Open AccessCarbon and alkalinity outwelling across the groundwater‐creek‐shelf continuum off Amazonian mangroves
Author(s) -
Cabral Alex,
Dittmar Thorsten,
Call Mitchell,
Scholten Jan,
Rezende Carlos E.,
Asp Nils,
Gledhill Martha,
Seidel Michael,
Santos Isaac R.
Publication year - 2021
Publication title -
limnology and oceanography letters
Language(s) - English
Resource type - Journals
ISSN - 2378-2242
DOI - 10.1002/lol2.10210
Subject(s) - alkalinity , mangrove , submarine groundwater discharge , dissolved organic carbon , groundwater , oceanography , total inorganic carbon , salinity , isotopes of carbon , radium , total organic carbon , environmental science , carbon fibers , hydrology (agriculture) , environmental chemistry , geology , carbon dioxide , chemistry , aquifer , ecology , geotechnical engineering , organic chemistry , radiochemistry , biology , materials science , composite number , composite material
Lateral fluxes (i.e., outwelling) of dissolved organic (DOC) and inorganic (DIC) carbon and total alkalinity were estimated using radium isotopes at the groundwater, mangrove creek, and continental shelf scales in the Amazon region. Observations of salinity and radium isotopes in the creek indicated tidally driven groundwater exchange as the main source of carbon. Radium‐derived transport rates indicate that mangrove carbon is exported out of the continental shelf on timescales of 22 ± 7 d. Bicarbonate was the main form (82% ± 11%) of total dissolved carbon in all samples, followed by DOC (13% ± 12%) and CO 2 (5% ± 4%). DIC (18.7 ± 15.7 mmol m −2 d −1 ) exceeded DOC (3.0 ± 4.1 mmol m −2 d −1 ) outwelling at all spatial scales. The interpretation of outwelling across the mangrove‐ocean continuum is related to the spatial and temporal scales investigated. At all scales, outwelling represented a major coastal carbon pathway driving bicarbonate storage in the ocean.