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Résultats 121-130 de 2,459
Characterizing the influence of highways on springtime NO2 and NH3 concentrations in regional forest monitoring plots
2014
Watmough, Shaun A. | McDonough, Andrew M. | Raney, Shanel M.
Highways are major sources of nitrogen dioxide (NO2) and ammonia (NH3). In this study, springtime NO2 and NH3 concentrations were measured at 17 Ontario Forest Biomonitoring Network (OFBN) plots using passive samplers. Average springtime NO2 concentrations were between 1.3 μg m−3 and 27 μg m−3, and NH3 concentrations were between 0.2 μg m−3 and 1.7 μg m−3, although concentrations measured in May (before leaf out) were typically twice as high as values recorded in June. Average NO2 concentrations, and to a lesser extent NH3, could be predicted by road density at all radii (around the plot) tested (500 m, 1000 m, 1500 m). Springtime NO2 concentrations were predicted for a further 50 OFBN sites. Normalized plant/lichen N concentrations were positively correlated with estimated springtime NO2 and NH3 concentrations. Epiphytic foliose lichen richness decreased with increasing NO2 and NH3, but vascular plant richness was positively related to estimated springtime NO2 and NH3.
Afficher plus [+] Moins [-]Determining the bioavailability and toxicity of lead contamination to earthworms requires using a combination of physicochemical and biological methods
2014
Luo, Wei | Verweij, Rudo A. | van Gestel, Cornelis A.M.
This study aimed at assessing the bioavailability and toxicity of lead to Eisenia andrei in shooting range soils representing different land uses (forest, grassland, bullet plot). Soils contained 47–2398 mg Pb/kg dry weight (dw), but also had different pH-CaCl2 (3.2–6.8) and organic matter contents (3.8–13%). Therefore artificial soils with different pH and organic matter contents and two natural soils were included as control soils. Earthworms were exposed for 28 days and toxicity and uptake of Pb were related to total, water and 0.01 M CaCl2 extractable and porewater Pb concentrations as well as to soil characteristics. Pb uptake in the earthworms linearly increased with increasing soil concentrations. At >2000 mg Pb/kg dw and pH 3.3–3.5, high earthworm mortality with significant weight loss and complete inhibition of reproduction were recorded. At <1000 mg/kg dw, earthworm reproduction was more related to differences in pH and other soil characteristics than to Pb.
Afficher plus [+] Moins [-]Different toxicity mechanisms between bare and polymer-coated copper oxide nanoparticles in Lemna gibba
2014
Perreault, François | Popović, Radovan | Dewez, David
In this report, we investigated how the presence of a polymer shell (poly(styrene-co-butyl acrylate) alters the toxicity of CuO NPs in Lemna gibba. Based on total Cu concentration, core–shell CuO NPs were 10 times more toxic than CuO NPs, inducing a 50% decrease of growth rate at 0.4 g l−1 after 48-h of exposure while a concentration of 4.5 g l−1 was required for CuO NPs for a similar effect. Toxicity of CuO NPs was mainly due to NPs solubilization in the media. Based on the accumulated copper content in the plants, core–shell CuO NPs induced 4 times more reactive oxygen species compared to CuO NPs and copper sulfate, indicating that the presence of the polymer shell changed the toxic effect induced in L. gibba. This effect could not be attributed to the polymer alone and reveals that surface modification may change the nature of NPs toxicity.
Afficher plus [+] Moins [-]Comprehensive probabilistic modelling of environmental emissions of engineered nanomaterials
2014
Sun, Tian Yin | Gottschalk, Fadri | Hungerbühler, Konrad | Nowack, Bernd
Concerns about the environmental risks of engineered nanomaterials (ENM) are growing, however, currently very little is known about their concentrations in the environment. Here, we calculate the concentrations of five ENM (nano-TiO2, nano-ZnO, nano-Ag, CNT and fullerenes) in environmental and technical compartments using probabilistic material-flow modelling. We apply the newest data on ENM production volumes, their allocation to and subsequent release from different product categories, and their flows into and within those compartments. Further, we compare newly predicted ENM concentrations to estimates from 2009 and to corresponding measured concentrations of their conventional materials, e.g. TiO2, Zn and Ag. We show that the production volume and the compounds' inertness are crucial factors determining final concentrations. ENM production estimates are generally higher than a few years ago. In most cases, the environmental concentrations of corresponding conventional materials are between one and seven orders of magnitude higher than those for ENM.
Afficher plus [+] Moins [-]Pharmaceuticals occurrence in a WWTP with significant industrial contribution and its input into the river system
2014
Collado, N. | Rodriguez-Mozaz, S. | Gros, M. | Rubirola, A. | Barceló, D. | Comas, J. | Rodriguez-Roda, I. | Buttiglieri, G.
Occurrence and removal of 81 representative Pharmaceutical Active Compounds (PhACs) were assessed in a municipal WWTP located in a highly industrialized area, with partial water reuse after UV tertiary treatment and discharge to a Mediterranean river. Water monitoring was performed in an integrated way at different points in the WWTP and river along three seasons.Consistent differences between therapeutic classes were observed in terms of influent concentration, removal efficiencies and seasonal variation. Conventional (primary and secondary) treatment was unable to completely remove numerous compounds and UV-based tertiary treatment played a complementary role for some of them. Industrial activity influence was highlighted in terms of PhACs presence and seasonal distribution.Even if global WWTP effluent impact on the studied river appeared to be minor, PhACs resulted widespread pollutants in river waters. Contamination can be particularly critical in summer in water scarcity areas, when water flow decreases considerably.
Afficher plus [+] Moins [-]Transport of perfluoroalkyl acids in a water-saturated sediment column investigated under near-natural conditions
2014
Vierke, Lena | Möller, Axel | Klitzke, Sondra
The aim of this study was to gain an understanding of the transport of C4–10 perfluoroalkyl carboxylic acids (PFCAs) and C4,6,8 perfluoroalkyl sulfonic acids (PFSAs) in a water-saturated sediment column representing a riverbank filtration scenario under near-natural conditions. Short-chain PFCAs and PFSAs with up to six C-atoms showed complete tracer-like breakthrough. Longer chain ones were retarded due to sorption to the sediment or due to other processes in the aqueous phase. The study reports the first column derived sediment–water partition coefficients ranging from 0.01 cm3 g−1 to 0.41 cm3 g−1 for C4,6 PFSAs and from 0.0 cm3 g−1 to 6.5 cm3 g−1 for C4,5,6,8,9 PFCAs. The results clearly indicate that short-chain PFCAs and PFSAs may pose a problem if contaminated surface waters are used for drinking water production via riverbank filtration.
Afficher plus [+] Moins [-]Soil removal as a decontamination practice and radiocesium accumulation in tadpoles in rice paddies at Fukushima
2014
Sakai, Masaru | Gomi, Takashi | Nunokawa, Masanori | Wakahara, Taeko | Onda, Yūichi
We investigated the biological accumulation of radiocesium in tadpoles [Rana (Pelophylax) porosa porosa] in rice paddies with and without decontamination practice at Fukushima. Radiocesium was accumulated in surface part of soils both in the control and decontaminated paddies one year after decontamination. Mean 134Cs and 137Cs concentrations in tadpoles in the control and decontaminated paddies were 3000 and 4500, and 600 and 890 Bq/kg dry weight, respectively. Radiocesium concentrations in surface soil (0–5 cm depth) and tadpoles in the decontaminated paddy were five times smaller than in the control paddy. These results suggest that decontamination practice can reduce radiocesium concentrations in both soil and tadpoles. However, at the decontaminated paddy, radiocesium concentrations in surface soils became 3.8 times greater one year after decontamination, which indicates that monitoring the subsequent movement of radiocesium in rice paddies and surrounding areas is essential for examining contamination propagation.
Afficher plus [+] Moins [-]Evaluation of the leucine incorporation technique for detection of pollution-induced community tolerance to copper in a long-term agricultural field trial with urban waste fertilizers
2014
Lekfeldt, Jonas Duus Stevens | Magid, Jakob | Holm, Peter E. | Nybroe, Ole | Brandt, Kristian Koefoed
Copper (Cu) is known to accumulate in agricultural soils receiving urban waste products as fertilizers. We here report the use of the leucine incorporation technique to determine pollution-induced community tolerance (Leu-PICT) to Cu in a long-term agricultural field trial. A significantly increased bacterial community tolerance to Cu was observed for soils amended with organic waste fertilizers and was positively correlated with total soil Cu. However, metal speciation and whole-cell bacterial biosensor analysis demonstrated that the observed PICT responses could be explained entirely by Cu speciation and bioavailability artifacts during Leu-PICT detection. Hence, the agricultural application of urban wastes (sewage sludge or composted municipal waste) simulating more than 100 years of use did not result in sufficient accumulation of Cu to select for Cu resistance. Our findings also have implications for previously published PICT field studies and demonstrate that stringent PICT detection criteria are needed for field identification of specific toxicants.
Afficher plus [+] Moins [-]Temporal trends (1999–2010) of perfluoroalkyl acids in commonly consumed food items
2014
Johansson, Jana H. | Berger, Urs | Vestergren, Robin | Cousins, Ian T. | Bignert, Anders | Glynn, Anders | Darnerud, Per Ola
The aim of this study was to determine how dietary exposure to PFAAs has changed over the period when major production changes occurred. Archived samples (1999–2010) of eggs, milk and farmed rainbow trout were analyzed by ultra performance liquid chromatography coupled to tandem mass spectrometry. Statistically significant decreasing trends were observed for concentrations of perfluorooctane sulfonic acid (PFOS) and perfluorohexane sulfonic acid (PFHxS) in fish (p < 0.002 and p < 0.032, respectively) and eggs (p < 0.001 for both compounds). Concentrations of PFOS in fish and eggs decreased by a factor of 10 and 40, respectively. In eggs there was also a statistically significant decreasing trend in concentrations of perfluorooctanoic acid (PFOA). The results of this study demonstrate that PFAA concentrations in food items from agricultural food chains and aquatic food chains close to sources respond rapidly to changes in environmental emissions. Implications for the overall understanding of human exposure are discussed.
Afficher plus [+] Moins [-]Urban ecosystem modeling and global change: Potential for rational urban management and emissions mitigation
2014
Chen, Shaoqing | Chen, Bin | Fath, Brian D.
Urbanization is a strong and extensive driver that causes environmental pollution and climate change from local to global scale. Modeling cities as ecosystems has been initiated by a wide range of scientists as a key to addressing challenging problems concomitant with urbanization. In this paper, ‘urban ecosystem modeling (UEM)’ is defined in an inter-disciplinary context to acquire a broad perception of urban ecological properties and their interactions with global change. Furthermore, state-of-the-art models of urban ecosystems are reviewed, categorized as top-down models (including materials/energy-oriented models and structure-oriented models), bottom-up models (including land use-oriented models and infrastructure-oriented models), or hybrid models thereof. Based on the review of UEM studies, a future framework for explicit UEM is proposed based the integration of UEM approaches of different scales, guiding more rational urban management and efficient emissions mitigation.
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