PCDD/F emissions from heavy duty vehicle diesel engines

The currently available information on PCDD/F emissions from diesel vehicles is briefly surveyed. Considerable uncertainty is identified concerning the emissions from heavy duty diesel trucks which have been measured only twice so far. These measurements led to emission factors differing by a factor of 200; similar discrepancy was also revealed by measurements of ambient air in traffic tunnels. New PCDD/F emission measurement results are presented which have been carried out at the exhaust systems of a stationary engine and of a modern heavy duty vehicle engine at transient operation conditions simulated on a test bench. PCDD/F concentrations in the exhaust gases were found to be in the range of control blank samples. Based on the highest concentration observed in the truck engine exhaust (9.7 pg I-TEQ/dry standard m3) a worst case estimate of the annual PCDD/F emission freight from diesel fuel combustion in the European countries of about 30 g I-TEQ/year is calculated. This emission appears to be irrelevant compared to the overall emission rate of more than 6,000 g I-TEQ/year being inventoried recently. Finally the possibilities to link congener/homologue profiles of diesel emission to profiles found in food or human samples are discussed.     

Mandibular bone fluoride levels and occurrence of fluoride induced dental lesions in populations of wild red deer (Cervus elaphus) from Central Europe

Analysis of chlordane contamination in selected finfish and shellfish species from estuarine and coastal marine waters of New Jersey, USA, indicates consistently highest organochlorine pesticide levels in samples from the north and northeast regions of the state. Gas chromatographic analysis of tissue samples from four finfish species (American eel, Anguilla rostrata; bluefish, Pomatomus saltatrix; striped bass, Morone saxatilis; and weakfish, Cynoscion regalis) and one shellfish species (blue crab, Callinectes sapidus) collected at 28 stations throughout the state during the 1986-1987 sampling period and 42 stations during the 1988-1991 sampling period revealed chlordane concentrations ranging from 5 to 2150 ppb wet weight (wet wt). Highest mean concentrations of chlordane (300 ppb wet wt) occurred in American eel from the Camden region, with secondary maxima (100 ppb wet wt) observed in the northeast region. Lower mean concentrations of chlordane (< 100 ppb wet wt) were recorded in tissue samples of other species collected elsewhere in the state. In general, the lowest levels of chlordane contamination (mean < 50 ppb wet wt) were found in samples from the south coast and Delaware regions. A major conclusion of this study is that some commercially and recreationally important finfish and shellfish species in New Jersey waters, especially those which are lipid-rich, have continued to accumulate chlordane from the environment long after restrictive regulations were first placed on its use in the US. The greatest impact of chlordane contamination is nearby metropolitan centers of the state (i.e., New York, Newark, Camden), although the total concentrations of chlordane in tissue samples from these areas are currently far less than the US Food and Drug Administration action level of 300 ppb wet wt.     

A study on the Cr(VI) removal from aqueous solutions by steel wool

The reduction of Cr(VI) by steel wool and the precipitation of reduced chromium by CaCO(3) powder and NaOH solution were investigated in continuous and batch systems, respectively. The effects of acid and initial Cr(VI) concentrations, volumetric rate and temperature of solution on Cr(VI) reduction were studied. The results showed that the reduction of Cr(VI), to a large extent, depended on, and increased with, acid concentration. The Cr(III) and iron ions in the reduced solution were completely precipitated by using NaOH solution at appropriate alkaline conditions. It was concluded that CaCO(3) powder could be used as a cheap precipitant for Cr(III) ions. But the iron ions in the reduced solution could not be fully removed by using this precipitant.     

Organochlorines in polar bears (Ursus maritimus) at Svalbard

A comprehensive survey on organochlorine (OC) contaminants in polar bears at Svalbard has been undertaken. Subcutaneous tissue, blood and milk have been sampled from anesthetized free-ranging bears of both sexes and different ages in the period from 1990 to 1994. A number of sexually mature females have been fitted with satellite transmitters which make it possible to follow their reproductive behaviour pattern. We report on contamination levels and pattern of PCB congeners, chlordanes, DDT-compounds, HCB and HCH-isomers in the various tissues. The relation of age, sex and reproductive status to OC contamination has been described, and the capacity of polar bears in metabolising OCs has been discussed from the isomer/metabolite composition of residues. Finally, the possible association between OC contamination and reproduction success has been assessed. The PCB levels present in polar bears at Svalbard are extremely high. Especially high levels of higher chlorinated PCBs are found, and they accumulate with age, particularly in males. With females, considerable amounts of OCs are transferred to the offspring via milk. However, more efficient OC transfer between subcutaneous depot lipid and circulatory lipids than from the circulatory system to milk is found particularly for the most lipophilic compounds. The OC pattern in suckling yearlings reflects the low transfer of the highest chlorinated PCBs into maternal milk. The levels of most other OCs, however, are higher in depot lipid of yearlings than in that of their mothers. The polar bears have high capacity to metabolise several OCs. This may protect them against toxic action of the contaminants. No relation between OC levels in females and their ability to get pregnant is found in this preliminary investigation on OC effects on the polar bears at Svalbard.     

Quality assurance of multivariate analytical measurements by principal components analysis

The use of principal components analysis for the quality control of a mass spectrometer is demonstrated and commented upon.     

Can the Earth's magnetic field be simulated in the laboratory?

Today it is generally accepted that the Earth's magnetic field, as well as that of many other planets, is generated by buoyancy driven convection in the electrically conducting liquid cores of these rotating celestial bodies. The conversion of mechanical energy into electromagnetic energy is known as the dynamo effect. In contrast to technical dynamos, which utilize the rotational motion of a complex arrangement of wire coils and other materials of different electrical and magnetic properties, the geodynamo is based on a freely developing spiral flow in a practically homogeneous, electrically conducting liquid core domain, and is therefore termed a homogeneous dynamo. This report outlines some fundamental properties of the Earth's magnetic field. The structure of the spiral flow in the liquid interior of planets is explained with the help of some model experiments in rapidly rotating spherical shells, which were carried out by Busse and Carrigan (1974). Based on the main ideas of electromagnetism it is shown that spiral motion in well-conducting fluids, like liquid metals, can amplify seed magnetic fields to generate dynamo action. Starting from the conjectured flow structure in the Earth's interior, a conceptional and engineering design is described for a laboratory dynamo experiment. Some details of the construction of the test facility and first experimental results are presented and discussed.