Carbon isotopes and alkalinity gradient for biogeochemical processes in modern stratified lakes

Redox-stratified water columns are a prevalent feature of Earth history, and ongoing environmental changes tend to promote a resurgence of such settings. Better understanding of these multifaceted carbon isotope signals requires further evaluation of how the processes occurring in redox-stratified water columns are transferred to the sediments. We therefore characterized and compared the isotopic signatures of dissolved inorganic carbon (DIC), carbonate, and organic matter reservoirs, at different depths in the water column and upper sediments of four stratified Mexican lakes that follow a gradient of alkalinity/salinity.