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Shallow Calcium Carbonate Cycling in the North Pacific Ocean
Author(s) -
Subhas Adam V.,
Dong Sijia,
Naviaux John D.,
Rollins Nick E.,
Ziveri Patrizia,
Gray William,
Rae James W. B.,
Liu Xuewu,
Byrne Robert H.,
Chen Sang,
Moore Christopher,
MartellBonet Loraine,
Steiner Zvi,
Antler Gilad,
Hu Huanting,
Lunstrum Abby,
Hou Yi,
Kemnitz Nathaniel,
Stutsman Johnny,
Pallacks Sven,
Dugenne Mathilde,
Quay Paul D.,
Berelson William M.,
Adkins Jess F.
Publication year - 2022
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2022gb007388
Subject(s) - alkalinity , calcite , coccolith , carbon cycle , carbonate , oceanography , calcium carbonate , ocean acidification , dissolution , total inorganic carbon , geology , aragonite , dissolved organic carbon , carbonate compensation depth , mineralogy , environmental chemistry , seawater , carbon dioxide , chemistry , ecology , ecosystem , biology , organic chemistry
The cycling of biologically produced calcium carbonate (CaCO 3 ) in the ocean is a fundamental component of the global carbon cycle. Here, we present experimental determinations of in situ coccolith and foraminiferal calcite dissolution rates. We combine these rates with solid phase fluxes, dissolved tracers, and historical data to constrain the alkalinity cycle in the shallow North Pacific Ocean. The in situ dissolution rates of coccolithophores demonstrate a nonlinear dependence on saturation state. Dissolution rates of all three major calcifying groups (coccoliths, foraminifera, and aragonitic pteropods) are too slow to explain the patterns of both CaCO 3 sinking flux and alkalinity regeneration in the North Pacific. Using a combination of dissolved and solid‐phase tracers, we document a significant dissolution signal in seawater supersaturated for calcite. Driving CaCO 3 dissolution with a combination of ambient saturation state and oxygen consumption simultaneously explains solid‐phase CaCO 3 flux profiles and patterns of alkalinity regeneration across the entire N. Pacific basin. We do not need to invoke the presence of carbonate phases with higher solubilities. Instead, biomineralization and metabolic processes intimately associate the acid (CO 2 ) and the base (CaCO 3 ) in the same particles, driving the coupled shallow remineralization of organic carbon and CaCO 3 . The linkage of these processes likely occurs through a combination of dissolution due to zooplankton grazing and microbial aerobic respiration within degrading particle aggregates. The coupling of these cycles acts as a major filter on the export of both organic and inorganic carbon to the deep ocean.