Global inland water greenhouse gas (GHG) geographical patterns and escape mechanisms under different water level

Abstract

Inland water ecosystems are unique, whereby water level changes can lead to variance in greenhouse gas (GHG) emissions. The GHG circulation intensity of inland waterbodies is high, so different water depths affect the temperature sensitivity of greenhouse gases, and have different cooling effects on CO₂ storage and warming effects on CH₄ emissions, being a typical GHG conversion channel. This study systematically reveals geographical GHG emission patterns from inland waterbodies and GHG impact mechanisms from regional waterbodies. Special emphasis is also paid to compounded environmental impact changes on GHG emissions under water level regulations. Additionally, we explore how increases in primary productivity can convert aquatic ecosystems from CO₂ sources to CO₂ sinks. However, GHG formation and emissions under ecological reservoir water level fluctuations in flood-ebb zones, intertidal tidal zones, wetlands, and lacustrine systems remain uncertain compared with those under natural hydrological conditions. Therefore, mechanisms that control GHG exchange and production processes under water level changes must first be determined, especially regarding post flood hydrological-based drying effects on GHG flux at the water-air interface. Finally, we recommend instituting environmental management and water-level control measures to reduce GHG emissions, which are favorable for minimizing GHG flux while protecting ecosystem functions and biodiversity.

Keywords: Escape mechanism; Greenhouse gas; Inland water; Water-air interface; Water-level.