Deployment of DGT units in marine waters to assess the environmental risk from a deep sea tailings outfall

Sherwood, John E., Barnett, Darlene, Barnett, Neil W., Dover, Kylie, Howitt, Julia, Ii, Hiroyuki, Kew, Peter and Mondon, Julie 2009, Deployment of DGT units in marine waters to assess the environmental risk from a deep sea tailings outfall, Analytica chimica acta, vol. 652, no. 1-2, pp. 215-223.

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Title Deployment of DGT units in marine waters to assess the environmental risk from a deep sea tailings outfall
Author(s) Sherwood, John E.
Barnett, Darlene
Barnett, Neil W.
Dover, Kylie
Howitt, Julia
Ii, Hiroyuki
Kew, Peter
Mondon, Julie
Journal name Analytica chimica acta
Volume number 652
Issue number 1-2
Start page 215
End page 223
Total pages 9
Publisher Elsevier
Place of publication Amsterdam, Netherlands
Publication date 2009-10
ISSN 0003-2670
1873-4324
Keyword(s) trace metals
sub-surface plumes
colloid
environmental risk
Lihir Island
oxyhydroxides
Summary Measurements of total, filterable and DGT-labile concentrations of nine metals (Al, Cd, Cr, Cu, Fe, Pb, Mn, Ni and Zn) have been made at five sites up to 4.2km from a deep sea tailings outfall operated by Lihir Gold Ltd. at Lihir Island, Papua New Guinea. At each site, pairs of DGT units (one containing a 0.4mm and the other a 0.8mm diffusive gel layer) were deployed at three depths (50–70; 105–130; 135–155m) for 4–7 days. Comparison of predicted water column DGT-labile metal concentrations in field deployments showed the 0.8mm DGT units were relatively enriched in metals, with the effect being greatest closer to the outfall for Pb and Mn and least for Fe, Cr, Ni and Zn. The most likely explanation for this is that in addition to simple ion diffusion, kinetic factors associated with ageing or desorption processes govern release of metals from iron and aluminium oxyhydroxide colloids which diffuse through the gels. The thicker gels have a longer residence time over which metals can be released for adsorption. This model explains why enrichment is most pronounced near the outfall; more distant sites have lower colloid concentrations because of the longer time for coagulation to increase particle sizes to the extent they cannot enter the gels. Total and filterable metal (FM) concentrations were frequently below the limits of detection (LOD) achievable by conventional ICP-AES (1–52gL−1) and this limited their usefulness for assessing environmental risk and for metal speciation determination. Because of its pre-concentration step DGT gave metal concentrations above their LODs and these decreased exponentially with distance from the outfall. Concentrations of DGT–labile metal fell below Australian water quality guidelines for protection of 99% of marine organisms within 0.13km of the outfall for Cd, Cr and Ni and below that for protection of 95% of marine organisms within 0.4, 0.7 and 3.6km for lead, zinc and copper, respectively.
Language eng
Field of Research 039901 Environmental Chemistry (incl Atmospheric Chemistry)
Socio Economic Objective 960508 Ecosystem Assessment and Management of Mining Environments
HERDC Research category C1 Refereed article in a scholarly journal
HERDC collection year 2009
Copyright notice ©2009, Elsevier B.V.
Persistent URL http://hdl.handle.net/10536/DRO/DU:30028317

Document type: Journal Article
Collection: School of Life and Environmental Sciences
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