| || || Maata, Matakite.|
| || || The decomposition of tributyltin (TBT) in tropical marine sediments |
Institution: University of the South Pacific.
Subject: Tributyltin -- Environmental aspects -- Fiji, Tributyltin -- Toxicology -- Fiji, Mollusks -- Effect of organotin compounds on
Call No.: Pac QD 412 .S7 M337
Copyright:Under 10% of this thesis may be copied without the authors written permission
Abstract: The thesis presents the results of a research into the processes of TBT decomposition under tropical conditions with particular emphasis on determining the degradation rate of this contaminant. The investigation was begun in 1994, due to a serious local contamination problem with TBT using a then current analytical system available, which could be established with the laboratory facilities at the University of the South Pacific (USP), in Fiji. The analytical system developed was a hydride generation technique with cold trapping and atomic absorption detection using a quartz furnace. (HG/AAS). An experimental mesocosm paradigm to provide TBT-loaded sediments, obtained both locally from the contaminated site and spiked with TBT, was implemented. Samples were taken at intervals from the mesocosm tanks, and analysed for TBT using the above system. A half-life (tin) of 122 days was determined for the silty/clayey sediments collected from the mesocosm tanks. A much shorter half-life of 39 days was also calculated for the much grainier, sandy sediments collected from the Sandbank. The slipway in Walu Bay recorded the highest TBT concentration of 360ug g'1, which is almost ten times the concentration recorded in the same place in 1991*. Sediment samples.from other ports in Fiji were also collected to ascertain the level of TBT contamination. This included a site for a proposed marina operation with the intent to provide a background TBT level which could be used later to assess its impact TBT concentration was measured using a different method once it is operational. The results do indicate that there is a serious problem of contamination with TBT in these ports. Concurrently, there have been a number of instrumental developments for TBT analysis in laboratories specialising in such work. Opportunity has been taken to compare the results obtained from the locally-used analytical system (HG/AAS) with the later- available instrumentation which employed gas chromatography with flame photometric detection (GC/FPD). The latter analytical exercise was carried out using the facilities at the Ocean Chemistry Section of trie Institute of Ocean Sciences (IOS), Sidney, British Columbia, in Canada. The results obtained from the GC/FPD method proved to be more reliable than the HG/AAS as it has a better reproducibility and higher percent recovery. It was for these reasons that the calculations for the degradation rates were based on the data obtained from the GC/FPD method. The contamination of marine sediments by TBT is a serious matter since this contaminant is quite toxic to molluscs, as known from the shell deformation in oysters (Appendix 3) and maseulinisation of female snails (Appendix 3). Some of the shell-bearing molluscs (eg., Anadara), are an important food source in Fiji. The sediments at the Walu Bay slipway appear to be severely poisoned by TBT and this would have very serious consequences on the biota of the area if it is not promptly addressed.