the field. The gas samples are transferred to a laboratory and then analyzed using a gas chromatography system. Comparisons between manual and automated sampling of standard gases showed good agreement (r(2) = 0.99996 for N2O, r(2) = 0.999 for CH4 and r(2) = 0.998 for CO2). In a field test, replicated flux measurements using two chambers generally showed good agreement. The sampling system allows frequent and long-term monitoring of fluxes under a wide range of weather conditions (tested temperatures ranged from -6.5 to 40 degrees C; 127 mm day(-1) max precipitation). The major advantages of the system are its increased portability, ease of operation and cost effectiveness compared with on-line automated sampling/analytical systems.