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Curricula for environmental chemistry in Germany 全文
1997
Lenoir, Dieter | May, Robert G.
Curricula for Environmental Chemistry have become established, not only recently in the US, but also in European countries. This article discusses the current situation in Germany. German students can make their choice among four possibilities: 1. full-time studies in environmental sciences, 2. classical chemistry program followed by an environmental supplementary program, 3. classical chemistry program with a mandatory choice between environmental or ecological chemistry, 4. classical introductory chemistry followed by a major course of studies in environmental subjects.The background of this development is the attempt to reform the German chemical curricula (Würzburger Modell) which emphasizes practice and the environmetally related subjects.
显示更多 [+] 显示较少 [-]Identification of material flow systems 全文
1997
Bauer, Gerd | Deistler, M. (Manfred) | Gleiß, Andreas | Glenck, Emmanuel | Matyus, Thomas
Material Flow Analysis (MFA) has become an important instrument in environmental science and pollution research. In this paper, we look at the MFA problem as a particularly structured system identification problem. Special emphasis is given to the linear, static case, where we describe a procedure for reconciliating the flow measurements and for estimating the unmeasured flows and the transfer coefficients by taking into account a priori restrictions such as balance equations.
显示更多 [+] 显示较少 [-]The suitability of gastropods as biomarkers : Induction of ethoxy-, pentoxy- and benzoxyresorufin-O-dealkylase in limnetic gastropods via aroclor 1254 全文
1997
Meimberg, Harald | Schrenk, Christiane | Steinberg, Christian | Klarenberg, Albert | Kettrup, A. A.
The measurement and induction of mixed function oxyigenases (MFOs) of limnetic gastropods were investigated to estimate their suitability as biomarkers. A determination of MFO activities was performed through the measurement of ethoxyresorufin-O-dealkylase (EROD), pentoxy-(PROD) and benzoxyresorufin-O-dealkylase-activity (BROD). Optimal measuring conditions of these activities were investigated in preparations of the digestive gland of 4 species of limnetic gastropods. Results indicate that MFO-activity inhibiting substances are accumulating in the microsomal pellet, the fraction commonly used for the measurement of MFO-activities. Therefore, the fraction used for induction studies was the postmitochondrial supernatant (PMS). EROD, PROD, and BROD activity ofPlanorbis planorbis andPlanorbis carinatus were measured after a treatment with Aroclor 1254 for 1–17 days. Maximal induction of EROD and PROD were 6 and 10 times the value in the control group ofP. carinatus, respectively induction inP. planorbis was lower. BROD-activity could not been measured inP. planorbis. InP. carinatus, BROD-activity increased to a maximum of 2 times after traetment with Aroclor 1254. The level of induction of EROD-activity is comparable to results described in analog studies with fish.
显示更多 [+] 显示较少 [-]Photolytic degradation of fluoroquinolone carboxylic acids in aqueous solution : Part I: Primary photoproducts and half-lives (ESPR 1/1997, pp. 10–15) Part II: Isolation and structural elucidation of polar photometabolites (ESPR 2/1997, pp. 61–67) 全文
1997
Burhenne, Jürgen | Ludwig, Marc | Spiteller, M. (Michael)
Subsequent to irradiation with a xenon lamp simulating sunlight, fluoroquinolone carboxylic acids in aqueous solution form polar pyridone dicarboxylic and tricarboxylic acids. After liquid/liquid partition with chloroform/water these substances can be isolated by ion exchange chromatography of the aqueous phase. They can be regarded as intermediate compounds on the route to a complete photomineralization. The structural elucidation is performed by such mass spectroscopic methods as MS, GC/MS and HPLC/MS, whereby HPLC/MS shows the highest reliability. Additionally¹H- and¹³C-NMR measurements confirm the structure of the main polar degradation product.
显示更多 [+] 显示较少 [-]Platinum emission rate of automobiles with catalytic converters : Comparison and assessment of results from various approaches 全文
1997
Helmers, Eckard
Inconsistent data presently available on the platinum emission rate of cars in Germany equipped with catalytic converters are evaluated. Automobile sources of Pt other than autocatalysts are quantified and found to be 1–6 orders of magnitudes lower than the Pt emissions attributed to catalytic converters. A transfer of emission rates derived from test stand experiments to more realistic street conditions reaches 0.8 μg Pt/km. In this manner, data from test stand experiments and from environmental investigations meet in the range of 0.5–0.8 μg Pt/km.
显示更多 [+] 显示较少 [-]Supercritical fluid extraction of recycled fibers: removal of dioxins, stickies, and inactivation of microbes
1997
Blaney, C.A. | Hossain, S.U.
Supercritical carbon dioxide and supercritical propane were found to be effective solvents in extracting stickies and trace chlorinated organics, including dioxins, from recycled fibers. These undesirable components are not effectively removed with current recycled fiber processing techniques. It was also found that endogenous yeast and mold spores on the fibers were inactivated with supercritical carbon dioxide. An economic analysis was performed for a recycled paper pretreatment process which utilizes semi-batch supercritical fluid extraction. Matrix effects were ignored owing to lack of data. Results are encouraging, estimating cost ranges of 7-17 cents per pound of fibers treated -- costs well within reasonable price targets to pretreat premium paper and tissue products.
显示更多 [+] 显示较少 [-]Inhibition of ethoxyresorufin-O-deethylase (EROD) activity in mixtures of 2,3,7,8-tetrachlorodibenzo-p-dioxin and polychlorinated biphenyls: EROD activity as biomarker in TCDD and PCB risk assessment 全文
1997
Tysklind, Mats | Bosveld, Albertus (Bart) T. C. | Andersson, Patrik | Verhallen, Eeske | Sinnige, Theo | Scinen, Willem | Rappe, Christoffer | Berg, Martin van den
Induction of ethoxyresorufin-O-deethylase (EROD) activity and porphyrin accumulation shows different structure-activity relationships for different polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD). Interactions between the two responses can strongly influence the induction and activity of EROD. The results support the conclusion that there are non-additive interactions between nondioxin-like PCBs and dioxin-like compounds. The interaction between EROD activity and the porphyrin biosynthesis makes the prerequisite of additivity in the toxic equivalency factor concept for environmental mixtures highly spurious. Inhibition of EROD activity caused by nondioxin-like compounds could have a significant impact on the value of EROD activity as a biomarker in the present methods of risk assessment for these compounds.
显示更多 [+] 显示较少 [-]Phase equilibria of vegetable oils with near-critical fluids
1997
Fuente B, J.C de la | Fornari, T. | Brignole, E.A. | Bottini, S.B.
The application of the SRK equation of state for the prediction of the phase behaviour of mixtures of vegetable oils with near critical solvents is studied. The use of binary interaction parameters in the combinatorial rules for both the co-volume and the energy parameter is discussed. Two different sets of binary interaction parameters are needed in order to correlate the vapor-liquid and liquid-liquid equilibria. This indicates a serious limitation of van der Waals type of equations of state for modeling the phase equilibria of this type of systems.
显示更多 [+] 显示较少 [-]Supercritical carbon dioxide extraction of volatile compounds from rosemary
1997
Coelho, J.A.P. | Mendes, R.L. | Provost, M.C. | Cabral, J.M.S. | Novais, J.M. | Palavra, A.M.F.
Supercritical CO2 extraction of oleoresin from portuguese rosemary (Rosmarinus officinalis L.) was carried out with a flow apparatus at temperatures of 35 and 40 degrees C and pressures of 100, 125 and 200 bar. The highest fraction of volatile compounds (oil) in the oleoresin was obtained at 100 bar and 40 degrees C. An unsteady mathematical model was able to give good representation of the supercritical extraction curves and a mass transfer coefficient was determined using the successive quadratic programming method. Values of this coefficient ranged between 4.49 and 15.07 kg/m3s and the shift to a diffusion-controlled regime occurred when 44% of the total oil was extracted.
显示更多 [+] 显示较少 [-]Biological degradation of VCCs and CFCs under simulated anaerobic landfill conditions in laboratory test digesters 全文
1997
Deipser, Anna | Stegmann, R. (Rainer)
The biological degradation of volatile halogenated hydrocarbons (chlorocarbons (VCCs) and chlorofluorocarbons (CFCs)) was investigated under simulated conditions of landfills in laboratory test digesters. Fully halogenated VCCs (tetrachloroethylene, 1,1,1-trichloroethane, tetrachloromethane and dichloromethane) and CFCs (trichlorofluoromethane (R11), dichlorodifluoromethane (R12) and 1,1,2-trichlorotrifluoroethane (R113)) were degraded under anaerobic conditions in addition to the methanogenic bacteria in municipal solid waste (MSW) and organic wastes. These substances showed different degradation reactions in the simulated acid and methanephases of MSW landfills. It is assumed that R11 and R113 could be decomposed completely under methanogenic conditions. Dichlorofluoromethane (R21) was oberved as the reductive degradation product of R11 and was further degraded during the methanephase, but hardly at all under acid conditions. Chlorodifluoromerhane (R22) as a degradation product of R12 was not degraded, even not in the methanephase. In the acidphase, R11 was the only CFC to be dechlorinated, although only in small quantities. The degradation products of tetrachloroethylene differed under the various environmental conditions. In the acidphase, 1,1-dichloroethylene was detected as the only dichloroethylene, whereas in particular cis-1,2-dichloroethylene but also trans-1,2-dichloroethylene, 1,1-dichloroethylene and vinyl chloride could be detected as metabolites in the methanephase. Dichloromethane and chloroethane, as metabolites of 1,1,1-trichloroethane, could hardly be degraded at all in the acidphase. The degradation of VCCs and CFCs is largely independent of the substrate used. The investigations have demonstrated that the measured biodegradation rates (0.3–15 mg/m³ ₘₐₜₑᵣᵢₐₗ ᵥₒₗ./h) cannot be improved considerably since they are limited by the inhibiting effect of the substances and their degradation products.
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