RESUMO
Urban geochemical maps of Wolverhampton and Nottingham, based on multielement analysis of surface soils, have shown distribution patterns of "total" metals concentrations relating to past and present industrial and domestic land use and transport systems. Several methods have been used to estimate the solubility and potential bioavailability of metals, their mineral forms and potential risks to urban population groups. These include sequential chemical extraction, soil pore water extraction and analysis, mineralogical analysis by scanning electron microscopy, source apportionment by lead isotope analysis and the development of models to predict metal uptake by homegrown vegetables to provide an estimate of risk from metal consumption and exposure. The results from these research strategies have been integrated with a geographical information system (GIS) to provide data for future land-use planning.
Assuntos
Cobre/análise , Monitoramento Ambiental/métodos , Recuperação e Remediação Ambiental , Chumbo/análise , Poluentes do Solo/análise , Zinco/análise , Disponibilidade Biológica , Cidades , Cobre/química , Cobre/farmacocinética , Sistemas de Informação Geográfica , Geografia , Humanos , Isótopos , Chumbo/química , Chumbo/farmacocinética , Microscopia Eletrônica de Varredura , Medição de Risco/métodos , Poluentes do Solo/química , Poluentes do Solo/farmacocinética , Solubilidade , Reino Unido , Verduras/metabolismo , Zinco/química , Zinco/farmacocinéticaRESUMO
By combining scanning electron microscopy (SEM) image analysis and laser ablation plasma ionisation multi-collector mass spectrometry (LA-PIMMS), high precision lead isotope analyses can be obtained from individual metal-rich particles. Soils from Wolverhampton and Nottingham were sampled on the basis of high Pb concentrations or brownfield location. Pressed powder pellets of each were rastered by LA-PIMMS to obtain a bulk Pb-isotope signature. The results plot along an apparent mixing line between the major sources of lead contamination in the UK, that is UK ore deposits and alkyl-lead from petrol additives (Australian ore). Two particularly lead-rich soils were chosen to investigate the lead distribution and isotope variability between size and density fractions. The fine-grained and low-density fractions contained most of the lead and have Pb-isotope ratios comparable with the bulk soils. By contrast, the small, lead-enriched denser fractions contained only a minor proportion of the total lead but Pb-isotope signatures indicating relative enrichment in one or other of the end-members from the mixing line. Further characterisation of individual Pb-rich grains is in progress.
