Browsing Theses & Dissertations by Subject "PDMS"
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Passive Sampling for Quality Monitoring of Irish Marine WatersThis study details the steps involved in fabrication, deployment and retrieval of mainly polydimethyl siloxane (PDMS) passive sampling devices deployed in a number of locations in and around Ireland in an attempt to derive dissolved water concentrations of contaminants in-situ. PDMS samplers were initially deployed in the Burrishoole catchment, Co. Mayo in conjunction with the collection of biological tissues and sediment to investigate the source of elevated dioxins in the catchment. Passive samplers were used to generate dissolved water concentrations of persistent organic pollutants (POPs) and also to successfully screen for the presence of dioxins in the water column. The dioxin profile present was also found in sediment and biological tissue and through statistical profiling potential sources were identified as being possibly related to the use of technical pentachlorophenol in the catchment though no direct evidence was found. Passive samplers (PDMS and SPMD) were then deployed at various depths on the M6 weather buoy, 400 miles off the West Coast of Ireland, in conjunction with temperature and salinity monitors to test how the technology would fare over a long period deployment (585 days) in a harsh, dynamic environment. The PDMS samplers were almost completly lost where the SPMDs last better (80 % recovered). Dissolved water concentrations estimated using both sampler types were found to be very low (<ppb) with polyaromatic hydrocarbons found in higher levels than polychlorinated biphenlys, and organochlorine compounds. The use of statistical analysis suggests that passive samplers can also be used to differentiate different water masses by investigating contaminant loadings at each depth sampled. Finally passive samplers were deployed in various inshore and inland waters across Ireland with the results indicating that the remote West of Ireland had the lowest levels of dissolved water concentrations estimated. Many estuaries and inland water bodies had levels of contaminants higher than the west of Ireland with the heavily industrialised Cork and Dublin sites having the highest levels estimated. The separation of sites based on concentrations found indicated that assessment criteria could be generated in an Irish context (IRef) which could be used to classify a site in relation to ‘background’ levels found in the West of Ireland and at M6. The results generated during this study were then assessed based on various legislative requirements and assessment criteria such as the Water Framework Directive (WFD) and the Oslo Paris convention (OSPAR). Results from the WFD assessment indicate that concentrations found at all sites were below the EQS values set down. However this EQS value is based on total water concentration hence the EQS was modified to a dissolved water concentration basis. This reduced the total water EQS values by up to 80 % for some analytes however in most locations the dissolved water concentrations found were at or below this dissolved water EQS value indicating that the levels of contaminants from across Ireland are below the EQS values generated as part of the WFD. Assessments were also made on the concentrations found across Ireland using background assessment criteria (BAC) suggested by OSPAR. The results indicate that the levels across Ireland are above the BAC for most compounds with the M6 weather buoy faring better. Concentrations from “pristine” Irish sites were then chosen to generate reference criteria on an Irish basis (IRef) which were found to be below the concentration levels suggested as part of the BAC assessment criteria in the majority of locations.