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Spatial and Temporal Variability of p CO 2 , Carbon Fluxes, and Saturation State on the West Florida Shelf
Author(s) -
Robbins L. L.,
Daly K. L.,
Barbero L.,
Wanninkhof R.,
He R.,
Zong H.,
Lisle J. T.,
Cai W.J.,
Smith C. G.
Publication year - 2018
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2018jc014195
Subject(s) - sink (geography) , oceanography , environmental science , saturation (graph theory) , flux (metallurgy) , seawater , carbon sink , carbon dioxide , atmospheric sciences , climatology , geology , geography , climate change , chemistry , cartography , mathematics , organic chemistry , combinatorics
Abstract The West Florida Shelf (WFS) is a source of uncertainty for the Gulf of Mexico carbon budget. Data from the synthesis of approximately 135,000 p CO 2 values from 97 cruises from the WFS show that the shelf waters fluctuate between being a weak source to a weak sink of carbon. Overall, the shelf acts as a weak source of CO 2 at 0.32 ± 1.5 mol m −2 yr −1 . Subregions, however, reveal slightly different trends, where surface waters associated with 40–200‐m isobath in the northern and southern WFS are generally weak sinks all year, except for summer when they act as sources of CO 2 . Conversely, nearshore waters (<40 m) are a source of CO 2 , particularly the southern shallow waters, which are a source all year round. The p CO 2 of seawater has been increasing at a rate of approximately 4.37 μatm/year as compared to atmospheric p CO 2 which has increased at a rate of about 1.7 μatm per year from 1996 to 2016. The annual CO 2 flux has increased from −0.78 to 0.92 mol m −2 yr −1 on the shelf from 1996–2016. The WFS is emitting 9.23 Tg C/year, with the southern nearshore region emitting the most at 9.01 Tg C/year and the northern region acting as a sink of −1.96 Tg C/year. Aragonite saturation state on the WFS shows seasonal and geographic trends with values ranging from 2 to 5. Lowest values are found in winter associated with subregion <40‐m isobath.