EXPLOIT-CSIA · Exploiting the potential use of compound specific isotope analysis (CSIA) in marine environment

Exploiting the potential use of compound specific isotope analysis (CSIA) in marine environment

The aim of this project was to explore, develop and exploit the potential use of compound-specific isotope analysis (CSIA) for the environmental and biological sciences. To achieve this aim, different tasks were foreseen for the two years period of the project. Task A: Training and development of CSIA Through a partnership arrangement with the manufacturer, Dr Cincinelli had the opportunity to spend some time with specialists at Isoprime Ltd (Manchester), which is a stable instrument manufacturer, learning about instrument design, operating principles of CSIA and maintenance. In the first six months, Dr Cincinelli, together with Dr D. Hughes (research technician at LEC) and Dr Y.Zhang (PhD student) set up the GC-MS - isotope ratio MS (IRMS) and become familiar with the scope and operation of the new instrumentation. In the following months, sample analysis were performed to determine (d13C) in environmental samples, in particular air and soil samples. Dr Cincinelli also conducted a deep research on the state of the art in CSIA applications in environmental and forensics sciences, editing a review paper (published in the journal Environmental Pollution). Task B: Field and laboratory analysis Dr Cincinelli focused her work on the development of protocol procedures for the determination of 13C ‰ signatures of selected individual polycyclic aromatic hydrocarbons (PAHs) and siloxanes (D3, D4, D5, D6) in environmental samples. Passive and active air samples, supposed to contain significant concentration levels of these classes of organic compounds, were chosen to this aim. - An extensive indoor air sampling campaign was performed in the UK and Italy during 2011. Air samples (n = 100) were collected on adsorption Tenax GR cartridges, using conventional portable air sampling pumps and desorbed in Italy using an automatic thermal desorber UNITY2 coupled to a gas chromatography - mass spectrometry (GC / MS) system. A smaller number of samples (n = 20) were collected on carbon cartridge (Orbo 32, Supelco) and extracted with CS2 in order to determine the carbon isotopic signatures of selected siloxanes. 13C ‰ of siloxanes standards supplied from different companies were measured to determine the variability of C isotopic compositions and compare the 13C ‰ variability of standard material to siloxanes found in environmental samples. Different siloxane concentrations were observed between the Italian and United-Kingdom (UK) indoor environment, reflecting different consumption and usage behaviours between these two countries. The average daily intake inhalation was also estimated for the UK atmosphere. The 13C ‰ values varied substantially for all individual cyclic siloxanes, the differences were particularly high for D5 (manuscript ready to be submitted). - To investigate the global distribution of linear and cyclic volatile methyl siloxanes, 85 sorbent-impregnated polyurethane foam (SIP) disk passive air samplers were deployed at 18 sites worldwide, along a rural/remote latitudinal transect from Portugal to Norway. Different extraction mixtures and clean up procedures were tested to obtain acceptable detection limits in CSIA, before starting the sample extractions. Samples were analysed for siloxanes and polybrominated diphenyl ethers (PBDEs). Berkeley-Trent (BETR) model was also applied to better understand the distribution and fate of these compounds in the environment (manuscript in preparation). - Air samples were collected at different sites in and around two wastewater treatment plants (WWTPs) located in central Italy to determine the concentrations, compositional profiles and contribution to ambient levels of 8 PBDEs. The investigated WWTPs were selected as they treat industrial wastewater produced by local textile industries along with municipal wastewater. PBDE concentrations within the WWTPs were higher than those measured at reference sites located 4 and 5 km away with BDE-209 dominating the BDE congener composition in all air samples. Ambient PBDE concentrations measured in and around the WWTPs and estimates of emissions from aeration tanks suggest that WWTPs are sources of PBDEs to ambient air. Principal component analysis and Pearson correlations confirmed this result. The effect of distance from the plant and wind direction on atmospheric concentrations was also investigated. Although the primary fate of PBDEs in WWTPs will be partitioning to sewage sludge, this study suggests that plants can provide a measurable source of these compounds to local ambient air (results published in the journal Environmental Pollution). The extracts were also used to test the CSIA procedures and confirm the source of these organic compounds. - An air sampling campaign was performed between 2010 - 2011 to determine the level of PAHs in the atmosphere of Ningbo Zhejiang (China) and investigate source apportionment by using CSIA. About 40 air samples were extracted and analysed. Dr Cincinelli worked in collaboration with Di Li, a PhD student from China (manuscript in preparation). - A method measuring stable chlorine isotope composition of dichlorodiphenyltrichloroethane (DDT) with a GC - quadrupole mass spectrometric detector (qMSD) was also evaluated. This direct qMSD method relies on the fragment bracketing strategy, in which different fragment ions yielded in the EI source respond differently and may cause varying sensitivity. In order to observe this effect on chlorine isotope measurement for DDT, a commercial DDT standard was tested in this study. 0.5 to 400 ng of DDT was introduced into the GC inlet (splitless mode, DDT degradation rate < 5 %). The selected fragment ions were scanned by the qMSD with settings adapted from previous publications. The Chlorine isotope ratio of each fragment group was then calculated by mathematical equations. Results show the chlorine isotope ratio in aromatic fragments had the best stability with standard deviation below 0.001 (n = 3) respectively, although the ratios varied within the full injection range. If this method is validated by a DDT standard of known ratio it can be practically applied to environmental samples. Task C: Dissemination Dr Cincinelli published two papers and other two are in preparation. She attended National and International conferences. Research results were included in classroom teaching for the Course Environmental Analytical Chemistry, for the Degree in Environmental Chemistry at the University of Florence.

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