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81.
Steven J. Granger Roland Bol Wolfram Meier‐Augenstein Melanie J. Leng Helen F. Kemp Tim H. E. Heaton Sue M. White 《Rapid communications in mass spectrometry : RCM》2010,24(5):475-482
Stable isotopes of water have been previously used in catchment studies to separate rain‐event water from pre‐event groundwater. However, there are a lack of studies at the smaller scale looking at the separation of event water from pre‐event water. This is particularly relevant for heavy clay soil systems through which the movement of water is uncertain but is thought to be rainwater‐dominated. The data presented here were collected at a rural site in the south‐west of England. The historic rainfall at the site was isotopically varied but similar to the global meteoric water line, with annual weighted means of ?37‰ for δ2H and ?5.7‰ for δ18O and with no seasonal variation. Drainage was sampled from the inter‐flow (surface runoff + lateral through‐flow) and drain‐flow (55 cm deep mole drains) pathways of two 1 ha lysimeters during two rainfall events, which had δ2H values of ?68‰ and ?92‰, respectively. The δ2H values of the lysimeter drainage water suggest that there was no contribution of event water during the first, small discharge (Q) event; however, the second larger event did show isotopic variation in δ2H values negatively related to Q indicating that rainwater was contributing to Q. A hydrograph separation indicated that only 49–58% of the inter‐flow and 18–25% of the drain‐flow consisted of event water. This was surprising given that these soil types are considered retentive of soil water. More work is needed on heavy clay soils to understand better the nature of water movement from these systems. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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O. Roerden K. Reisinger W. Leymann C. B. G. Frischkorn 《Fresenius' Journal of Analytical Chemistry》1989,334(5):413-417
Summary A simple, rapid, low cost and uniform single-step clean-up procedure with a column containing two silica gel packings of different mesh size for the quantitative determination of PCBs by capillary gas chromatography (ECD) is reported. Its application to 9 complex matrices, among them a transformer oil, a waste motor oil, and an oil from a tempering bath, shows that in contradiction to other clean-Up methods nearly all accompanying substances can be separated. The reproducibility of 4.7% and the recovery rate of 92.7% for the PCBs are comparable with data found in literature.
Einfaches Clean-up-Verfahren zur quantitativen Bestimmung von PCBs in komplexen Materialien相似文献
89.
Michael Schmuker Marien de Bruyne Melanie Hähnel Gisbert Schneider 《Chemistry Central journal》2007,1(1):11-10
Background
Olfactory receptors work at the interface between the chemical world of volatile molecules and the perception of scent in the brain. Their main purpose is to translate chemical space into information that can be processed by neural circuits. Assuming that these receptors have evolved to cope with this task, the analysis of their coding strategy promises to yield valuable insight in how to encode chemical information in an efficient way. 相似文献90.
A wide variety of 3-alkyne-1,2-diols have been found to undergo exceptionally clean 5-endo-dig cyclisations followed by dehydration at ambient temperature to give the corresponding furans in essentially quantitative yields when exposed to 10 mol % of 10% w/w silver(I) nitrate absorbed on silica gel. 相似文献