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Application of an in situ passive sampling technique for assessment of contaminants in the Antarctic environment

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Larner, BL (2006) Application of an in situ passive sampling technique for assessment of contaminants in the Antarctic environment. PhD thesis, University of Tasmania.

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Available under University of Tasmania Standard License.

Abstract

This study investigates the use ofthe in situ passive sampling technique of diffusive
gradients in thin films (DGT) to measure trace metal contaminants in overlying
water and sediment porewater adjacent to a waste disposal site at the year-round
Australian Antarctic research base, Casey Station. Marine sediment in a bay
adjacent to the waste disposal site has been previously identified as having elevated
levels oftrace metals, in particular Cd, Pb, Sn, Cu and Zn.
Further development of the DGT technique was investigated with the application
and testing of a new paper-based DGT sampler. These samplers were more cheaper,
robust and easier to assemble than the original gel-based model, and were less
affectedby pH and ionic strength. The paper-based DGT samplers had a lower than
expected uptake of metals compared to the gel-based samplers in a field trial, so
these samplers were not considered for Antarctic field work. Calibration ofthe gelbased
DGT samplers using the "DGT uptake method" at a temperature suitable for
Antarctic deployments resulted in diffusion coefficients 93 - 114% of the literature
values, indicating that the technique is suitable for use in Antarctic waters.
Deployment of DGT water samplers in Antarctic waters adjacent to the waste
disposal site and in pristine waters resulted in only Cd, Fe and Ni being measured,
with other metals being less than detection limits. The annual summer melt draining
through the tip did not appear to affect the concentrations of these metals in the
water. The use of Empore preconcentration disks resulted in the quantification of all
metals analysed, except Cr, and the comparison ofresults between Empore and DGT supports previous findings that metals in the marine environment are associated with
colloidal or particulate material.
The use of DGT sediment probes demonstrated elevated levels of Sn, Pb, Fe and As
in the sediment porewater, consistent with direct porewater measurements which
showed elevated levels of Sn, Pb, Mn and Fe compared to pristine locations.
Comparison of DGT sediment probe results to direct porewater measurements
showed that Sn and Fe were resupplied to the porewater from the solid phase.
Further sediment characterisation work was undertaken to investigate why some of
the metals (such as Cd, Cu and Zn) were present in low concnetraions in the
porewater. Very high levels of acid volatile sulfides, up to 1600 pg g"', were
detected in sediment adjacent to-the waste disposal site. The high concentration of
reactive sulfides in the sediment appears to be the main controlling factor of metal
availability in the porewater.

Item Type: Thesis (PhD)
Keywords: Trace elements, Waste disposal sites
Copyright Holders: The Author
Copyright Information:

Copyright 2006 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Available for library use only and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2006. Includes bibliographical references. Ch. 1. General introduction -- Ch. 2. Diffusive gradients in thin film samplers -- Ch. 3. Further development of the diffusive gradients in thin film sampling technique -- Ch. 4. Evaluation of the diffusive gradients in thin film sampling technique for the monitoring of trace metals in Antarctic overlying waters -- Ch. 5. Evaluation of the diffusive gradients in thin film sampling tedchnique for the measurement of trace metals in contaminated Antarctic sediments -- Ch. 6. Sediment core characterisation -- Ch. 7. Conclusions and further research

Date Deposited: 19 Dec 2014 02:50
Last Modified: 17 May 2017 01:21
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