Comparative aquatic greenhouse gas emission rates across multiple land-use types and along impounded river systems

Inland water greenhouse gas (GHG) emissions are increasingly influenced by
anthropogenic activities, with significant shifts in both the magnitude
and composition of the emissions. To quantify this impact, we
systematically synthesized data from 33 peer-reviewed publications
reporting aquatic GHG emission rates across three anthropogenically
modified landscapes—agricultural, urban, and impounded river systems. Our
analysis reveals that inland waters within these systems exhibit
substantially elevated GHG emissions compared to natural counterparts.
Methane (CH₄) and nitrous oxide (N₂O) emissions show the most pronounced
enhancements, with median amplification ratios of 2.0–10 and 2.4–13,
respectively, across the studied systems. In contrast, carbon dioxide
(CO₂) emissions demonstrate comparatively lower amplification (median
ratios of <2.0–3.1). These findings highlight a pronounced human
footprint on aquatic GHG fluxes and their associated biogeochemical
drivers, emphasizing the need to prioritize anthropogenic landscapes in
GHG mitigation strategies.