Large sediment methane production potential in reservoirs compared to lakes and rivers.

Inland waters emit a globally significant amount of methane (CH4) into the atmosphere. Measurements of potential CH4 production rates in the sediment can help constrain the magnitude of CH4 sources and time‐averaged emission rates. We explored the magnitude, variability, and drivers of potential CH4 production rates in the sediment, based on compiled measurements (238 sediment cores from 72 aquatic systems) following a standardized laboratory incubation procedure. The data reveal > 4‐fold higher potential CH4 production rates in reservoir sediments than lakes and > 14‐fold higher than rivers after being standardized for temperature. Sediment organic carbon content and depth below the sediment–water interface are universal drivers for potential CH4 production rates across freshwater ecosystems. The disproportional high CH4 production rate in sediments from human‐made water bodies calls for more comprehensive monitoring of their CH4 emissions to inform carbon footprint and inventory efforts. This first meta‐analysis of potential CH4 production rates in sediments from different types of freshwater aquatic systems may help with process‐based modeling of CH4 emissions from individual water bodies in larger‐scale assessments. [ABSTRACT FROM AUTHOR]