
Limnology and Oceanography Letters, Journal Year: 2025, Volume and Issue: unknown
Published: April 2, 2025
Abstract Coastal waters play a pivotal role in the global carbon cycle, showing increased short‐term variability of dissolved oxygen saturation (DOsat) and partial pressure greenhouse gases like dioxide ( p CO 2 ), especially underrepresented tropical eutrophic environments. Here, we conducted high‐frequency (1‐min interval) diel measurements surface DOsat Guanabara Bay, Brazil, highly nutrient‐enriched coastal ecosystem. The predominant metabolic controls on were revealed by its strong negative correlation with DOsat. Air–sea fluxes derived from sampling showed emissions 533 mmol C m −2 annually. Conventional estimates based daylight‐only ~73% 319% higher morning (10:00–12:00 h sunrise–8:00 h, respectively) or ~172% 244% lower afternoon (12:00–14:00 14:00–16:00 respectively). Our findings indicate that rapid shifts between sinks sources can introduce significant uncertainty estimating air–water regional to budgets.
Language: Английский