خيارات البحث
النتائج 351 - 360 من 3,189
Interspecies variation in the risks of metals to bats
2015
Hernout, Béatrice V. | Pietravalle, Stéphane | Arnold, Kathryn E. | McClean, Colin J. | Aegerter, James | Boxall, Alistair B.A.
A modeling framework was used to assess the risk of four metals to UK bat species. Eight species of bats were predicted to be “at risk” from one or more of the metals in over 5% of their ranges. Species differed significantly in their predicted risk. Contamination by Pb was found to pose the greatest risk, followed by Cu, Cd and Zn. A sensitivity analysis identified the proportion of invertebrates ingested as most important in determining the risk. We then compared the model predictions with a large dataset of metals concentrations in the tissues (liver, kidney) of Pipistrellus sp. from across England and Wales. Bats found in areas predicted to be the most “at risk” contained higher metal concentrations in their tissues than those found in areas predicted “not at risk” by the model. Our spatially explicit modeling framework provides a useful tool for further environmental risk assessment studies for wildlife species.
اظهر المزيد [+] اقل [-]Aerosol deposition doses in the human respiratory tree of electronic cigarette smokers
2015
Manigrasso, Maurizio | Buonanno, Giorgio | Fuoco, Fernanda Carmen | Stabile, Luca | Avino, Pasquale
Aerosols from eight e-cigarettes at different nicotine levels and flavoring were characterized as particle number size distributions in the range 5.6–560 nm by FMPS and CPC. Results were used to provide dosimetry estimates applying the MMPD model.Particle number concentrations varied between 3.26 × 109 and 4.09 × 109 part cm−3 for e-liquids without nicotine and between 5.08 × 109 and 5.29 × 109 part cm−3 for e-liquids with nicotine. No flavor effects were detected on particle concentration data. Particle size distributions were unimodal with modes between 107–165 nm and 165–255 nm, for number and volume metrics, respectively.Averagely, 6.25 × 1010 particles were deposited in respiratory tree after a single puff. Highest deposition densities and mean layer thickness of e-cigarette liquid on the lung epithelium were estimated at lobar bronchi.Our study shows that e-cigarette aerosol is source of high particle dose in respiratory system, from 23% to 35% of the daily dose of a no-smoking individual.
اظهر المزيد [+] اقل [-]Ambient air pollution, temperature and out-of-hospital coronary deaths in Shanghai, China
2015
Dai, Jinping | Chen, Renjie | Meng, Xia | Yang, Changyuan | Zhao, Zhuohui | Kan, Haidong
Few studies have evaluated the effects of ambient air pollution and temperature in triggering out-of-hospital coronary deaths (OHCDs) in China. We evaluated the associations of air pollution and temperature with daily OHCDs in Shanghai, China from 2006 to 2011. We applied an over-dispersed generalized additive model and a distributed lag nonlinear model to analyze the effects of air pollution and temperature, respectively. A 10 μg/m3 increase in the present-day PM10, PM2.5, SO2, NO2 and CO were associated with increases in OHCD mortality of 0.49%, 0.68%, 0.88%, 1.60% and 0.08%, respectively. A 1 °C decrease below the minimum-mortality temperature corresponded to a 3.81% increase in OHCD mortality on lags days 0–21, and a 1 °C increase above minimum-mortality temperature corresponded to a 4.61% increase over lag days 0–3. No effects were found for in-hospital coronary deaths. This analysis suggests that air pollution, low temperature and high temperature may increase the risk of OHCDs.
اظهر المزيد [+] اقل [-]Exposure to household endotoxin and total and allergen-specific IgE in the US population
2015
Min, Kyoung-Bok | Min, Chin-yŏng
Background: Although endotoxin has strong pro-inflammatory properties, endotoxin-allergy relationship in adults and children have been inconsistent. Objectives: We investigated the association between household endotoxin levels and total immunoglobulin E (IgE) or specific IgE in the US general population, classified into three age ranges: children/adolescent, adults, and older adults. Methods: We analyzed the 2005–2006 National Health and Nutrition Examination Surveys. A total of 5220 participants for whom serum IgE and household endotoxin data were available was included in the analyses. Results: Exposure to endotoxin reduced the risk for allergic sensitization, especially in specific IgE to plants (OR in Quartile 3 = 0.58; 95% CI = 0.44–0.76) and pets (OR in Quartile 3 = 0.62; 95% CI = 0.41–0.92), for children/adolescents. In contrast, the risk among adults and older adults increased with increasing endotoxin levels. Conclusions: Our findings suggest that the effect of endotoxin on allergic reaction is likely to depend on age.
اظهر المزيد [+] اقل [-]Characterization of the exchange of PBDEs in a subtropical paddy field of China: A significant inputs of PBDEs via air–foliage exchange
2015
Wang, Yan | Wang, Shaorui | Xu, Yue | Luo, Chunling | Li, Jun | Zhang, Gan
Rice and the distinctive cultivation practices employed in rice growth can significantly influence the environmental fate of polybrominated diphenyl ethers (PBDEs) in a paddy field. We studied variations in PBDE concentrations in multiple compartments of a paddy field in the suburban area of Guangzhou, South China, including air, soil, water, and rice tissues. The input/output fluxes of air–surface and air–foliage exchange, atmospheric deposition and water input during different rice growth stages were measured simultaneously. Air–foliage and air–water diffusion exchanges were the key processes controlling inputs and outputs of PBDEs in paddy fields, respectively, whereas atmospheric deposition dominated inputs of higher brominated PBDEs. The high input of PBDEs via air–foliage exchange suggested that vegetation can significantly increase the air-to-field transport of PBDEs in ecosystems. The annual input of PBDEs in all paddy fields in Guangdong Province was estimated to be 22.1 kg.
اظهر المزيد [+] اقل [-]Metal extent in blood of livestock from Dandora dumping site, Kenya: Source identification of Pb exposure by stable isotope analysis
2015
Nakata, Hokuto | Nakayama, Shouta M.M. | Ikenaka, Yoshinori | Mizukawa, Hazuki | Ishii, Chihiro | Yohannes, Yared B. | Konnai, Satoru | Darwish, Wageh Sobhy | Ishizuka, Mayumi
Nairobi city in Kenya produces 2000 tons/day of garbage, and most of it is dumped onto the Dandora dumping site, home to a quarter-million residents. This study was conducted (1) to assess the contamination levels of nine metals and a metalloid (arsenic) in the blood of pigs, goats, sheep and cattle from Dandora, and (2) to identify a possible source of lead (Pb) pollution. Cadmium (Cd, 0.17–4.35 μg/kg, dry-wt) and Pb (90–2710 μg/kg) levels in blood were generally high, suggesting human exposure to Cd through livestock consumption and Pb poisoning among pigs (2600 μg/kg) and cattle (354 μg/kg). Results of Pb isotope ratios indicated that the major exposure route might differ among species. Our results also suggested a possibility that the residents in Dandora have been exposed to the metals through livestock consumption.
اظهر المزيد [+] اقل [-]Simultaneous assessments of occurrence, ecological, human health, and organoleptic hazards for 77 VOCs in typical drinking water sources from 5 major river basins, China
2015
Chen, Xichao | Luo, Qian | Wang, Donghong | Gao, Jijun | Wei, Zi | Wang, Zijian | Zhou, Huaidong | Mazumder, Asit
Owing to the growing public awareness on the safety and aesthetics in water sources, more attention has been given to the adverse effects of volatile organic compounds (VOCs) on aquatic organisms and human beings. In this study, 77 target VOCs (including 54 common VOCs, 13 carbonyl compounds, and 10 taste and odor compounds) were detected in typical drinking water sources from 5 major river basins (the Yangtze, the Huaihe, the Yellow, the Haihe and the Liaohe River basins) and their occurrences were characterized. The ecological, human health, and olfactory assessments were performed to assess the major hazards in source water. The investigation showed that there existed potential ecological risks (1.30 × 10 ≤ RQtotals ≤ 8.99 × 10) but little human health risks (6.84 × 10−7 ≤ RQtotals ≤ 4.24 × 10−4) by VOCs, while that odor problems occurred extensively. The priority contaminants in drinking water sources of China were also listed based on the present assessment criteria.
اظهر المزيد [+] اقل [-]Growth overcompensation against O3 exposure in two Japanese oak species, Quercus mongolica var. crispula and Quercus serrata, grown under elevated CO2
2015
Kitao, Mitsutoshi | Komatsu, Masabumi | Yazaki, Kenichi | Kitaoka, Satoshi | Tobita, Hiroyuki
To assess the effects of elevated concentrations of carbon dioxide (CO2) and ozone (O3) on the growth of two mid-successional oak species native to East Asia, Quercus mongolica var. crispula and Quercus serrata, we measured gas exchange and biomass allocation in seedlings (initially 1-year-old) grown under combinations of elevated CO2 (550 μmol mol−1) and O3 (twice-ambient) for two growing seasons in an open-field experiment in which root growth was not limited. Both the oak species showed a significant growth enhancement under the combination of elevated CO2 and O3 (indicated by total dry mass; over twice of ambient-grown plants, p < .05), which probably resulted from a preferable biomass partitioning into leaves induced by O3 and a predominant enhancement of photosynthesis under elevated CO2. Such an over-compensative response in the two Japanese oak species resulted in greater plant growth under the combination of elevated CO2 and O3 than elevated CO2 alone.
اظهر المزيد [+] اقل [-]Effects of sulfide reduction on adsorption affinities of colloidal graphene oxide nanoparticles for phenanthrene and 1-naphthol
2015
Wang, Fanfan | Wang, Fang | Zhu, Dongqiang | Chen, Wei
The abiotic transformation of nanomaterials in the natural environment can significantly affect their fate, transport, and effects. We observed that the adsorption affinities of graphene oxide nanoparticles (GONPs) for both phenanthrene and 1-naphthol were profoundly enhanced in the presence of sulfide, an environmentally relevant reductant, with doses as low as 0.5 mM Na2S per 10 mg/L GONPs. For phenanthrene adsorption enhancement was predominantly caused by the increased surface hydrophobicity from Na2S treatment. For 1-naphthol, however, adsorption enhancement was caused mainly by the conversion of the epoxy/ether groups on the surface of graphene oxide (GO) to the phenolic hydroxyl and carbonyl groups, which allowed more significant H-bonding between 1-naphthol and GONPs. The findings of this study underline that abiotic transformation of GO not only affects the stability and mobility of GONPs, but also influences the adsorptive interactions between GONPs and environmental contaminants, and consequently, may increase the environmental risks of GONPs.
اظهر المزيد [+] اقل [-]Agglomeration of Ag and TiO2 nanoparticles in surface and wastewater: Role of calcium ions and of organic carbon fractions
2015
Topuz, Emel | Traber, Jacqueline | Sigg, Laura | Talinli, Ilhan
This study aims to investigate factors leading to agglomeration of citrate coated silver (AgNP-Cit), polyvinylpyrrolidone coated AgNPPVP and titanium dioxide (TiO2) nanoparticles in surface waters and wastewater. ENPs (1 mg/L) were spiked to unfiltered, filtered, ultrafiltered (<10 kDa and <1 kDa) samples. Z-average particle sizes were measured after 1 h, 1 day and 1 week. AgNP-PVP was stable in all fractions of the samples and kept their original size around 60 nm over 1 week. Agglomeration of AgNP-Cit and TiO2 was positively correlated with Ca2+ concentration, but dissolved organic carbon concentrations > 2 mg/L contributed to stabilizing these NP. Moreover, agglomeration of AgNP-Cit in the various organic matter fractions showed that high molecular weight organic compounds such as biopolymers provide stabilization in natural water. A generalized scheme for the agglomeration behavior of AgNP-Cit, AgNP-PVP and TiO2 in natural waters was proposed based on their relation with Ca2+, Mg2+ and DOC concentration.
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