Eine Bemerkung zu den Quadrupolmomenten der Atomkerne

The Science of Nature -     

Emissions from baled municipal solid waste: II. Effects of different treatments and baling techniques on the emission of volatile organic compounds.

This paper focuses on the volatile organic compound emissions from baled municipal solid waste (MSW). The analytical methodology was based on sampling with adsorbent tubes once a month during seven occasions within a time period of 1 year. Automated analyses were carried out on-line work-up with thermal desorption directly connected to a gas chromatograph-mass spectrometer. The effect of different baling techniques, cylindrical and rectangular baling was compared. It was found that cylindrically baled MSW emitted larger concentration of esters than their rectangular counter parts. Conversely, aromatic compounds emissions dominated in rectangularly baled MSW. This indicates that different degradation mechanisms operate in the waste bales. Cylindrical and rectangular bales are generally wrapped with six layers of 250 microm thick low density polyethylene (LDPE). It was observed that by wrapping an extra six layers of LDPE film onto the bales, the emissions from cylindrical bales increased while emissions from the rectangular counterpart decreased. Over time, the volatile organic compound emissions from cylindrical bales decreased two orders of magnitudes from 96.2 +/- 20.8 microg m(-3) in September 2003 to 0.80 +/- 0.07 microg m(-3) in July 2004. The rectangular bales exhibited an almost identical relative emission reduction from 54.4 +/- 4.3 microg m(-3) in September 2003 to 0.46 +/- 0.02 microg m(-3) in July 2004. Future work will concentrate on full-scale storages, taking into account waste type, storage size, temperature development and the different baling techniques among other variables.     

MAGNETOHYDRODYNAMIC POWER GENERATION

The paper describes research and development in the field of magnetohydrodynamic power generation technology, based on discussions held in the Joint IAEA/UNESCO International Liaison Group on MHD electrical power generation. Research and development programmes on open cycle, closed cycle plasma and liquid-metal MHD are described. Open cycle MHD has now entered the engineering development stage. The paper reviews the results of cycle analyses and economic and environmental evaluations: substantial agreement has been reached on the expected overall performance and necessary component specifications. The achievement in the Soviet Union on the U-25 MHD pilot plant in obtaining full rated electrical power of 20.4 MW is described, as well as long duration testing of the integrated operation of MHD components. Work in the United States on coal-fired MHD generators has shown that, with slagging of the walls, a run time of about one hundred hours at the current density and electric field of a commercial MHD generator has been achieved. Progress obtained in closed cycle plasma and liquid metal MHD is reviewed. Electrical power densities of up to 140 MWe/m³ and an enthalpy extraction as high as 24 per cent have been achieved in noble gas MHD generator experiments.     

Staubfilterung und immissionshistorische Aspekte am Beispiel fassadenbegrünenden Wilden Weines (Parthenocissus tricuspidata)

Goal and Scope

At the present, air borne particulate matter is in the focus of public and scientific interest. In this context, it makes sense to remember the buffer function of vegetation for particulate air pollutants, notwithstanding technical and traffic management measures. Since trees with large and dense crowns might be able to shade windows and minimise the turbulent dilution of pollutants, natural-scientific results and socio-scientific aspects will point to the potentials of vertical greening with creeping plants.

Methods

To differentiate the endogenous and exogenous element fractions, the pollution caused by dust that covers the façade climbing creepers leaves was removed by a polyvinyl-butyrale based stripping method. The cleaning success is proven by SEM-Scans. The results of cleaned and not cleaned leaf-samples from an inner-city vertical greening for the element concentrations of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Pt, Rh, Sb and Zn between 1991 and 1997 are shown by AAS- and ICP-MS analyses.

Results and Conclusion

The results show the increasing element concentrations during the course of the separate vegetation periods. Due to the long investigation period, it is possible to detect historical aspects concerning pollution, such as the end of the use of leaded fuel and the introduction of the catalytic converters. The comparison of dust deposition data from different cities shows the relevance of the pollution filtering by vertical greenings with Japanese Creeper. The comparison of investigation results of sycamore leaves refer to entirely different filtering characteristics of the leaf-surfaces.

Recommendation and Perspective

If appropriate planning and maintenance is assured, vertical greening can be a useful contribution for air pollution control and neighbourhood improvement. As selected results from a survey show, from the citizens point of view, the aesthetical and psychosocial aspects of well-being are of more relevant than ecological arguments. Therefore it seems to be wise to implement the combined fields of interest.     

Cross‐sectional epidemiological study on arsenic excretion in urine of children and workers in Greece

An investigation was undertaken to study the exposure of children in areas with different air pollution and of adults working in three different plants (lead processing, battery plant, oil refinery) using arsenic in urine as a biological parameter. The arsenic excretion of the children are in agreement with the air pollution in the investigated areas. The workers in the lead processing plant are found to have the highest urine excretion values of the three worker collectives. The mean excretion values is nearly ten times higher than that found in the normal population.     

Net fluxes of pesticides from the Scheldt Estuary into the North Sea: a model approach

A hydrological model was constructed with the commercially available modelling environment ECoS for the calculation of mixing plots of dissolved pesticide concentrations in the Scheldt Estuary. The model was based on a one-dimensional advection-dispersion equation and dispersion coefficients were calculated from measured salinity profiles. The model could correctly predict the movement of water masses within the estuary. Nominal flushing times of the estuary were calculated with the fraction-of-freshwater method and ranged between 25 and 95 days, depending on the freshwater discharge. Model calculations demonstrated that the application-related time profiles of pesticide input may well induce curvature in the calculated estuarine mixing plot even if the pesticide behaves conservatively. Calculated mixing plots were compared with experimental data and good agreement was obtained between the measurements and the conservative mixing plot of atrazine. For metolachlor an additional direct emission had to be modelled to explain the differences between the experimental data and the conservative mixing plot. For dichlorvos and simazine. on the other hand, an estuarine loss constant had to be included in the model. Using a least-squares procedure the estuarine loss constants for dichlorvos and simazine were estimated at half-lives of five and 26 days, respectively. Because mixing plots were strongly influenced by the time profiles of pesticide input, standard procedures in which net fluxes are calculated from mixing plots, were not applicable. Therefore, net fluxes were calculated with a newly developed procedure in which the estuarine loss constants and the estuarine flushing time were combined. For the non-conservative compounds dichlorvos and simazine, the net fluxes to the North Sea were found to be 96 and 64%, respectively, lower than the gross fluxes transported by the River Scheldt.