Global inland-water oxygen cycle has changed in the Anthropocene
Junjie Wang, Xiaochen Liu, Lex Bouwman, Lauriane Vilmin, Arthur Beusen, José M. Mogollón, Wim J. van Hoek, Jack J. Middelburg
Abstract
Inland waters are an important resource, a highly diverse habitat, and a key component of global biogeochemical cycles. Oxygen plays a major role in inland-water ecosystem functioning, but long-term changes in its cycling remain unknown. Here, we quantify global inland-water oxygen production, consumption, and exchange with the atmosphere during 1900–2010 using a spatially explicit, mass-balanced, mechanistic model that takes into account changes in climate, hydrology, human activities, and the coupled biogeochemical (oxygen-nutrient-organic matter) dynamics. The model results show that global inland-water oxygen turnover increased during 1900–2010: production from 0.16 to 0.94 Pg year −1 and consumption from 0.44 to 1.47 Pg year −1 . Inland waters overall remained heterotrophic and a sink of atmospheric oxygen. Direct human perturbations (changes in hydrology and nutrient supply) were more important in increasing oxygen turnover than indirect effects via warming.