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 (F_c). 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 F_c in alkaline soils of arid areas. An automated flux system was employed to measure F_c in the Manas River Basin of Xinjiang Uygur autonomous region, China. Soil pH, soil temperature at 0–5 cm (T_s), soil volumetric water content at 0–5 cm (θ_s) and air temperature at 10 cm above the soil surface (T_as) were simultaneously analyzed. Results highlight reduced sensitivity of F_c to T_s and good prediction of Fc by the model F_c=R₁₀Q₁₀^{(T_as–10)/10+r7q7(pH–7)}+λT_as+µθ_s+e which represents F_c as a sum of biotic and abiotic components. This presents an approximate method to quantify the contribution of soil abiotic CO₂ exchange to F_c in alkaline soils of arid areas.