Towards a quality-controlled and accessible Pitzer model for seawater and related systems

Turner, David, Achterberg, Eric P., Chen, Chen-Tung A., Clegg, Simon, Hatje, Vanessa, Maldonado, Maria, Sander, Sylvia G., van den Berg, Constant M. and Wells, Mona (2016) Towards a quality-controlled and accessible Pitzer model for seawater and related systems. Frontiers in Marine Science, 3. ISSN 2296-7745

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Abstract

We elaborate the need for a quality-controlled chemical speciation model for seawater and related natural waters, work which forms the major focus of SCOR Working Group 145. Model development is based on Pitzer equations for the seawater electrolyte and trace components. These equations can be used to calculate activities of dissolved ions and molecules and, in combination with thermodynamic equilibrium constants, chemical speciation. The major tasks to be addressed are ensuring internal consistency of the Pitzer model parameters (expressing the interactions between pairs and triplets of species, which ultimately determines the calculated activities), assessing uncertainties, and identifying important data gaps that should be addressed by new measurements. It is recognised that natural organic matter plays an important role in many aquatic ecosystems, and options for including this material in a Pitzer-based model are discussed. The process of model development begins with the core components which include the seawater electrolyte and the weak acids controlling pH. This core model can then be expanded by incorporating additional chemical components, changing the standard seawater composition and/or broadening the range of temperature and pressure, without compromising its validity. Seven important areas of application are identified: open ocean acidification; micro-nutrient biogeochemistry and geochemical tracers; micro-nutrient behaviour in laboratory studies; water quality in coastal and estuarine waters; cycling of nutrients and trace metals in pore waters; chemical equilibria in hydrothermal systems; brines and salt lakes.

Item Type: Article
Additional Information: © 2016 Turner, Achterberg, Chen, Clegg, Hatje, Maldonado, Sander, Van_den_berg and Wells. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution and reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Uncontrolled Keywords: chemical speciation,seawater,modelling,equilibria,ph,trace metals,biogeochemical cycles
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: Pure Connector
Date Deposited: 24 Sep 2016 00:22
Last Modified: 19 Nov 2020 00:39
URI: https://ueaeprints.uea.ac.uk/id/eprint/60014
DOI: 10.3389/fmars.2016.00139

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