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21.
Organo-arsenic has been isolated from sole, lemon sole, flounder, dab, crab and shrimps by extraction or ion-exchange in combination with thin-layer chromatography. An alkaline digestion of the samples, followed by a reduction with sodiumborohydride leads to the formation of trimethylarsine. The behaviour of the organo-arsenic compound was very similar to that of synthesized arsenobetaine. Field desorption mass spectrometry (FDMS) can be used to identify arsenobetaine in the isolates. Sufficient purification by thin-layer chromatography is found to be a prerequisite for the detection of a protonated molecular ion of arsenobetaine. If this situation is not met acid enhanced FDMS or Fast Atom Bombardment mass spectrometry in high resolution can be used successfully. 相似文献
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Jeroen van der Heijden Ernst ten Heuvelhof Bertien Broekhans Sonja van der Arend Ellen van Bueren Casper Harteveld 《Local Environment》2013,18(3):318-333
The European Union Water Framework Directive (WFD) has provided the European Member States with a range of interacting governance challenges. This article studies three of these (the need for new administrative arrangements, public participation, and the enforced strict time frame). It questions how these interacting governance challenges were addressed in implementing the WFD in the Netherlands – a particularly interesting country since the European Commission assesses its implementation process in relatively positive terms, while an in-depth study reported on in this article tells a contrasting story. Based on this study, the article concludes that especially the interaction effects between the governance challenges may help us to better understand the outcome of the WFD-implementation process, and to provide more suitable advice as to how to improve the implementation process in future rounds. 相似文献
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José S. Antunes do Carmo Mechteld ten Voorde Maria G. Neves 《Journal of Coastal Conservation》2011,15(4):531-546
Surfing has becoming more and more attractive in the past few decades, constituting nowadays an important source of revenue
for many countries with extensive coastlines. For this purpose and also for environmental reasons, the conventional ways of
protecting a coastline appear to entail some disadvantages. An innovative and interesting way of improving surfing capacities
and contributing to protect a local coastal zone is by means of multifunctional artificial reefs. A multifunctional artificial
reef (MFAR) is a submerged structure that serves several purposes; in particular, it may enhance the surfing possibilities
and the environmental value of the local area. This structure has some promising new aspects, too: first, it provides an unimpaired
visual amenity; second, it offers tourist and economic benefits by improving the surfing conditions; third, it can enhance
the environmental value of the area where it is built, and fourth, if designed properly, the down drift erosion can be minimal.
An appropriate reef design in terms of ‘surfability’, i.e. the possibility to surf a wave, for the Leirosa beach, located
to the south of Figueira da Foz, midway along Portugal’s West Atlantic coast, has been investigated. In order to achieve the
best design several steps were conducted. First, the performance of the Boussinesq-type COULWAVE model is tested with experimental
data. Next, this numerical model is used to define the best values for three design parameters: reef angle; geometry of the
reef (without or with a platform), and horizontal dimensions for the appropriate geometry. A preliminary design was achieved
step by step, making use of the theory and of the state of the art of multifunctional reefs. This reef geometry is used in
the numerical study. In terms of ‘surfability’ and for the conditions of the local coastline of Leirosa, the following values
were found for the main parameters: a reef angle of 66°; a structure height of 3.20 m; a reef geometry composed of a delta
without a platform; a reef submergence of 1.50 m, and a structure seaward slope of 1:10. 相似文献
30.
Legislative and environmental issues on the use of ash from coal and municipal sewage sludge co-firing as construction material 总被引:7,自引:0,他引:7
For the economy of any co-firing process, it is important that the common waste management options of ash remain practical. Ash from bituminous coal combustion is typically handed to the construction industry. This paper describes the current European legislation on use of ash for construction purposes. Also, it presents an experimental study on the suitability of fly ash from combustion of mixtures of bituminous coal and municipal sewage sludge as additive to cement and concrete, and for use in open-air construction works, based on the ash chemical composition and the characteristics of the extract of the ash. Presently, two European standards forbid the use of ash from co-firing as additive to cement or concrete. This study shows that ash derived from coal and sewage sludge co-firing contains generally less unburned carbon, alkali, magnesium oxide, chlorine, and sulfate than coal ash. Only the concentration of free lime in mixed ash is higher than in coal, even though, at least up to 25% of the thermal input, still below the requirements of the standards. This ash also meets the requirements for the use of fly ash in open-air construction works--concentration and mobility of few elements--although this management option is forbidden to ash from co-firing. The leaching of Cd, Cr, Cu, Ni, Pb and Zn was investigated with three leaching tests. The concentration of these metals in the extracts was below the detection limit in most cases. The concentration of Cu and Zn in the extract from fly ash was found to increase with increasing share of sewage sludge in the fuel mixture. However, the concentration of these two metals in the extract is not regulated. This study indicates that excluding a priori the use of ash from co-firing as a suitable additive for construction material could cause an unnecessary burden on the environment, since probably ash would have to be disposed of in landfill. However, allowing this requires the modification of current European standards to include limitations on all elements and compounds, absent in coal but which might be present in other fuels, that are deleterious for the quality of construction materials. 相似文献