خيارات البحث
النتائج 301 - 310 من 3,208
Are imported consumer products an important diffuse source of PFASs to the Norwegian environment? النص الكامل
2015
Vestergren, Robin | Herzke, Dorte | Wang, Thanh | Cousins, Ian T.
The aim of this study was to measure perfluoroalkyl substances in a selection of imported consumer products (n = 45) and estimate population normalized emission rates during the use phase. 6:2 and 8:2 fluorotelomer alcohol (FTOH) were found in the highest concentrations ranging from <MDL to 374 and 163 μg m−2 respectively. Concentrations of FTOHs were approximately 2–3 orders of magnitude higher than those of perfluoroalkyl carboxylic acids (PFCAs). Although perfluorooctane sulfonate (PFOS) was detected in one carpet sample at 1.7 μg m−2, the majority of samples complied with regulatory limits for PFOS in the EU. Population normalized emission rates of perfluorooctanoic acid, 6:2 FTOH and 8:2 FTOH from imported consumer products were estimated to be 6.6, 2130 and 197 μg year−1 capita−1 respectively for the “intermediate” emission scenario. The results from this study suggest that emissions from imported products would have a small impact on the environmental concentrations of perfluoroalkyl acids on a regional scale.
اظهر المزيد [+] اقل [-]Are levels of perfluoroalkyl substances in soil related to urbanization in rapidly developing coastal areas in North China? النص الكامل
2015
Meng, Jing | Wang, Tieyu | Wang, Pei | Zhang, Yueqing | Li, Qifeng | Lü, Yonglong | Giesy, John P.
Concentrations of 13 perfluoroalkyl substances (PFASs) were quantified in 79 surface soil samples from 17 coastal cities in three provinces and one municipality along the Bohai and Yellow Seas. The ∑PFASs concentrations ranged from less than limitation of quantification (LOQ) to 13.97 ng/g dry weight (dw), with a mean of 0.98 ng/g dw. The highest concentration was observed along the Xiaoqing River from Shandong province, followed by that from the Haihe River in Tianjin (10.62 ng/g dw). Among four regions, ∑PFASs concentrations decreased in the order of Tianjin, Shandong, Liaoning and Hebei, which was consistent with levels of urbanization. Fluorine chemical industries allocated in Shandong and Liaoning played important roles in terms of point emission and contamination of PFASs, dominated by perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Intensive anthropogenic activities involved in urbanization possibly resulted in increasing releases of PFASs from industrial and domestic sources.
اظهر المزيد [+] اقل [-]Persistent and emerging micro-organic contaminants in Chalk groundwater of England and France النص الكامل
2015
Lapworth, D.J. | Baran, N. | Stuart, M.E. | Manamsa, K. | Talbot, J.
The Chalk aquifer of Northern Europe is an internationally important source of drinking water and sustains baseflow for surface water ecosystems. The areal distribution of microorganic (MO) contaminants, particularly non-regulated emerging MOs, in this aquifer is poorly understood. This study presents results from a reconnaissance survey of MOs in Chalk groundwater, including pharmaceuticals, personal care products and pesticides and their transformation products, conducted across the major Chalk aquifers of England and France. Data from a total of 345 sites collected during 2011 were included in this study to provide a representative baseline assessment of MO occurrence in groundwater. A suite of 42 MOs were analysed for at each site including industrial compounds (n=16), pesticides (n=14) and pharmaceuticals, personal care and lifestyle products (n=12). Occurrence data is evaluated in relation to land use, aquifer exposure, well depth and depth to groundwater to provide an understanding of vulnerable groundwater settings.
اظهر المزيد [+] اقل [-]Detection of Copper (II) and Cadmium (II) binding to dissolved organic matter from macrophyte decomposition by fluorescence excitation-emission matrix spectra combined with parallel factor analysis النص الكامل
2015
Yuan, Dong-hai | Guo, Xu-jing | Wen, Li | He, Lian-sheng | Wang, Jing-gang | Li, Jun-qi
Fluorescence excitation-emission matrix (EEM) spectra coupled with parallel factor analysis (PARAFAC) was used to characterize dissolved organic matter (DOM) derived from macrophyte decomposition, and to study its complexation with Cu (II) and Cd (II). Both the protein-like and the humic-like components showed a marked quenching effect by Cu (II). Negligible quenching effects were found for Cd (II) by components 1, 5 and 6. The stability constants and the fraction of the binding fluorophores for humic-like components and Cu (II) can be influenced by macrophyte decomposition of various weight gradients in aquatic plants. Macrophyte decomposition within the scope of the appropriate aquatic phytomass can maximize the stability constant of DOM-metal complexes. A large amount of organic matter was introduced into the aquatic environment by macrophyte decomposition, suggesting that the potential risk of DOM as a carrier of heavy metal contamination in macrophytic lakes should not be ignored.
اظهر المزيد [+] اقل [-]Carbon fluxes from an urban tropical grassland النص الكامل
2015
Ng, B.J.L. | Hutyra, L.R. | Nguyen, H. | Cobb, A.R. | Kai, F.M. | Harvey, C. | Gandois, L.
Turfgrass covers a large fraction of the urbanized landscape, but the carbon exchange of urban lawns is poorly understood. We used eddy covariance and flux chambers in a grassland field manipulative experiment to quantify the carbon mass balance in a Singapore tropical turfgrass. We also assessed how management and variations in environmental factors influenced CO2 respiration. Standing aboveground turfgrass biomass was 80 gC m−2, with a mean ecosystem respiration of 7.9 ± 1.1 μmol m−2 s−1. The contribution of autotrophic respiration was 49–76% of total ecosystem respiration. Both chamber and eddy covariance measurements suggest the system was in approximate carbon balance. While we did not observe a significant relationship between the respiration rates and soil temperature or moisture, daytime fluxes increased during the rainy interval, indicating strong overall moisture sensitivity. Turfgrass biomass is small, but given its abundance across the urban landscape, it significantly influences diurnal CO2 concentrations.
اظهر المزيد [+] اقل [-]A multibiomarker approach to explore interactive effects of propranolol and fluoxetine in marine mussels النص الكامل
2015
Franzellitti, Silvia | Buratti, Sara | Du, Bowen | Haddad, Samuel P. | Chambliss, C Kevin | Brooks, Bryan W. | Fabbri, Elena
A multi-biomarker approach, including several lysosomal parameters, activity and mRNA expression of antioxidant enzymes, and DNA damage, was employed to investigate the nominal effects of 0.3 ng/L fluoxetine (FX) and 0.3 ng/L propranolol (PROP) alone or in combination (0.3 ng/L FX + 0.3 ng/L PROP) on Mediterranean mussels after a 7 day treatment. FX co-exposure appears to facilitate PROP bioaccumulation because PROP only accumulated in digestive gland of FX + PROP treated mussels. Lysosomal parameters were significantly impaired by FX + PROP treatment, while no clear antioxidant responses at the catalytic and transcriptional levels were observed. Biomarker responses led to a “medium stress level” diagnosis in FX + PROP treated mussels, according to the Expert System, whereas 0.3 ng/L PROP or FX alone did not induce consistent stress conditions. These findings suggest vulnerability of coastal marine mussels to FX and PROP contamination at environmentally relevant levels.
اظهر المزيد [+] اقل [-]Assessing levels and seasonal variations of current-use pesticides (CUPs) in the Tuscan atmosphere, Italy, using polyurethane foam disks (PUF) passive air samplers النص الكامل
2015
Estellano, Victor H. | Pozo, Karla | Efstathiou, Christos | Pozo, Katerine | Corsolini, Simonetta | Focardi, S. (Silvano)
Polyurethane foam disks (PUF) passive air samplers (PAS) were deployed over 4 sampling periods of 3–5-months (≥ 1 year) at ten urban and rural locations throughout the Tuscany Region. The purpose was to assess the occurrence and seasonal variations of ten current-use pesticides (CUPs). PUF disk extracts were analyzed using GC–MS. The organophosphates insecticides; chlorpyrifos (3–580 pg m−3) and chlorpyrifos-methyl (below detection limit – to 570 pg m−3) presented the highest levels in air, and showed seasonal fluctuation coinciding with the growing seasons. The relative proportion urban/(urban + rural) ranged from 0.4 to 0.7 showing no differences between urban and rural concentrations. Air back trajectories analysis showed air masses passing over agricultural fields and potentially enhancing the drift of pesticides into the urban sites. This study represents the first information regarding CUPs in the atmosphere of Tuscany region using PAS-PUF disk.
اظهر المزيد [+] اقل [-]Contribution of coated humic acids calculated through their surface coverage on nano iron oxides for ofloxacin and norfloxacin sorption النص الكامل
2015
Peng, Hongbo | Liang, Ni | Li, Hao | Chen, Fangyuan | Zhang, Di | Pan, Bo | Xing, Baoshan
Sorption of organic contaminants on organo-mineral complexes has been investigated extensively, but the sorption contribution of mineral particles was not properly addressed before calculating KOC, especially for ionic organic contaminants. We measured the surface coverage of a humic acid (HA) on nano iron oxides (n-Fe2O3) in a series of synthesized organo-mineral complexes. The contribution of the coated HA to ofloxacin (OFL) and norfloxacin (NOR) sorption in HA–n-Fe2O3 complexes was over 80% of the total sorption with the surface coverage of 36% and fOC of 1.6%. All the coated HA showed higher sorption to NOR and OFL in comparison to the original HA, suggesting HA fractionation and/or physical re-conformation during organo-mineral complex formation. The decreased KOC with multilayer coating may suggest the importance of site-specific interactions for OFL sorption, while the increased KOC with multilayer coating may suggest the importance of partitioning in hydrophobic region for NOR sorption.
اظهر المزيد [+] اقل [-]The contrasting responses of soil microorganisms in two rice cultivars to elevated ground-level ozone النص الكامل
2015
Feng, Youzhi | Yu, Yongjie | Tang, Haoye | Zu, Qianhui | Zhu, Jianguo | Lin, Xiangui
Although elevated ground-level O3 has a species–specific impact on plant growth, the differences in soil biota responses to O3 pollution among rice cultivars are rarely reported. Using O3 Free-Air Concentration Enrichment, the responses of the rhizospheric bacterial communities in the O3-tolerant (YD6) and the O3-sensitive (IIY084) rice cultivars to O3 pollution and their differences were assessed by pyrosequencing at rice tillering and anthesis stages. Elevated ground-level O3 negatively influenced the bacterial community in cultivar YD6 at both rice growth stages by decreasing the bacterial phylogenetic diversities and response ratios. In contrast, in cultivar IIY084, the bacterial community responded positively at the rice tillering stage under O3 pollution. However, several keystone bacterial guilds were consistently negatively affected by O3 pollution in two rice cultivars. These findings indicate that continuously O3 pollution would negatively influence rice agroecosystem and the crop cultivar is important in determining the soil biota responses to elevated O3.
اظهر المزيد [+] اقل [-]Mining web-based data to assess public response to environmental events النص الكامل
2015
Cha, YoonKyung | Stow, Craig A.
We explore how the analysis of web-based data, such as Twitter and Google Trends, can be used to assess the social relevance of an environmental accident. The concept and methods are applied in the shutdown of drinking water supply at the city of Toledo, Ohio, USA. Toledo's notice, which persisted from August 1 to 4, 2014, is a high-profile event that directly influenced approximately half a million people and received wide recognition. The notice was given when excessive levels of microcystin, a byproduct of cyanobacteria blooms, were discovered at the drinking water treatment plant on Lake Erie. Twitter mining results illustrated an instant response to the Toledo incident, the associated collective knowledge, and public perception. The results from Google Trends, on the other hand, revealed how the Toledo event raised public attention on the associated environmental issue, harmful algal blooms, in a long-term context. Thus, when jointly applied, Twitter and Google Trend analysis results offer complementary perspectives. Web content aggregated through mining approaches provides a social standpoint, such as public perception and interest, and offers context for establishing and evaluating environmental management policies.
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