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71.
Robert M. Kahn Bruce D. Smith Austin Long 《Journal of the American Water Resources Association》1996,32(3):629-635
ABSTRACT: A study of 222Rn concentrations in the water distribution system of Tucson, Arizona, revealed levels of 60 to 1260 pCi/L in domestic waters. These measurements are comparable to levels of between 80 and 1400 pCi/l for 222Rn found in ground water samples in the North-Central Tucson basin (Kahn et al., 1994). Estimated loss of 222Rn due to radioactive decay during travel from the well head to the home ranges from 8 to 50 percent. 相似文献
72.
Continuous in-line gasification/vitrification process for thermal waste treatment: process technology and current status of projects 总被引:1,自引:0,他引:1
The Thermoselect High Temperature Recycling process has been developed in order to make available a thermal waste treatment technology avoiding major problems as known from traditional techniques like landfills or ashes, filter dust and emission producing processes. It combines slow degassing with fixed bed oxygen blown gasification and mineral and metal residue melting in a closed loop system. Municipal, industrial and other kinds of waste are compacted to less than one fifth of their original volume by means of an armored hydraulic press, and then periodically pushed into an indirectly heated degasification channel. As the waste plugs are pushed down the channel in an oxygen-free environment, waste humidity is evaporated and the organic components in the refuse are partially degasified and to a certain extent converted into a carbon-like product as the temperature increases. This flaky product and the enclosed inorganic components such as metals and minerals are continuously fed into a high-temperature reactor (HTR). Pure oxygen is added in controlled quantities and reacts with the material following exothermic oxidisation reactions. Due to overall under-stoichiometric conditions, gasification products form a combustible synthesis gas. The heat of reaction leading to temperatures up to about 2000°C in the core of the lower HTR section acts to also smelt the metal and mineral components of the waste. Chlorinated hydrocarbons such as dioxins and furans are reliably destroyed along with other organic compounds in the gaseous and the liquid phase. Material conversion equilibria are assured due to high temperatures and sufficient residence times. The synthesis gas is purified before use as combustible or primary material. After long term operation of the industrial scale demonstration plant in northern Italy, recent orders of differently sized Thermoselect plants can be announced and are illustrated on the basis of three cases out of five [with Herten 225,000 Mg/a and Berlin 300,000 Mg/a] in Germany: (1) Karlsruhe plant, 3 lines, 225,000 Mg/a, under construction; (2) Ansbach plant, 1 line, 75,000 Mg/a, completely purchased in July 1997; (3) Hanau plant, 2 lines, 90,000 Mg/a, partially purchased in October 1997. The technical concepts of these projects are illustrated with special emphasis on the flexibility of tailor-made energy recovery solutions. 相似文献
73.
Soeroes C Goessler W Francesconi KA Schmeisser E Raml R Kienzl N Kahn M Fodor P Kuehnelt D 《Journal of environmental monitoring : JEM》2005,7(7):688-692
In contrast to the large body of data on naturally-occurring arsenic compounds in marine organisms, relatively little is known about arsenic speciation in freshwater biota. We report an investigation using HPLC-ICPMS into the arsenic compounds in five species of freshwater mussels collected from five sites from the Danube in Hungary. Total arsenic concentrations in the mussels ranged from 3.8-12.8 mg As kg(-1). The arsenic speciation patterns were broadly similar for mussels representing each of the five species and five sites, but quite different from those reported for marine mussels. The major extractable arsenicals were two oxo arsenosugars (glycerol sugar and phosphate sugar), and their thio analogues (thio glycerol sugar and thio phosphate sugar). Arsenobetaine, usually the major arsenical in marine organisms, was not a significant compound in the freshwater mussels and was detected in only three of the 11 samples. This is the first report of thio arsenosugars in freshwater biota and suggests that these compounds may be common and widespread naturally-occurring arsenicals. 相似文献
74.
Maria Lehnung Bernd Leplow Vegard
ksendal Haaland Maximilian Mehdorn Roman Ferstl 《Journal of environmental psychology》2003,23(4):419-425
We investigated the influence of age, sex and familiarity on spatial performance assessed with a pointing task in 84 children: 21 kindergartners, 21 first-graders, 21 fifth-graders and 21 sixth-graders. Spatial performance was assessed in the children's natural environment, their respective school or kindergarten. The children had to indicate the direction of prominent landmarks on the school campus while sitting in their classroom, drawing an arrow on a sheet of paper. Since the children had spent different amounts of time at their respective schools, experience with the environment was regarded as a covariate.Data analysis revealed significant effects for age, sex and experience. Fifth-graders aged around 10 years outperformed the younger children. Sex differences revealed male superiority at all ages. Experience with the environment was also shown to play a vital role. Children who had spent a longer time at the school were able to demonstrate better spatial knowledge by pointing more accurately towards unseen landmarks. 相似文献
75.
Leaching tests are becoming more relevant in assessing solid waste material, particularly with respect to groundwater risks. In the field, water infiltration is the dominant leaching mechanism, which is simulated in the lab with batch and column tests. In this study, we compared percolation, through analytical solutions of the advection–dispersion equation, to laboratory batch and sequential leaching tests. The analytical solutions are supported with comprehensive data from various field and laboratory leaching of different solutes from waste materials and soils collected in long-term joint research projects funded by the German Federal Ministry for Education and Research and the Federal Environment Agency. The comparison of theory and data is facilitated if concentrations and cumulative release are plotted versus the liquid–solid ratios (LS). Both theory and data indicate that leaching behaviour is independent of duration and physical dimensions of the leaching tests. This holds even if field lysimeters are compared to laboratory columns of different size, different flow velocities as well as different contact times. In general, laboratory batch tests over predict effluent concentrations (for LS < Kd). Leaching of solutes from solid samples of certain materials (e.g. chloride from incineration ashes or sulphate from demolition waste) in column and lysimeter tests compares very well and agrees with the analytical solutions. Overall, reproducibility and agreement with theory of column tests are better than batch tests, presumably because the latter are prone to artefacts (e.g. in liquid–solid separation steps). Theory and data fit surprisingly well, despite the fact that the theory is based on the local equilibrium assumption; non-linear sorption and chemical reactions in the solid waste materials are not considered. 相似文献
76.
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78.
Background, Aim and Scope
Metal ions generally share the ability/tendency of interacting with biological material by forming complexes, except possibly for the heavy alkali metals K, Rb and Cs. This is unrelated to the metals being either essential for sustaining life and its reproduction, apparently insignificant for biology, although perhaps undergoing bioconcentration or even being outright toxic, even at low admission levels. Yet, those different kinds of metal-biomass interactions should in some way depend on properties describing coordination chemistries of these very metals. Nevertheless, both ubiquitously essential metals and others sometimes used in biology should share these properties in numeric terms, since it can be anticipated that they will be distinguished from nonessential and/or toxic ones. These features noted above include bioconcentration, the involvement of metal ions such as Zn, Mg, Cu, Fe, etc. in biocatalysis as crucial components of metalloenzymes and the introduction of a certain set of essential metals common to (almost) all living beings (K, Mg, Mo, Mn, Fe, Cu and Zn), which occurred probably very early in biological evolution by ‘natural selection of the chemical elements’ (more exactly speaking, of the metallomes).Materials and Methods
The approach is semiempirical and consists of three consecutive steps: 1) derivation of a regression equation which links complex stability data of different complexes containing the same metal ion to electrochemical data pertinent to the (replaced) ligands, thus describing properties of metal ions in complexes, 2) a graphical representation of the properties-two typical numbers c and x for each metal ion-in some map across the c/x-space, which additionally contains information about biological functions of these metal ions, i.e. whether they are essential in general (e.g. Mg, Mn, Zn) or, for a few organisms of various kinds (e.g. Cd, V), not essential (e.g. rare earth element ions) or even generally highly toxic (Hg, U). It is hypothesized that, if coordination properties of metals control their biological ‘feasibility’ in some way, this should show up in the mappings (one each for mono and bidentate-bonding ligands). 3) eventually, the regression equation produced in step 1) is inverted to calculate complex stabilities pertinent to biological systems: 3a) complex stabilities are mapped for ligands delivered to soil (-water) by green plants (e.g. citrate, malate) and fungi and, compared to their unlike selectivities and demands of metal use (photosynthesis taking place or not), 3b) the evolution of the metallome during late chemical evolution is reconstructed.Results
These maps show some ‘window of essentiality’, a small, contrived range/area of c and x parameters in which essential metal ions gather almost exclusively. c and x thus control the possibility of a metal ion becoming essential by their influencing details of metal-substrate or (in cases of catalytic activities) metal-product interactions. Exceptions are not known to be involved in biocatalysis anyhow.Discussion
Effects of ligands secreted, e.g. from tree roots or agaric mycelia to the soil on the respective modes (selectivities) of metal bioconcentration can be calculated by the equation giving complex stability constants, with obvious ramifications for a thorough, systematic interpretation of biomonitoring data. Eventually, alterations of C, N and P-compounds during chemical evolution are investigated — which converted CH4 or CO2, N2 and other non-ligands to amino acids, etc., for example, with the latter behaving as efficient chelating ligands: Did they cause metal ions to accumulate in what was going to become biological matter and was there a selectivity, a positive bias in favour of nowessential metals (see above) in this process? Though there was no complete selectivity of this kind, neither a RNA world in which early ribozymes effected most of biocatalysis, nor a paleoatmosphere containing substantial amounts of CO could have paved the way to the present biochemistry and metallomes.Conclusions
This way of reasoning provides a causal account for abundance distributions described earlier in the Biological System of Elements (BSE; Markert 1994, Fränzle &; Markert 2000, 2002). There is a pronounced change from chemical evolution, where but few transformations depended on metal ion catalysis to biology.Recommendations and Perspectives
The application of this numerical approach can be used for modified, weighted evaluation of biomonitoring analytical data, likewise for the prediction of bioconcentration hazards due to a manifold of metal ions, including organometallic ones. This is relevant in ecotoxicology and biomonitoring. In combining apoproteins or peptides synthesized from scratch for purposes of catalysing certain transformations, the map and numerical approaches might prove useful for the selection of central ions which are even more efficient than the ‘natural’ ones, like for Co2+ in many Zn enzymes.79.
Bernd Hanisch Bettina Abbas Werner Kratz Gerrit Schüürmann 《Environmental Sciences Europe》2004,16(4):223-238
Goal
In the Brandenburg State Office for the Environment an approach to assess the potential risk of drug residues in aquatic ecosystems has been developed based on an investigation of the consumption amounts in 1999 to identify or to exclude a potential environmental risk of important human drugs and further to define priority substances for monitoring programs in Brandenburg in the future.Method
This assessment approach tested with 60 drug agents is based on an exposure estimation considering the main path for the entry human—waste water—sewage plant—surface water, on a substance specific analysis of effects and on an analysis of the environmental fate as compartment distribution, bioaccumulation and persistence.Results
In Brandenburg surface waters the drug agent concentration for eight of the considered substances is supposed to be greater than 1 μg/l and for at least 13 of the considered substanoes the PNEC in aquatic ecosystems is assumed to be lower than 1 μg/l. A potential risk for the environment can be seen for the antibiotics Ciprofloxacin-HCl and Clarithromycin, the disinfectants Benzalkonium Chloride, Cocospropylendiaminguaniacetat, Glucoprotamine, Laurylpropylenediamine and Polyvidone-iodine, the sexual hormon Ethinylestradiol, the antidiabetic Metformin-HCl, the antiepileptic Carbamazepine and the lipid regulator Clofibrinic acid on the basis of effects because their PEC:PNEC-relation is about 1 or higher. For further 19 drug agents an environmental risk is to be assumed because of their environmental behaviour without support by ecotoxicological data at present.Conclusion
Although there is only a small base of valid ecotoxicological data, this risk assessment shows that adverse effects in the aquatic environment by some drug agents cannot be excluded. However, it should be noted that this first assessment gives only a crude orientation. Appropriate test data are necessary to refine the assessment in future. 相似文献80.
Winfried Schröder Inga Hornsmann Roland Pesch Gunther Schmidt Stefan Fränzle Simone Wünschmann Heike Heidenreich Bernd Markert 《Environmental Sciences Europe》2008,20(1):62-74