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  • 1
    Electronic Resource
    Electronic Resource
    AUTUMN CHEMISTRY OF OREGON COAST RANGE STREAMS (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 34 (1998), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : During an autumn runoff event we sampled 48 streams with predominantly forested watersheds and igneous bedrock in the Oregon Coast Range. The streams had acid neutralizing capacities (ANC) 〉 90 μeq/L and pH 〉 6.4. Streamwater Na +, Ca2 +, and Mg2 + concentrations were greater than K + concentrations. Anion concentrations generally followed the order of Cl- 〉 NO3- 〉 SO42-. Chloride and Na + concentrations were highest in samples collected in streams near the Pacific Ocean and decreased markedly as distance from the coast increased. Sea salt exerted no discernible influence on stream water acid-base status during the sampling period. Nitrate concentrations in the study streams were remarkably variable, ranging from below detection to 172 μeq/L. We hypothesize that forest vegetation is the primary control of spatial variability of the NO3- concentrations in Oregon Coast Range streams. We believe that symbiotic N fixation by red alder in pure or mixed stands is the primary source of N to forested watersheds in the Oregon Coast Range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1998.tb04152.x
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  • 2
    Electronic Resource
    Electronic Resource
    Helix formation by poly{bis(hydroxyethyl)-L-glutamine} (1986)
    Springer
    Colloid & polymer science 264 (1986), S. 469-472 
    Details
    ISSN: 1435-1536
    Keywords: Helix-coil transition ; poly(hydroxyalkyl-L-glutamine) ; poly{bis(hydroxyethyl)-L-glutamine}
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Circular dichroism spectra are reported for poly {bis(hydroxyethyl)-L-glutamine}. Its conformation is predominantly that of a statistical coil at or above ambient temperature in water. It becomes partially helical upon cooling. The helix-forming potential of this polypeptide in water is between that of poly(hydroxyethyl-L-glutamine) and poly(hydroxypropyl-L-glutamine). The polypeptide has a large helix content when the solvent is rich in trifluoroethanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01421998
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  • 3
    Electronic Resource
    Electronic Resource
    Formation and mineralization of organic sulfur in forest soils (1984)
    Springer
    Biogeochemistry 1 (1984), S. 79-95 
    Details
    ISSN: 1573-515X
    Keywords: Organic sulfur formation ; organic sulfur turnover ; forest floor and soil horizons ; regulation ; energy availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The incorporation of sulfur from inorganic sulfate into organic matter was examined using35S for O1, O2 and A-horizon samples from two hardwood forests located at the Coweeta hydrologic laboratory, near Franklin, NC. This temperature-dependent transformation was stimulated by increased availability of sulfate or energy and the process was inhibited by sodium azide, erythromycin and candicidin. These data suggest that bacteria and fungi mediate sulfur incorporation via the formation of the covalent linkages. The latter possibility was confirmed by characterization of the organic sulfur fraction after isolation and partial purification from O2 layer material. Evidence is presented which indicates that the sulfur of this fraction is subject to mineralization after depolymerization of the carbon matrix and methods are given for the direct and indirect assessment of potential turnover rates. The availability of sulfate from mineralization appears to depend upon the rate of incorporation of sulfur into organic matter. Thus, substantially higher levels of extractable sulfate were detected when turnover of the isolated organosulfur fraction was assayed for in the presence of azide, an inhibitor of sulfate incoporation. However, the reverse was true when turnover was monitored in the presence of glucose and succinate which stimulate sulfate incorporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181122
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation and partial characterization of forest floor and soil organic sulfur (1985)
    Springer
    Biogeochemistry 1 (1985), S. 155-167 
    Details
    ISSN: 1573-515X
    Keywords: Organic sulfur isolation ; forest floor and soil ; C:N:S ratios ; ester sulfate content ; hydriodic acid reduction ; HCl hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The formation of organic sulfur from inorganic sulfate was investigated in hardwood forest floor and mineral horizons. All samples converted sulfate-sulfur into a non-salt extractable form which was recoverable only under conditions which release organic matter. This conversion was inhibited by azide, and depending upon the horizon, by erythromycin, candicidin, chloramphenicol and tetracycline. The form of sulfur generated in the 02 forest floor layer and in Al-horizon soil was characterized after isolation by pyrophosphate extraction at pH 8. The organosulfur extracts exhibited an average C:N:S ratio of 103:6:1. The ester sulfate content of the 02 extract was 61% by hydriodic acid (HI) reduction and 62% by hydrolysis in 3N HCl at 121 °C. However, compared to hydrolysis, reduction yielded lower estimates of ester sulfate for two of the three soil extracts analyzed. In view of the electrophoretic heterogeneity of all extracts, it is suggested that some may contain stable ester linkages that hydrolyze only after prolonged treatment and that the standard procedure for HI-reduction may provide conditions of temperature and contact time with the acid which are insufficient for the release of sulfate from these esters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185039
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