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Accession: CHM-OTH-1702 Research Theme: Chemistry (Research Study)
Contributors: Hannah Whitby, Tim Hollibaugh, Stan van den Berg
Title: Chemical speciation of copper in a salt marsh estuary near Sapelo Island, Georgia
Abstract: The concentrations of dissolved copper (Cud), copper-binding ligands, thiourea-type thiols and humic substances (HSCu) 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 oxidising archaea (AOA) Thaumarchaeota, which require copper for many enzymes. Two types of complexing ligands (L1 and L2) were found to dominate with mean complex stabilities (log K'CuL) of 14.5 and 12.8. Strong complexation resulted in lowering of the free cupric ion (Cu2+) concentration 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 L1 ligand class with a thiourea-type thiol and the L2 ligand class with HSCu provide convincing evidence for the identity of the ligands. Due to the stronger complex stability, 82 - 99 % of the copper was bound to L1. Thiourea-type thiols form strong Cu(I) species, suggesting that ~90% copper is present as Cu(I) in this region, upsetting the paradigm of its predominance as Cu(II). 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 the thiol-bound copper directly.
DOI: (not assigned)
Key Words: ammonia, ammonia oxidising archaea, Archaea, blooms, cathodic stripping voltammetry, chemistry, copper, copper speciation, humic soils, microbial, organic ligands, Thaumarchaeota, thiols, thiourea
LTER Core Area: Other Site Research
Research Themes: GCE3 Area2 - Patterns within the Domain, Chemistry, Microbiology
Study Period: 08-Apr-2014 to 01-Dec-2014
Study Sites:
GCE-DP -- Duplin River, Georgia, USA
» Download Geographic Coverage: Google Earth, ESRI Shapefile (polygons)
Project References: Ammonia oxidation in the GCE domain
Research Protocols:

Trace metal sampling protocol (Georgia Coastal Ecosystems LTER)


Whitby, H., Hollibaugh, J.T. and van den Berg, C.M. (in review). Chemical speciation of copper in a salt marsh estuary and bioavailability to Thaumarchaeota. Frontiers in Marine Sciences.

Whitby, H. 2016. Identifying the factors affecting copper speciation in estuarine, coastal and open ocean waters. Ph.D. Dissertation. University of Liverpool, School of Environmental Sciences, Department of Earth, Ocean and Ecological Sciences, Liverpool, England. 181 pages.

Downloads: Information

Data Table: CHM-OTH-1702 (Main data table for data set CHM-OTH-1702, 48 records)

Access: GCE Members only (public release on 07-Feb-2019)

Metadata: Text (ESA FLED), XML (Ecological Metadata Language)

Data Files: Spreadsheet (CSV) [5.45kb],  Text File [4.97kb],  Text Report [32.51kb],  MATLAB (GCE Toolbox) [158.86kb],  MATLAB (Variables) [123.66kb]

Column List:(hide)

Column Name Units Type Description
1 Station none string Station identifier
2 Date YYYY-MM-DD hh:mm EDT string Sampling date and time (local time)
3 Latitude degrees floating-point Station latitude
4 Longitude degrees floating-point Station longitude
5 Depth m floating-point Nominal depth at which the sample was taken (arm''s length, avoiding surface microlayer)
6 Salinity PSU floating-point Salinity measured using LTER Hydrolab sonde
7 Temperature °C floating-point Temperature measured using LTER Hydrolab sonde
8 Copper_Conc nM floating-point Total dissolved copper using CSV with standard additions
9 Thiol_Conc nM floating-point Concentration of thiourea-type thiols using CSV with standard additions
10 SRHA_Conc mg/L floating-point Concentration of copper-binding Suwanee River Humic Acid (SRHA, International Humic Substances Society (IHSS) Standard II 2S101H) as mg SRHA L-1 using CSV with standard additions
11 Ligand1_Conc nM floating-point Concentration of Cu-binding ligand class 1 using CLE-CSV
12 Ligand1_logK none floating-point Log10 of the dissociation constant of ligand class 1
13 Ligand2_Conc nM floating-point Concentration Cu-binding ligand class 2 using CLE-CSV
14 Ligand2_logK none floating-point Log10 of the dissociation constant of ligand class 2
15 Copper2_Conc M exponential Free Cu2+
16 CuL1_Bound % floating-point Copper bound by ligand class 1, percent of total Copper
17 CuL2_Bound % floating-point Copper bound by ligand class 2, percent of total Copper
Citation: Whitby, Hannah (2017): Chemical speciation of copper in a salt marsh estuary near Sapelo Island, Georgia. Georgia Coastal Ecosystems LTER Project; University of Georgia; Long Term Ecological Research Network. (http://gce-lter.marsci.uga.edu/data/CHM-OTH-1702)

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This material is based upon work supported by the National Science Foundation under grants OCE-9982133, OCE-0620959 and OCE-1237140. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.