Metabolic inland water carbon cycling processes and associated biological regulation mechanisms that drive shifts in unstable carbon sources and sinks

Due to complexity, inland water carbon (C) cycling processes have a significant impact on the C source-sink status of terrestrial ecosystems over short-term (days, months, and years), long-term (decades, centuries, and millennia), and geological timescales. This has a determining effect on the C source-sink stability status of inland waterbodies. In such waterbodies, stable C source-sink processes primarily include terrestrial biosphere production, lithospheric organic carbon (OC) oxidization, rock weathering, and riverine C transport. Conversely, metabolic C processes have an unstable effect on the C source-sink status of inland waterbodies. Moreover, these inland water processes may cause significant C sink underestimations, which relevant studies have largely ignored. A new means to account for this “missing C” in inland waterbodies is an in-depth understanding of the metabolic C processes and associated driving effects of biological regulation mechanisms on the C source-sink status. This new approach can help us to more accurately quantify the global ecosystem C budget. The purpose of this study is threefold: (i) to clarify metabolic C processes and associated biological regulation mechanisms in inland waterbodies; (ii) to systematically analyze C cycling processes and associated C source-sink effects in inland waterbodies; (iii) to reveal driving mechanisms of metabolic C processes on C source-sink stability in inland waterbodies. This will allow us to gain a better understanding into how to more accurately calibrate C source-sink functions globally. It will also provide an in-depth understanding of the role that terrestrial ecosystems play in C neutralization under global climate change.