Polycyclic aromatic hydrocarbon transport processes on the scale of a flood event in the rural watershed of Le Bebec, France

Transport processes of polycyclic aromatic hydrocarbons (PAHs) were investigated in a rural watershed in France, which led to new quantitative results on the scale of a flood event. For that purpose, principal components analysis (PCA) combined with signal decomposition of PAH Breakthrough curves were used. The results obtained by PCA enabled us to distinguish (i) the transport of low molecular weight PAHs in dissolved form and (ii) the transport of high molecular weight PAHs in particulate form. The intermediate molecular weight PAHs are distributed in these two clusters. The application of a signal decomposition method confirms the results of PCA and makes it possible to quantify the mass PAH resulting, respectively, from resuspension (13.3mg, i.e. 77% of the total mass) and from direct transfer (2.8mg=16% of the total mass). For the resuspension phase, desorption of PAH (38% of the total exported mass) could be also distinguished from sediment resuspension (39%).     

Mobile measurements of aerosol number and volume size distributions in an Alpine valley: Influence of traffic versus wood burning

The spatial variability of highly time resolved size distributions was investigated in a narrow valley which provides the opportunity to study the impact of different sources on ambient particle concentrations during summer and winter time. The measurements were performed with a Fast Mobility Particle Sizer (FMPS) from TSI, Inc. on a mobile laboratory in Southern Switzerland. The results indicate enhanced number concentrations (between 150 000 and 500 000 cm^?3) along the busy highway A2 which is the main transit route through the Swiss Alps connecting the northern and southern part of Switzerland. Especially the nanoparticles with diameters lower than 30 nm showed strongly increased number concentrations on the highway both in summer and winter. In winter time, high aerosol volume concentrations (PM_0.3) were found in villages where wood burning is often used for heating purposes. Both traffic and wood burning were found to be important sources for particulate mass which accumulates during temperature inversions in winter time. Traffic was the dominant and wood burning a minor source for the nanoparticle number concentration. This is important regarding health impacts and its attribution to different sources because wood burning might contribute most to particulate mass whereas at the same time and place traffic contributes most to particulate number. In addition, during summer time volatility measurements were performed with the FMPS showing that the nucleation mode prevalently seen on the highway was removed by more than 95% by thermal treatment.     

Low impact of phenanthrene dissipation on the bacterial community in grassland soil

The effect of phenanthrene on the bacterial community was studied on permanent grassland soil historically presenting low contamination (i.e. less than 1 mg kg^?1) by polycyclic aromatic hydrocarbons (PAHs). Microcosms of soil were spiked with phenanthrene at 300 mg kg^?1. After 30 days of incubation, the phenanthrene concentration decreased rapidly until its total dissipation within 90 days. During this incubation period, significant changes of the total bacterial community diversity were observed, as assessed by automated-ribosomal intergenic spacer analysis fingerprinting. In order to get a deeper view of the effect of phenanthrene on the bacterial community, the abundances of ten phyla and classes (Actinobacteria, Acidobacteria, Bacteroidetes, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, Verrucomicrobiales, Gemmatimonadetes, and Planctomycetes) were monitored by quantitative polymerase chain reaction performed on soil DNA extracts. Interestingly, abundances of some bacterial taxa significantly changed as compared with controls. Moreover, among these bacterial groups impacted by phenanthrene spiking, some of them presented the potential of phenanthrene degradation, as assessed by PAH-ring hydroxylating dioxygenase (PAH-RHD_α) gene detection. However, neither the abundance nor the diversity of the PAH-RHD_α genes was significantly impacted by phenanthrene spiking, highlighting the low impact of this organic contaminant on the functional bacterial diversities in grassland soil.     

Polycyclic aromatic hydrocarbons in wastewater, WWTPs effluents and in the recipient waters of Beijing, China

In this study, surface water samples from the Wenyu River and the North Canal, effluent from major wastewater treatment plants (WWTPs) in Beijing, and wastewater from open sewers that discharge directly into the river system were collected and analyzed for 16 priority USEPA polycyclic aromatic hydrocarbons (PAHs). Concentrations of these 16 PAHs ranged from 193 to 1790 ng/L in river surface waters, 245 to 404 ng/L in WWTP effluents, and 431 to 2860 ng/L in the wastewater from the small sewers. The WWTP effluent was the main contributor of dissolved PAHs to the river, while wastewater from the small sewers contributed both dissolved and suspended particulate matter-associated PAH to the river as indicated by the high dissolved organic carbon and suspended particulate matter contents in the wastewater. Although the flow from each open sewer was small, a PAH discharge as high as 44 kg/year could occur into the river from these types of sewers. This amount was equivalent to about 22 % of the PAH loads discharged into the North Canal downstream from Beijing, whereas the remainder was mainly released by the major WWTPs in Beijing.     

PCDD/PCDF, dl-PCB and PBDE serum levels of Slovak general population

Blood serum specimens from 81 non-occupationally exposed adults residing in four areas close to municipal and waste incinerators as well as metallurgical industry plant and 44 adult subjects coming from control area of Slovakia were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (dl-PCBs) and polybrominated diphenylethers (PBDEs). The concentration of total WHO(98)TEQ PCDD/F/dl-PCBs in whole group of donors from areas where known sources causing dioxin contamination are present was significantly higher than in control group of donors (p<0.001). Correlation between the age of donors and PCDD/F and dl-PCB levels was confirmed (Spearman's r(PCDD/Fs)=0.543, r(dl-PCBs)=0.521, p<0.001). Furthermore, this study presents first results concerning the PBDE congeners in human serum of Slovak general population. The total concentration (congeners 28, 47, 99, 100, 153, 154, 183) in control group was approximately 1.5-times higher in comparison to that of residents coming from areas with supposed environmental pollution. The most abundant congeners in all samples were BDE-47 and BDE-153 with median values of 0.24 ng g(-1) lipid and 0.23ngg(-1) lipid, respectively. The positive association between PBDE values and age of donors was not found.     

Object-Based Classification as an Alternative Approach to the Traditional Pixel-Based Classification to Identify Potential Habitat of the Grasshopper Sparrow

The traditional method of identifying wildlife habitat distribution over large regions consists of pixel-based classification of satellite images into a suite of habitat classes used to select suitable habitat patches. Object-based classification is a new method that can achieve the same objective based on the segmentation of spectral bands of the image creating homogeneous polygons with regard to spatial or spectral characteristics. The segmentation algorithm does not solely rely on the single pixel value, but also on shape, texture, and pixel spatial continuity. The object-based classification is a knowledge base process where an interpretation key is developed using ground control points and objects are assigned to specific classes according to threshold values of determined spectral and/or spatial attributes. We developed a model using the eCognition software to identify suitable habitats for the Grasshopper Sparrow, a rare and declining species found in southwestern Québec. The model was developed in a region with known breeding sites and applied on other images covering adjacent regions where potential breeding habitats may be present. We were successful in locating potential habitats in areas where dairy farming prevailed but failed in an adjacent region covered by a distinct Landsat scene and dominated by annual crops. We discuss the added value of this method, such as the possibility to use the contextual information associated to objects and the ability to eliminate unsuitable areas in the segmentation and land cover classification processes, as well as technical and logistical constraints. A series of recommendations on the use of this method and on conservation issues of Grasshopper Sparrow habitat is also provided.     

Temporal trend of mercury in polar bears (Ursus maritimus) from Svalbard using teeth as a biomonitoring tissue

We examined the use of mercury (Hg) and nitrogen and carbon stable isotopes in teeth of polar bear (Ursus maritimus) from Svalbard as biotracers of temporal changes in Hg pollution exposure between 1964 and 2003. Teeth were regarded as a good matrix of the Hg exposure, and in total 87 teeth of polar bears were analysed. Dental Hg levels ranged from 0.6 to 72.3 ng g(-1) dry weight and increased with age during the first 10 years of life. A decreasing time trend in Hg concentrations was observed over the recent four decades while no temporal changes were found in the stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C). This suggests that the decrease of Hg concentrations over time was more likely due to a lower environmental Hg exposure in this region rather than a shift in the feeding habits of Svalbard polar bears.     

Characterization of trace element geochemistry in continuous flow-through microcosms: a preliminary step to environmentally meaningful ecotoxicological experiments

The increasing use of freshwater/sediment microcosms in geochemical and ecotoxicological studies requires additional efforts to characterize and understand their functioning and the main parameters that can influence the pollutants' behavior and bioavailability inside the microcosms themselves. In this study, we investigated the geochemical behavior of four elements (Cr(III), Cu, Cd, and Pb) in microcosms containing one type of natural water and sediment. The microcosms were operated under flow-through conditions with continuous metal spiking (2.5-40 μgL(-1) for Cr(III) and Pb; 1.25-20 μgL(-1) for Cu and Cd) over a period of 1 month. During this period, metal concentrations and partitioning between colloidal and truly dissolved phases in the microcosm water columns showed very little variability indicating that the system rapidly reached and maintained a steady state. Metal concentrations in pore waters also showed little variability, while Cd, Cr, and Pb levels in the top layer of sediments increased linearly from day 0 to day 28 (no significant variations in sedimentary Cu levels were observed). These features make this type of microcosms particularly suitable for ecotoxicological studies with zooplanktonic or epibenthic organisms. Characterizing the geochemical properties of microcosms provides critical information for properly interpreting microcosms-based ecotoxicity data and for reducing uncertainty in laboratory-to-field extrapolation.     

PM10 emission factors for non-exhaust particles generated by road traffic in an urban street canyon and along a freeway in Switzerland

Recent studies have shown clear contributions of non-exhaust emissions to the traffic related PM10 load of the ambient air. These emissions consist of particles produced by abrasion from brakes, road wear, tire wear, as well as vehicle induced resuspension of deposited road dust. The main scope of the presented work was to identify and quantify the non-exhaust fraction of traffic related PM10 for two roadside locations in Switzerland with different traffic regimes. The two investigated locations, an urban street canyon with heavily congested traffic and an interurban freeway, are considered as being typical for Central Europe. Mass-relevant contributions from abrasion particles and resuspended road dust mainly originated from particles in the size range 1–10 μm. The results showed a major influence of vehicle induced resuspension of road dust. In the street canyon, the traffic related PM10 emissions (LDV: 24 ± 8 mg km^?1 vehicle^?1, HDV: 498 ± 86 mg km^?1 vehicle^?1) were assigned to 21% brake wear, 38% resuspended road dust and 41% exhaust emissions. Along the freeway (LDV: 50 ± 13 mg km^?1 vehicle^?1, HDV: 288 ± 72 mg km^?1 vehicle^?1), respective contributions were 3% brake wear, 56% resuspended road dust and 41% exhaust emissions. There was no indication for relevant contributions from tire wear and abrasion from undamaged pavements.