To review and describe the potential sources of CO2 enrichment in aquatic ecosystems, identifying and distinguishing those from natural and anthropogenic activities. It will be described and characterized the different sources of CO2 that produce enrichment of this compound in the aquatic ecosystem. It will not only focus on the dissolution of the atmospheric CO2 but also on other anthropogenic sources like the leakages during carbon capture and storage operation (CCS) and natural sources (diagenesis – organic matter oxidation, volcanic emissions, etc.). © 2022 Elsevier Inc. All rights reserved.