Major inputs and mobility of potentially toxic elements contamination in urban areas

Soil quality in urban areas is affected by anthropogenic activities, posing a risk to human health and ecosystems. Since the pseudo-total concentrations of potentially toxic elements may not reflect their potential risks, the study of element mobility is very important on a risk assessment basis. This study aims at characterising the distribution and major sources of 34 elements in two Portuguese urban areas (Lisbon and Viseu), with different geological characteristics, industrial and urban development processes. Furthermore, the potential availability of As, Co, Cr, Cu, Ni, Pb and Zn was assessed, by measuring the fraction easily mobilised. Lisbon is enriched in elements of geogenic and anthropogenic origin, whereas in the smaller city, the high levels observed are mainly related to a geogenic origin. Background values can be more relevant than the dimension of the city, even when anthropogenic components may be present, and this parameter should be considered when comparing results from different cities. Regarding the potential available fraction, a high variability of results was observed for elements and for sampling sites with an influence of the soil's general characteristics. Elements showing very high concentrations due to geological reasons presented, in general, a low mobility and it was not dependent on the degree of contamination. For elements with major anthropogenic origin, only Zn was dependent on the pseudo-total content. Yet, the highest available fractions of some elements, both with major geogenic and anthropogenic origin, were observed in specific contaminated samples. Therefore, a site-specific evaluation in urban soils is important due to the high spatial variability and heterogeneity.This work was supported by CESAM and by the Fundação para a Ciência e Tecnologia through the research project POCTI/CTA/44851/2002:SOLURB (‘Towards a methodology for the assessment of environmental quality in urban soils’) and individual research grants attributed to A. Cachada (SFRH/BD/38418/2007), P. Pato (SFRH/BPD/35068/ 2007), C. Mieiro (SFRH/BD/28733/2006) and T. Rocha-Santos (SFRH/BPD/65410/2009). The authors wish to thank Pedro Faria for the English revisions.publishe

Distribution of heavy metals in the dissolved and suspended phase of the sea-surface microlayer, seawater column and in sediments of Singapore's coastal environment

10.1007/s10661-007-9795-yEnvironmental Monitoring and Assessment1381-3255-272EMAS