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  • 1
    Publication Date: 2013-06-02
    Description: [1]  Organic aerosols (OA) in Pasadena are characterized using multiple measurements from the CalNex campaign. Five OA components are identified using positive matrix factorization including hydrocarbon-like OA (HOA), and two types of oxygenated OA (OOA). The Pasadena OA elemental composition when plotted as H:C versus O:C follows a line less steep than that observed for Riverside, California. The OOA components from both locations follow a common line, however, indicating similar secondary organic aerosol (SOA) oxidation chemistry at the two sites such as fragmentation reactions leading to acid formation. In addition to the similar evolution of elemental composition, the dependence of SOA concentration on photochemical age displays quantitatively the same trends across several North American urban sites. First, the OA/ΔCO values for Pasadena increase with photochemical age exhibiting a slope identical to or slightly higher than those for Mexico City and the northeastern United States. Second, the ratios of OOA to odd-oxygen (a photochemical oxidation marker) for Pasadena, Mexico City, and Riverside are similar, suggesting a proportional relationship between SOA and odd-oxygen formation rates. Weekly cycles of the OA components are examined as well. HOA exhibits lower concentrations on Sundays versus weekdays, and the decrease in HOA matches that predicted for primary vehicle emissions using fuel sales data, traffic counts, and vehicle emission ratios. OOA does not display a weekly cycle – after accounting for differences in photochemical aging and emissions – which suggests the dominance of gasoline emissions in SOA formation under the assumption that most urban SOA precursors are from motor vehicles.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 162 (1948), S. 733-734 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE action of numerous inorganic and organic substances on the growth of bacteria has been investigated in the hope of demonstrating properties useful either in the laboratory for selective and enrichment methods for isolation, or clinically for the treatment of the diseases which they cause. ...
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2009-12-17
    Description: Organic aerosol (OA) particles affect climate forcing and human health, but their sources and evolution remain poorly characterized. We present a unifying model framework describing the atmospheric evolution of OA that is constrained by high-time-resolution measurements of its composition, volatility, and oxidation state. OA and OA precursor gases evolve by becoming increasingly oxidized, less volatile, and more hygroscopic, leading to the formation of oxygenated organic aerosol (OOA), with concentrations comparable to those of sulfate aerosol throughout the Northern Hemisphere. Our model framework captures the dynamic aging behavior observed in both the atmosphere and laboratory: It can serve as a basis for improving parameterizations in regional and global models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jimenez, J L -- Canagaratna, M R -- Donahue, N M -- Prevot, A S H -- Zhang, Q -- Kroll, J H -- DeCarlo, P F -- Allan, J D -- Coe, H -- Ng, N L -- Aiken, A C -- Docherty, K S -- Ulbrich, I M -- Grieshop, A P -- Robinson, A L -- Duplissy, J -- Smith, J D -- Wilson, K R -- Lanz, V A -- Hueglin, C -- Sun, Y L -- Tian, J -- Laaksonen, A -- Raatikainen, T -- Rautiainen, J -- Vaattovaara, P -- Ehn, M -- Kulmala, M -- Tomlinson, J M -- Collins, D R -- Cubison, M J -- Dunlea, E J -- Huffman, J A -- Onasch, T B -- Alfarra, M R -- Williams, P I -- Bower, K -- Kondo, Y -- Schneider, J -- Drewnick, F -- Borrmann, S -- Weimer, S -- Demerjian, K -- Salcedo, D -- Cottrell, L -- Griffin, R -- Takami, A -- Miyoshi, T -- Hatakeyama, S -- Shimono, A -- Sun, J Y -- Zhang, Y M -- Dzepina, K -- Kimmel, J R -- Sueper, D -- Jayne, J T -- Herndon, S C -- Trimborn, A M -- Williams, L R -- Wood, E C -- Middlebrook, A M -- Kolb, C E -- Baltensperger, U -- Worsnop, D R -- New York, N.Y. -- Science. 2009 Dec 11;326(5959):1525-9. doi: 10.1126/science.1180353.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cooperative Institute for Research in the Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA. jose.jimenez@colorado.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20007897" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2005-04-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernhardt, E S -- Palmer, M A -- Allan, J D -- Alexander, G -- Barnas, K -- Brooks, S -- Carr, J -- Clayton, S -- Dahm, C -- Follstad-Shah, J -- Galat, D -- Gloss, S -- Goodwin, P -- Hart, D -- Hassett, B -- Jenkinson, R -- Katz, S -- Kondolf, G M -- Lake, P S -- Lave, R -- Meyer, J L -- O'donnell, T K -- Pagano, L -- Powell, B -- Sudduth, E -- New York, N.Y. -- Science. 2005 Apr 29;308(5722):636-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15860611" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Conservation of Natural Resources/economics ; Costs and Cost Analysis ; *Databases, Factual ; *Ecosystem ; Environment ; Fishes ; *Rivers ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2013-07-23
    Description: [1]  We study the organic aerosol (OA) budget in a tropical forest by analyzing a case that is representative for the OP3 campaign at Borneo. A model is designed that combines the essential dynamical and chemical processes that drive the diurnal evolution of reactants in the atmospheric boundary layer (BL). In this way, the model simultaneously represents the effects and interactions of various dynamical and chemical factors on the OA budget. The model is able to reproduce the observed diurnal dynamics of the BL, including the evolution of most chemical species involved in secondary organic aerosol (SOA) formation. A budget analysis of the contributions of the dynamic and chemical processes reveals the significance of the entrainment process in the diurnal evolution of SOA. Further, we perform a series of sensitivity analyses to determine the effect of meteorological forcings and isoprene chemical pathways on the OA budget. Subsidence and advection of cool air have opposing effects on the OA concentration, although both suppress BL growth. Recycling of the OH radical in the oxidation of isoprene may affect the amount of SOA that is formed, but must be understood better before its impact can be definitely determined. SOA formation from isoprene is calculated for both the low- and high-NO x pathway, with the latter dominating the isoprene peroxy radical chemistry. Finally, we study the significance of SOA formation through the reactive uptake of isoprene epoxydiols (IEPOX) on acidic sulfate aerosol. Despite the incorporation of these new pathways, the OA concentration is systematically underestimated by about a factor of 2.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-10-02
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Allan, J D -- New York, N.Y. -- Science. 1987 Oct 2;238(4823):93-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17835667" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 1948-11-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 43 (1977), S. 317-331 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The grazing of juvenile Eurytemora affinis, Acartia tonsa and A. clausi from the Chesapeake Bay (USA) was investigated using natural particle distributions and freshly caught copepods, live-sorted into stages. Data were analyzed in ≥110 size channels using an electronic particle counter, and filtering rates (FR) were estimated based on total particle removal (mean FR), and that for each size channel (giving maximum FR). Mean and maximum filtering rates increased from NVI (Nauplius Stage VI) through CVI (Copepodid Stage VI). Both rates plotted against weight satisfied a log fit best for A. tonsa, and a linear fit best for E. affinis. Results for A. tonsa were quite variable, apparently due to differences in temperature between experiments. Particle selection was investigated from the shape of the filtering rate curve over particle size. We define selective feeding by a FR curve which is higher in some size categories, and non-selective feeding by a flat FR curve. The general pattern was one of selective feeding in all copepodid stages of the three calanoid copepods investigated. E. affinis tended to “track” biomass peaks while Acartia spp.'s feeding was more variable, including feeding in size ranges of greatest particle concentration, on larger particles, and in other size categories as well. Experiments with nauplii tended to yield flat FR curves, and it may be that selective grazing appears with, or is greatly accentuated by, metamorphosis from NVI to CI (Copepodid Stage I).
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 66 (1982), S. 179-184 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Life table estimates of intrinsic rate of natural increase (r) were used to assess chronic toxicity of Kepone to the copepod Eurytemora affinis (Poppe). The acute toxicity (48-h LC 50) was determined to be 40μg 1-1 (95% CL 33.9–47.2). A reduction in r was observed at all concentrations above 5 μg 1-1, and r was near zero at 20 μg 1-1. This was due to the combination of lowered survivorship, delayed onset of reproduction and reduced fecundity. We discuss the value of the life table approach both as an experimental protocol and an ecologically realistic bioassay of chronic effects, and document that as few as 21 d are sufficient as an adequate test duration.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. We investigated the diversity and distribution of freshwater mussels at 40 sites in an agricultural catchment, the River Raisin in south-eastern Michigan, to relate mussel assemblages and individual taxa to reach and catchment-scale variables. Unionids were surveyed by timed searches in 100-m reaches, and in-stream and riparian habitat were quantified as well as flow, water chemistry and channel morphology. Land use/cover and surficial geology were determined for site subcatchments and riparian buffers.2. Some 21 mussel species were found overall; richness ranged from 0 to 12 living species per site. From the upper to middle to lower catchment, the number of individuals, number of species, Shannon–Weaver diversity and relative abundance of intolerant unionids all declined significantly.3. Four groupings based on overall mussel diversity and abundance were significantly related to reach-scale habitat variables. The richest mussel assemblages were associated with sites with higher overall habitat quality, greater flow stability, less fine substratum, and lower specific conductance.4. Stepwise multiple regressions revealed that the distribution and abundance of the total mussel assemblage, as well as the most common species, could be predicted from a combination of reach- and catchment-scale variables (R2 = 0.63 for total mussels, R2 = 0.51–0.86 for individual species).5. Flow stability, substratum composition and overall reach habitat quality were the most commonly identified reach-scale variables, and measures of surficial geology were the most effective catchment-scale variables. The spatial pattern of geology is likely to be responsible for the diversity gradient from the upper to the lower catchment.6. Prior studies, attempting to explain mussel distributions from local habitat features alone, have found relatively weak relationships. By employing a combination of reach- and catchment-scale habitat variables, this study was able to account for a substantial amount of the spatial variability in mussel distributions.
    Type of Medium: Electronic Resource
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