خيارات البحث
النتائج 261 - 270 من 762
PCB accumulation in osprey exposed to local sources in lake sediment
2009
De Solla Shane R. | Martin, Pamela A.
We examined the accumulation of PCBs in ospreys (Pandion haleaetus) that were exposed to local sediment sources. Eggs, chick plasma, and sediment samples were collected over a range of 14 km (0.2-14.2 km) from a PCB source in Sturgeon Lake, ON. Sum PCB concentrations declined in chick plasma (range 422.5-58.3 ng/g) as distance from the PCB source increased, but there was a poor relationship with sum PCBs in eggs. Both tissues indicated an Aroclor 1248/1254 source. Aroclor 1254 comprised an average of 66.9% of sum PCBs in chick plasma from Sturgeon Lake, but comprised only from 27.0 to 44.4% in plasma from other Great Lake colonies. Dietary differences among osprey colonies were not sufficient to explain the PCB patterns observed. There was weak evidence that the ability to metabolize PCBs may differ between juveniles and adults, based upon the PCB profile in eggs and chick plasma. PCBs in plasma and eggs of osprey reflect local sources of PCBs in sediment.
اظهر المزيد [+] اقل [-]Suitability of a magnetic particle immunoassay for the analysis of PBDEs in Hawaiian euryhaline fish and crabs in comparison with gas chromatography/electron capture detection-ion trap mass spectrometry
2009
Xu, Ting | Cho, Ii Kyu | Wang, Dongli | Rubio, Fernando M. | Shelver, Weilin L. | Gasc, Anne M.E. | Li, Ji | Li, Qing X.
A gas chromatograph/electron capture detector-ion trap mass spectrometer (GC/ECD-ITMS) was used for the determination of polybrominated diphenyl ethers (PBDEs) in euryhaline fish and crabs. GC/ECD-ITMS results showed that average recoveries from the spiked fish samples are in a range of 58-123% with relative standard deviations (RSDs) of 5-19%. PBDE concentrations obtained from GC/ECD-ITMS ranged from 28 ng/g to 1845 ng/g lipid weight (lw) in all aquatic species collected from Hawaiian brackish waters. The general BDE congener concentration profile observed in this study is BDE-47 > BDE-100 > BDE-154 > BDE-99 > BDE-153 > BDE-28 > BDE-183. The ELISA results expressed as BDE-47 equivalents correlated well with those of GC/ECD-ITMS, with a correlation coefficient (R2 = 0.68) and regression coefficient (slope = 0.82). Comparison of ELISA with GC/ECD-ITMS results demonstrated that ELISA provides a timely and cost-effective method to screen PBDEs in fish and crab samples. PBDEs (with the most abundant being BDE-47) at concentrations of 28-1845 ng/g lipid weight in fish and crabs from Hawaiian freshwater were detected with both ELISA and GC/MS.
اظهر المزيد [+] اقل [-]Contaminants reduce the richness and evenness of marine communities: A review and meta-analysis
2009
Johnston, Emma L. | Roberts, David A.
Biodiversity of marine ecosystems is integral to their stability and function and is threatened by anthropogenic processes. We conducted a literature review and meta-analysis of 216 studies to understand the effects of common contaminants upon diversity in various marine communities. The most common diversity measures were species richness, the Shannon-Wiener index (H') and Pielou evenness (J). Largest effect sizes were observed for species richness, which tended to be the most sensitive index. Pollution was associated with marine communities containing fewer species or taxa than their pristine counterparts. Marine habitats did not vary in their susceptibility to contamination, rather a 40% reduction in richness occurred across all habitats. No class of contaminant was associated with significantly greater impacts on diversity than any other. Survey studies identified larger effects than laboratory or field experiments. Anthropogenic contamination is strongly associated with reductions in the species richness and evenness of marine habitats. Contamination substantially reduces the biodiversity of marine communities in all major habitat types and across all major contaminant classes.
اظهر المزيد [+] اقل [-]Predicting bioremediation of hydrocarbons: Laboratory to field scale
2009
Diplock, E.E. | Mardlin, D.P. | Killham, K.S. | Paton, G.I.
There are strong drivers to increasingly adopt bioremediation as an effective technique for risk reduction of hydrocarbon impacted soils. Researchers often rely solely on chemical data to assess bioremediation efficiently, without making use of the numerous biological techniques for assessing microbial performance. Where used, laboratory experiments must be effectively extrapolated to the field scale. The aim of this research was to test laboratory derived data and move to the field scale. In this research, the remediation of over thirty hydrocarbon sites was studied in the laboratory using a range of analytical techniques. At elevated concentrations, the rate of degradation was best described by respiration and the total hydrocarbon concentration in soil. The number of bacterial degraders and heterotrophs as well as quantification of the bioavailable fraction allowed an estimation of how bioremediation would progress. The response of microbial biosensors proved a useful predictor of bioremediation in the absence of other microbial data. Field-scale trials on average took three times as long to reach the same endpoint as the laboratory trial. It is essential that practitioners justify the nature and frequency of sampling when managing remediation projects and estimations can be made using laboratory derived data. The value of bioremediation will be realised when those that practice the technology can offer transparent lines of evidence to explain their decisions. Detailed biological, chemical and physical characterisation reduces uncertainty in predicting bioremediation.
اظهر المزيد [+] اقل [-]Biomonitoring airborne parent and alkylated three-ring PAHs in the Greater Cologne Conurbation I: Temporal accumulation patterns
2009
Lehndorff, E. | Schwark, L.
Polycyclic aromatic hydrocarbons (PAHs) comprise an important group of air pollutants, with three-ring components (PAH-3) often dominating. Spatiotemporal variation in atmospheric PAH-3 can be analyzed by biomonitoring but high vapour pressure and low octanol-air-partitioning of PAH-3 cause dynamic accumulation on plant surfaces. This study for the first time shows that PAH-3 exhibit systematic accumulation trends on pine needles of 3-48 months of exposure time at six sites in Germany. Correlation of needle exposure time with PAH-3 concentration was r² = 0.83 for phenanthrene and methylphenanthrenes, r² = 0.77 for cyclopenta[def]phenanthrene, r² = 0.60 for dibenzothiophene, r² = 0.57 for dimethylphenanthrenes and r² = 0.32 for retene. Variations in PAH-3 for summer and winter collected needles emphasize vegetation-air-partitioning influence on cumulative PAH-3 loads. PAH-3 ratios calculated for needle cohorts indicate persistence of original PAH patterns thus demonstrating the source-diagnostic potential of pine needle biomonitoring, which is utilized in part II of this study where spatial distribution of PAH-3 is investigated and related to emission sources. Accumulation of volatile three-ring PAHs on pine needles was found to be systematic over a period of 50 months thus qualifying PAHs for regional air quality studies.
اظهر المزيد [+] اقل [-]Effects of different inorganic arsenic species in Cyprinus carpio (Cyprinidae) tissues after short-time exposure: Bioaccumulation, biotransformation and biological responses
2009
Ventura-Lima, Juliane | Fattorini, Daniele | Regoli, Francesco | Monserrat, José M.
Differences in the toxicological and metabolic pathway of inorganic arsenic compounds are largely unknown for aquatic species. In the present study the effects of short-time and acute exposure to AsIII and AsV were investigated in gills and liver of the common carp, Cyprinus carpio (Cyprinidae), measuring accumulation and chemical speciation of arsenic, and the activity of glutathione-S-transferase omega (GST Ω), the rate limiting enzyme in biotransformation of inorganic arsenic. Oxidative biomarkers included antioxidant defenses (total glutathione-S-transferases, glutathione reductase, glutathione, and glucose-6-phosphate dehydrogenase), total scavenging capacity toward peroxyl radicals, reactive oxygen species (ROS) measurement and lipid peroxidation products. A marked accumulation of arsenic was observed only in gills of carps exposed to 1000 ppb AsV. Also in gills, antioxidant responses were mostly modulated through a significant induction of glucose-6-phosphate dehydrogenase activity which probably contributed to reduce ROS formation; however this increase was not sufficient to prevent lipid peroxidation. No changes in metal content were measured in liver of exposed carps, characterized by lower activity of GST Ω compared to gills. On the other hand, glutathione metabolism was more sensitive in liver tissue, where a significant inhibition of glutathione reductase was concomitant with increased levels of glutathione and higher total antioxidant capacity toward peroxyl radicals, thus preventing lipid peroxidation and ROS production. The overall results of this study indicated that exposure of C. carpio to AsIII and AsV can induce different responses in gills and liver of this aquatic organism. Common carp (Cyprinus carpio) presented marked differences between gills and liver after arsenic exposure in terms of antioxidant responses and also in biotransformation.
اظهر المزيد [+] اقل [-]Altitude profiles of total chlorinated paraffins in humus and spruce needles from the Alps (MONARPOP)
2009
Iozza, Saverio | Schmid, Peter | Oehme, Michael | Bassan, Rodolfo | Belis, Claudio | Jakobi, Gert | Kirchner, Manfred | Schramm, Karl-Werner | Kräuchi, Norbert | Moche, Wolfgang | Offenthaler, Ivo | Weiss, Peter | Simoncic, Primoz | Knoth, Wilhelm
Chlorinated paraffins (CPs) are toxic, bioaccumulative, persistent, and ubiquitously present in the environment. CPs were analyzed in humus and needle samples, which were taken within the Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants (MONARPOP) at sampling sites of 7 different altitude profiles in the Alps. Gas chromatography combined with electron ionization tandem mass spectrometry (EI-MS/MS) was used for the determination of total CPs (sum of short, medium and long chain CPs). CPs were found in all samples; the concentrations varied between 7 and 199 ng g−1 dry weight (dw) and within 26 and 460 ng g−1 dw in humus and needle samples, respectively. A clear vertical tendency within the individual altitude profiles could not be ascertained. Within all altitude profiles, elevated concentrations were observed in humus samples taken between 700 and 900 m and between 1300 and 1500 m. In the needle samples no similar correlation could be observed due to higher variation of the data. For the first time, CP levels of humus and spruce needle samples from the Alps (MONARPOP) were presented including the evaluation of altitude profiles.
اظهر المزيد [+] اقل [-]POP bioaccumulation in macroinvertebrates of alpine freshwater systems
2009
Bizzotto, E.C. | Villa, S. | Vighi, M.
This study serves to investigate the uptake of POPs in the different trophic levels (scrapers, collectors, predators, shredders) of macroinvertebrate communities sampled from a glacial and a non-glacial stream in the Italian Alps. The presented results show that the contaminant concentrations in glacial communities are generally higher compared to those from non-glacial catchments, highlighting the importance of glaciers as temporary sinks of atmospherically transported pollutants. Moreover, the data also suggests that in mountain systems snow plays an important role in influencing macroinvertebrate contamination. The main chemical uptake process to the macroinvertebrates is considered to be bioconcentration from water, as similar contaminant profiles were observed between the different trophic levels. The role of biomagnification/bioaccumulation is thought to be absent or negligible. The enrichment of chemicals observed in the predators is likely to be related to their greater lipid content compared to that of other feeding groups. Influence of POP release in glacial-fed streams, enhanced by global warming, on pristine aquatic ecosystems.
اظهر المزيد [+] اقل [-]A comparison of Alpine emissions to forest soil and spruce needle loads for persistent organic pollutants (POPs)
2009
Belis, C.A. | Offenthaler, I. | Uhl, M. | Nurmi-Legat, J. | Bassan, R. | Jakobi, G. | Kirchner, M. | Knoth, W. | Kräuchi, N. | Levy, W. | Magnani, T. | Moche, W. | Schramm, K.W. | Simončič, P. | Weiss, P.
The project MONARPOP analysed the concentrations of semivolatile organic compounds (SVOCs) in two important sink compartments, needles of Norway spruce (Picea abies [L.] Karst.) and forest soil from 40 remote Alpine forest sites in Austria, Germany, Italy, Slovenia and Switzerland. In the present study the load of PCDD/F, PCB, PBDE, PAH, HCB, HCH and DDT in the Alps calculated on the basis of measured data are compared with their estimated emissions in the Alpine region. It comes out that the masses of the studied pollutants stored in the forests are higher than the corresponding emissions in the Alpine area indicating that the Alps are a sink for POPs advected from surrounding areas. It is assumed that local emissions of PCDD/F and PAH deriving from biomass burning are probably underestimated and that the pool of these pollutants in the forests represents the accumulation over some decades. The loads of POPs in the Alps are higher than their emissions in the Alpine region.
اظهر المزيد [+] اقل [-]Soil humic acids may favour the persistence of hexavalent chromium in soil
2009
Leita, Liviana | Margon, Alja | Pastrello, Arnold | Arčon, Iztok | Contin, Marco | Mosetti, Davide
The interaction between hexavalent chromium Cr(VI), as K₂CrO₄, and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils. Humic acids (HAs) did not induce reduction of Cr(VI) to its trivalent chemical form, as the interaction between Cr(VI) and HAs rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes.
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