Juxtaposing the spatiotemporal drivers of sediment CO2, CH4, and N2O effluxes along ecoregional, wet-dry, and diurnal gradients

Abstract

Globally, lakes are facing greater drying rates than before the industrial revolution due to global climate change, water withdrawals, and land use and land cover changes. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes of the lakeshore sediments still remain poorly represented and understood, with important implications for the global carbon (C) and nitrogen (N) budget closures. This study quantifies spatiotemporal dynamics and (non-)linear drivers of CO2, CH4, and N2O effluxes from sediments of 20 lakes along wet-dry lakeshore, diurnal, and ecoregional gradients in the western part of Turkey. Mean daily CO2, CH4, and N2O effluxes were estimated at 98.64 ± 386.47, 1.42 ± 1.71, and 0.12 ± 0.24 from wet sediments and at 393.60 ± 386.94, 0.82 ± 1.58, and 0.24 ± 0.22 from dry sediments, with an overall mean of 242.28 ± 404.1, 1.09 ± 1.53, and 0.18 ± 0.23 mmol m−2 d−1, respectively. The variability in the GHG effluxes was most sensitive to the interaction between latitude and wet-dry location. Out of 14 significant environmental drivers, the most important ones that minimized and maximized CO2, CH4, and N2O effluxes were PO4–P content, three-summer month standardized precipitation index, and redox potential, respectively, based on a random forest-based optimization.