Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Environmental soil quality of the city of Glasgow

Potentially toxic elements have been measured and fractionated in soil samples from public-access areas in Glasgow, UK. The spatial variability of analyte concentrations has been studied (a) within two urban parks and (b) across 94 sites (including parks, roadsides, riverbanks and ornamental gardens) within the city. Levels of analytes were broadly similar to those reported in previous studies of large, industrial cities. A few soils contained chromium, nickel or lead concentrations in excess of the UK CLEA soil guideline values.

Distribution profiles, and variability in analyte concentrations, were assessed in order to distinguish elements arising mainly from natural sources from those influenced more strongly by Man. Aluminium, iron, lithium, magnesium and manganese levels were least variable and more frequently normally distributed, indicating that these elements are predominantly natural in origin. Barium, calcium, copper, chromium, lead and zinc were characterised by higher variability and non-normal concentration distributions, suggesting anthropogenic sources are important. Principal component analysis confirmed these relationships, grouping the "natural" elements separately from the "urban" metals, and revealed that chromium behaved differently from either group. PCA scores constitute a potentially useful tool for Local Authorities attempting to identify particularly contaminated sites.

When applied to soils from Glasgow, the four-step sequential extraction protocol developed under the auspices of the EU BCR, revealed no differences between analyte fractionation patterns in park and roadside soils, nor between samples with markedly different pseudototal (aqua-regia soluble) metal concentrations. Chromium and nickel were found predominantly in associated with the residual phase of the soils, but ~ 73% of the lead content was released in step 2, indicating this elements has high potential mobility. The work illustrates the need to consider lability, as well as total concentrations of potential toxic elements in both contaminated site risk assessment and the setting of legislative limits.

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Reported by

University of Strathclyde
Department of Pure and Applied Chemistry, University of Strathclyde
United Kingdom