Affiner votre recherche
Résultats 101-110 de 1,310
Oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) in urban soils of Bratislava, Slovakia: Patterns, relation to PAHs and vertical distribution Texte intégral
2011
Musa Bandowe, Benjamin A. | Sobocka, Jaroslava | Wilcke, Wolfgang
We determined concentrations, sources, and vertical distribution of OPAHs and PAHs in soils of Bratislava. The ∑14 OPAHs concentrations in surface soil horizons ranged 88–2692ngg⁻¹ and those of ∑34 PAHs 842–244,870ngg⁻¹. The concentrations of the ∑9 carbonyl-OPAHs (r=0.92, p=0.0001) and the ∑5 hydroxyl-OPAHs (r=0.73, p=0.01) correlated significantly with ∑34 PAHs concentrations indicating the close association of OPAHs with parent-PAHs. OPAHs were quantitatively dominated by 9-fluorenone, 9,10-anthraquinone, 1-indanone and benzo[a]anthracene-7,12-dione. At several sites, individual carbonyl-OPAHs had higher concentrations than parent PAHs. The concentration ratios of several OPAHs to their parent-PAHs and contribution of the more soluble OPAHs (1-indanone and 9-fluorenone) to ∑14 OPAHs concentrations increased with soil depth suggesting that OPAHs were faster vertically transported in the study soils by leaching than PAHs which was supported by the correlation of subsoil:surface soil ratios of OPAH concentrations at several sites with KOW.
Afficher plus [+] Moins [-]Trace element uptake by Eleocharis equisetina (spike rush) in an abandoned acid mine tailings pond, northeastern Australia: Implications for land and water reclamation in tropical regions Texte intégral
2011
Lottermoser, Bernd G. | Ashley, Paul M.
This study was conducted to determine the uptake of trace elements by the emergent wetland plant species Eleocharis equisetina at the historic Jumna tin processing plant, tropical Australia. The perennial emergent sedge was found growing in acid waters (pH 2.45) and metal-rich tailings (SnAsCuPbZn). E. equisetina displayed a pronounced acid tolerance and tendency to exclude environmentally significant elements (Al, As, Cd, Ce, Co, Cu, Fe, La, Ni, Pb, Se, Th, U, Y, Zn) from its above-substrate biomass. This study demonstrates that geobotanical and biogeochemical examinations of wetland plants at abandoned mined lands of tropical areas can reveal pioneering, metal-excluding macrophytes. Such aquatic macrophytes are of potential use in the remediation of acid mine waters and sulfidic tailings and the reclamation of disturbed acid sulfate soils in subtropical and tropical regions.
Afficher plus [+] Moins [-]Mapping urban climate zones and quantifying climate behaviors – An application on Toulouse urban area (France) Texte intégral
2011
Houet, Thomas | Pigeon, Grégoire
Facing the concern of the population to its environment and to climatic change, city planners are now considering the urban climate in their choices of planning. The use of climatic maps, such Urban Climate Zone‑UCZ, is adapted for this kind of application. The objective of this paper is to demonstrate that the UCZ classification, integrated in the World Meteorological Organization guidelines, first can be automatically determined for sample areas and second is meaningful according to climatic variables. The analysis presented is applied on Toulouse urban area (France). Results show first that UCZ differentiate according to air and surface temperature. It has been possible to determine the membership of sample areas to an UCZ using landscape descriptors automatically computed with GIS and remote sensed data. It also emphasizes that climate behavior and magnitude of UCZ may vary from winter to summer. Finally we discuss the influence of climate data and scale of observation on UCZ mapping and climate characterization.
Afficher plus [+] Moins [-]Distribution, speciation and availability of antimony (Sb) in soils and terrestrial plants from an active Sb mining area Texte intégral
2011
Okkenhaug, Gudny | Zhu, Yong-Guan | Luo, Lei | Lei, Ming | Li, Xi | Mulder, Jan
Here, we present one of the first studies investigating the mobility, solubility and the speciation-dependent in-situ bioaccumulation of antimony (Sb) in an active Sb mining area (Xikuangshan, China). Total Sb concentrations in soils are high (527–11,798 mg kg⁻¹), and all soils, including those taken from a paddy field and a vegetable garden, show a high bioavailable Sb fraction (6.3–748 mg kg⁻¹), dominated by Sb(V). Elevated concentrations in native plant species (109–4029 mg kg⁻¹) underpin this. Both chemical equilibrium studies and XANES data suggest the presence of Ca[Sb(OH)₆]₂, controlling Sb solubility. A very close relationship was found between the citric acid extractable Sb in plants and water or sulfate extractable Sb in soil, indicating that citric acid extractable Sb content in plants may be a better predictor for bioavailable Sb in soil than total acid digestible Sb plant content.
Afficher plus [+] Moins [-]Planting woody crops on dredged contaminated sediment provides both positive and negative effects in terms of remediation Texte intégral
2011
Hartley, William | Riby, Philip | Dickinson, Nicholas M. | Shutes, B. (Brian) | Sparke, Shaun | Scholz, Miklas
There is currently a requirement for studies focusing on the long-term sustainability of phytoremediation technologies. Trace element uptake by Salix, Populus and Alnus species planted in dredged contaminated canal sediment and concentrations in sediment and pore waters were investigated, eight years after a phytoremediation trial was initiated in NW England. Soil biological activity was also measured using invertebrate and microbial assays to determine soil quality improvements. Zinc was the dominant trace metal in foliage and woody stems, and the most mobile trace element in sediment pore water (∼14 mg l⁻¹). Biological activity had improved; earthworm numbers had increased from 5 to 24, and the QBS index (an index of microarthropod groups in soil) had increased from 70 to 88. It is concluded that biological conditions had improved and natural processes appear to be enhancing soil quality, but there remains a potential risk of trace element transfer to the wider environment.
Afficher plus [+] Moins [-]Engineered nanomaterials in rivers – Exposure scenarios for Switzerland at high spatial and temporal resolution Texte intégral
2011
Gottschalk, F. | Ort, C. | Scholz, R.W. | Nowack, B.
Probabilistic material flow analysis and graph theory were combined to calculate predicted environmental concentrations (PECs) of engineered nanomaterials (ENMs) in Swiss rivers: 543 river sections were used to assess the geographical variability of nano-TiO₂, nano-ZnO and nano-Ag, and flow measurements over a 20-year period at 21 locations served to evaluate temporal variation. A conservative scenario assuming no ENM removal and an optimistic scenario covering complete ENM transformation/deposition were considered. ENM concentrations varied by a factor 5 due to uncertain ENM emissions (15%–85% quantiles of ENM emissions) and up to a factor of 10 due to temporal river flow variations (15%–85% quantiles of flow). The results indicate highly variable local PECs and a location- and time-dependent risk evaluation. Nano-TiO₂ median PECs ranged from 11 to 1′623 ng L⁻¹ (conservative scenario) and from 2 to 1′618 ng L⁻¹ (optimistic scenario). The equivalent values for nano-ZnO and nano-Ag were by factors of 14 and 240 smaller.
Afficher plus [+] Moins [-]N deposition as a threat to the World’s protected areas under the Convention on Biological Diversity Texte intégral
2011
Bleeker, A. | Hicks, W.K. | Dentener, F. | Galloway, J. | Erisman, J.W.
This paper combines the world’s protected areas (PAs) under the Convention on Biological Diversity (CBD), common classification systems of ecosystem conservation status, and current knowledge on ecosystem responses to nitrogen (N) deposition to determine areas most at risk. The results show that 40% (approx. 11% of total area) of PAs currently receive >10 kg N/ha/yr with projections for 2030 indicating that this situation is not expected to change. Furthermore, 950 PAs are projected to receive >30 kg N/ha/yr by 2030 (approx. twice the 2000 number), of which 62 (approx. 11,300 km²) are also Biodiversity Hotspots and G200 ecoregions; with forest and grassland ecosystems in Asia particularly at risk. Many of these sites are known to be sensitive to N deposition effects, both in terms of biodiversity changes and ecosystem services they provide. Urgent assessment of high risk areas identified in this study is recommended to inform the conservation efforts of the CBD.
Afficher plus [+] Moins [-]Occurrence and distribution of antibiotics in coastal water of the Bohai Bay, China: Impacts of river discharge and aquaculture activities Texte intégral
2011
Zou, Shichun | Xu, Weihai | Zhang, Ruijie | Tang, Jianhui | Chen, Yingjun | Zhang, Gan
The presence of 21 antibiotics in six different groups was investigated in coastal water of the Bohai Bay. Meantime, to illuminate the potential effects caused by the river discharge and aquaculture activities, wastewater from three breeding plants and surface water from six rivers flowing into the Bohai Bay were also analyzed for the selected antibiotics. The result revealed that measured antibiotics in the North Bobai Bay were generally higher than those in the South, highlighting the remarkable effects of high density of human activities on the exposure of antibiotics in environment. The antibiotics found in the six rivers were generally higher than those in the Bohai Bay reflecting the important antibiotics source of river discharge. This study reveals that the high consumption of some antibiotics in aquaculture activities may pose high ecological risk to the bay.
Afficher plus [+] Moins [-]Mercury exposure in terrestrial birds far downstream of an historical point source Texte intégral
2011
Jackson, Allyson K. | Evers, David C. | Folsom, Sarah B. | Condon, Anne M. | Diener, John | Goodrick, Lizzie F. | McGann, Andrew J. | Schmerfeld, John | Cristol, Daniel A.
Mercury (Hg) is a persistent environmental contaminant found in many freshwater and marine ecosystems. Historical Hg contamination in rivers can impact the surrounding terrestrial ecosystem, but there is little known about how far downstream this contamination persists. In 2009, we sampled terrestrial forest songbirds at five floodplain sites up to 137 km downstream of an historical source of Hg along the South and South Fork Shenandoah Rivers (Virginia, USA). We found that blood total Hg concentrations remained elevated over the entire sampling area and there was little evidence of decline with distance. While it is well known that Hg is a pervasive and long-lasting aquatic contaminant, it has only been recently recognized that it also biomagnifies effectively in floodplain forest food webs. This study extends the area of concern for terrestrial habitats near contaminated rivers for more than 100 km downstream from a waterborne Hg point source.
Afficher plus [+] Moins [-]Reduced European emissions of S and N – Effects on air concentrations, deposition and soil water chemistry in Swedish forests Texte intégral
2011
Pihl Karlsson, Gunilla | Akselsson, Cecilia | Hellsten, Sofie | Karlsson, Per Erik
Changes in sulphur and nitrogen pollution in Swedish forests have been assessed in relation to European emission reductions, based on measurements in the Swedish Throughfall Monitoring Network. Measurements were analysed over 20 years with a focus on the 12-year period 1996 to 2008. Air concentrations of SO₂ and NO₂, have decreased. The SO₄-deposition has decreased in parallel with the European emission reductions. Soil water SO₄-concentrations have decreased at most sites but the pH, ANC and inorganic Al-concentrations indicated acidification recovery only at some of the sites. No changes in the bulk deposition of inorganic nitrogen could be demonstrated. Elevated NO₃-concentrations in the soil water occurred at irregular occasions at some southern sites. Despite considerable air pollution emission reductions in Europe, acidification recovery in Swedish forests soils is slow. Nitrogen deposition to Swedish forests continues at elevated levels that may lead to leaching of nitrate to surface waters.
Afficher plus [+] Moins [-]