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Eutrophication‐induced acidification of coastal waters in the northern Gulf of Mexico: Insights into origin and processes from a coupled physical‐biogeochemical model
Author(s) -
Laurent Arnaud,
Fennel Katja,
Cai WeiJun,
Huang WeiJen,
Barbero Leticia,
Wanninkhof Rik
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl071881
Subject(s) - oceanography , biogeochemical cycle , eutrophication , benthic zone , environmental science , ocean acidification , hypoxia (environmental) , biogeochemistry , bottom water , water column , stratification (seeds) , phytoplankton , nutrient , geology , environmental chemistry , seawater , ecology , oxygen , chemistry , seed dormancy , germination , botany , organic chemistry , dormancy , biology
Nutrient inputs from the Mississippi/Atchafalaya River system into the northern Gulf of Mexico promote high phytoplankton production and lead to high respiration rates. Respiration coupled with water column stratification results in seasonal summer hypoxia in bottom waters on the shelf. In addition to consuming oxygen, respiration produces carbon dioxide (CO 2 ), thus lowering the pH and acidifying bottom waters. Here we present a high‐resolution biogeochemical model simulating this eutrophication‐driven acidification and investigate the dominant underlying processes. The model shows the recurring development of an extended area of acidified bottom waters in summer on the northern Gulf of Mexico shelf that coincides with hypoxic waters. Not reported before, acidified waters are confined to a thin bottom boundary layer where the production of CO 2 by benthic metabolic processes is dominant. Despite a reduced saturation state, acidified waters remain supersaturated with respect to aragonite.