Anthropogenic platinum group element (Pt, Pd and Rh) concentrations in road dusts and roadside soils from Perth, Western Australia

The emission of platinum group elements (PGE) from automobile catalytic converters has led to rapid increases in Pt, Pd and Rh concentrations in roadside media. This article represents the first detailed study to assess PGE levels in road dusts and roadside soils in Australia. Road dust and roadside soil samples were analysed by ICP-MS following microwave digestion and cation exchange. All samples show elevation of PGE above average upper crust values, with maximum values of 420 ng g(-1) Pt, 440 ng g(-1) Pd and 91 ng g(-1) Rh. PGE ratios in road dusts and soils are consistent with known catalytic converter compositions and while Pt and Rh abundances are comparable with European studies, Pd levels are substantially higher in Australian samples. PGE in these samples are not correlated with Pb, though positive correlations with Ce, Cu and Y are evident. No straightforward relationship between traffic volume and PGE abundance is evident and factors such as driving style, topography, road drainage and potentially climate exert considerable influences.     

Accumulating characteristics of platinum group elements (PGE) in urban environments, China

The three-way catalytic converters [mainly using platinum, palladium and rhodium of platinum group elements (PGE)] have been widely used to reduce the pollution arising from vehicular traffic. Since the late 1990s, the Chinese government has implemented measures for new vehicles, equipped with the three-way catalytic converters in metropolitan cities. However, the PGE spreading on environments has not been strongly concerned in developing countries. This study investigated the accumulation characteristics of PGE in urban environments in China. A few samples from India were also analyzed and compared with those from China. The collected soil, aerosol and plant samples were determined for PGE by inductively coupled plasma-mass spectrometry (ICP-MS) after nickel sulphide fire assay preconcentration. The results have shown higher PGE contents in the samples from the cities where vehicles were fitted with autocatalysts for longer time periods. The highest values are 160 ng/g for Pt, 107 ng/g for Pd and 34.5 ng/g for Rh in Hong Kong soils, whereas the lowest values are 2.59 ng/g for Pt, 1.31 ng/g for Pd and 0.40 ng/g for Rh in Kolkata soils. In Beijing and Guangzhou aerosol samples, the PGE concentrations are 6.22 to 24.3 pg/m³ for Pt and 1.16 to 8.60 pg/m³ for Rh and 7.68 to 12.2 pg/m³ for Pt and 2.15 to 5.15 pg/m³ for Rh, respectively. The levels of PGE abundances in the urban environments of China have been significantly elevated with increasing number of vehicles equipped with autocatalysts.     

PGEs and other traffic-related elements in roadside soils from São Paulo, Brazil

The distribution of platinum, palladium, and rhodium in soils adjacent to a major road in S?o Paulo, Brazil, is presented. Sampling was made at four sites with varying traffic volumes and driving styles (stop/start vs. constant speed). High-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) with NiS fire assay collection and Te coprecipitation was used as analytical procedure. The platinum group element (PGE) pattern distribution in the analyzed roadside soil was similar to that of other traffic-related elements such as Zn and Cu, characterized by a strong decrease of the PGE content with increasing distance from the traffic lane. The results indicate that the PGE concentrations in roadside soil are directly influenced by traffic conditions and distance, which characterize their catalytic converter origin. Pt, Pd, and Rh contents range between 0.3 and 17 ng g(-1), 1.1 and 58 ng g(-1), and 0.07 and 8.2 ng g(-1) respectively. Lower levels of Pt and lower Pt/Pd ratios in relation to similar studies in other countries were observed due to the different Pt/Pd ratios in Brazilian automobile catalytic converters. This is the first study to assess traffic-derived Pt, Pd, and Rh deposition in Brazil.     

Determination of anthropogenic input of Ru, Rh, Pd, Re, Os, Ir and Pt in soils along Austrian motorways by isotope dilution ICP-MS

A joint study with the Federal Environment Agency of Austria was carried out to determine the distribution of Ru, Rh, Pd, Os, Ir and Pt (PGE) and Re in soils along major motorways. Emphasis was put on Ir as to date little is known about its anthropogenic input as this metal is now also used in automobile catalytic converters. Soil samples were analysed by ICP-MS through online-coupling of a chromatographic column to separate the PGEs from interfering matrix constituents. At all sampled sites not only Rh, Pd and Pt but also Ir and Re significantly exceed natural background values; concentrations reached 13 ng/g, 25 ng/g, 134 ng/g, 1.1 ng/g and 9.8 ng/g, respectively. The analytical procedure proved to be very selective and sensitive and, therefore applicable to routine soil analysis.     

Autocatalyst-derived platinum, palladium and rhodium (PGE) in infiltration basin and wetland sediments receiving urban runoff

The emission of platinum group elements (PGE) from automobile catalytic converters has led to rapid increases in Pt, Pd and Rh concentrations in roadside media. Significant quantities of the PGE may enter and accumulate in fluvial systems via road runoff. This paper examines the occurrence and spatial distribution of autocatalyst-derived PGE in surface sediments of infiltration basin and wetland sediments receiving road-runoff in Perth, Western Australia. Samples were analysed by ICP-MS following microwave digestion and cation exchange. PGE concentrations ranged between 1.5-17.2 Rh, 5.4-61.2 Pd and 9.0-103.8 ng g(-1) Pt. The highest levels of PGE were generally found at basin topographic low points and these concentrations were found to be strongly related to the area of road surface drained and the traffic volume. PGE ratios in infiltration basin and wetland sediments were within the typical range of catalytic converter compositions. However, comparisons of PGE ratios between parent road dusts and infiltration basin sediments revealed a systematic shift in Pt/Pd ratios, suggesting that PGE fractionation can occur during transport through the drainage system and that a small portion of Pd in road dust may be solubilised under natural conditions.     

Palladium and platinum concentration in soils from the Napoli metropolitan area,Italy: possible effects of catalytic exhausts

Soils from the Napoli metropolitan area (Italy) were evaluated for Pt and Pd concentrations. One hundred and ninety-five (195) samples were collected from residual soils and non-residual soils from flower-beds in a 120 km(2) area on a 0.5 km grid in the downtown-urbanized area and on 1 km grid in suburban zones. The soils <100 mesh size fraction (150 microm) was analyzed for Pt, Pd and 37 other elements by ICP-ES and ICP-MS after aqua regia digestion. Pt and Pd contents range between <2 and 52 microg/kg and between <10 and 110 microg/kg, respectively. A large number of samples from the metropolitan area were characterized by anomalous values for Pt (>6 microg/kg) and Pd (>17 microg/kg). Non-residual soils from flower-beds are located mainly in the urbanized downtown areas subject to heavy traffic and have higher Pt and Pd contents than residual soils from suburban areas. Geochemical maps show a strong correlation between roads with major traffic flow and high Pt and Pd concentrations. In addition, data from most of the downtown flower-beds fall within the three-way catalytic converters (TWC) field identified by [Ely JC, et al. Environ Sci Technol; 35:3816-3822]. This suggests that emissions of abraded fragments from vehicle exhausts may be the source of the high values and geographic distributions of Pd and especially Pt in urban soils of Napoli. Catalytic converters (Pt/Pd/Rh) have been mandatory for gasoline-powered vehicles in Europe since 1993. Italy permitted the use of non-catalytic motor until January, 2002. This is responsible for the high values for both Pt and Pd in the non-residual soils of the urban areas of Napoli.     

Platinum and palladium variations through the urban environment: evidence from 11 sample types from Sheffield, UK

Platinum (Pt) and Palladium (Pd) concentrations have been analysed in 194 samples from within the city of Sheffield in the UK. The samples were taken from road dust, gully pots (also known as drains), soils, a motorway drainage pipe, rivers, lakes, sewage sludge, incinerator ash, incinerator ash in landfill, street cleansers and gully cleansers. The introduction of Pt- and Pd-bearing automobile catalysts, has been cited as the cause of a rise in the concentration of urban Pt and Pd accumulations. Geochemical analyses for the different sample types are used here to show how the Pt and Pd accumulate in different urban environments as they are transported from their catalytic source. Initially Pt and Pd collect in road dust and gully pots at values of up to 450 ppb although most analyses for both elements are around 100 ppb. The four roadside soils analysed, have a great range in values, the highest with a value of over 600 ppb Pt and 1000 ppb Pd. Then the fate of the Pt and Pd is either to be removed by gully flushers and road sweepers (which contain around half the concentration of that in road dust) or to be washed from the roads, through the gully pots, into either the river or urban drainage systems. Due to the addition of terrestrial sediments, river samples contain much reduced values of Pt and Pd, at approximately an order of magnitude lower than in road dust. Similarly, sewage sludge contains Pt and Pd values which are lower than road dust. However, the Pt and Pd analyses are much higher in incinerated sewage (with many samples over 150 ppb for both metals), probably due to the loss of the mass of other material during the incineration process. Weathered incinerator ash in landfill has lower values of Pt and Pd than fresh ash from the incinerator. Although the range in values of Pt and Pd is similar for road dust and gully pot sediments their modal values tell a different story. The mode for Pt is very similar for both road dust and gully pot sediments, at around 100 ppb, whereas there is a drop of 50 ppb in the mode for Pd in the gully pots (from 80 ppb to around 40 ppb). Given that gully pot sediment is derived from road dust, it is suggested that in gully pots, Pd is preferentially mobilized over Pt. Furthermore, a comparison of the modal values of Pt and Pd in river sediments suggests that this process continues into the natural drainage system of the city.     

Bioaccumulation of palladium, platinum and rhodium from urban particulates and sediments by the freshwater isopod Asellus aquaticus.

The three-way catalytic converters introduced to oxidize and reduce gaseous automobile emissions represent a source of platinum group elements (PGEs), in particular platinum, palladium and rhodium, to the urban environment. Abrasion of automobile exhausts leads to an increase of the concentration of PGEs in environmental matrices such as vegetation, soil and water bodies. The bioaccumulation of Pd, Pt and Rh by the freshwater isopod Asellus aquaticus was studied in natural ecosystems and under laboratory conditions. Owing to the low concentration level (ng g(-1)) of PGEs in the animals studied. analyses were performed with a quadrupole inductively coupled plasma mass spectrometry (ICP-MS) and hafnium, copper, yttrium, rubidium, strontium and lead were monitored for spectral interference correction. Asellus aquaticus collected in an urban river showed a content (mean +/- s) of 155.4 +/- 73.4, 38.0 +/- 34.6, and 17.9 +/- 12.2 ng g(-1) (dry weight) for Pd, Pt and Rh, respectively. The exposure of Asellus aquaticus to PGE standard solutions for a period of 24h give bioaccumulation factors of Bf: 150, 85, and 7 for Pd, Pt and Rh, respectively. Exposure of Asellus aquaticus to environmental samples for different exposure periods demonstrated that PGE bioaccumulation is time dependent. and shows a higher accumulation for the materials with a higher PGE content. While all three elements have the same uptake rate for exposure to catalyst materials, for exposure to environmental materials they havc a different uptake rate which can be attributed to transformations of the PGE species in the environment.     

The distribution of automobile catalysts-cast platinum, palladium and rhodium in soils adjacent to roads and their uptake by grass

The introduction of automobile catalysts has raised environmental concern, as this pollution control technology is also an emission source for the platinum group elements (PGE). The main aim of this study was to assess the concentrations of Pt, Pd, Rh and Au in soil and grass herbage collected adjacent to 5 roads. Soil and grass samples were collected from 4 fixed distances (0, 1, 2 and 5 m) from the road edge at each site. PGE and Au were determined by ICP-MS in all samples after acid digestion. The maximum soil Pt, Rh and Pd concentrations were measured at the road perimeters. Averaged across the sites, the Pt and Rh concentrations of 15.9+/-7.5 microg Pt kg(-1) and 22.40+/-4.73 microg Rh kg(-1) at 0-m distance decreased to 2.04+/-1.7 microg Pt kg(-1) and 3.51+/-1.96 microg Rh kg(-1), respectively at 5-m away from the roads. Pd concentrations were much higher than Pt or Rh, ranging from 120.8+/-12.0 microg Pd kg(-1) (0-m) to 84.2+/-10.9 microg Pd kg(-1) (5-m), possibly due to differences in its use, emission and/or soil chemistry. Au showed little or no change with distance from the roads. However, the average Au concentration of 18.98+/-0.98 microg Au kg(-1) provides clear evidence of some input possibly due to attrition of automobile electronics. No straightforward influence of traffic flow rates on PGE distribution was found. A combination of dispersal impeding local features and slow moving and stop-and-start traffic conditions or fast moving traffic with flat open spaces may have offset the expected impacts. Rh and Pt soil concentration accounted for 66% and 34% (P<0.01) of the variability observed, respectively in their plant concentrations. Grass Pd and Au concentrations had no relationship with their respective soil concentrations.     

Compositions of first flush and composite storm water runoff in small urban and rural watersheds,north-central Texas

The objective of this study was to evaluate chemical compositions of first flush and composite storm water runoff in four small, mixed land use watersheds in north-central Texas. The watersheds range from urban to rural, all discharging to a local lake providing aquatic habitat, recreation, flood control and drinking water. Automated devices near watershed outlets collected samples from seven storm events, from April 2001 to September 2003. Samples were analyzed for suspended solids, pesticides (diazinon, triazine and chlorpyrifos), nutrients (nitrogen and phosphorus), fecal coliforms and metals. Observed concentrations of most parameters were low relative to drinking water maximum contaminant levels (MCLs) and aquatic life criteria. Fecal coliforms and lead were detected in most samples, with highest lead concentrations in the most developed watershed, likely influenced by building material and automobile traffic. Pesticide concentrations were higher in an initial spring storm event following applications to control weeds and insects. Typical of urban runoff, most ammonia and phosphorus observations exceeded freshwater criteria for streams draining to lakes. Treated wastewater effluent accounted for the highest nitrogen and phosphorus observations. For most constituents, composite concentrations exceeded first flush concentrations, though differences were significant only for fecal coliforms.     

Effects of platinum from vehicle exhaust catalyst on carbon and nitrogen mineralization in soils

There is strong evidence of continuously increasing contamination of soils with platinum group elements (PGE), in particular with platinum (Pt) from vehicle exhaust catalysts in roadside soils. However, knowledge about the effects of Pt contamination on soil processes is very limited. The objective of this study was to investigate whether the contamination of soils with Pt at realistic environmental levels leads to observable adverse effects on selected indicator parameters of the carbon and nitrogen turnover in soils. Incubation experiments with artificially contaminated soils and solutions containing dissolved organic matter (DOM) were carried out by the use of milled material from a Pt-containing vehicle exhaust catalyst. Interaction of the catalyst material with the soil resulted in a mobilization of Pt into the dissolved phase reaching up to 0.1% of the added Pt. The amount of Pt mobilization seemed to be mainly driven by the pH of the soil. Mineralization of carbon and nitrogen did not reveal any significant adverse effect of the Pt addition as compared to the control samples. Future studies dealing with Pt effects on soil processes should focus on environmental conditions favoring Pt mobilization, e.g. such as very low pH values or large concentrations of DOM.     

Evaluation of the health risk of platinum group metals emitted from automotive catalytic converters

A health risk assessment of platinum (Pt) emitted from automotive catalytic converters is presented. Following a stepwise approach, the relevant literature is discussed in order to characterize Pt emissions as well as the toxic potential of Pt and its compounds. In an exposure assessment, ambient Pt concentrations in air are predicted to range from approximately 4 pg/m3 (street canyon, typical conditions) up to approximately 112 pg/m3 (express motorway, severe conditions). These values agree well with the few measured concentrations, which are also in the low pg/m3 range. Pt is emitted from catalytic converters in very small amounts (ng/km range), mainly in the (0)-oxidation state (elemental Pt). The nanocrystalline Pt particles are attached to microm-sized aluminum oxide particles. Whether free ultrafine Pt particles may be emitted and result in biological effects has not been studied sufficiently. Hence, risk assessment can only be based on the respiratory sensitizing potential of halogenated Pt salts. The presence of such compounds in automotive Pt emissions cannot definitely be excluded. From recent occupational studies conducted in catalytic converter production, a conservative no-effect level (NOEL) of 1.5 ng/m3 can be derived for the sensitizing effect of halogenated Pt salts. In a (reasonable) worst case approach, it is assumed that such compounds comprise 1% (0.1%) of the total Pt emissions. Applying a safety factor of 10 to account for interindividual variability, a guidance value of 15 (150) ng/m3 is derived for catalyst-borne Pt. The exposure to Pt in ambient air as measured or predicted is at least two orders of magnitude below this guidance range. Rhodium is also contained in automotive catalysts, palladium has increasingly substituted Pt, and iridium-based catalysts have recently been introduced. Although the database on these platinum group metals is rather small, there is no evidence that they pose a health risk to the general population.     

Quantities and associations of lead, zinc, cadmium, manganese, chromium, nickel, vanadium, and copper in fresh Mississippi delta alluvium and New Orleans alluvial soils

The topic of this study is the effect of anthropogenic metals on the geochemical quality of urban soils. This is accomplished by comparing the metal contents and associations between two alluvial soils of the lower Mississippi River Delta, freshly deposited alluvial parent materials and alluvial soils collected from a nearby urban environment. Fresh alluvium samples (n = 97) were collected from the Bonnet Carré Spillway. The urban alluvial soil samples (n = 4026) were collected from New Orleans and stratified by census tracts (n = 286). The Spillway samples tend to have less Pb and Zn than generally noted for the baseline of natural soils. Except for Mn and V, Spillway alluvium contains significantly less metal than urban soils. For Spillway samples, the median metal content (in microg g(-1)) is 4.7 Pb, 11.1 Zn, 0.7 Cd, 164 Mn, 0.8 Cr, 3.9 Ni, 3.2 V, and 3.9 Cu. For urban soils, the median metal content (in microg g(-1)) is 120 Pb, 130 Zn, 3.2 Cd, 138 Mn, 2.1 Cr, 9.8 Ni, 3.8 V, and 12.7 Cu. Metal associations also differ between Spillway alluvium and urban alluvial soils. Fresh alluvium correlation coefficients between individual metals vary from 0.87 to 0.99 (P < 10(-13)) except for Cr which ranges from 0.57 to 0.68 (P < 10(-7)). The urban soil correlation coefficients for metals and the index value are 0.40-0.98. In urban soils, Pb, Zn, Cr, and Cu are dominant metals and highly associated, with a correlation coefficient ranging from 0.83 to 0.98 (P < 10(-25)). Their strong association justifies the use of GIS to map the integrated soil metal index (sum of the medians of metals by census tract) of New Orleans. Although also positively correlated (0.40-0.68, P < 10(-10)), Cd, Mn, Ni and V differ in their distribution in the city compared to Pb, Zn, Cr and Cu. Overall, significantly higher metal values occur in the inner city and lower values occur in outlying areas. The human health impact of the mixture of metals is not well understood. This study provides empirical data about the mixture and distribution of metals in New Orleans alluvial soils. Given common technical development, especially of traffic flows in cities, similar patterns of soil metals are expected for all US cities and probably international cities as well. Primary prevention of urban metal accumulations is necessary to enhance and sustain the development of urban culture.     

Polycyclic Aromatic Hydrocarbons (PAHs) in urban topsoils: Concentration and source analysis in Xuzhou,China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants in urban environments and are considered as the priority pollutants by the US Environmental Protection Agency (EPA). In this study, surface soils (0–10 cm) samples from 41 sampling sites in Xuzhou (China) were collected and analysed for 16 EPA priority polycyclic aromatic hydrocarbons via gas chromatograph/mass spectrometry (GC-MS). Total PAHs concentrations were in the range of 526 to 8612 ng/g with a mean of 2468 ng/g. Total PAHs concentrations were compared to guideline and results showed that nearly all urban soils in our study can be classified as heavily contaminated (>1000 ng/g). Carcinogenic PAHs were detected in relatively high concentrations and contributed 40.2% of the total PAHs in the urban soils. Multivariate statistical analysis including cluster analysis and factor analysis were performed and grouped the 16 PAHs under 2 clusters, which could indicate that the PAHs had different origins. The values of PAHs isomer indicated that vehicular emission might contribute to the soil PAHs in urban topsoils. The carcinogenic potency of PAH compounds was calculated and was found to be insignificant at the present level of emissions in Xuzhou.     

Platinum-group elements in sewage sludge and incinerator ash in the United Kingdom: Assessment of PGE sources and mobility in cities

Platinum-group element (PGE) concentrations in sewage sludge and incinerator ash compared with average PGE concentrations in road dust show a common pattern, characterized by a negative Rh anomaly. This similarity, found at 9 UK incinerators, suggests that there is a universal characteristic PGE pattern produced by common processes of dispersal of Pt, Pd and Rh derived from automobile catalytic converters.Ninety-one sewage sludge and incinerator ash samples from the sewage treatment facilities in Sheffield, Birmingham and 7 other UK cities were analyzed for PGE. The highest concentrations are 602 ppb Pt and 710 ppb Pd with lower maximum concentrations of 65 ppb Rh, 100 ppb Ru, 33 ppb Ir and 12 ppb Os. Ash from incinerated sewage was found to have higher PGE concentrations compared to the original sludge and the PGE ratios are preserved during incineration.Rh is more mobilized and dispersed than the other PGE as it is transported from roads into the drainage system and into sewage. Pt/Pd ratios of 1.0 in road dust and 0.9 in sewage and incinerator ash suggest that Pd is more mobile than Pt during dispersal. PGE abundances in stored incinerator ash of varying ages appear to have been affected by the variation in use of Pt, Pd and Rh in catalytic converters due to variation in their market prices.Concentrations of Os, Ir and Ru in ashes are greater in Sheffield and London than all the other city sites and may be derived from point industrial sources.     

Heavy metals in urban soils: a case study from the city of Palermo (Sicily), Italy

Concentrations of V, Mn, Cd, Zn, Ni, Cr, Co, Cu, Pb, Hg and Sb were measured on 70 topsoil samples collected from green areas and parks in the city of Palermo (Sicily) in order to: (1) assess the distribution of these heavy metals in the urban environment; (2) discriminate natural and anthropic contributions; and (3) identify possible sources of pollution. Mineralogy, physico-chemical parameters, and major element contents of the topsoils were determined to highlight the influence of 'natural' features on the heavy metal concentrations and their distribution. Medians of Pb, Zn, Cu and Hg concentrations of the investigated urban soils are 202, 138, 63 and 0.68 mgkg(-1), respectively. These values are higher, in some case by different orders of size, than those of unpolluted soils in Sicily that average 44, 122, 34 and 0.07 mg kg(-1). An ensemble of basic and multivariate statistical analyses (cluster analysis and principal component analysis) was performed to reduce the multidimensional space of variables and samples, thus defining two sets of heavy metals as tracers of natural and anthropic influences. Results demonstrate that Pb, Zn, Cu, Sb and Hg can be inferred to be tracers of anthropic pollution, whereas Mn, Ni, Co, Cr, V and Cd were interpreted to be mainly inherited from parent materials. Maps of pollutant distribution were constructed for the whole urban area pointing to vehicle traffic as the main source of diffuse pollution and also showing the contribution of point sources of pollution to urban topsoils.     

PAHs in soils: contemporary UK data and evidence for potential contamination problems caused by exposure of samples to laboratory air

Archived (1951–1974) and contemporary (1993) surface soil samples collected from the same 46 locations widely distributed over the UK have been analyzed for 12 polynuclear aromatic hydrocarbons (PAHs). Contemporary soils were analyzed wet, ensuring that contamination, losses or alteration of PAHs in the samples was minimal. Archived soils had been air-dried prior to storage. The ΣPAH concentration of the contemporary and archived soils range from approx. 20 μg kg⁻¹ to 7.4 mg kg⁻¹ (mean = 1.1 mg kg⁻¹) and from approx. 160 μg kg⁻¹ to 7.1 mg kg⁻¹ (mean = 2.1 mg kg⁻¹), respectively. Comparison of the concentrations of PAHs in the archived and contempcrary soils revealed no significant trends for compounds heavier than benzanthracene. For some of the lighter molecular weight compounds the concentrations were notably higher in the archived soils than in the contemporary soils. Two soils of contrasting PAH content (0.08 and 9.8 mg kg⁻¹) were used in an experiment to compare the effects of air-drying on soils with relatively low and high PAH concentrations. Subsamples of soil (10 g) were placed into foil trays and exposed to laboratory air for up to 64 days. A clear increase in theiconcentration of the lighter molecular weight compounds (acenaphthene, fluorene, phenanthrene) occurred in both soils. No marked changes were observed for the heavier molecular weight PAH compounds. This experiment suggests that the higher concentrations of the lower molecular weight compounds measured in the archived soil samples is due to contamination during air drying.     

A further discussion of the factors controlling the distribution of Pt, Pd, Rh and Au in road dust, gullies, road sweeper and gully flusher sediment in the city of Sheffield, UK

Forty paired road dust and gully sediments from the city of Sheffield in NE England show that high platinum, palladium and rhodium concentrations derived from catalytic converters depend on proximity to both roundabouts rather than traffic lights and to topographic lows. Road dust outside schools and control samples, further away on the same road, show that Pt, Pd and Rh concentrations are dependant on passing traffic flow rather than numbers of stopping vehicles. Highest values of Pt + Pd in road dust are 852 ppb and 694 ppb in gullies. Rh has maximum values of 113 ppb in road dust and 49 ppb in gullies. Pt and Pd values of a few ppb to just over 100 ppb occur in road dust where traffic does not stop, on roads away from junctions. Pt, Pd, Rh and Au are all picked up by road sweepers and gully flushers both with maximum values of just over 100 ppb Pt and Pd. High Au values (maximum 610 ppb in a road dust) were located on pavements, in suburbs, outside schools and in road sweepers collecting in residential areas rather than on high traffic flow roads. Stratification of Pt and Pd in gullies was not observed whereas a high Au value was recorded at the bottom of a gully suggesting gravity concentration for Au. Anomalous Pd grades of 1050 ppb in road dust from a school entrance and 2040 ppb in a street sweeper sample were recorded. These high Pd- and Au-bearing samples do not have anomalous Pt or Rh values and may be sourced from jewellery or dental fillings. However, most samples have consistent Pt/Pd ratios of about 1 and Pt/Rh values of 4 to 5 indicating a catalytic converter source. Pt and Pd are concentrated in road dust at levels well above background in all the samples, including on high and low traffic flow roads.     

The concentration of some trace elements in human milk from Italy

The concentration of some trace elements has been measured in samples of breast milk collected from several subjects over a period of about 1–3 months starting 15 days post-partum.A decrease of Zn concentration during the lactation period was observed in all subjects. The marked relation existing between dietary intake and milk content of trace elements is confirmed by the finding that Cs concentration in diet, fresh waters and human milk samples from Latium were one to two orders of magnitude higher than those measured in a small town in the south of Italy. In most subjects Cs, Zn, Rb, Fe concentrations during the same day, and in the same feed, are fairly constant. Larger variations are observed for concentrations of Co, Sc, and Sb.     

Critical budget of metal sources and pathways in the Seine River basin (1994-2003) for Cd, Cr, Cu, Hg, Ni, Pb and Zn

River basin metal pollution originates from heavy industries (plating, automobile) and from urban sources (Paris conurbation: 2740 km(2), 9.47 million inhabitants). The natural sources of metal have been found to be limited due to sedimentary nature of this catchment and to the very low river sediment transport (10 t km(-2) y(-1)). Several types of data have been collected to build the metal budget within the whole Seine River basin: field surveys, economical statistics and environmental models. Environmental contamination and related fluxes have been measured on atmospheric fallout, rural streams particles, and Seine River particles upstream and downstream of Paris and at river mouth. Metal pathways and budgets have been set up for (i) a typical cultivated area, (ii) a Paris combined sewer system, (iii) Paris conurbation and (iv) the whole catchment metal retention effect in floodplain and dredged material. Metal fluxes to the estuary have been decomposed into natural, urban domestic and other sources. The latter are within 1-2 orders of magnitude larger than waste water fluxes directly released into rivers according to an industrial census. These fluxes have been further compared to the annual use (1994-2003) of these metals. Metal excess fluxes exported by the river are now a marginal leak of metal inputs to the catchment (i.e. "raw" metals, metals in goods, atmospheric fallout), generally from 0.2 to 5 per thousand. However, due to the very limited dilution power in this basin, the contamination of particles is still relatively high. The Seine River basin is gradually storing metals, mostly in manufactured products used in construction, but also in various waste dumps, industrial soils, agricultural and flood plain soils.