خيارات البحث
النتائج 331 - 340 من 1,310
Biomagnetic monitoring of industry-derived particulate pollution النص الكامل
2011
Hansard, R. | Maher, B.A. | Kinnersley, R.
Clear association exists between ambient PM₁₀ concentrations and adverse health outcomes. However, determination of the strength of associations between exposure and illness is limited by low spatial-resolution of particulate concentration measurements. Conventional fixed monitoring stations provide high temporal-resolution data, but cannot capture fine-scale spatial variations. Here we examine the utility of biomagnetic monitoring for spatial mapping of PM₁₀ concentrations around a major industrial site. We combine leaf magnetic measurements with co-located PM₁₀ measurements to achieve inter-calibration. Comparison of the leaf-calculated and measured PM₁₀ concentrations with PM₁₀ predictions from a widely-used atmospheric dispersion model indicates that modelling of stack emissions alone substantially under-predicts ambient PM₁₀ concentrations in parts of the study area. Some of this discrepancy might be attributable to fugitive emissions from the industrial site. The composition of the magnetic particulates from vehicle and industry-derived sources differ, indicating the potential of magnetic techniques for source attribution.
اظهر المزيد [+] اقل [-]Distribution of perfluorochemicals between sera and milk from the same mothers and implications for prenatal and postnatal exposures النص الكامل
2011
Kim, Seung-Kyu | Lee, Kyu Tae | Kang, Chang Seong | Tao, Lin | Kannan, Kurunthachalam | Kim, Kyung-Ryul | Kim, Chan-Kook | Lee, Jung Suk | Park, Pan Soo | Yoo, Yung Wook | Ha, Jeong Yi | Shin, Yong-Seung | Lee, Jong Hyeon
The levels of six perfluorocarboxylates (PFCAs), four perfloroalkylsulfonates (PFASs), and one sulfonamide were measured in paired samples of maternal serum, umbilical cord serum, and breast milk. The maternal and cord sera were strongly correlated with each other for all measured compounds (r > 0.5 and p < 0.01). Nevertheless, there was a significant difference in compound composition profile between the two sera matrices, with a more depletion of the longer chain compounds in cord serum. The transfer efficiency values from maternal to cord serum (TFCS/MS) decreased by 70% with each increasing unit of –CF₂ chain within a PFCA group, and for perfluorooctanesulfonate (PFOS), by a half compared to perfluorooctanoate (PFOA). In contrast to the strong correlation in concentrations between the two sera matrices, the pattern of compounds in breast milk differed considerably with those in sera. Accordingly, compound- and matrix-specific transfer must be considered when assessing prenatal and postnatal exposure.
اظهر المزيد [+] اقل [-]In situ evaluation of cadmium biomarkers in green algae النص الكامل
2011
Simon, Dana F. | Davis, Thomas A. | Tercier-Waeber, Mary-Lou | England, Roxane | Wilkinson, Kevin J.
In situ measurements provide data that are the highly representative of the natural environment. In this paper, laboratory-determined biomarkers of Cd stress that were previously identified for the green alga Chlamydomonas reinhardtii, were tested in two French rivers: a contaminated site on the Riou Mort River and an “uncontaminated” reference site on the Lot River. Transcript abundance levels were determined by real time qPCR for biomarkers thought to be Cd sensitive. Transcript levels were significantly higher (>5 fold) for organisms exposed to the contaminated site as compared to those exposed at the uncontaminated site. Biomarker mRNA levels were best correlated to free Cd (Cd²⁺) rather than intracellular Cd, suggesting that they may be useful indicators of in situ stress. The paper shows that biomarker expression levels increased with time, were sensitive to metal levels and metal speciation and were higher in the “contaminated” as opposed to the “reference” site.
اظهر المزيد [+] اقل [-]Methane emissions from a dairy feedlot during the fall and winter seasons in Northern China النص الكامل
2011
Gao, Zhiling | Yuan, Huijun | Ma, Wenqi | Liu, Xuejun | Desjardins, R.L.
Accurately determining methane emission factors of dairy herd in China is imperative because of China’s large population of dairy cattle. An inverse dispersion technique in conjunction with open-path lasers was used to quantify methane emissions from a dairy feedlot during the fall and winter seasons in 2009–2010. The methane emissions had a significant diurnal pattern during both periods with three emission peaks corresponding to the feeding schedule. A 10% greater emission rate in the fall season was obtained most likely by the higher methane emission from manure during that period. An annual methane emission rate of 109 ± 6.7 kg CH₄ yr⁻¹ characterized with a methane emission intensity of 32.3 ± 1.59 L CH₄ L⁻¹ of milk and a methane conversion factor (Yₘ) of 7.3 ± 0.38% for mature cattle was obtained, indicating the high methane emission intensity and low milk productivity in Northern China.
اظهر المزيد [+] اقل [-]Solubilization properties of polycyclic aromatic hydrocarbons by saponin, a plant-derived biosurfactant النص الكامل
2011
Zhou, Wenjun | Yang, Juanjuan | Lou, Linjie | Zhu, Lizhong
The enhanced solubilization of polycyclic aromatic hydrocarbons (PAHs) by saponin, a plant-derived non-ionic biosurfactant, was investigated. The results indicated that the solubilization capabilities of saponin for PAHs were greater than some representative synthetic non-ionic surfactants and showed strong dependence on solution pH and ionic strength. The molar solubilization ratio (MSR) of saponin for phenanthrene was about 3–6 times of those of the synthetic non-ionic surfactants, and decreased by about 70% with the increase of solution pH from 4.0 to 8.0, but increased by approximately 1 times with NaCl concentration increased from 0.01 to 1.0 M. Heavy metal ions can enhance saponin solubilization for phenanthrene and the corresponding MSR values increased by about 25% with the presence of 0.01 M of Cd²⁺ or Zn²⁺. Saponin is more effective in enhancing PAHs solubilization than synthetic non-ionic surfactants and has potential application in removing organic pollutants from contaminated soils.
اظهر المزيد [+] اقل [-]Cocaine and other illicit drugs in airborne particulates in urban environments: A reflection of social conduct and population size النص الكامل
2011
Viana, M. | Postigo, C. | Querol, X. | Alastuey, A. | López de Alda, M.J. | Barceló, D. | Artíñano, B. | López-Mahia, P. | García Gacio, D. | Cots, N.
Levels of cocaine and other psychoactive substances in atmospheric particulate matter (PM) were determined in urban environments representing distinct social behaviours with regard to drug abuse: night-life, university and residential areas. Three cities (with population >1 million and <0.3 million inhabitants) were selected. Mean daily levels of drugs in PM were 11–336 pg/m³ for cocaine, 23–34 pg/m³ for cannabinoids, and 5–90 pg/m³ for heroin. The highest levels were recorded on weekends, with factors with respect to weekdays of 1–3 for cocaine, 1–2 for cannabinoids and 1.1–1.7 for heroin. Higher levels were detected in the night-life areas, pointing towards consumption and trafficking as major emission sources, and possibly ruling out drug manufacture. The similarities in temporal trends at all sites suggested a city-scale transport of psychoactive substances. Correlations were detected between cocaine and amphetamine consumption (r² = 0.98), and between heroin and cannabinoids (r²>0.82).
اظهر المزيد [+] اقل [-]Occurrence and profiles of organic sun-blocking agents in surface waters and sediments in Japanese rivers and lakes النص الكامل
2011
Kameda, Yutaka | Kimura, Kumiko | Miyazaki, Motonobu
Sun-blocking agents including eight UV filters (UVF) and 10 UV light stabilizers (UVLS) were measured in water and sediment collected from 22 rivers, four sewage treatment plant effluents (STPE) and three lakes in Japan. Total sun blocking agents levels ranged from N.D. to 4928ng/L and from 2.0 to 3422μg/kg dry wt in surface water and in sediment, respectively. Benzyl salicylate, benzophenone-3, 2-ethyl hexyl-4-methoxycinnamte (EHMC) and octyl salicylate were dominant in surface water receiving wastewater effluents and STPE, although UV-328, benzophenone and EHMC were dominant in other surface water except background sites. Three UVF and nine UVLS were observed from all sediment and their compositions showed similar patterns with UV-328 and UV-234 as the most prevalent compounds. Homosalate, octocrylene, UV-326, UV-327, UV-328 and UV-234 were significantly correlated with Galaxolide® in sediments. Concentrations of UV-327 and UV-328 also had strong correlation between those of UV-326 in sediment.
اظهر المزيد [+] اقل [-]Accumulation and maternal transfer of polychlorinated biphenyls in Steller Sea Lions (Eumetopias jubatus) from Prince William Sound and the Bering Sea, Alaska النص الكامل
2011
Wang, Jun | Hülck, Kathrin | Hong, Su-Myeong | Atkinson, Shannon | Li, Qing X.
The western stock of the Steller sea lion (Eumetopias jubatus) in the northern Pacific Ocean has declined by approximately 80% over the past 30 years. This led to the listing of this sea lion population as an endangered species in 1997. Chemical pollution is a one of several contributing causes. In the present study, 145 individual PCBs were determined in tissues of male sea lions from Tatitlek (Prince William Sound) and St. Paul Island (Bering Sea), and placentae from the Aleutian Islands. PCBs 90/101, 118, and 153 were abundant in all the samples. The mean toxic equivalents (TEQ) were 2.6, 4.7 and 7.4pg/g lw in the kidney, liver, and blubber samples, respectively. The mean TEQ in placentae was 8pg/g lw. Total PCBs concentrations (2.6–7.9μg/g lw) in livers of some males were within a range known to cause physiological effects. Further suggesting the possibility of adverse effects on this stock.
اظهر المزيد [+] اقل [-]The effects of tertiary treated municipal wastewater on fish communities of a small river tributary in Southern Ontario, Canada النص الكامل
2011
Brown, Carolyn J.M. | Knight, Brendan W. | McMaster, Mark E. | Munkittrick, Kelly R. | Oakes, Ken D. | Tetreault, Grald R. | Servos, Mark R.
Fish community changes associated with a tertiary treated municipal wastewater effluent outfall in the Speed River, Ontario, Canada, were evaluated at nine sites over two seasons (2008) using standardized electrofishing. Habitat evaluations were conducted to ensure that the riffle sites selected were physically similar. The fish community was dominated by several species of darters that differed in their response to the effluent outfall. There was a significant decrease in Greenside Darter (Etheostoma blennioides) but an increase in Rainbow Darter (E. caeruleum) abundance directly downstream of the outfall. Stable isotope signatures (δ¹³C and δ¹⁵N), which indicate shifts in energy utilization and flow, increased in Rainbow Darter downstream, but showed no change in Greenside Darter. Rainbow Darter may be exploiting a food source that is not as available at upstream sites giving them a competitive advantage over the Greenside Darter immediately downstream of the outfall.
اظهر المزيد [+] اقل [-]Influence of pesticides contamination on the emission of PCDD/PCDF to the land from open burning of corn straws النص الكامل
2011
Zhang, Tingting | Huang, Jun | Deng, Shubo | Yu, Gang
Open burning of crop residues has been identified as an important emission source of PCDD/PCDF to the environment. This paper presents the first known data on the emission of PCDD/PCDF to the land considering the influence of pesticides applied in crops planting. Emission factor for PCDD/PCDF to the land from open burning of corn straw with pesticides contamination ranged from 0.07 to 0.57ng WHO₂₀₀₅-TEQ/kg straw burned with a mean value of 0.24ng WHO₂₀₀₅-TEQ/kg straw burned and median value of 0.20ng WHO₂₀₀₅-TEQ/kg straw burned, respectively. The concentration was 35 to 270 times higher than that without additional pesticide contaminated. Initial observation was that emission factor for PCDD/PCDF from open burning of crop residues was overestimated in the former UNEP Dioxin Toolkit. Pesticides contamination should be considered in some hotpots where special and over dosed pesticides has been sprayed especially in developing countries.
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