Hoare, DJ; (2007) Ecological change in shallow lakes through antifoulant biocide contamination. Doctoral thesis , UCL (University College London).

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Abstract

This study sought to determine whether tributyltin (TBT), a toxic environmental contaminant now banned from use in antifoulant paints, could have contributed to ecological degradation in shallow lakes. Anthropogenic stresses have often led to changes in ecological structure and functioning within such waterbodies, with catastrophic loss of submerged macrophytes a common phenomenon. An area that has experienced intense TBT contamination and widespread macrophyte loss, is the Broads, a popular inland navigable waterway in E. England. Development of an online SPE-LC-MSn analytical method enabled identification and quantification of contemporary organic antifoul biocides in water and sediment samples. This contemporary analysis improved understanding of the transport mechanisms that would have been responsible for dilution and dispersion of TBT. Within the River Bure study area, a distinct antifoul biocide contamination gradient was observed, that related to the level and type of boating activity. Most significantly, biocide transportation has led to areas not directly exposed to boating activity, but in hydrological connection, to become contaminated. The recent ecological histories of contaminated lakes was reconstucted using multi-proxy palaeoecological analytical techniques on cores collected using a new wide-diameter corer. Data from the radiometrically-dated cores indicated that at least twenty years of continuous TBT pollution occurred in the Broads, against a backgound of eutrophication. The pre-TBT period was characterised by presence of macrophyte remains with abundant plant-associated diatoms, cladocera and invertebrates, which switched to predominantly planktonic assemblages after initial detection of TBT. Environmental concentrations of TBT present during its active usage in antifoulant paints, would have adversely affected functionally important aquatic organisms, as indicated by ecotoxicological test data. The spatio-temporal assessment of contamination, combined with a palaeoecological approach, has been successful in reconstructing relative toxicant exposure and patterns of ecological change in the Broads. This methodology could be applied to the study of other persistent pollutants.

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