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The carbonic anhydrase activity of sinking and suspended particles in the North Pacific Ocean

Subhas, Adam V. and Adkins, Jess F. and Dong, Sijia and Rollins, Nick E. and Berelson, William M. (2020) The carbonic anhydrase activity of sinking and suspended particles in the North Pacific Ocean. Limnology and Oceanography, 65 (3). pp. 637-651. ISSN 0024-3590. doi:10.1002/lno.11332.

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The enzyme carbonic anhydrase (CA) is crucial to many physiological processes involving CO₂, from photosynthesis and respiration, to calcification and CaCO₃ dissolution. We present new measurements of CA activity along a North Pacific transect, on samples from in situ pumps, sediment traps, discreet plankton samples from the ship's underway seawater line, plankton tows, and surface sediment samples from multicores. CA activity is highest in the surface ocean and decreases with depth, both in suspended and sinking particles. Subpolar gyre surface particles exhibit 10× higher CA activity per liter of seawater compared to subtropical gyre surface particles. Activity persists to 4700 m in the subpolar gyre, but only to 1000 m in the subtropics. All sinking CA activity normalized to particulate organic carbon (POC) follows a single relationship (CA/POC = 1.9 ± 0.2 × 10⁻⁷ mol mol⁻¹). This relationship is consistent with CA/POC values in subpolar plankton tow material, suspended particles, and core top sediments. We hypothesize that most subpolar CA activity is associated with rapidly sinking diatom blooms, consistent with a large mat of diatomaceous material identified on the seafloor. Compared to the basin‐wide sinking CA/POC relationship, a lower subtropical CA/POC suggests that the inventory of subtropical biomass is different in composition from exported material. Pteropods also demonstrate substantial CA activity. Scaled to the volume within pteropod shells, first‐order CO₂ hydration rate constants are elevated ≥ 1000× above background. This kinetic enhancement is large enough to catalyze carbonate dissolution within microenvironments, providing observational evidence for CA‐catalyzed, respiration‐driven CaCO₃ dissolution in the shallow North Pacific.

Item Type:Article
Related URLs:
URLURL TypeDescription
Subhas, Adam V.0000-0002-7688-6624
Adkins, Jess F.0000-0002-3174-5190
Dong, Sijia0000-0002-5811-9333
Additional Information:© 2019 Association for the Sciences of Limnology and Oceanography. Issue Online: 05 March 2020; Version of Record online: 11 October 2019; Manuscript accepted: 22 August 2019; Manuscript revised: 02 May 2019; Manuscript received: 12 December 2018. We thank the entire science party and the R/V Kilo Moana crew on the CDisK‐IV cruise. In particular, we thank Doug Hammond and Alex Sessions for providing the in situ pumps, Nathan Kemnitz, Yi Hou, and Abby Lunstrum for help in working up pump filter and multicore samples, and Will Gray for helping to pick pteropod samples. We greatly thank Brian Hopkinson and two anonymous reviewers for their helpful and insightful comments and suggestions throughout the review process. This manuscript was significantly improved thanks to their efforts. We also acknowledge funding sources from NSF (OCE1220600 and OCE1220302), and the Resnick Sustainability Institute Graduate Fellowship for A.V.S. Conflict of Interest: None declared.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Resnick Sustainability InstituteUNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20191024-091357425
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Official Citation:Subhas, A.V., Adkins, J.F., Dong, S., Rollins, N.E. and Berelson, W.M. (2020), The carbonic anhydrase activity of sinking and suspended particles in the North Pacific Ocean. Limnol Oceanogr, 65: 637-651. doi:10.1002/lno.11332
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99432
Deposited By: Tony Diaz
Deposited On:24 Oct 2019 16:55
Last Modified:16 Nov 2021 17:46

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