Modeling the contribution of abiotic exchange to CO2 flux in alkaline soils of arid areas

Recent studies on alkaline soils of arid areas suggest a possible contribution of abiotic exchange to soil CO2 flux (Fc). However, both the overall contribution of abiotic CO2 exchange and its drivers remain unknown. Here we analyzed the environmental variables suggested as possible drivers by previous studies and constructed a function of these variables to model the contribution of abiotic exchange to Fc in alkaline soils of arid areas. An automated flux system was employed to measure Fc in the Manas River Basin of Xinjiang Uygur autonomous region, China. Soil pH, soil temperature at 0–5 cm (Ts), soil volumetric water content at 0–5 cm (θs) and air temperature at 10 cm above the soil surface (Tas) were simultaneously analyzed. Results highlight reduced sensitivity of Fc to Ts and good prediction of Fc by the model $$F_c = R_{10} Q_{10} ^{{{\left( {T_{as} - 10} \right)} \mathord{\left/ {\vphantom {{\left( {T_{as} - 10} \right)} {10}}} \right. \kern-\nulldelimiterspace} {10}}} + r_7 q_7 ^{\left( {pH - 7} \right)} + \lambda T_{as} + \mu \theta _s + e$$ which represents Fc as a sum of biotic and abiotic components. This presents an approximate method to quantify the contribution of soil abiotic CO2 exchange to Fc in alkaline soils of arid areas.