Alkalinity, inorganic carbon and CO2 flux variability during extreme rainfall years (2010-2011) in two polluted tropical estuaries NE Brazil

• Published in: Brazilian journal of oceanography 2018-03, Vol.66 (1), p.115-130
• Main Authors: Gaspar, Felipe Lima, Pinheiro, Barbara Ramos, Noriega, Carlos Esteban Delgado, Araujo, Moacyr, Lefèvre, Nathalie, Montes, Manuel de Jesus Flores
• Format: Article
• Language: English
• Subjects: Acidification; Acidificação marinha; Alkalinity; Anthropogenic factors; Biogeochemical cycle; Biogeochemistry; Blooms; Brackishwater environment; Carbon; Carbon dioxide; Carbonates; Chlorophyll; Chlorophyll a; Climate change; Coastal environments; Coastal processes; Dissolved oxygen; Dry season; Earth Sciences; Estuaries; Estuarine dynamics; Estuarine pollution; Eutrofização; Eutrophication; Evento extremo; Flooding; Fluctuations; Fluxes; Human influences; Inorganic carbon; MARINE & FRESHWATER BIOLOGY; Mineral nutrients; Nutrient cycles; Nutrients; OCEANOGRAPHY; Organic matter; Oxygen; Partial pressure; Phosphorus; Phytoplankton; Plumes; Poluição antrópica; Rain; Rainfall; Rainy season; Rivers; Salinity; Sciences of the Universe; Seasonal variation; Seasonal variations; Seasons; Surface water; Variability; Water quality
• ISSN: 1679-8759; 1982-436X; 1982-436X
• DOI: 10.1590/s1679-87592018149406601

Abstract The susceptibility of coastal environments to shifts in the biogeochemical cycles of carbon and nutrients driven by anthropogenic pressure and climate change is a real challenge for the scientific community. This paper evaluated the effects of an extreme rainfall event over the nutrients and carbonate parameters in two polluted tropical estuaries. Surface water samples were taken seasonally along a salinity gradient in the Capibaribe and Barra de Jangadas estuaries in order to investigate the spatial and seasonal variability of dissolved nutrients, chlorophyll-a, dissolved oxygen, total alkalinity, inorganic carbon, partial pressure of CO2 (pCO2) and CO2 fluxes. The increased riverine influence caused by the fluvial flooding during the extremely rainy season augmented the nitrogen concentrations in the plumes, which also presented reduced salinity, alkalinity and dissolved oxygen values. In the Capibaribe plume it has also shifted the mean CO2 flux value of - 4.01 mmolC m-2 d-1 during the dry season, to a positive mean flux of + 5.7 mmolC m-2 d-1 during the rainy season. Within the estuaries the BOD5,20 and dissolved phosphorus values were higher during the dry season (p