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C60 fullerene: A powerful antioxidant or a damaging agent? The importance of an in-depth material characterization prior to toxicity assays 全文
2009
Spohn, P. | Hirsch, C. | Hasler, F. | Bruinink, A. | Krug, H.F. | Wick, P.
Since the discovery of fullerenes in 1985, these carbon nanospheres have attracted attention regarding their physico/chemical properties. Despite little knowledge about their impact on the environment and human health, the production of fullerenes has already reached an industrial scale. However, the toxicity of C60 is still controversially discussed. The aim of this study was to clarify the biological effects of tetrahydrofuran (THF) suspended C60 fullerene in comparison to water stirred C60 fullerene suspensions. Beyond that, we analyzed the effects on the Crustacea Daphnia magna an indicator for ecotoxicological effects and the human lung epithelial cell line A549 as a simplified model for the respiratory tract. We could demonstrate that water-soluble side products which were formed in THF nC60 suspension were responsible for the observed acute toxic effects, whereas fullerenes themselves had no negative effect regardless of the preparative route on either A549 cell in vitro or D. magna in vivo. THF suspended nC60 did not show any toxic effect to Daphnia and lung cells when side products were eliminated by additional washing steps.
显示更多 [+] 显示较少 [-]Stability of titania nanoparticles in soil suspensions and transport in saturated homogeneous soil columns 全文
2009
Fang, Jing | Shan, Xiao-quan | Wen, Bei | Lin, Jin-Ming | Owens, Gary
The stability of TiO2 nanoparticles in soil suspensions and their transport behavior through saturated homogeneous soil columns were studied. The results showed that TiO2 could remain suspended in soil suspensions even after settling for 10 days. The suspended TiO2 contents in soil suspensions after 24 h were positively correlated with the dissolved organic carbon and clay content of the soils, but were negatively correlated with ionic strength, pH and zeta potential. In soils containing soil particles of relatively large diameters and lower solution ionic strengths, a significant portion of the TiO2 (18.8-83.0%) readily passed through the soils columns, while TiO2 was significantly retained by soils with higher clay contents and salinity. TiO2 aggregate sizes in the column outflow significantly increased after passing through the soil columns. The estimated transport distances of TiO2 in some soils ranged from 41.3 to 370 cm, indicating potential environmental risk of TiO2 nanoparticles to deep soil layers. TiO2 nanoparticles could efficiently suspend in soil suspensions and potentially transport to deeper soil layers.
显示更多 [+] 显示较少 [-]Introducing an integrated climate change perspective in POPs modelling, monitoring and regulation 全文
2009
This paper presents a review on the implications of climate change on the monitoring, modelling and regulation of persistent organic pollutants (POPs). Current research gaps are also identified and discussed. Long-term data sets are essential to identify relationships between climate fluctuations and changes in chemical species distribution. Reconstructing the influence of climatic changes on POPs environmental behaviour is very challenging in some local studies, and some insights can be obtained by the few available dated sediment cores or by studying POPs response to inter-annual climate fluctuations. Knowledge gaps and future projections can be studied by developing and applying various modelling tools, identifying compounds susceptibility to climate change, local and global effects, orienting international policies. Long-term monitoring strategies and modelling exercises taking into account climate change should be considered when devising new regulatory plans in chemicals management. Climate change implications on POPs are addressed here with special attention to monitoring, modelling and regulation issues.
显示更多 [+] 显示较少 [-]Inter- and intra-specific responses to elevated ozone and chamber climate in northern birches 全文
2009
We studied the responses of micropropagated, northern provenances of downy, mountain and silver birches to elevated ozone (O₃) and changing climate using open-top chambers (OTCs). Contrary to our hypothesis, northern birches were sensitive to O₃, i.e. O₃ levels of 31-36 ppb reduced the leaf and root biomasses by -10%, whereas wood biomass was affected to a lesser extent. The warmer and drier OTC climate enhanced growth in general, though there were differences among the species and clones, e.g. in bud burst and biomass production. Inter- and intra-specific responses to O₃ and changing climate relate to traits such as allocation patterns between the above- and belowground parts (i.e. root/shoot ratio), which further relate to nutrient and water economy. Our experiments may have mimicked future conditions quite well, but only long-term field studies can yield the information needed to forecast responses at both tree and ecosystem levels. Northern birches are responsive to ambient ozone levels.
显示更多 [+] 显示较少 [-]Modelling the risk of Pb and PAH intervention value exceedance in allotment soils by robust logistic regression 全文
2009
Soils of allotments are often contaminated by heavy metals and persistent organic pollutants. In particular, lead (Pb) and polycyclic aromatic hydrocarbons (PAHs) frequently exceed legal intervention values (IVs). Allotments are popular in European countries; cities may own and let several thousand allotment plots. Assessing soil contamination for all the plots would be very costly. Soil contamination in allotments is often linked to gardening practice and historic land use. Hence, we predict the risk of IV exceedance from attributes that characterize the history and management of allotment areas (age, nearby presence of pollutant sources, prior land use). Robust logistic regression analyses of data of Swiss allotments demonstrate that the risk of IV exceedance can be predicted quite precisely without costly soil analyses. Thus, the new method allows screening many allotments at small costs, and it helps to deploy the resources available for soil contamination surveying more efficiently. The contamination of allotment soils, expressed as frequency of intervention value exceedance, depends on the age and further attributes of the allotments and can be predicted by logistic regression.
显示更多 [+] 显示较少 [-]Fate of CL-20 in sandy soils: Degradation products as potential markers of natural attenuation 全文
2009
Monteil-Rivera, Fanny | Halasz, Annamaria | Manno, Dominic | Kuperman, Roman G. | Thiboutot, Sonia | Ampleman, Guy | Hawari, Jalal
Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH2N-C(N-NO2)-CHN-CHO or its isomer N(NO2)CH-CHN-CO-CHNH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil. Two key intermediates of CL-20 degradation are potential markers of its natural attenuation in soil.
显示更多 [+] 显示较少 [-]Follow-up trends of parasite community alteration in a marine fish after the Prestige oil-spill: Shifting baselines 全文
2009
Pérez-del-Olmo, A. | Montero, F.E. | Raga, J.A. | Fernández, M. | Kostadinova, A.
This study evaluates the follow-up trends in the composition and structure of the parasite communities in the marine sparid Boops boops after the Prestige oil-spill. A total of 400 fish comprising 11 seasonal samples was analyzed from three impacted localities on the Atlantic coast of Spain. A large number of parasite species was recovered only after the spill thus suggesting a substantial alteration of the marine food webs. Post-spill communities exhibited higher richness and abundance due to the significant changes in the abundance of the common species, the latter indicating accelerated parasite transmission rates. Multivariate analyses at two nested scales detected a directional trend in parasite community succession towards the pre-spill situation, however, with no full support for community recovery. The state of parasite communities in 2005-2006 may provide the new baseline data which can serve as a framework for quantifying the impact of potential future spills in the region. Prestige oil-spill impact on parasite communities in the sparid fish B. boops.
显示更多 [+] 显示较少 [-]Mercury cycling and species mass balances in four North American lakes 全文
2009
Qureshi, Asif | Macleod, Matthew | Scheringer, Martin | Hungerbuhler, Konrad
A mass balance model for mercury based on the fugacity concept is applied to Lake Superior, Lake Michigan, Onondaga Lake and Little Rock Lake to evaluate model performance, analyze cycling of three mercury species groups (elemental, divalent and methyl mercury), and identify important processes that determine the source-to-concentration relationship of the three mercury species groups in these lakes. This model application to four disparate ecosystems is an extension of previous applications of fugacity-based models describing mercury cycling. The model performs satisfactorily following site-specific parameterization, and provides an estimate of minimum rates of species interconversion that compare well with literature. Volatilization and sediment burial are the main processes removing mercury from the lakes, and uncertainty analyses indicate that air-water exchange of elemental mercury and water–sediment exchange of divalent mercury attached to particles are influential in governing mercury concentrations in water. Any new model application or field campaign to quantify mercury cycling in a lake should consider these processes as important.
显示更多 [+] 显示较少 [-]An exposure study with polybrominated diphenyl ethers (PBDEs) in female European starlings (Sturnus vulgaris): Toxicokinetics and reproductive effects 全文
2009
Steen, Evi van den | Eens, Marcel | Covaci, Adrian | Dirtu, Alin C. | Jaspers, Veerle L.B. | Neels, Hugo | Pinxten, Rianne
We exposed female European starlings to a pentabromodiphenyl ether (Penta-BDE) mixture through subcutaneous implants, and examined levels and profiles of polybrominated diphenyl ethers (PBDEs) together with reproductive effects. Sum PBDE levels increased significantly in the serum of the exposed females from 218 ± 43 to 23,400 ± 2035 pg/ml. Sum PBDE concentrations in the eggs of the exposed group ranged from 130 ± 12 to 220 ± 37 ng/g wet weight (ww). The profile in serum after egg laying was very similar to that in eggs. There were no detectable levels of HO-PBDEs in both serum and eggs. Fewer females of the exposed group initiated egg laying compared to the control group, although the difference was not significant. In addition, egg weight and volume were significantly higher in the exposed group. These results suggest that, at the investigated exposure levels (150 μg sum PBDEs/bird), PBDEs may have a negative effect on reproductive performance.
显示更多 [+] 显示较少 [-]Accelerated delivery of polychlorinated biphenyls (PCBs) in recent sediments near a large seabird colony in Arctic Canada 全文
2009
Michelutti, Neal | Liu, Huijun | Smol, J. P. (John P) | Kimpe, Lynda E. | Keatley, Bronwyn E. | Mallory, Mark | Macdonald, Robie W. | Douglas, Marianne S.V. | Blais, Jules M.
Polychlorinated biphenyls (PCBs) were measured in sediment cores from ponds located near a large seabird colony at Cape Vera, Devon Island, Arctic Canada. Surface sediment PCB concentrations were approximately 5x greater in seabird-affected sites relative to a nearby control pond and were correlated with independent indicators of seabird activity including, sedimentary δ¹⁵N and lakewater chlorophyll a and cadmium concentrations. PCB fluxes were amongst the highest recorded from the High Arctic, ranging from 290 to 2400 ng m⁻² yr⁻¹. Despite a widespread ban of PCBs in the mid-1970s, PCB accumulation rates in our cores increased, with the highest values recorded in the most recent sediments. Possible mechanisms for the recent PCB increases include a vertical flux step driven by seabird-delivered nutrients and/or delayed loading of PCBs from the catchment into the ponds. The high PCB levels recorded in the seabird-affected sites suggest that seabird colonies are exposing coastal ecosystems to elevated levels of contaminants.
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