Chemical Speciation of Copper in a Salt Marsh Estuary and Bioavailability to Thaumarchaeota

Whitby, Hannah ORCID: 0000-0002-0064-3052, Hollibaugh, James T and van den Berg, Constant MG (2017) Chemical Speciation of Copper in a Salt Marsh Estuary and Bioavailability to Thaumarchaeota Frontiers in Marine Science, 4 (JUN). 178-. ISSN 2296-7745, 2296-7745

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Abstract

The concentrations of dissolved copper (Cu<inf>d</inf>), copper-binding ligands, thiourea-type thiols, and humic substances (HS<inf>Cu</inf>) were measured in estuarine waters adjacent to Sapelo Island, Georgia, USA, on a monthly basis from April to December 2014. Here we present the seasonal cycle of copper speciation within the estuary and compare it to the development of an annually occurring bloom of Ammonia Oxidizing Archaea (AOA), which require copper for many enzymes. Two types of complexing ligands (L<inf>1</inf> and L<inf>2</inf>) were found to dominate with mean complex stabilities (log KCuL') of 14.5 and 12.8. Strong complexation resulted in lowering the concentration of free cupric ion (Cu²⁺) to femtomolar (fM) levels throughout the study and to sub-fM levels during the summer months. A Thaumarchaeota bloom during this period suggests that this organism manages to grow at very low Cu²⁺ concentrations. Correlation of the concentration of the L<inf>1</inf> ligand class with a thiourea-type thiol and the L<inf>2</inf> ligand class with HS<inf>Cu</inf> provide an interesting dimension to the identity of the ligand classes. Due to the stronger complex stability, 82-99% of the copper was bound to L<inf>1</inf>. Thiourea-type thiols typically form Cu(I) species, which would suggest that up to ~90% copper could be present as Cu(I) in this region. In view of the very low concentration of free copper (pCu > 15 at the onset and during the bloom) and a reputedly high requirement for copper, it is likely that the Thaumarchaeota are able to access thiol-bound copper directly.

Item Type:	Article
Uncontrolled Keywords:	copper speciation, cathodic stripping voltammetry, humic substances, thiols, thiourea, organic ligands, thaumarchaeota, ammonia-oxidizing archaea
Depositing User:	Symplectic Admin
Date Deposited:	06 Sep 2017 12:52
Last Modified:	01 Mar 2026 04:35
DOI:	10.3389/fmars.2017.00178
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3009318
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