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An important component of monitoring pollution of urban road-deposited sediment (RDS) is an understanding of the temporal variability in its composition and physical characteristics. This study set out to determine what the monthly variability in metal concentrations, organic matter content, grain-size and grain-size fraction metal-loadings are in inner city sites in Manchester, northwest England. The results show that there is significant temporal variability in metal (Pb, Zn, Fe, Mn) concentration in RDS from inner city Manchester. There was no significant temporal variability in grain-size characteristics or organic matter content, indicting that these metal variations were the result of variation in sources and accumulation processes. Pb and Zn displayed local variability, suggesting local controls on variability, whereas Fe and Mn displayed consistent variability across all sites, suggesting a common, largerscale control on variability. The finest grain-size fraction (<63 μm) contained the highest Pb, Cu and Zn concentrations, but for the case of Fe and Mn, the coarser fractions (>300 μm) commonly contained the highest concentrations, again suggesting differing controls. For all metals, due to the weight percent dominance of the coarser fractions, the dominant loading of metals is in the coarser fractions. This has implications on management strategies, via street sweeping and the subsequent waste disposal, and on the modelling of the input of RDS and associated metals into surface waterways. The recognition of significant temporal variability of metal concentrations in RDS, independent of grainsize changes, implies that the monitoring of urban road sediment pollution will require not just consideration of spatial variability, but the design of schemes that will capture temporal variability also.

Background, aim and scope The urban environment in Bratislava is, in association with rapid urbanisation and industrialisation, significantly influenced by several potential sources of pollution, including automobile exhaust and industry emmissions. Urban road-deposited sediments contain many potentially toxic elements such as Pb, Cr, Cu, Zn and also Fe at concentrations much higher than in soil. In this study, the chemical composition and spatial variability of road-deposited sediments in urban area of Bratislava were assessed for the elements As, Cd, Cr, Cu, Hg, Ni, Pb, Fe and Mn. Additional evaluation of archive data for soil, snow and atmospheric dust was undertaken to provide an integrated view on urban environment contamination. Materials and methods Urban road-deposited sediments (RDS) were collected during summer 2003 and 2004 mainly from major city crossroads. RDS samples were analysed for total metal content, pseudo-total metal content (HNO 3 digestion) and by a sequential extraction method, grain fraction composition and mineralogical composition (X-ray analysis). Metal concentrations in soil and snow samples from urban and non urban city area were compared. Results and discussionThe highest concentrations for all metals were found in the finest RDS fraction (<0.125 mm). Whilst in the fraction <1 mm mean concentrations of Cr, Cu and Pb reached 55.2, 143.8 and 34.4 mg kg −1 , respectively, for the fraction <0.125 mm, markedly higher contents of these elements were documented at the level of 86.8, 218.4 and 63.1 mg kg −1 , respectively. The soil contents of potentially toxic risk elements in the urban area including As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn were higher than in the non-urban area (except for Cd with similar contents). This distribution pattern of evaluated chemicals in urban and non-urban area is more evident in the case of winter precipitation (snow). The snow concentrations of As, Cr, Cu, Fe, Mn, Pb and Zn in the urban area were two tot five times higher than in non-urban area. Conclusions and recommendations Monitoring of roaddeposited sediments, dust, soil and precipitation has confirmed the significant contamination of the urban environment in Bratislava with potentially toxic elements that can pose a threat for the health of its residents. Future works should be based on analyses of temporal variability of RDS and analyses of organic matter content.Keywords Bratislava . Geochemistry . Precipitation . Road sediment . Soil . Urban environment 1 Background, aim and scopePresently, approximately half of the global population live in urban centres, a figure set to increase. As a consequence, there is an increasing need to understand the controls on environmental quality in urban environments. Urban centres are characterised by a heavily modified physical and chemical environment and possess a wide range of J Soils Sediments (

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