Speciation of mercury in different environmental compartments. Design, development and optimization of analytical methods and procedures

摘要

The widespread use of organometallic compounds and their subsequent releaseudinto the environment has created a great environmental concern about the toxicityudand effects of these pollutants. Mercury pollution is a growing concern worldwideudbecause its can reach high concentrations in various environmental media and thusudadversely affect humans, wildlife and ecosystem functioning.udMercury is present in the environment in different molecular forms with specificudbiogeochemical transformation and ecotoxicity. Inorganic Hg2+ is the main form inudwater and sediment samples. Concentration levels of organomercury species isudvery low (usually ng L-1) in aquatic environments but the toxic effect of theseudcompounds can be significant due to their tendency for bioaccumulation andudbiomagnification in the food chain.udThe development of a sensitive, reliable, simple, and cost effective procedure forudspeciation analysis of mercury in different environmental compartments isudcurrently one of the principal research challenges in environmental analyticaludchemistry. To this end, this study aimed to develop and optimize analyticaludmethods and procedures for the determination of total mercury and the speciationudof inorganic and organic forms of mercury. The hyphenation of gas chromatography and inductively coupled plasma mass spectrometry (GC-ICP-MS)udwas achieved and used successfully.udRapid and efficient sample preparation procedures based on microwave-assistedudextraction for solid samples were developed. The optimized analytical methodsudand procedures were validated by the analysis of environmental certified referenceudmaterials (CRM 015-050 sediment for HgTOT and CRM 463 tuna fish for HgTOT and MeHg). The developed methodologies were finally applied to real environmental samples,udnamely soil, sediment, water, fish and human hair, collected in some SouthudAfrican regions affected by environmental pollution due to reprocessing of oldudtailings dumps and chlor-alakali facilities. The study included collection ofudancillary data (pH, redox potential) which are critically important for mercuryudmonitoring program. Predictive models of mercury speciation in water samplesudbased on thermodynamic solution equilibria were also established.