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Результаты 151-160 из 1,299
Monitoring of heavy metal concentrations in home outdoor air using moss bags
2011
Rivera, Marcela | Zechmeister, Harald | Medina-Ramón, Mercedes | Basagaña, Xavier | Foraster, Maria | Bouso, Laura | Moreno, Teresa | Solanas, Pascual | Ramos, Rafael | Köllensperger, Gunda | Deltell, Alexandre | Vizcaya, David | Künzli, Nino
One monitoring station is insufficient to characterize the high spatial variation of traffic-related heavy metals within cities. We tested moss bags (Hylocomium splendens), deployed in a dense network, for the monitoring of metals in outdoor air and characterized metals’ long-term spatial distribution and its determinants in Girona, Spain. Mosses were exposed outside 23 homes for two months; NO₂ was monitored for comparison. Metals were not highly correlated with NO₂ and showed higher spatial variation than NO₂. Regression models explained 61–85% of Cu, Cr, Mo, Pb, Sb, Sn, and Zn and 72% of NO₂ variability. Metals were strongly associated with the number of bus lines in the nearest street. Heavy metals are an alternative traffic-marker to NO₂ given their toxicological relevance, stronger association with local traffic and higher spatial variability. Monitoring heavy metals with mosses is appealing, particularly for long-term exposure assessment, as mosses can remain on site many months without maintenance.
Показать больше [+] Меньше [-]Direct and indirect impact of sewage sludge compost spreading on Quercus coccifera monoterpene emissions in a Mediterranean shrubland
2011
Olivier, Romain | Staudt, Michael | Lavoir, Anne-Violette | Ormeño, Elena | Rizvi, Syed Hussain | Baldy, Virginie | Rivoal, Annabelle | Greff, Stephane | Lecareux, Caroline | Fernandez, Catherine
Monoterpene emissions of Quercus coccifera L. were repeatedly measured during the two years following the spreading of a sewage sludge compost at rates of 50Mgha⁻¹ and 100Mgha⁻¹, in a twelve-year-old post-fire Mediterranean shrubland. We also monitored the patterns of change in soil and leaf nutrient content, plant water potential, chlorophyll fluorescence, and plant growth. Compost spreading resulted in weak changes in leaf nutrient content and plant water status, and therefore no significant effect on monoterpene emissions at leaf scale, except during one summer sampling, probably related to advanced leaf maturity with the highest compost rate. However, compost increased plant growth, particularly the leaf biomass. The results suggest that compost spreading in Mediterranean shrublands has no strong short-term effect on Q. coccifera monoterpene emissions at leaf level, but may indirectly increase volatile organic compound fluxes at the stand scale, which may contribute to regional ozone pollution.
Показать больше [+] Меньше [-]Sorption of apolar and polar organic contaminants by waste tire rubber and its chars in single- and bi-solute systems
2011
Lian, Fei | Huang, Fang | Chen, Wei | Xing, Baoshan | Zhu, Lingyan
Single- and bi-solute sorption of organic compounds [1,3-dichlorbenzene (DCB), 1,3-dinitrobenzene (DNB) and 2,4-dichlorophenol (DCP)] on ground tire rubber and its chars was studied. The chars were prepared by pyrolyzing tire rubber at different temperatures (200–800 °C). Their surface area, aromaticity and hydrophobicity increase greatly with pyrolytic temperature, and the polymeric phase is partly converted into a condensed phase. The sorption of DNB and DCP increases with pyrolytic temperature and is characterized by a transition from a partition dominant to an adsorption dominant process. However, the sorption of DCB linearly decreases with the pyrolytic temperature. The enhanced adsorption of DNB and DCP on carbonized phase is primarily attributed to nonhydrophobic interactions such as π–π electron-donor–acceptor interactions and/or H bonding. The higher partition of DCB to polymeric phase is attributed to its high hydrophobicity. Competitive sorption between DCB and DCP on the tire chars is highly dependent on dissociation of the latter.
Показать больше [+] Меньше [-]Long-chain perfluorinated chemicals in digested sewage sludges in Switzerland
2011
Sun, Hongwen | Gerecke, Andreas C. | Giger, W. (Walter) | Alder, Alfredo C.
This study focused on the occurrence of long-chain perfluorinated chemicals (PFCs) in anaerobically stabilized sewage sludges from 20 municipal WWTPs using current and historic samples to evaluate the levels of PFCs and to identify the relative importance of commercial and industrial sources. A quantitative analytical method was developed based on solvent extraction of the analytes and a LC-MS/MS system. For total perfluoralkyl carboxylates (PFCAs), the concentrations ranged from 14 to 50μg/kg dry matter. Concentrations of perfluorooctane sulfonic acid (PFOS) ranged from 15 to 600μg/kg dry matter. In three WWTPs, the PFOS levels were six to nine times higher than the average values measured in the other plants. These elevated PFOS concentrations did not correlate with higher levels of PFCAs, indicating specific additional local sources for PFOS at these WWTPs. Average concentrations in selected samples from the years 1993, 2002, and 2008 did not change significantly.
Показать больше [+] Меньше [-]Molecular effects and bioaccumulation of levonorgestrel in the non-target organism Dreissena polymorpha
2011
Contardo-Jara, Valeska | Lorenz, Claudia | Pflugmacher, Stephan | Nützmann, Gunnar | Kloas, Werner | Wiegand, Claudia
Bioaccumulation and effects of the contraceptive hormone levonorgestrel were examined in the non-target organism Dreissena polymorpha. Molecular biomarkers of biotransformation, elimination, antioxidant defence and protein damage were analyzed after exposure to increasing concentrations of levonorgestrel in a flow-through system. The lowest concentration (0.312 μg L⁻¹) was 100-fold bioconcentrated within four days. A decrease of the bioconcentration factor was observed within one week for the highest test concentrations (3.12 and 6.24 μg L⁻¹) suggesting enhanced excretory processes. The immediate mRNA up-regulation of pi class glutathione S-transferase proved that phase II biotransformation processes were induced. Disturbance of fundamental cell functions was assumed since the aryl hydrocarbon receptor has been permanently down-regulated. mRNA up-regulation of P-glycoprotein, superoxide dismutase and metallothioneine suggested enhanced elimination processes and ongoing oxidative stress. mRNA up-regulation of heat shock protein 70 in mussels exposed to the two highest concentrations clearly indicated impacts on protein damage.
Показать больше [+] Меньше [-]Triclosan affects the microbial community in simulated sewage-drain-field soil and slows down xenobiotic degradation
2011
Svenningsen, Hanne | Henriksen, Trine | Priemé, Anders | Johnsen, Anders R.
Effects of the common antibacterial agent triclosan on microbial communities and degradation of domestic xenobiotics were studied in simulated sewage-drain-field soil. Cultivable microbial populations decreased 22-fold in the presence of 4 mg kg⁻¹ of triclosan, and triclosan-resistant Pseudomonas strains were strongly enriched. Exposure to triclosan also changed the general metabolic profile (Ecoplate substrate profiling) and the general profile (T-RFLP) of the microbial community. Triclosan degradation was slow at all concentrations tested (0.33–81 mg kg⁻¹) during 50-days of incubation. Mineralization experiments (¹⁴C-tracers) and chemical analyses (LC–MS/MS) showed that the persistence of a linear alkylbenzene sulfonate (LAS) and a common analgesic (ibuprofen) increased with increasing triclosan concentrations (0.16–100 mg kg⁻¹). The largest effect was seen for LAS mineralization which was severely reduced by 0.16 mg kg⁻¹ of triclosan. Our findings indicate that environmentally realistic concentrations of triclosan may affect the efficiency of biodegradation in percolation systems.
Показать больше [+] Меньше [-]Temporal and spatial distribution of atmospheric antimony emission inventories from coal combustion in China
2011
Tian, H.Z. | Zhao, D. | He, M.C. | Wang, Y. | Cheng, K.
A multiple-year inventory of atmospheric antimony (Sb) emissions from coal combustion in China for the period of 1980–2007 has been calculated for the first time. Specifically, the emission inventories of Sb from 30 provinces and 4 economic sectors (thermal power, industry, residential use, and others) are evaluated and analyzed in detail. It shows that the total Sb emissions released from coal combustion in China have increased from 133.19t in 1980 to 546.67t in 2007, at an annually average growth rate of 5.4%. The antimony emissions are largely emitted by industrial sector and thermal power generation sector, contributing 53.6% and 26.9% of the totals, respectively. At provincial level, the distribution of Sb emissions shows significant variation. Between 2005 and 2007, provinces always rank at the top five largest Sb emissions are: Guizhou, Hunan, Hebei, Shandong, and Anhui.
Показать больше [+] Меньше [-]Avoidance tests with Folsomia candida for the assessment of copper contamination in agricultural soils
2011
Boiteau, Gilles | Lynch, D.H. | MacKinley, P.
The feasibility of assessing copper accumulation in agricultural soils using avoidance tests with a Canadian strain of Folsomia candida was investigated under laboratory conditions. The avoidance response to nominal copper sulfate concentrations of 0, 200, 800, 1600 and 3200 mg kg⁻¹ in OECD soil was inconsistent between trials with the standard plastic cup or a modified Petri dish method requiring less soil. However, combined results from three Petri dish trials decreased variability and provided a 75% avoidance level, close to the 80% criterion proposed for avoidance tests. A Copper avoidance EC₅₀ₛ of 18 mg kg⁻¹was obtained using the Petri dish method whether tests were conducted with or without light. While Petri dish tests have potential as a cheap tool to distinguish metal contaminated soils from uncontaminated soils they would be unsuitable for tracking or quantifying changes in metal concentrations. throughout remediation. Advantages and limitations of the method have been presented.
Показать больше [+] Меньше [-]Inside-sediment partitioning of PAH, PCB and organochlorine compounds and inferences on sampling and normalization methods
2011
Opel, Oliver | Palm, Wolf-Ulrich | Steffen, Dieter | Ruck, Wolfgang K.L.
Comparability of sediment analyses for semivolatile organic substances is still low. Neither screening of the sediments nor organic-carbon based normalization is sufficient to obtain comparable results. We are showing the interdependency of grain-size effects with inside-sediment organic-matter distribution for PAH, PCB and organochlorine compounds. Surface sediment samples collected by Van-Veen grab were sieved and analyzed for 16 PAH, 6 PCB and 18 organochlorine pesticides (OCP) as well as organic-matter content. Since bulk concentrations are influenced by grain-size effects themselves, we used a novel normalization method based on the sum of concentrations in the separate grain-size fractions of the sediments. By calculating relative normalized concentrations, it was possible to clearly show underlying mechanisms throughout a heterogeneous set of samples. Furthermore, we were able to show that, for comparability, screening at <125 μm is best suited and can be further improved by additional organic-carbon normalization.
Показать больше [+] Меньше [-]Road deicing salt irreversibly disrupts osmoregulation of salamander egg clutches
2011
Karraker, Nancy E. | Gibbs, James P.
It has been postulated that road deicing salts are sufficiently diluted by spring rains to ameliorate any physiological impacts to amphibians breeding in wetlands near roads. We tested this conjecture by exposing clutches of the spotted salamander (Ambystoma maculatum) to three chloride concentrations (1 mg/L, 145 mg/L, 945 mg/L) for nine days, then transferred clutches to control water for nine days, and measured change in mass at three-day intervals. We measured mass change because water uptake by clutches reduces risks to embryos associated with freezing, predation, and disease. Clutches in controls sequestered water asymptotically. Those in the moderate concentrations lost 18% mass initially and regained 14% after transfer to control water. Clutches in high concentration lost 33% mass and then lost an additional 8% after transfer. Our results suggest that spring rains do not ameliorate the effects of deicing salts in wetlands with extremely high chloride concentrations.
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