Occurrence of platinum and additional traffic related heavy metals in sediments and biota

Biodynamics and Environmental Concentrations of the Platinum Group Elements in Freshwater Systems

Growing reliance on platinum group elements (PGEs) as critical minerals for emerging technologies raises concerns regarding their ecotoxicological behavior. We studied their environmental fate in various inorganic and biological matrices from Canada using ICP-MS/MS analysis. Our findings confirmed previously published rhodium, palladium, and platinum concentration gradients from road dust to sediments, soils, and water, but differed from the literature reporting high biological contamination, which was not observed in our study. We also conducted experiments using a predator-prey model by exposing Chaoborus americanus to PGE mixtures for 24 h and to contaminated prey (Daphnia magna) for 8 days, followed by a 3-day excretion period. We estimated water uptake rate constants (kuw = 1.6-3.5 mL g-1 d-1), assimilation efficiencies (AEs = 0.024-32.2%), and efflux rate constants (ke = 0.51-0.69 d-1) for four PGEs. Overall, Chaoborus showed poor bioaccumulation and low trophic transfer of the PGEs, which were rapidly excreted. Experimental results supported low detection of PGEs in wild organisms, underscoring the need for caution when interpreting studies reporting high PGE levels in biological matrices. Nonetheless, this study improves our understanding of the PGEs' environmental fate, revealing correlations with several quantitative ion character-activity relationships (QICARs) and highlighting chemical bond softness (σParr) as a predictor of biological assimilation and excretion.

Fate of antimony contamination generated by road traffic - A focus on Sb geochemistry and speciation in stormwater ponds

Although antimony (Sb) contamination has been documented in urban areas, knowledge gaps remain concerning the contributions of the different sources to the Sb urban biogeochemical cycle, including non-exhaust road traffic emissions, urban materials leaching/erosion and waste incineration. Additionally, details are lacking about Sb chemical forms involved in urban soils, sediments and water bodies. Here, with the aim to document the fate of metallic contaminants emitted through non-exhaust traffic emissions in urban aquatic systems, we studied trace element contamination, with a particular focus on Sb geochemistry, in three highway stormwater pond systems, standing as models of surface environments receiving road-water runoff. In all systems, differentiated on the basis of lead isotopic signatures, Sb shows the higher enrichment factor with respect to the geochemical background, up to 130, compared to other traffic-related inorganic contaminants (Co, Cr, Ni, Cu, Zn, Cd, Pb). Measurements of Sb isotopic composition (δ¹²³Sb) performed on solid samples, including air-exposed dusts and underwater sediments, show an average signature of 0.07 ± 0.05‰ (n = 25, all sites), close to the δ¹²³Sb value measured previously in certified reference material of road dust (BCR 723, δ¹²³Sb = 0.03 ± 0.05‰). Moreover, a fractionation of Sb isotopes is observed between solid and dissolved phases in one sample, which might result from Sb (bio)reduction and/or adsorption processes. SEM-EDXS investigations show the presence of discrete submicrometric particles concentrating Sb in all the systems, interpreted as friction residues of Sb-containing brake pads. Sb solid speciation determined by linear combination fitting of X-Ray Absorption Near Edge Structure (XANES) spectra at the Sb K-edge shows an important spatial variability in the ponds, with Sb chemical forms likely driven by local redox conditions: "dry" samples exposed to air exhibited contributions from Sb(V)-O (52% to 100%) and Sb(III)-O (<10% to 48%) species whereas only underwater samples, representative of suboxic/anoxic conditions, showed an additional contribution from Sb(III)-S (41% to 80%) species. Altogether, these results confirm the traffic emission as a specific source of Sb emission in surface environments. The spatial variations of Sb speciation observed along the road-to-pond continuum likely reflect a high geochemical reactivity, which could have important implications on Sb transfer properties in (sub)surface hydrosystems.

Aquatic Ecological Risk of Heavy-Metal Pollution Associated with Degraded Mining Landscapes of the Southern Africa River Basins: A Review

Africa accounts for nearly 30% of the discovered world’s mineral reserves, with half of the world’s platinum group metals deposits, 36% of gold, and 20% of cobalt being in Southern Africa (SA). The intensification of heavy-metal production in the SA region has exacerbated negative human and environmental health impacts. In recent years, mining waste generated from industrial and artisanal mining has significantly affected the ecological integrity of SA aquatic ecosystems due to the accelerated introduction and deposition of heavy metals. However, the extent to which heavy-metal pollution associated with mining has impacted the aquatic ecosystems has not been adequately documented, particularly during bioassessments. This review explores the current aquatic ecological impacts on the heavily mined river basins of SA. It also discusses the approaches to assessing the ecological risks, inherent challenges, and potential for developing an integrated ecological risk assessment protocol for aquatic systems in the region. Progress has been made in developing rapid bioassessment schemes (RBS) for SA aquatic ecosystems. Nevertheless, method integration, which also involves heavy-metal pollution monitoring and molecular technology, is necessary to overcome the current challenges of the standardisation of RBS protocols. Citizenry science will also encourage community and stakeholder involvement in sustainable environmental management in SA.

Metal contamination and toxicity of soils and river sediments from the world's largest platinum mining area

Mining activities in the world's largest platinum mining area in South Africa have resulted in environmental contamination with Pt (e.g., the Hex River's vicinity). The present study compared a Pt mining area with a non-mining area along this river in terms of (1) metal concentrations in different grain size fractions from soils and aquatic sediments; (2) the toxicological potential of aquatic sediments based on the Consensus-Based Sediment Quality Guideline (CBSQG); and (3) the chronic toxicity of aqueous eluates from soils and sediments to Caenorhabditis elegans. Platinum concentrations were higher in the mining area than in the non-mining area. For most metals, the sediment silt and clay fraction contained the highest metal concentrations. Based on the CBSQG, most sampling sites exhibited a high toxicological potential, driven by Cr and Ni. Eluate toxicity testing revealed that C. elegans growth, fertility, and reproduction inhibition were not dependent on mining activities or the CBSQG predictions. Toxicity was instead likely due to Cd, Fe, Mn, Ni, Pt, and Pb. In conclusion, the investigated region is loaded with a high geogenic background resulting in high reproduction inhibition. The mining activities lead to additional environmental metal contamination (particularly Pt), contributing to environmental soil and sediment toxicity.

A chemical and ecological assessment into elemental loading from ford crossings in Ashdown Forest, Sussex, United Kingdom

Numerous studies have identified the issue of road surface runoff as a source of contamination into waterways but the impact of vehicular wash-off is less well understood. A ford crossing provides a pathway for vehicle-derived contaminants emanating from both road surface runoff and vehicular wash-off into a river system. Twyford Lane Ford (Ford 1) and Birchgrove Lane Ford (Ford 2), located ca. 600 m apart on a tributary of the River Ouse in Sussex (UK), were the focus of this study. A combination of biomonitoring (assessment of benthic macroinvertebrates) and chemical assessments of water and sediments has been undertaken to determine any detrimental impacts, such as a lack in biodiversity, resulting from the ford crossings. Sediment concentrations of chromium (Cr³⁺), lead (Pb) and zinc (Zn) were generally elevated at Ford 1, attenuating at sampling points between the fords to then peak at Ford 2. However, sediment particle size was seen to have an influence on elemental concentrations. In general, an increase in elemental concentrations was associated with a higher percentage of fine-grained sediments (≤63 μm). Elevated concentrations of Zn and magnesium (Mg) were identified within water samples taken during a precipitation event following a prolonged dry period. The biomonitoring results found reduced BMWP (Biological Monitoring Working Party) scores at positions close to the ford crossings, and where the stream was in proximity to the roadside. Sensitive Ephemeroptera were largely absent at sampling points closest to the fords, which is likely to be associated with elevated Zn. The results suggest that careful consideration should be applied when selecting crossing points over sensitive waters.

Assessment of heavy metal pollution in Vistula river (Poland) sediments by using magnetic methods

The present study evaluated the level of heavy metal (HM) pollution in Vistula river sediments in a highly urbanized Warsaw agglomeration (Poland). Magnetometry was used to assess the pollution level by measuring the fine fractions (0.071 mm and < 0.071 mm) of sediments collected from the surface layer of the riverbank. The magnetic methods (e.g., mass magnetic susceptibility χ, temperature-dependence magnetic susceptibility, and hysteresis loop parameters) were supplemented by microscopy observations and chemical element analyses. The results showed the local impact of Warsaw's activity on the level of HM pollution, indicated by the maximum concentrations of magnetic particles and HM in the city center. The sediment fraction < 0.071 mm was dominated by magnetite and by a large amount of spherical-shaped anthropogenic magnetic particles. The pollution from the center of Warsaw was transported down-river over a relatively short distance of approximately 11 km. There was a gradual decrease in the concentrations of magnetic particles and HM in areas located to the north of the city center (down-river); furthermore, χ and concentrations of HM did not decrease to the values observed for the area to the south of Warsaw (up-river). The study showed two possible sources of sediment pollution: traffic-related and heat and power plant emissions. The influence of an additional source of pollution cannot be excluded as the amount of spherules in the sediments at the center was extremely high. The present study demonstrates that magnetometry has a practical application in detecting and mapping HM pollution in river systems.

Comparative study of cytotoxicity by platinum nanoparticles and ions in vitro systems based on fish cell lines

Emission of platinum nanoparticles (Pt NPs) especially from vehicle exhaust catalysts and pharmaceutics cause an increase in concentrations of this metal in aquatic environments. In this study, small (4-9 nm) uncoated and polyvinylpyrrolidone (PVP) coated Pt NPs were synthetized and their dispersion in different exposure media were evaluated. Pt NP uptake in two established fish cell lines were investigated and comparative in vitro cytotoxicity of Pt NPs and ions were assessed. The coated and uncoated Pt NPs dispersions in minimum essential medium (MEM) with fetal bovine serum (FBS) displayed high colloidal stability. Transmission electron microscopy (TEM) and high-resolution scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (STEM/EDX) indicated no detectable cellular uptake of Pt NPs in both cell line monolayers. But with ICP-MS analysis, trace amount of Pt content was determined in all digested monolayer cell samples. The cytotoxicity of both Pt NPs and Pt ions on both fish cell lines after 48 h exposure was investigated through three assays to monitor different endpoints of cytotoxicity. In all studied concentrations (0.325-200 mg/L) no significant cytotoxicity (p > .5) compared to controls were observed in the cells exposed to coated Pt NPs. Uncoated Pt NP and ion exposed cells indicated similar concentration dependent cytotoxicity on both cell lines.

Metal accumulation in riverine macroinvertebrates from a platinum mining region

South Africa is the world's main supplier of Pt. The Bushveld Igneous Complex in South Africa contains 75% of the world's Pt resources. Mining of this precious metal requires large volumes of water for production and removal of waste products. Most of this wastewater is discharged into river systems. Although the source of contamination with Pt in aquatic systems due to mining activities is known, little to no information is available about the impact of Pt on aquatic organisms. Additionally, other metals are released as byproducts of Pt mining, which might also be discharged into the environment. Therefore, concentrations of Cr, Ni, Cu, Zn, Cd, Pt and Pb were determined in water, sediment and macroinvertebrate samples from a reference site (Site 1), a highly impacted site (Site 2) and a moderately impacted site (Site 3) along the Hex River, South Africa. Aquatic invertebrate families representing different functional feeding groups i.e. scraper-grazers (Lymnaeidae), collector-gatherers (Potamonautidae, Hydropsychidae, Tubificidae and Chironomidae), shredders (Baetidae) and predators (Coenagrionidae and Libellulidae) were studied. In the sediments, the concentrations of Cr and Pt were significantly higher at Site 2 than at Sites 1 and 3, respectively, whereas concentrations of Ni, Cu, Cd, and Pb showed no significant differences between the sites. Depending on the metal, the aquatic invertebrate families showed different grades of bioaccumulation. The results from especially Lymnaeidae, Baetidae, Tubificidae and Chironomidae showed great promise for the use of these taxa for biomonitoring of metal contaminations. The macroinvertebrates accumulated metals associated with Pt mining, with epi-benthic dwelling taxa (Tubificidae) accumulating higher concentrations of Pt and Cr than other families (e.g. Potamonautidae, Coenagrionidae and Lymnaeidae). These results provide valuable information on the behavior of metals related to Pt mining in aquatic ecosystems and therefore can contribute to the risk assessment of these intensive mining activities.

The freshwater isopod Asellus aquaticus as a model biomonitor of environmental pollution: A review

Anthropogenic substances pollute freshwater systems worldwide, with serious, long-lasting effects to aquatic biota. Present methods of detecting elevated levels of trace metal pollutants are typically accurate but expensive, and therefore not suitable for applications requiring high spatial resolution. Additionally, these methods are not efficient solutions for the determination of long-term averages of pollution concentration. This is the rationale for the implementation of a biomonitoring programme as an alternative means of pollutant detection. This review summarises recent literature concerning the past and potential uses of the benthic isopod Asellus aquaticus as a biomonitor for pollution in freshwater systems. Recent studies indicate that A. aquaticus is well suited for this purpose. However, the mechanisms by which it bioaccumulates toxins have yet to be fully understood. In particular, the interactions between coexisting trace metal pollutants in the aquatic environment have only recently been considered, and it remains unclear how a biomonitoring programme should adapt to the effects of these interactions. It is evident that failing to account for these additional stressors will result in an ineffective biomonitoring programme; for this reason, a comprehensive understanding of the bioaccumulation mechanisms is required in order to reliably anticipate the effects of any interferences on the outcome.

Concentration, Distribution, and Potential Aquatic Risk Assessment of Metals in Water from Chott Merouane (Ramsar Site), Algeria

In this study, 28 surface water samples were collected from eight different sites throughout the Chott Merouane. Samples were detected by atomic absorption spectrometry for Cd, Co, Cr, Cu, Fe, Ni, Mn, Pb, and Zn. The dissolved metal concentrations (mg/L) ranged from 0.05 to 0.90 mg/L for Cd, 0.13-6.45 mg/L for Co, bDL-2.05 mg/L for Cr, 0.03-0.27 mg/L for Cu, 0.34-7.41 mg/L for Fe, 01.6-4.54 mg/L for Ni, 0.15-1.19 mg/L for Mn, 0.23-5.88 mg/L for Pb, and 0.01-0.28 mg/L for Zn. Compared with U.S. EPA standards and other freshwaters worldwide, the most mean concentration of metals in surface water of this salt lake are higher than the guideline levels of aquatic life. This was further corroborated by results from the water quality indices that Chott Merouane is seriously polluted by metals. The values of the metal pollution index indicated that metal pollution level was Cd > Pb > Ni > Fe > Cr > Cu > Mn > Zn, and those metals belong to moderate or high pollution level. The Nemerow pollution index further indicated that Chott Merouane was suffering from serious metal contamination. Based on geostatistics analyses, generally distributions of these metal contents decreased in the order of the North Chott Merouane ≈ the Northwest Chott Merouane > the Eastern part of Chott Merouane > the South Chott Merouane. The quality of water has drastically deteriorated due to the mixed source of anthropogenic inputs. Therefore, necessary conservation and management measures should be taken to improve the water quality of this Ramsar wetland.

Impact of environmental factors on aquatic biodiversity in roadside stormwater ponds

Constructed stormwater ponds mitigate runoff volumes and pollution, and provide other ecosystem services, such as supporting biodiversity, but these services attracted relatively less attention. The impacts of the pollution levels in the water column and sediments, the physical characteristics of ponds, and the presence of amphibians on the macroinvertebrate community composition and biodiversity were explored in twelve stormwater ponds in Norway. Also, the similarities between macroinvertebrate, zooplankton and plant communities were explored. Most of the taxa displayed in the ordination diagram were positively correlated with the pond size and the number of neighbouring ponds, and negatively correlated with the pollution levels in the water column and sediments. However, no statistically significant impacts on the number of taxa and Shannon index were observed. There were low similarities between the macroinvertebrate and zooplankton community compositions as well as between the plant and macroinvertebrate community compositions in the stormwater ponds. We observed a significant positive correlation between the number of plant and of zooplankton taxa, and a weak non-significant positive correlation between the number of plant and of macroinvertebrate taxa. Overall, the explanatory variables had a significant impact on the community composition, but not on the number of taxa nor Shannon index.

Active biomonitoring for assessing effects of metal polluted sediment resuspension on gammarid amphipods during fluvial traffic

The resuspension of polluted sediments by boat traffic could release substantial amounts of metals to the water column, affecting at the same time their bioavailability. In order to characterize the impact of sediment resuspensions on biota, caged amphipods have been deployed on three different channelized watercourses in Northern France. Firstly, the biological responses of transplanted freshwater gammarid amphipods, Gammarus fossarum, described by trace metal accumulation, feeding and reproduction activities were quite similar for the three water courses despite the differences of metal contamination and navigability. Secondly, the concentrations of metals accumulated in gammarids never exceeded the contamination thresholds previously defined for Co, Cu, Cr and Zn. Values were in the same order of magnitude whatever the studied site despite: (i) large differences noticed in the sediment quality and (ii) some concentrations in the overlying waters exceeding the Environmental Quality Standards (EQS) defined by the Water Framework Directive. Conversely, Pb was highly bioaccumulated with values systematically exceeding the threshold value whatever the site. Therefore, the impact of navigation cannot be proved and the difference between the 3 monitoring periods is rather attributed to environmental variability, probably linked to the seasonality. Moreover, this study also confirms that organisms sampled from a local population in the vicinity of the three studied watercourses could be used as test organisms, leading to similar results than the ones obtained with reference gammarids initially used for developing all the biological responses. This would simplify and then promote the development of studies based on gammarid amphipod, G. fossarum, as bioindicators.

A Multimethod Approach for Investigating Algal Toxicity of Platinum Nanoparticles

The ecotoxicity of platinum nanoparticles (PtNPs) widely used in for example automotive catalytic converters, is largely unknown. This study employs various characterization techniques and toxicity end points to investigate PtNP toxicity toward the green microalgae Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii. Growth rate inhibition occurred in standard ISO tests (EC₅₀ values of 15-200 mg Pt/L), but also in a double-vial setup, separating cells from PtNPs, thus demonstrating shading as an important artifact for PtNP toxicity. Negligible membrane damage, but substantial oxidative stress was detected at 0.1-80 mg Pt/L in both algal species using flow cytometry. PtNPs caused growth rate inhibition and oxidative stress in P. subcapitata, beyond what was accounted for by dissolved Pt, indicating NP-specific toxicity of PtNPs. Overall, P. subcapitata was found to be more sensitive toward PtNPs and higher body burdens were measured in this species, possibly due to a favored binding of Pt to the polysaccharide-rich cell wall of this algal species. This study highlights the importance of using multimethod approaches in nanoecotoxicological studies to elucidate toxicity mechanisms, influence of NP-interactions with media/organisms, and ultimately to identify artifacts and appropriate end points for NP-ecotoxicity testing.

The pH-dependent release of platinum group elements (PGEs) from gasoline and diesel fuel catalysts: Implication for weathering in soils

Powdered samples of new and old gasoline catalysts (Pt, Pd, Rh) and new and old diesel (Pt) catalysts were subjected to a pH-static leaching procedure (pH 2-9) coupled with thermodynamic modeling using PHREEQC-3 to verify the release and mobility of PGEs (platinum group elements). PGEs were released under acidic conditions, mostly exhibiting L-shaped leaching patterns: diesel old: 5.47, 0.005, 0.02; diesel new: 68.5, 0.23, 0.11; gasoline old: 0.1, 11.8, 4.79; gasoline new 2.6, 25.2, 35.9 in mg kg(-1) for Pt, Pd and Rh, respectively. Only the new diesel catalyst had a strikingly different leaching pattern with elevated concentrations at pH 4, probably influenced by the dissolution of the catalyst carrier and washcoat. The pH-static experiment coupled with thermodynamic modeling was found to be an effective instrument for understanding the leaching behavior of PGEs under various environmental conditions, and indicated that charged Pt and Rh species may be adsorbed on the negatively charged surface of kaolinite or Mn oxides in the soil system, whereas uncharged Pd and Rh species may remain mobile in soil solutions.

Assessment of palladium footprint from road traffic in two highway environments

Palladium (Pd) is an emerging eco-toxic pollutant from vehicle catalytic converters, emitted worldwide for more than two decades. Nowadays, the spatial extent of Pd fallout is growing along roads, but its subsequent fate in neighboring terrestrial ecosystems has not been extensively addressed yet. Two sites representative of contrasted natural environments (field, forest) but located under similar ambient conditions were selected to isolate and analyze the specific impact of vehicular Pd, along highway A71, France. Pd impregnation was assessed along 200-m-long transects perpendicular to the highway. Contents were measured in soils, earthworms, plant communities of the right of way (ROW), and the neighboring field (crop weeds), as well as in a moss, and bramble and ivy leaves in the forest. The direct impact of Pd fallouts appears to be confined in the grassy verge of the highway: ROW soils ([Pd] = 52-65 ng g(-1)), earthworms ([Pd] = 18-38 ng g(-1)), and plant community ([Pd] = 10-23 ng g(-1)). Pd footprint is pointed out by the accumulation index calculated for earthworms and plant communities even though transfer coefficients indicate the absence of bioaccumulation (TCs < 1). An indirect longer range transfer of Pd is identified, induced by hydric transport of organic matter.

Evidence of increased anthropogenic emissions of platinum: time-series analysis of mussels (1991-2011) of an urban beach

The anthropogenic emissions of Pt to the environment have increased significantly over the past decades, especially after the introduction of the catalytic converters in motor vehicles. In order to check whether this is affecting the levels of this trace metal on living organisms, time-series analysis of freeze-dried soft tissue material of wild mussels (Mytilus galloprovincialis) covering the period from 1991 to 2001 and collected at an urban beach in the city of Vigo (NW Iberian Peninsula) was conducted. Concentrations ranged from 0.30 to 0.68 ng g(-1) with an average concentration of 0.47 ± 0.10 ng g(-1) (n=21); these concentrations were higher than those obtained for samples collected at a control location away from anthropogenic pressure (0.31 ± 0.10 ng g(-1); n=5). Platinum concentrations followed a statistically significant temporal trend (at the 0.020 level), and the excess of Pt in mussels over the 1991-2011 period compared to the control location were correlated with the European Pt autocatalyst demand (p=0.0006) and, especially, the car sales in Spain (p=0.0001). A bioaccumulation factor of ~5·10(3) was derived, which is greater than those previously calculated for Pt from exposure experiments, but 1-2 orders of magnitude lower than other trace elements (e.g. Zn, Cu, Pb, Cd).

Trace metal concentrations in hairs of three bat species from an urbanized area in Germany

Metal-contaminated soils and sediments are widespread in urbanized areas due to atmospheric deposition close to emission sources. These metals are bio-available for organisms, e.g., insects, and accumulate in food chains of insectivorous mammals. Especially bats, which live in urban regions and ingest large amounts of food relative to their body mass, are at risk of being poisoned due to the accumulation of trace metals. To determine species-specific trace metal contents in bats from urban environments, hair samples were analyzed by ICP-OES. Observed trace metal concentrations were related to species-specific foraging habitat, prey spectrum and degree of synanthropy. The species studied were Pipistrellus pipistrellus, Myotis daubentonii and Nyctalus noctula. P. pipistrellus showed the highest concentrations of lead and zinc and slightly higher concentrations of cadmium than the other two species, which was related to its high degree of synanthropy with foraging habitat mostly located in cities. In contrast, N. noctula displayed the highest contents of manganese and copper. The reason might be found in its prey spectrum, as N. noctula feeds mainly on beetles that are caught in cultured areas. Trace metal concentrations determined in hair samples of M. daubentonii ranged between the values of P. pipistrellus and N. noctula, probably reflecting an intermediate level of synanthropy. Positive correlations were observed between the concentrations of cadmium and lead and those of manganese and copper. Hair samples from bats are suitable monitoring tools to study trace metal exposure and can be used to determine differences in trace metal levels between species.

Distribution of platinum and other traffic related metals in sediments and clams (Corbicula sp.)

Platinum is part of traffic-emitted metals since the introduction of automotive catalyst converters. Still, automobile emissions are one of the major sources for metals in European river systems. However, field data on Pt is scarce and there is a lack of knowledge concerning the distribution and biological availability of Pt. Therefore, the distribution of traffic related metals (Cd, Cr, Cu, Ni, Pb, Pt, and Zn) was analyzed in sediment samples and in the Asian clam Corbicula sp. Samples were taken from three transects following road runoff inlets. Pt was introduced into the river by road runoff. The highest Pt concentrations in sediments were analyzed in the silt/clay fraction (45 ng/g), while the highest total Pt burden was obtained for the sand fraction, that makes up more than 60% of the sediment. Metal concentrations were related to the area of the drained street section as well as to their distance from the discharge point, and to grain size distribution within the sediment. Pt and other traffic related metals were accumulated by clams. Due to the feeding behavior of the freshwater mussel Corbicula sp. Pt concentrations in the soft tissue remain relatively low (max Pt concentration: 1.3 ng/g freeze dried soft tissue) and acute lethal or toxic effects therefore appear to be unlikely. Nonetheless, chronic exposure effects still have to be examined.

Alteration of root growth by lettuce, wheat, and soybean in response to wear debris from automotive brake pads

Brakes from motor vehicles release brake pad wear debris (BPWD) with increased concentrations of heavy metals. Germination and root-elongation assays with lettuce, wheat, and soybean were used to provide an initial evaluation of the phytotoxicity of either a water extract of BPWD or BPWD particulates. In terms of germination, the only effect observed was that lettuce germination decreased significantly in the BPWD particulate treatment. Lettuce and wheat showed decreased root length and root-elongation rate in the presence of the BPWD particulates, whereas lettuce produced a significantly greater number of lateral roots in response to BPWD extract. There was no significant effect of either BPWD treatment on soybean root elongation or lateral roots. Treatment with BPWD extracts or particulates caused significant alterations in the bending pattern of the plant roots. These initial results suggest that BPWD may have effects on the early growth and development of plants.

Fate of platinum metals in the environment

For many years now automotive exhaust catalysts have been used to reduce the significant amounts of harmful chemical substances generated by car engines, such as carbon monoxide, nitrogen oxides, and aromatic hydrocarbons. Although they considerably decrease environmental contamination with the above-mentioned compounds, it is known that catalysts contribute to the environmental load of platinum metals (essential components of catalysts), which are released with exhaust fumes. Contamination with platinum metals stems mainly from automotive exhaust converters, but other major sources also exist. Since platinum group elements (PGEs): platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru) and iridium (Ir) seem to spread in the environment and accumulate in living organisms, they may pose a threat to animals and humans. This paper discusses the modes and forms of PGE emission as well as their impact on the environment and living organisms.

Dissolution of copper and iron from automotive brake pad wear debris enhances growth and accumulation by the invasive macrophyte Salvinia molesta Mitchell

Automotive vehicles release particulate matter into the environment when their brakes are applied. The environmental effects of this automotive brake pad wear debris (BPWD) on the environment is a matter of growing debate yet the effects on plants have been largely untested. In this study, the effect of BPWD on the growth of the aquatic invasive Salvinia molesta Mitchell was examined. Salvinia molesta, plants were grown hydroponically in distilled water or in a distilled water extract containing BPWD. Growth of floating leaves, submerged leaves, and leaf nodes were measured over 20 d at 4-d intervals. At the conclusion of the study the amount of BPWD present in solutions and plant tissues was quantified using atomic absorption spectrometry (AAS). Cultivation of S. molesta in the water containing BPWD resulted in greater dissolution of Cu and Fe than occurred in the absence of plants. The tissue Cu and Fe concentrations of plants cultivated in the BPWD were significantly higher than plants grown in the absence of BPWD. Growth of S. molesta significantly increased when cultivated in the BPWD solutions in comparison to the distilled water. The results suggest that S. molesta and similar aquatic plants may be capable of increasing the dissolution of metal micronutrients from BPWD and utilizing those micronutrients to increase growth. Such growth responses could indicate that BPWD may interact with invasive floating macrophytes to more rapidly degrade the quality and stability of aquatic communities.

Distribution of metals in surface sediments from a small river flowing through urban and agricultural areas

The characteristic distributions of 12 metals (Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd and Pb) were investigated in surface sediments from a small river (Niitsu River) flowing through both urban and agricultural areas by comparison with those from the upper main stream (Nodai River). Among the investigated metals, the mean concentrations of Al, Cr, Fe, Zn, Cd and Pb in the Niitsu River were significantly higher than those in the Nodai River. The investigated sites can be characterized by the principal components 1-3.

Anthropogenic atmospheric emissions of antimony and its spatial distribution characteristics in China

An integrated inventory of atmospheric antimony (Sb) emissions from anthropogenic activities in China is compiled for the years 2005-2009. Emissions are estimated for all major anthropogenic sources for the first time. We estimate that the national emissions of antimony are 818 metric tons (t) in 2009, with the largest contribution from coal combustion at 61.8% of the total, while 26.7% of Sb is emitted from nonferrous metals smelting. Emissions are heaviest in Guizhou province, mainly due to small-scale combustion of high-Sb coal without emission control devices, and in Hunan province, where extensive smelting occurs. Furthermore, Sb emissions from 2188 large point sources and area sources are distributed within latitude/longitude-based grids with a resolution of 30 min × 30 min where Sb emissions are largely concentrated in highly populated and industrialized southwestern China, the east central region, and coastal areas. The uncertainties in our bottom-up inventory are quantified as -11% to 40% by Monte Carlo simulation. We recommend continuous field testing of coal combustors and smelters in China to improve the accuracy of these estimates.

Estimation of daily intake of potentially toxic elements from urban street dust and the role of oral bioaccessibility testing

The pseudo-total and oral bioaccessible concentration of six potentially toxic elements (PTEs) in urban street dust was investigated. Typical pseudo-total concentrations across the sampling sites ranged from 4.4 to 8.6 mg kg(-1) for As, 0.2-3.6 mg kg(-1) for Cd, 25-217 mg kg(-1) for Cu, 14-46 mg kg(-1) for Ni, 70-4261 mg kg(-1) for Pb, and, 111-652 mg kg(-1) for Zn. This data compared favourably with other urban street dust samples collected and analysed in a variety of cities globally; the exception was the high level of Pb determined in a specific sample in this study. The oral bioaccessibility of PTEs in street dust is also assessed using in vitro gastrointestinal extraction (Unified Bioaccessibility Method, UBM). Based on a worst case scenario the oral bioaccessibility data estimated that Cd and Zn had the highest % bioaccessible fractions (median >45%) while the other PTEs i.e. As, Cu, Ni and Pb had lower % bioaccessible fractions (median <35%). The pseudo-total and bioaccessible concentrations of PTEs in the samples has been compared to estimated tolerable daily intake values based on unintentional soil/dust consumption. Cadmium, Cu and Ni are well within the oral tolerable daily intake rates. With respect to As and Pb, only the latter exceeds the TDI(oral) if we model ingestion rate based on atmospheric 'dustiness' rather than the US EPA (2008) unintentional soil/dust consumption rate of 100 mg d(-1). We consider it unlikely that even a child with pica tendencies would ingest as much as 100mg soil/dust during a daily visit to the city centre, and in particular to the sites with elevated Pb concentrations observed in this study.

A minimum data set of water quality parameters to assess and compare treatment efficiency of stormwater facilities

Urban stormwater runoff is often of poor quality, impacting aquatic ecosystems and limiting the use of stormwater runoff for recreational purposes. Several stormwater treatment facilities (STFs) are in operation or at the pilot testing stage, but their efficiencies are neither well documented nor easily compared due to the complex contaminant profile of stormwater and the highly variable runoff hydrograph. On the basis of a review of available data sets on urban stormwater quality and environmental contaminant behavior, we suggest a few carefully selected contaminant parameters (the minimum data set) to be obligatory when assessing and comparing the efficiency of STFs. Consistent use of the minimum data set in all future monitoring schemes for STFs will ensure broad-spectrum testing at low costs and strengthen comparability among facilities. The proposed minimum data set includes: (i) fine fraction of suspended solids (<63 μm), (ii) total concentrations of zinc and copper, (iii) total concentrations of phenanthrene, fluoranthene, and benzo(b,k)fluoranthene, and (iv) total concentrations of phosphorus and nitrogen. Indicator pathogens and other specific contaminants (i.e., chromium, pesticides, phenols) may be added if recreational or certain catchment-scale objectives are to be met. Issues that need further investigation have been identified during the iterative process of developing the minimum data set.

Evaluation of surface runoff and road dust as sources of nitrogen using nitrate isotopic composition

Stable nitrogen and oxygen isotope ratios of nitrate (δ(15)N-NO(3) and δ(18)O-NO(3)) have recently been used to identify nitrogen sources in water environments. However, there have been no investigations designed to determine nitrate isotopes in non-point sources in urban areas for evaluating the impact of surface deposits on nitrogen in surface runoff. In this study, we collected rainwater, surface runoff and surface deposits (road dust, roof dust and soil) to evaluate the nitrogen sources in surface runoff using nitrate isotopes. There were no large differences in δ(15)N-NO(3) among rainwater (-0.3‰ to 1.5‰), surface runoff (-2.7‰ to 0.4‰), leachates from road dust (-5.8‰ to 6.2‰) and soil (-11.5‰ to 0.6‰). In contrast, the δ(18)O-NO(3) in surface runoff (28.5-47.9‰) was lower than that in rainwater (62.7-78.6‰), and higher than that in leachates from road dust (6.1-27.6‰) and soil (-1.1‰ to 6.6‰). δ(18)O-NO(3) is a useful indicator for evaluating the NO(3)-N sources in surface runoff. Using this indicator, NO(3)-N from road dust was estimated to account for more than half of the NO(3)-N in surface runoff. This is consistent with a result based on a comparison of their loads per unit surface between rainwater and surface runoff, which also showed that most of the nitrogen in surface runoff was derived from surface deposits.

Evaluating the use of predatory insects as bioindicators of metals contamination due to sugarcane cultivation in neotropical streams

Streams located in areas of sugarcane cultivation receive high concentrations of metal ions from soils of the adjacent areas causing accumulation of metals in the aquatic sediment. This impact results in environmental problems and leads to bioaccumulation of metal ions in aquatic organisms. In the present study, metal concentrations in different predatory insects were studied in streams near sugarcane cultivation and compared to reference sites. Possible utilisation of predatory insects as bioindicators of metal contamination due to sugarcane cultivation from 13 neotropical streams was evaluated. Ion concentrations of Al, Cd, Cr, Cu, Zn, Fe, and Mn in adult Belostomatidae (Hemiptera) and in larvae of Libellulidae (Odonata) were analysed. Nine streams are located in areas with sugarcane cultivation, without riparian vegetation (classified as impacted area) and four streams were located in forested areas (reference sites). Metal concentrations in insects were higher near sugarcane cultivations than in control sites. Cluster analysis, complemented by an ANOSIM test, clearly showed that these insect groups are good potential bioindicators of metal contamination in streams located in areas with sugarcane cultivation and can be used in monitoring programmes. We also conclude that Libellulidae appeared to accumulate higher concentrations of metals than Belostomatidae.

Evaluation of the contamination of platinum in estuarine and coastal sediments (Tagus Estuary and Prodelta, Portugal)

Platinum contamination in estuarine and coastal sediments has been evaluated in three cores collected from the Tagus Estuary and Prodelta shelf sediments. Elevated concentrations, up to 25-fold enrichment compared to background values, were found in the upper layers of the estuarine sediments. The degree of Pt enrichment in the estuarine sediments varied depending on the proximity to vehicular traffic sources, with a maximum concentration of 9.5 ng g(-1). A considerable decrease of Pt concentrations with depth indicated the absence of significant contamination before the introduction of catalytic converters in automobiles. Platinum distribution in the Tagus Prodelta shelf sediment core showed no surface enrichment; instead a sub-surface maximum at the base of the mixed layer suggested the possibility of post-depositional mobility, thereby blurring the traffic-borne contamination signature in coastal sediments.

Bioaccumulation of PGEs and other traffic-related metals in populations of the small mammal Apodemus sylvaticus

The accumulation of the platinum group elements (PGEs), Pd, Pt, Rh, and other heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, Zn) in the wood mouse Apodemus sylvaticus was investigated in relation to environmental availability, comparing levels in the commonly used target tissues, the liver and kidney, to hair responses. In particular the research aimed to evaluate the suitability of a non-destructive hair-based biomonitoring approach and the responsiveness of PGEs as tracers for the environmental hazard assessment of pollutants linked to traffic in intensively anthropized areas. The four populations considered, inhabiting an urban, a suburban, an agricultural and a reference site, respectively, were shown to be capable of characterizing the differently polluted areas. In particular, multivariate analysis showed a significant correlation between metal levels in tissues and soils. Animals from both the urban and suburban sites, compared to those from the reference site, showed higher levels of those elements (PGEs, Cd, Cr, Ni, Pb and Zn), the availability of which is likely to be related to road traffic. On the contrary, Mn and Cu characterized the animals from the agricultural site. Even though the detected metal concentrations in tissues did not exceed the LOAEL levels, stress indices such as the PGE, Cd and Pb kidney/liver ratios and the kidney/body weight ratios were found to be altered. Significant correlations were established between hair and both internal tissues and soils, for non-essential metals PGEs, Cd, Ni and Pb, and also for biologically essential Zn, the level of which was high in urban soils. Hair proved to be a suitable non-invasive tool for monitoring metal exposure responses in small mammals.

Histopathological alterations and induction of hsp70 in ramshorn snail (Marisa cornuarietis) and zebrafish (Danio rerio) embryos after exposure to PtCl(2)

The platinum group metals (PGMs) platinum (Pt), palladium (Pd), and rhodium (Rh) are used in automobile catalytic converters, from which they have been emitted into the environment to an increasing degree during the last 20 years. Despite the bioavailability of these metals to plants and animals, studies determining the effects of PGMs on organisms are extremely rare. In the present study, effects of various concentrations of PtCl(2) (0.1, 1, 10, 50 and 100 microg/L) were investigated with respect to the induction of hsp70 and histopathological alterations in the zebrafish, Danio rerio and the ramshorn snail, Marisa cornuarietis. Histopathological investigations revealed effects of Pt on both species, which varied between slight and strong cellular reactions, depending on the PtCl(2) concentration. The hsp70 level in M. cornuarietis did not show an increase following Pt exposure whereas it was significantly elevated at 100 micorg/L PtCl(2) in D. rerio.

Exposure of brown trout (Salmo trutta L.) to tunnel wash water runoff--chemical characterisation and biological impact

Washing and cleaning of road tunnels are a routinely performed maintenance task, which generate significant amount of polluted wash-water runoff that normally is discharged to the nearest recipient. The present study was designed to quantify chemical contaminants (trace metals, hydrocarbons, PAH and detergents) in such wash water and assess the short term impact on brown trout (Salmo trutta L.) based on in situ experiments. Selected endpoints were accumulation of trace metals in gills, haematological variables and hepatic mRNA transcription of five biomarkers reflecting defence against free radicals, trace metals, planar aromatic hydrocarbons and endocrine disruptions which were measured prior (-3h), during (1 and 3h) and after the tunnel wash (14, 38 and 86h). Our findings showed that the runoff water was highly polluted, but most of the contaminants were associated with particles which are normally considered biologically inert. In addition, high concentrations of calcium and dissolved organic carbon were identified in the wash water, thus reducing metal toxicity. However, compared to the control fish, a rapid accumulation of trace metals in gills was observed. This was immediately followed by a modest change in blood ions and glucose in exposed fish shortly after the exposure start. However, after 38-86h post wash, gill metal concentrations, plasma ions and glucose levels recovered back to control levels. In contrast, the mRNA transcription of the CYP1A and the oxidative stress related biomarkers TRX and GCS did not increase until 14h after the exposure start and this increase was still apparent when the experiment was terminated 86h after the beginning of the tunnel wash. The triggering of the defence systems seemed to have successfully restored homeostasis of the physiological variables measured, but the fish still used energy for detoxification four days after the episode, measured as increased biomarker synthesis.

Uptake of platinum by zebrafish (Danio rerio) and ramshorn snail (Marisa cornuarietis) and resulting effects on early embryogenesis

Platinum group elements (PGEs), platinum, palladium and rhodium are widely used in automobile catalytic converters. PGEs are emitted into the environment and enter the aquatic ecosystem via runoff rainwater. The present study investigated the bioavailability of platinum chloride for the zebrafish (Danio rerio) and the ramshorn snail (Marisa cornuarietis) and determined the bioaccumulation rate of platinum. Applying the fish early life stage assay for D. rerio (DarT) and the Marisa embryo toxicity test ("Mariett") for M. cornuarietis, effects of platinum chloride on the embryonic development were investigated. Platinum concentrations tested in this study ranged from environmentally relevant concentrations of 38 ng L(-1) up to a concentration of 74.2 microg L(-1) for D. rerio and of 200 ngL(-1) up to 98.7 microg L(-1) for M. cornuarietis. Platinum was found to be accumulated in both organisms. Bioaccumulation factors (BAFs) were in the range of 5-55 for D. rerio and of 218.4-723.9 for M. cornuarietis, depending on the tested Pt concentrations. During the embryonic development, platinum was shown to alter the heart rate of both organisms already at the lowest tested concentration. At higher concentrations, platinum decelerated the hatching rate of the embryos of both species. Additionally, a retardation of the general development and a loss of weight due to platinum exposure was observed in M. cornuarietis. Results of this study contribute important data on the ecotoxicity of a rarely studied element.

Possible markers of traffic-related emissions

Looking for robust indicators of motor vehicle emissions it has been found that brake wear and linings are significant contributors of Cu, Mo and Sb to air particulate matter. These trace elements, whose mutual ratios in airborne particulate matter resulted quite different from those in crustal material, appear to be available fingerprinting tools to identify the contribution of on-road vehicles to traffic-derived particulate matter. In this study, the results of analytical determinations of Cu, Mo and Sb on PM(10), PM(2.5), vegetation and brake dust samples, together with gas (CO, NOx) concentrations, are discussed. Highly significant correlations among Cu, Sb and Mo were observed in particulate matter from Palermo and between Cu-Sb and Cu-Mo at Catania. Further significant positive correlations have been found in pine needles from Palermo, Gela and in platanus leaves from Catania.

Estimation of platinum in environmental water samples with solid phase extraction technique using inductively coupled plasma mass spectrometry

A solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma mass spectromA solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma mass spectrometry (ICP-MS) was developed. The method was based on retention of platinum in a sample on silica gel modified with aminepropyl groups. The retention of platinum(IV) from the sample solution and the recovery of platinum with 1.0 mol L−1 thiourea solution were quantitative. The relative standard deviation (RSD) was calculated as 5% (n = 7) at the 10 ng L−1 level. The enrichment factor was found to be (50-fold) for 250 mL of water sample. Under optimum conditions, the method detection limit (MDL) was found to be 1 ng L−1 for platinum in water matrices. Recoveries of Pt from spike addition to atmospheric water samples were quantitative (80–95%). The present method was used for the determination of platinum in precipitation, throughfall and runoff water samples.

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 dependent 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 amphipod Hyalella azteca as a biomonitor in field deployment studies for metal mining

Specimens of the amphipod Hyalella azteca were deployed, in June-July 2003, along metal contamination gradients in two rivers affected by metal mining in the Abitibi-James Bay region, northwestern Québec. The amphipods were placed along with natural food items in small, acrylic cages and left in six riverine sites for 17 days. Twelve metals (As, Cu, La, Mn, Ni, Sb, Se, Tl, U, V, Zn, and CrO4(2-) modelled by WHAM VI) in transplanted H. azteca varied along metal contamination gradients in a consistent manner, i.e., as a function of metal exposure. Bioaccumulation of As, Cr, La, Ni, Sb, Se, Tl, U and V, as defined by a field BCF, was significantly correlated with their chronic toxicity potential towards the amphipod. We conclude that H. azteca may be a useful field biomonitor for metal mining. In addition, our results suggest that such biomonitoring programs should include less studied elements such as Se in mining effluents.

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.

Metallothionein (MT) response after chronic palladium exposure in the zebra mussel, Dreissena polymorpha

The effects of different exposure concentrations of palladium (Pd) on relative metallothionein (MT) response and bioaccumulation were investigated in zebra mussels (Dreissena polymorpha). The mussels were exposed to 0.05, 5, 50, and 500 microg/L Pd2+ for 10 weeks under controlled temperature and fasting conditions. Relative MT contents were assessed by a modified Ag-saturation method, which allows to discriminate between MT bound to Pd (Pd-MT) and MT bound to unidentified metals (Ag-MT). Determination of metal contents resulted from atomic absorption spectrometry following a microwave digestion. For unexposed mussels and mussels exposed to 0.05 microg/L Pd no metal accumulation could be detected. All other exposure concentrations resulted in detectable Pd accumulation in mussels with final tissue concentrations of 96 microg/g (500 microg/L), 45 microg/g (50 microg/L), and 9 microg/g (5 microg/L). Compared with initial levels Pd-MT concentrations at the end of the exposure period were 600 (500 microg/L), 160 (50 microg/L), and 27 (5 microg/L) times higher. These results show that an increase in MTs in D. polymorpha already occurs at relatively low aqueous Pd concentrations indicating that there is the need for detoxification of Pd in the mussel. Furthermore, correlations between Ag-MT and Pd accumulation indicate that higher exposure concentrations are associated with adverse effects on the mussels. Thus, harmful effects of chronic Pd exposure of organisms even in lowest concentrations cannot be excluded in the environment.