Ocean pH and other biogeochemical measurements in the coastal Amundsen Sea, Antarctica

Pickup, Daisy Drew (2025) Ocean pH and other biogeochemical measurements in the coastal Amundsen Sea, Antarctica. Doctoral thesis, University of East Anglia.

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Abstract

The increased uptake of anthropogenic carbon dioxide is reducing the pH of the oceans. In order to monitor this effect, the development and utilisation of accurate, high resolution pH sensors is paramount. The Amundsen Sea, in the Southern Ocean, is a region with intense primary production and rapidly melting ice shelves. Studies of carbonate chemistry in this area are limited to the surface ocean, or encompass only a handful of discrete samples. In this study, two novel pH sensors were deployed in the Amundsen Sea for the first time. One was attached to an autonomous Seaglider, with comparison to in situ measurements revealing an associated uncertainty of 0.01. Another was integrated on a ship’s surface seawater supply and had an uncertainty of 0.1 when compared to in situ measurements.

The first high-resolution, in the horizontal and vertical, pH measurements in the Amundsen Sea fill a critical observational gap and unlock previously inaccessible insights, for example, the effects of meltwater dilution. Glider measurements also reveal cold water masses that have implications for the transport of heat in a region subject to basal melting. Surface measurements reveal that pH and fCO2 in different regions of the Amundsen Sea are subject to variation by different drivers. In the seasonal ice zone, continued sea ice melt into February affects carbonate chemistry through dilution. In the central polynya, variation is due to the effect of the transition to late austral summer and the lasting impact of photosynthesis. Along the coast, at the ice shelf fronts, variation in pH and fCO2 is dominated by the transport of water that has been unventilated under fast ice. This research highlights the value of utilising sensors in remote regions to capture features that have not been observed previously and represents a significant advancement in autonomous sensing in extreme environments.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Environmental Sciences
Depositing User:	Chris White
Date Deposited:	02 Dec 2025 09:38
Last Modified:	02 Dec 2025 09:38
URI:	https://ueaeprints.uea.ac.uk/id/eprint/101175
DOI:

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