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Результаты 361-370 из 2,512
Comprehensive probabilistic modelling of environmental emissions of engineered nanomaterials Полный текст
2014
Sun, Tian Yin | Gottschalk, Fadri | Hungerbühler, Konrad | Nowack, Bernd
Concerns about the environmental risks of engineered nanomaterials (ENM) are growing, however, currently very little is known about their concentrations in the environment. Here, we calculate the concentrations of five ENM (nano-TiO2, nano-ZnO, nano-Ag, CNT and fullerenes) in environmental and technical compartments using probabilistic material-flow modelling. We apply the newest data on ENM production volumes, their allocation to and subsequent release from different product categories, and their flows into and within those compartments. Further, we compare newly predicted ENM concentrations to estimates from 2009 and to corresponding measured concentrations of their conventional materials, e.g. TiO2, Zn and Ag. We show that the production volume and the compounds' inertness are crucial factors determining final concentrations. ENM production estimates are generally higher than a few years ago. In most cases, the environmental concentrations of corresponding conventional materials are between one and seven orders of magnitude higher than those for ENM.
Показать больше [+] Меньше [-]Decreasing effect and mechanism of FeSO4 seed particles on secondary organic aerosol in α-pinene photooxidation Полный текст
2014
Chu, Biwu | Liu, Yongchun | Li, Junhua | Takekawa, Hideto | Liggio, John | Li, Shao-Meng | Jiang, Jingkun | Hao, Jiming | He, Hong
α-Pinene/NOx and α-pinene/HONO photooxidation experiments at varying humidity were conducted in smog chambers in the presence or absence of FeSO4 seed particles. FeSO4 seed particles decrease SOA mass as long as water was present on the seed particle surface, but FeSO4 seed particles have no decreasing effect on SOA under dryer conditions at 12% relative humidity (RH). The decreasing effect of FeSO4 seed particles on the SOA mass is proposed to be related to oxidation processes in the surface layer of water on the seed particles. Free radicals, including OH, can be formed from catalytic cycling of Fe2+ and Fe3+ in the aqueous phase. These radicals can react further with the organic products of α-pinene oxidation on the seed particles. The oxidation may lead to formation of smaller molecules which have higher saturation vapor pressures and favor repartitioning to the gas phase, and therefore, reduces SOA mass.
Показать больше [+] Меньше [-]Degradation and bound-residue formation of nonylphenol in red soil and the effects of ammonium Полный текст
2014
Liu, Jie | Shan, Jun | Jiang, Bingqi | Wang, Lianhong | Yu, Bin | Chen, Jianqiu | Guo, Hongyan | Ji, Rong
Fate of nonylphenol (NP) in soils and the effects of nitrogen fertilizers are unclear. Using 14C-tracer, we studied the aerobic and anaerobic degradation of 4-NP111 in a paddy red soil amended without and with ammonium chloride. Under oxic conditions, 4-NP111 had a half-life of 16.1 ± 1.6 days and minor mineralization (3.84 ± 0.02%), forming no extractable metabolite but abundant bound residues (60.9 ± 1.7%, mostly bound to humin) after 49 days of incubation. The ammonium amendment (8 mmol/kg soil) significantly inhibited the degradation (half-life of 68.0 ± 7.7 days), mineralization (2.0 ± 1.1%), and bound-residue formation (23.7 ± 0.2%). Under anoxic conditions, 4-NP111 did not degrade during 49 days of incubation and the ammonium amendment (40 mmol/kg soil) did not affect its persistence. Our results demonstrate that bound-residue formation was a major mechanism for NP dissipation in the red soil under oxic conditions and that chemical nitrogen fertilizer at average field application rate may already considerably increase NP recalcitrance in agricultural soils.
Показать больше [+] Меньше [-]Characteristics of particulate matter (PM10) and its relationship with meteorological factors during 2001–2012 in Beijing Полный текст
2014
Tian, Guangjin | Qiao, Zhi | Xu, Xinliang
Atmospheric pollution has become a significant challenge in Beijing metropolitan region, China. In this study, wavelet analysis and gray analysis were proposed to explore the temporal characteristics of particulate matter (PM10) and its relationships with meteorological factors during 2001–2012. The analysis indicated that air quality had got better significantly over the last decade. It was clearly interannual, seasonal, and monthly variation of atmospheric pollution, which represented that the air quality was the worst in spring, and got better in summer, subsequently tended to be more serious in autumn and winter. Generally atmospheric pressure was the most important meteorological feature influencing on PM10, followed by relative humidity and wind speed. However, the dominant meteorological factors influencing the atmospheric pollution were different in the four seasons. The results suggest that urban design and effective measures based on the relationship between meteorological factors and PM10 would be effective for improving atmospheric pollution.
Показать больше [+] Меньше [-]Acute effects of air pollution on asthma hospitalization in Shanghai, China Полный текст
2014
Cai, Jing | Zhao, Ang | Zhao, Jinzhuo | Chen, Renjie | Wang, Weibing | Ha, Sandie | Xu, Xiaohui | Kan, Haidong
Air pollution has been accepted as an important contributor to asthma development and exacerbation. However, the evidence is limited in China. In this study, we investigated the acute effect of air pollution on asthma hospitalization in Shanghai, China. We applied over-dispersed generalized additive model adjusted for weather conditions, day of the week, long-term and seasonal trends. An interquartile range increase in the moving average concentrations of PM10, SO2, NO2 and BC on the concurrent day and previous day corresponded to 1.82%, 6.41%, 8.26% and 6.62% increase of asthmatic hospitalization, respectively. The effects of SO2 and NO2 were robust after adjustment for PM10. The associations appeared to be more evident in the cool season than in the warm season. Our results contribute to the limited data in the scientific literature on acute effects of air pollution on asthma in high exposure settings, which are typical in developing countries.
Показать больше [+] Меньше [-]Effects of the geophagous earthworm Metaphire guillelmi on sorption, mineralization, and bound-residue formation of 4-nonylphenol in an agricultural soil Полный текст
2014
Shan, Jun | Wang, Yongfeng | Wang, Lianhong | Yan, Xiaoyuan | Ji, Rong
Effects of earthworms on fate of nonylphenol (NP) are obscure. Using 14C-4-NP111 as a representative, we studied the fate of 4-NP in an agricultural soil with or without the earthworm Metaphire guillelmi and in fresh cast of the earthworm. Sorption of 4-NP on the cast (Kd 1564) was significantly higher than on the parent soil (Kd 1474). Mineralization of 4-NP was significantly lower in the cast (13.2%) and the soil with earthworms (10.4%) than in the earthworm-free soil (16.0%). One nitro metabolite of 4-NP111 (2-nitro-4-NP111) was identified in the soil and cast, and the presence of the earthworm significantly decreased its amounts. The presence of earthworm also significantly decreased formation of bound residues of 4-NP in the soil. Our results demonstrate that earthworms could significantly change the fate of 4-NP, underlining that earthworm effects should be considered when evaluating behavior and risk of 4-NP in soil.
Показать больше [+] Меньше [-]A new analytical approach for monitoring microplastics in marine sediments Полный текст
2014
Nuelle, Marie-Theres | Dekiff, Jens H. | Rémy, Dominique | Fries, Elke
A two-step method was developed to extract microplastics from sediments. First, 1 kg sediments was pre-extracted using the air-induced overflow (AIO) method, based on fluidisation in a sodium chloride (NaCl) solution. The original sediment mass was reduced by up to 80%. As a consequence, it was possible to reduce the volume of sodium iodide (NaI) solution used for the subsequent flotation step. Recoveries of the whole procedure for polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polystyrene and polyurethane with sizes of approximately 1 mm were between 91 and 99%. After being stored for one week in a 35% H2O2 solution, 92% of selected biogenic material had dissolved completely or had lost its colour, whereas the tested polymers were resistant. Microplastics were extracted from three sediment samples collected from the North Sea island Norderney. Using pyrolysis gas chromatography/mass spectrometry, these microplastics were identified as PP, PVC and PET.
Показать больше [+] Меньше [-]Adsorption of polar, nonpolar, and substituted aromatics to colloidal graphene oxide nanoparticles Полный текст
2014
Wang, Fang | Haftka, Joris J.-H. | Sinnige, Theo L. | Hermens, Joop L.M. | Chen, Wei
We conducted batch adsorption experiments to understand the adsorptive properties of colloidal graphene oxide nanoparticles (GONPs) for a range of environmentally relevant aromatics and substituted aromatics, including model nonpolar compounds (pyrene, phenanthrene, naphthalene, and 1,3-dichlorobenzene) and model polar compounds (1-naphthol, 1-naphthylamine, 2,4-dichlorophenol, and 2,4-dinitrotoluene). GONPs exhibited strong adsorption affinities for all the test compounds, with distribution coefficients on the order of 103–106 L/kg. Adsorption to GONPs is much more linear than to carbon nanotubes (CNTs) and C60, likely because GO nanoflakes are essentially individually dispersed (rendering adsorption sites of similar adsorption energy) whereas CNT/C60 are prone to bundling/aggregation. For a given compound GONPs and CNTs often exhibit different adsorption affinities, which is attributable to the differences in both the morphology and surface chemistry between the two nanomaterials. Particularly, the high surface O-content of GONPs enables strong H-bonding and Lewis acid–base interactions with hydroxyl- and amino-substituted aromatics.
Показать больше [+] Меньше [-]If you could turn back time: Understanding transgenerational latent effects of developmental exposure to contaminants Полный текст
2014
Kimberly, David A. | Salice, Christopher J.
Latent effects result from embryonic experiences but manifest in later stages of ontogeny. Our objective was to better understand how developmental exposure to contaminants influence life history traits and tolerance to novel stress in the freshwater gastropod, Physa pomilia. Ten egg masses were exposed to each of three initial treatments including control, 2.5 μg/L cadmium (Cd), and 10 μg/L Cd; there was no effect of this initial treatment on hatching success. At hatching, snails were transferred to cadmium-free water. Three weeks later, snails were divided among four secondary treatments including control, 50 μg/L Cd, 150 μg/L Cd, and 35 °C. Developmental Cd exposure plus secondary temperature stress caused the most adverse effects. Surprisingly, developmental Cd exposure alone was enough to cause significant decreases in reproductive success a generation later. That effects can manifest as transgenerational decrements in reproductive success suggests that latent effects are important and have longer lasting consequences than previously considered.
Показать больше [+] Меньше [-]Lead contamination and transfer in urban environmental compartments analyzed by lead levels and isotopic compositions Полный текст
2014
Hu, Xin | Sun, Yuanyuan | Ding, Zhuhong | Zhang, Yun | Wu, Jichun | Lian, Hongzhen | Wang, Tijian
Lead levels and isotopic compositions in atmospheric particles (TSP and PM2.5), street dust and surface soil collected from Nanjing, a mega city in China, were analyzed to investigate the contamination and the transfer of lead in urban environmental compartments. The lead contents in TSP and PM2.5 are significantly higher than them in the surface soil and street dust (p < 0.05). The enrichment factor using the mass ratio of lead to the major crustal elements (Al, Sr, Ti and Fe) indicates significant lead enrichment in atmospheric particles. The plots of 206Pb/207Pb vs.208Pb/206Pb and 206Pb/207Pb vs. 1/Pb imply that the street dust and atmospheric particles (TSP and PM2.5) have very similar lead sources. Coal emissions and smelting activities may be the important lead sources for street dust and atmospheric particles (TSP and PM2.5), while the deposition of airborne lead is an important lead source for urban surface soil.
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