Elevated heavy metal concentrations in urban top soils are principal indicators of environmental pollution; however, relative data on the heavy metal status in soils of Greek island towns, that are regional administrative centers and popular tourist destinations, are missing. A survey was conducted to examine heavy metal concentrations in the urban soils of Ermoupolis, the capital of Syros island and of the prefecture of Cyclades complex in the Aegean Sea. Total (aqua-regia extracted) and available (DTPA extracted) concentrations of Cu, Pb, Zn, Ni, Cr, Sn and Fe were determined in top soil samples collected from green areas and open spaces of the town and in surface samples from inland reference soils of the island. Mean values for the aqua-regia extracted fraction of Cu, Pb and Zn were 117, 155 and 440 mg kg(-1) respectively, up to four times higher than the respective mean values of the reference soils. Enrichment factors (EFs) for these metals indicated high accumulation in the urban top soils and the available to total concentration ratio of Cu, Pb, Zn and Fe was higher for the urban compared to the reference soils, suggesting differences in metal sequestration, resulting in higher metal availability in the urban soils. GIS analysis was used to visualize the spatial distribution of EFs of the studied heavy metals. Factor Analysis and Cluster Analysis, applied to aqua-regia and DTPA data sets, adequately elucidated the origin of metals grouped under each factor or cluster.
Abstract. Tillage displaces large amounts of soil from upper slopes and deposits soil in lower landscape positions, greatly affecting productivity in these areas. The long‐term effect of tillage on soil erosion was studied in four field sites growing mainly rainfed wheat. The soil loss from landscape positions with slopes, ranging from 3 to 28%, was estimated by: (a) comparing data of horizon thickness described at the same position at different times; and (b) using soil movement tracers added to the soil. Existing empirical relationships were used for estimating soil loss by tillage and runoff water, and loss in wheat biomass production. The experimental data showed soil losses of 0.4 to 1.4 cm yr–1 depending on slope gradient, plough depth, and tillage direction. In two of the sites, soil depth has been reduced by 24–30 cm in a period of 63 years. The mean soil displacement of the plough layer (30 cm thick), measured by soil movement tracers, ranged from 31 to 95 cm yr–1 depending mainly on slope gradient, corresponding to a rate of soil loss of 0.3 cm to 1.4 cm yr–1. Soil eroded from the upper slopes was deposited on the lower slopes increasing soil thickness by 0.4 cm to 1.4 cm yr–1. The application of empirical relationships, estimating soil loss by tillage and water runoff, showed that soil erosion at the field sites can be mainly attributed to tillage. The loss in wheat biomass production due to erosion was estimated at 26% on upper slopes for a period of 63 years, while a 14.5% increase in wheat production was estimated due to deposition of soil material in the lower landscape.
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