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761.
762.
763.
This paper describes techniques which provide for both qualitative and quantitative identification of major components in a process stream. The techniques and instrumentation have been deliberately chosen so as to be within the technical and financial reach of all but the smallecompany laboratory. The sample preparation steps consist of an initial series of extractions which isolate compounds into organic acid, base, and neutral compounds and a totally water soluble phase. Each fraction is then concentrated and subjected to thin-layer chromatography, gas chromatography, infrared spectroscopy or ultraviolet spectroscopy as appropriate. Results are given for laboratory samples, one a mixture of aniline, phenol, benzoic acid, m-nitrobenzaldehyde, 1-butanol, 2-hexanone, nonane, and cyclohexane, and the other a mixture of benzene, ethylbenzene, and styrene. Also, a qualitative analysis of a petroleum refinery desalter water is presented.  相似文献   
764.
For several years tracer migration experiments are performed at Nagra's Grimsel Test Site in the Swiss Alps as a joint undertaking of Nagra, PNC and PSI. The aim is to develop methods for field experiments at possible sites for nuclear waste repositories and to test radionuclide transport models.A hydraulic dipole field is generated in a well-defined fracture zone in granite. The tracers used are non-sorbing (uranine, 3He, 4He, 82Br, 123I), mildly sorbing (22Na+, 24Na+), and more strongly sorbing (85Sr2+, 86Rb+, 134Cs+, 137Cs+). These experiments have been complemented by extensive laboratory investigations on petrography, on water-rock and nuclide-rock interaction as well as by migration experiments with bore cores.The main questions addressed are: What are the relevant geometric factors and mechanisms for transport, how well can breakthrough curves be extrapolated from one dipole arrangement to another, which parameters are scale dependent, is there a difference in sorption values between laboratory and field experiments or between static and dynamic experiments. Evaluating the experimental results for the non-sorbing uranine and the mildly sorbing tracers sorption, Strontium, we show that a consistent picture of tracer transport, and specifically of tracer sorption, is obtained when exploiting all available experimental information and using not too simplistic models.  相似文献   
765.
Part II: Persistence and Degradability of Organic Chemicals The criteria “Persistence” and “Degradability” are defined and explained, starting from the “functional” definition of the environment. In this definition, theenvironment is the counterpart of thetechnosphere, which consists of all processes controlled by man. A substance is persistent if there are no sinks (degradation processes). It is shown that persistence is the central and most important critérium of environmental hazard assessment of organic chemicals. It follows that all substances released into the environment should be degradable, preferentially into small inorganic molecules (mineralization). As examples for persistent substances, the polychlorinated biphenyls (PCB), the chlorofluorohydrocarbons (CFC), bis (2-ethylhexyl) phthalate (DEHP), and 2,3,7,8-tetrachloro-dibenzo-dioxin (TCDD) are discussed. Finally, an attempt to quantify persistence is made.  相似文献   
766.
Changes in soil heavy metal extractability following the cessation of biosolids applications were studied in a long-term field experiment. Two anaerobically digested biosolids from wastewater treatment plants in Madrid (Sur and Viveros) were applied to cropland from 1983 to 1990. Soil samples were collected in the 1st, 5th and 9th year after the last biosolids application. Soil pH did not vary significantly after biosolids applications. Organic matter and total heavy metals (Zn, Pb, Cd, Ni, Cr and Cu) concentrations initially increased but then declined over time, mostly after the first 5 years following biosolids application. Metal extracted with DPTA increased in Sur treatments during the 1st year and diminished thereafter. However, in Viveros treatments, heavy metals extracted increased during the 1st year, declined in 1995, and showed a slight increase in 1999. These changes in heavy metal extractability were widely observed in the percentage of extractable metal recovery (EMR). The differences observed in the pattern of the two sources of biosolids applied could be due to the different rates of decomposition of their organic matter.  相似文献   
767.
Environmental levels and detailed congener profiles (31 congeners and 3 coeluting congener groups) of polybrominated diphenyl ethers (PBDEs) were assessed in a number of biota samples taken over a large geographic range covering harbours and industrial sites on Canada's West Coast. Additionally, PBDE congener profiles were determined using semipermeable membrane devices (SPMDs) deployed in the Fraser River, the river in Western Canada with the largest industrial activity. PBDE levels detected in biota were between 4 and 2300 ng/g lipid and these levels were compared with those reported in selected European biota to provide a wider perspective on PBDE contamination on Canada's West Coast. Thirteen-congener PBDE patterns in the environmental samples were examined using principal component analysis (PCA), and additionally, comparisons were made between the PBDE profiles in the sample groups and commercially used PBDE technical mixtures (e.g., Bromkals) on a percent composition basis. PCA on congener specific data revealed that PBDE patterns are remarkably similar over a wide geographical range in Western Canada, however, the general pattern in environmental samples varies significantly from those of the predominant technical mixtures. Finally, correlations between PBDE and other persistent and toxic co-occurring contaminants found in Dungeness crab were determined.  相似文献   
768.
769.
Vetter W  Jun W  Althoff G 《Chemosphere》2003,52(2):415-422
This presentation adds new spectroscopic and analytical data on the natural product Q1 that was recently identified by synthesis as 2,3,3('),4,4('),5,5(')-heptachloro-1(')-methyl-1,2(')-bipyrrole. Solid state magic angle spinning 13C NMR data of Q1 is presented as an option for structural proof. Furthermore, the UV spectrum of neat Q1 (absorption maximum at 223 nm) was recorded and, with NMR spectroscopic data, confirmed a twisted bipyrrole ring system. A quantitative standard of Q1 was prepared which allowed to correct previous concentration estimates relative to the electron capture detector response factor of trans-nonachlor. As a result, the actual Q1 response was only 0.65+/-15% of the response factor of trans-nonachlor. Therefore, actual Q1 levels are about 50% higher than the previous estimates. With this result the highest (corrected) Q1 concentration determined to date in the blubber of marine mammals from Australia is 14 mg/kg lipid. Analysis of Q1 and trans-nonachlor in specimens from the German North Sea coast suggests that harbor seals are more able to metabolize Q1 than harbor porpoises. Finally, we calculated that 79 congeners of Q1 (i.e. lower chlorinated 1(')-methyl-1,2(')-bipyrroles) are theoretically possible and present their structures.  相似文献   
770.
Zur Cytologie der Strasburger-Zellen in Coniferennadeln   总被引:1,自引:0,他引:1  
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