Affiner votre recherche
Résultats 81-90 de 1,908
Fuzzy model for risk assessment of persistent organic pollutants in aquatic ecosystems
2013
Seguí, X. | Pujolasus, E. | Betrò, S. | Àgueda, A. | Casal, J. | Ocampo-Duque, W. | Rudolph, I. | Barra, R. | Páez, M. | Barón, E. | Eljarrat, E. | Barceló, D. | Darbra, R.M.
We developed a model for evaluating the environmental risk of persistent organic pollutants (POPs) to aquatic organisms. The model is based on fuzzy theory and uses information provided by international experts through a questionnaire. It has been tested in two case studies for a particular type of POPs: brominated flame retardants (BFRs). The first case study is related to the EU-funded AQUATERRA project, with sampling campaigns carried out in two Ebro tributaries in Spain (the Cinca and Vero Rivers). The second one, named the BROMACUA project, assessed different aquatic ecosystems in Chile (San Vicente Bay) and Colombia (Santa Marta Marsh). In both projects, the BFRs under study were polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). However, the model can be extrapolated to other POPs and to different aquatic ecosystems to provide useful results for decision-makers.
Afficher plus [+] Moins [-]Occurrence and distribution of pharmaceutically active and endocrine disrupting compounds in Singapore's marine environment: Influence of hydrodynamics and physical–chemical properties
2013
The fate and exposure risks of pharmaceutically active compounds (PhACs) and endocrine disrupting chemicals (EDCs) in marine environments are not well-understood. In this study we developed a multi-residue analytical method for quantifying concentrations of forty target compounds in seawater from Singapore. Analyses of samples (n = 24) from eight sites showed the occurrence of several compounds, including gemfibrozil (<0.09–19.8 ng/L), triclosan (<0.55–10.5 ng/L), carbamazepine (<0.28–10.9 ng/L) and ibuprofen (<2.2–9.1 ng/L). A 3D hydrodynamic model for Singapore was used to predict residence time (tR). Principal Components Analysis revealed a strong relationship between tR and contaminant concentrations. While source emissions are undoubtedly important, proximate distance to a wastewater treatment plant had little influence on concentrations. The site with the greatest tR, which exhibited the highest concentrations, is adjacent to Singapore's largest protected wetland reserve. The results highlight an important linkage between hydrodynamic behavior and contaminant exposure risks in complex coastal marine ecosystems.
Afficher plus [+] Moins [-]Artifact weathering, anthropogenic microparticles and lead contamination in urban soils at former demolition sites, Detroit, Michigan
2013
Howard, Jeffrey L. | Dubay, Brian R. | Daniels, W Lee
A chronological sequence of urban soils 3–92 years old was studied to determine the effects of time on morphogenesis, artifact weathering, and the geochemical partitioning of Pb. Key chronofunctions determined are an increase in ˆA horizon Development Index (defined herein based on soil color) and water-soluble Pb, and a decrease in pH and C/N, with increasing soil age. Key artifact weathering reactions are: 1) portlandite in mortar altered to calcite, 2) ferrite in wrought-iron altered to ferrihydrite and goethite, and 3) carbonaceous materials altered to water-soluble organic substances. Mortar and wrought-iron were found to be Pb-bearing, but weather to produce immobilizing agents. Hence, they are both a source and a sink for Pb. The origin and mobilization of water-soluble Pb is complex and probably includes microbial extracellular polymeric substances, biodegraded soil organic matter, and solubilized organic substances derived from carbonaceous anthropogenic microparticles (soot, char and coal-related wastes).
Afficher plus [+] Moins [-]Ecotoxicological effects evoked in hydrophytes by leachates of invasive Acer negundo and autochthonous Alnus glutinosa fallen off leaves during their microbial decomposition
2013
Krevš, Alina | Darginavičienė, Jūratė | Gylytė, Brigita | Grigutytė, Reda | Jurkonienė, Sigita | Karitonas, Rolandas | Kučinskienė, Alė | Pakalnis, R. | Sadauskas, Kazys | Vitkus, Rimantas | Manusadžianas, Levonas
Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of Ntot, ammonium and generating higher BOD7. Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H+-ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems.
Afficher plus [+] Moins [-]Assessing microbial carbon sources and potential PAH degradation using natural abundance 14C analysis
2013
Mahmoudi, Nagissa | Fulthorpe, Roberta R. | Burns, Leanne | Mancini, Silvia | Slater, Greg F.
Natural abundance 14C analysis was applied to PLFAs collected from an industrial site in southern Ontario in order to assess microbial carbon sources and potential PAH biodegradation in soils. Δ14C of microbial phospholipid fatty acids (PLFA) at the site ranged from +54‰ to −697‰. Comparison of these values to surrounding carbon sources found that microbial carbon sources were derived primarily from vegetation and/or natural organic matter present in the soils rather than PAHs. This study highlights that microbes are able to utilize almost all available pools of organic matter including older pools which are thought to contain recalcitrant compounds. Furthermore, it shows that even with the presence of an active microbial community, there may be little biodegradation of PAHs. This study illustrates challenges in assessing microbial activity in the environment and the advantage of using natural abundance 14C analysis as a tool to elucidate microbial carbon sources.
Afficher plus [+] Moins [-]In vitro assessment of thyroid hormone disrupting activities in drinking water sources along the Yangtze River
2013
Hu, Xinxin | Shi, Wei | Zhang, Fengxian | Cao, Fu | Hu, Guanjiu | Hao, Yingqun | Wei, Si | Wang, Xinru | Yu, Hongxia
The thyroid hormone disrupting activities of drinking water sources from the lower reaches of Yangtze River were examined using a reporter gene assay based on African green monkey kidney fibroblast (CV-1) cells. None of the eleven tested samples showed thyroid receptor (TR) agonist activity. Nine water samples exhibited TR antagonist activities with the equivalents referring to Di-n-butyl phthalate (DNBP) (TR antagonist activity equivalents, ATR-EQ50s) ranging from 6.92 × 101 to 2.85 × 102 μg DNBP/L. The ATR-EQ50s and TR antagonist equivalent ranges (ATR-EQ30–80 ranges) for TR antagonist activities indicated that the water sample from site WX-8 posed the greatest health risks. The ATR-EQ80s of the water samples ranging from 1.56 × 103 to 6.14 × 103 μg DNBP/L were higher than the NOEC of DNBP. The results from instrumental analysis showed that DNBP might be responsible for the TR antagonist activities in these water samples. Water sources along Yangtze River had thyroid hormone disrupting potential.
Afficher plus [+] Moins [-]Air Quality Standards for Particulate Matter (PM) at high altitude cities
2013
Bravo Alvarez, H. | Sosa Echeverria, R. | Sanchez Alvarez, P. | Krupa, S.
The Air Quality Standards for Particulate Matter (PM) at high altitude urban areas in different countries, must consider the pressure and temperature due to the effect that these parameters have on the breath volume.This paper shows the importance to correct Air Quality Standards for PM considering pressure and temperature at different altitudes. Specific factors were suggested to convert the information concerning PM, from local to standard conditions, and adjust the Air Quality Standards for different high altitudes cities. The correction factors ranged from: 1.03 for Santiago de Chile to 1.47 for El Alto Bolivia. Other cities in this study include: Mexico City, México; La Paz, Bolivia; Bogota, Cali and Medellin, Colombia; Quito, Ecuador and Cuzco, Peru.If these corrections are not considered, the atmospheric concentrations will be underestimated.
Afficher plus [+] Moins [-]Effect of substrate depth and rain-event history on the pollutant abatement of green roofs
2013
Seidl, Martin | Gromaire, Marie-Christine | Saad, Mohamed | Gouvello, Bernard de
This study compares the effectiveness of two different thickness of green roof substrate with respect to nutrient and heavy metal retention and release. To understand and evaluate the long term behaviour of green roofs, substrate columns with the same structure and composition as the green roofs, were exposed in laboratory to artificial rain. The roofs act as a sink for C, N, P, zinc and copper for small rain events if the previous period was principally dry. Otherwise the roofs may behave as a source of pollutants, principally for carbon and phosphorus. Both field and column studies showed an important retention for Zn and Cu. The column showed, however, lower SS, DOC and metal concentrations in the percolate than could be observed in the field even if corrected for run-off. This is most probably due to the difference in exposition history and weathering processes.
Afficher plus [+] Moins [-]Tracing decadal environmental change in ombrotrophic bogs using diatoms from herbarium collections and transfer functions
2013
Poulíčková, Aloisie | Hájková, Petra | Kintrová, Kateřina | Bat'ková, Romana | Czudková, Markéta | Hájek, Michal
Central European mountain bogs, among the most valuable and threatened of habitats, were exposed to intensive human impact during the 20th century. We reconstructed the subrecent water chemistry and water-table depths using diatom based transfer functions calibrated from modern sampling. Herbarium Sphagnum specimens collected during the period 1918–1998 were used as a source of historic diatom samples. We classified samples into hummocks and hollows according to the identity of dominant Sphagnum species, to reduce bias caused by uneven sampling of particular microhabitats. Our results provide clear evidence for bog pollution by grazing during the period 1918–1947 and by undocumented aerial liming in the early 90-ies. We advocate use of herbarized epibryon as a source of information on subrecent conditions in recently polluted mires.
Afficher plus [+] Moins [-]Assessing ecotoxicity and uptake of metals and metalloids in relation to two different earthworm species (Eiseina hortensis and Lumbricus terrestris)
2013
Leveque, Thibaut | Capowiez, Yvan | Schreck, Eva | Mazzia, Christophe | Auffan, Mélanie | Foucault, Yann | Austruy, Annabelle | Dumat, Camille
Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris).The combination of behavioural factors measurements (cast production and biomass) and physico-chemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation.
Afficher plus [+] Moins [-]