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Synthesis of isotopically modified ZnO nanoparticles and their potential as nanotoxicity tracers
2011
Dybowska, Agnieszka D. | Croteau, Marie-Noele | Misra, Superb K. | Berhanu, Deborah | Luoma, Samuel N. | Christian, Paul | O’Brien, Paul | Valsami-Jones, Eugenia
Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn (⁶⁷Zn) ZnO nanoparticles and measured the uptake of ⁶⁷Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range (<15 μg g⁻¹). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 μg g⁻¹ which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions.
显示更多 [+] 显示较少 [-]Carbon isotope signature of dissolved inorganic carbon (DIC) in precipitation and atmospheric CO₂
2011
Górka, Maciej | Sauer, Peter E. | Lewicka-Szczebak, Dominika | Jędrysek, Mariusz Orion
This paper describes results of chemical and isotopic analysis of inorganic carbon species in the atmosphere and precipitation for the calendar year 2008 in Wrocław (SW Poland). Atmospheric air samples (collected weekly) and rainwater samples (collected after rain episodes) were analysed for CO₂ and dissolved inorganic carbon (DIC) concentrations and for δ¹³C composition. The values obtained varied in the ranges: atmospheric CO₂: 337–448ppm; δ¹³CCO₂ from −14.4 to −8.4‰; DIC in precipitation: 0.6–5.5mgdm⁻³; δ¹³CDIC from −22.2 to +0.2‰. No statistical correlation was observed between the concentration and δ¹³C value of atmospheric CO₂ and DIC in precipitation. These observations contradict the commonly held assumption that atmospheric CO₂ controls the DIC in precipitation. We infer that DIC is generated in ambient air temperatures, but from other sources than the measured atmospheric CO₂. The calculated isotopic composition of a hypothetical CO₂ source for DIC forming ranges from −31.4 to −11.0‰, showing significant seasonal variations accordingly to changing anthropogenic impact and atmospheric mixing processes.
显示更多 [+] 显示较少 [-]A rapid and high-throughput quantum dots bioassay for monitoring of perfluorooctane sulfonate in environmental water samples
2011
Zhang, Jiong | Wan, Yanjian | Li, Yuanyuan | Zhang, Qiongfang | Xu, Shunqing | Zhu, Huijun | Shu, Baihua
Currently HPLC/MS is the state of the art tool for environmental/drinking water perfluorooctane sulfonate (PFOS) monitoring. PFOS can bind to peroxisomal proliferator-activated receptor-alpha (PPARα), which forms heterodimers with retinoid X receptors (RXRs) and binds to PPAR response elements. In this bioassay free PFOS in water samples competes with immobilized PFOS in ELISA plates for a given amount of PPARα–RXRα. It can be determined indirectly by immobilizing PPARα–RXRα–PFOS complex to another plate coated with PPARα antibody and subsequent measuring the level of PPARα–RXRα by using biotin-modified PPARα–RXRα probes–quantum dots–streptavidin detection system. The rapid and high-throughput bioassay demonstrated a detection limit of 2.5 ng L⁻¹ with linear range between 2.5 ng L⁻¹ and 75 ng L⁻¹. Detection results of environmental water samples were highly consistent between the bioassay and HPLC/MS.
显示更多 [+] 显示较少 [-]Combustion-derived substances in deep basins of Puget Sound: Historical inputs from fossil fuel and biomass combustion
2011
Kuo, Li-Jung | Louchouarn, Patrick | Herbert, Bruce E. | Brandenberger, Jill M. | Wade, Terry L. | Crecelius, Eric
Reconstructions of 250 years historical inputs of two distinct types of black carbon (soot/graphitic black carbon (GBC) and char-BC) were conducted on sediment cores from two basins of the Puget Sound, WA. Signatures of polycyclic aromatic hydrocarbons (PAHs) were also used to support the historical reconstructions of BC to this system. Down-core maxima in GBC and combustion-derived PAHs occurred in the 1940s in the cores from the Puget Sound Main Basin, whereas in Hood Canal such peak was observed in the 1970s, showing basin-specific differences in inputs of combustion byproducts. This system showed relatively higher inputs from softwood combustion than the northeastern U.S. The historical variations in char-BC concentrations were consistent with shifts in climate indices, suggesting an influence of climate oscillations on wildfire events. Environmental loading of combustion byproducts thus appears as a complex function of urbanization, fuel usage, combustion technology, environmental policies, and climate conditions.
显示更多 [+] 显示较少 [-]Contaminants in the coastal karst aquifer system along the Caribbean coast of the Yucatan Peninsula, Mexico
2011
Metcalfe, Christopher D. | Beddows, Patricia A. | Bouchot, Gerardo Gold | Metcalfe, Tracy L. | Li, Hongxia | Lavieren, Hanneke van
Intensive land development as a result of the rapidly growing tourism industry in the “Riviera Maya” region of the Yucatan Peninsula, Mexico may result in contamination of groundwater resources that eventually discharge into Caribbean coastal ecosystems. We deployed two types of passive sampling devices into groundwater flowing through cave systems below two communities to evaluate concentrations of contaminants and to indicate the possible sources. Pharmaceuticals and personal care products accumulated in the samplers could only have originated from domestic sewage. PAHs indicated contamination by runoff from highways and other impermeable surfaces and chlorophenoxy herbicides accumulated in samplers deployed near a golf course indicated that pesticide applications to turf are a source of contamination. Prevention and mitigation measures are needed to ensure that expanding development does not impact the marine environment and human health, thus damaging the tourism-based economy of the region.
显示更多 [+] 显示较少 [-]Sequestration of organochlorine pesticides in soils of distinct organic carbon content
2011
Zhang, Na | Yang, Yu | Tao, Shu | Liu, Yan | Shi, Ke-Lu
In the present study, five soil samples with organic carbon contents ranging from 0.23% to 7.1% and aged with technical dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) for 15 months were incubated in a sealed chamber to investigate the dynamic changes of the OCP residues. The residues in the soils decreased over the incubation period and finally reached a plateau. Regression analysis showed that degradable fractions of OCPs were negatively correlated with soil organic carbon (SOC) except for α-HCH, while no correlation was found between degradation rate and SOC, which demonstrated that SOC content determines the OCP sequestration fraction in soil. Analysis of the ratio of DDT and its primary metabolites showed that, since it depends on differential sequestration among them, magnitude of (p,p′-DDE + p,p′-DDD)/p,p′-DDT is not a reliable criterion for the identification of new DDT sources.
显示更多 [+] 显示较少 [-]Responses of evergreen and deciduous Quercus species to enhanced ozone levels
2011
Calatayud, Vicent | Cerveró, Júlia | Calvo, Esperanza | García Breijo, Francisco José | Reig-Armiñana, José | Sanz, María José
Plants of one evergreen oak (Quercus ilex) and three deciduous oaks (Q. faginea, with small leaves; Q. pyrenaica and Q. robur, with large leaves) were exposed both to filtered air and to enhanced ozone levels in Open-Top Chambers. Q. faginea and Q. pyrenaica were studied for the first time. Based on visible injury, gas exchange, chlorophyll content and biomass responses, Q. pyrenaica was the most sensitive species, and Q. ilex was the most tolerant, followed by Q. faginea. Functional leaf traits of the species were related to differences in sensitivity, while accumulated ozone flux via stomata (POD₁.₆) partly contributed to the observed differences. For risk assessment of Mediterranean vegetation, the diversity of responses detected in this study should be taken into account, applying appropriate critical levels.
显示更多 [+] 显示较少 [-]Behaviour of arsenic in forested catchments following a high-pollution period
2011
Novák, Martin | Erbanova, Lucie | Fottova, Daniela | Cudlin, P. (Pavel) | Kubena, Ales
Due to high availability of adsorption sites, forested catchments could be net sinks for pollutant arsenic both during the period of increasing and decreasing pollution. We tested this hypothesis along a north–south pollution gradient in spruce die-back affected areas of Central Europe. For two water years (2007–2008), we monitored As fluxes via spruce-canopy throughfall, open-area precipitation, and runoff in four headwater catchments (Czech Republic). Since 1980, atmospheric As inputs decreased 26 times in the north, and 13 times in the south. Arsenic export by runoff was similar to atmospheric inputs at three sites, resulting in a near-zero As mass balance. One site exhibited a net export of As (2.2 g ha⁻¹ yr⁻¹). In contrast, the preceding period (1995–2006) showed much higher As fluxes, and higher As export. Czech catchments do not serve as net sinks of atmospheric As. A considerable proportion of old industrial arsenic is flushed out of the soil.
显示更多 [+] 显示较少 [-]Inherent mineralization of 2,6-dichlorobenzamide (BAM) in unsaturated zone and aquifers – Effect of initial concentrations and adaptation
2011
Janniche, Gry Sander | Clausen, Liselotte | Albrechtsen, Hans-Jørgen
The dichlobenil metabolite BAM (2,6-dichlorobenzamide) is frequently detected in aquifers e.g. in Denmark despite the mother compound dichlobenil was banned here since 1997. BAM mineralization was investigated at environmentally relevant concentrations in sediment samples. Undisturbed sediment cores with known dichlobenil application were collected from topsoil to 8.5 m below surface resulting in 57 samples hereof 4 aquifer samples. Mineralization was only substantial (>10%) in the uppermost meter of the unsaturated zone. Microbial adaptation, observed as faster mineralization in pre-exposed than in pristine sediments from the same location, was only evident in sandy sediment where dichlobenil was still present, but not in clayey sediments. Higher initial concentrations (1–5000 μg/kg) did not stimulate mineralization in pristine clayey or sandy sediments, or in pre-exposed sand. However, in pre-exposed clay mineralization was stimulated at high concentrations. Furthermore BAM was for the first time mineralized in aerobic aquifer sediments from different BAM-contaminated groundwater locations.
显示更多 [+] 显示较少 [-]Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. I. From the tree crown to leaf cell level
2011
Vollenweider, Pierre | Menard, Terry | Günthardt-Goerg, Madeleine S.
In order to achieve efficient phytoextraction of heavy metals using trees, the metal allocation to aboveground tissues needs to be characterised. In his study, the distribution of heavy metals, macro- and micronutrients and the metal micro-localisation as a function of the leaf position and heavy metal treatment were analysed in poplars grown on soil with mixed metal contamination. Zinc was the most abundant contaminant in both soil and foliage and, together with cadmium, was preferentially accumulated in older foliage whereas excess copper and lead were not translocated. Changes in other element concentrations indicated an acceleration in aging as a consequence of the metal treatment. Excess zinc was irregularly accumulated inside leaf tissues, tended to saturate the veins and was more frequently stored in cell symplast than apoplast. Storage compartments including metabolically safe and sensitive subcellular sites resulted in sizable metal accumulation as well as stress reactions.
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