EuroBionet: a pan-European biomonitoring network for urban air quality assessment.

EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites.

Fluoride distribution and transport along rivers in the French Alps.

Fluoride concentrations in water, sediments, and plants were determined at 26 locations along five rivers in the French Alps where aluminum factories have been discharging fluoride into the surrounding environment since the end of the last century. Despite a wide range of biological and constructional damages caused by fluoride contamination in the past, there was no alarming level of fluoride found in the water, sediments, or plants. Fluoride concentration in water ranged from 0.11 ppm (considered to be natural background level) to 0.62 ppm (moderate contamination). The highest fluoride concentration was 360 ppm in sediments and 207 ppm in plants. The increase of fluoride concentration along the rivers was gradual from upstream to downstream. This gradual increase suggested that the fluoride pathway was from factory to stack, to air, to the entire valley, and to the river. The amount of fluoride transported from the Maurienne valley by the Arc river was estimated to be 680 tons per year. Of this 97.8% tons (665 tons) was transported by the flowing water and the rest (2.2% or 15 tons) by sediments moving downstream.

[The concentration of fluorine in different dairy products made from contaminated milk]. / Repartition du fluor dans les differents produits laitiers obtenus a partir de lait contamine.

The total fluoride levels in milk from cows grazing in fluoride-contaminated pastures (0.26 microgram g-1) are found to be about twice as high as those in milk from cows on a "normal" grass diet (0.11 microgram g-1). Among dairy products from contaminated milk, the fluoride concentrations in cream and cheese are the highest. During processing, large amounts of fluoride accumulate in these products, and the fluoride concentrations of cream and cheese are about three times (0.80 microgram g-1) those of milk. However, the study demonstrates that not only milk but also dairy products are poor sources of fluoride even in cases in which the fluoride content of the ambient air is notably high.

[Compartmental analysis of 6Li/7Li isotope exchange in equilibrium conditions in mouse plasma]. / Analyse compartimentale de l'échange isotopique 6Li/7Li en conditions stationnaires dans le plasma de la souris.

The compartmental analysis of lithium in the mouse plasma has been performed using the stable isotopes, 6Li and 7Li, as tracers. The animals were kept under stationary conditions (concentration of total lithium in plasma maintained equal to 0.28 mM) during the experiment. The isotopic exchange, 6Li/7Li, was described to a good approximation by combining two first-order processes (characteristic parameters: 89 microM and 2.071 X 10(-3) X min-1 for the first one, and 193 microM and 2.215 X 10(-4) X min-1 for the second one). From these kinetic data, it was estimated that the lithium capacities of the plasma and of the cells were 282 and 454 nmol X ml-1, and that the unidirectional fluxes of lithium between plasma and cells and through the kidneys were 0.259 and 0.227 nmol X ml-1 X mn-1. Since the method makes use only of stable, hence harmless, isotopes, one might think of extending it to direct experimentation in man.

Accidental release of fluoride into experimental pond and accumulation in sediments, plants, algae, molluscs and fish.

The fate of fluoride in a simulated accidental release into an experimental pond was observed for 30 days in Grenoble, France. The components investigated were water, sediments, plants, algae, molluscs, and fish. Twenty-four hours after the release, most (99.8%) of the fluoride was distributed in the physical components (water and sediments), and the biological agents contained only 0.2% of the fluoride released. Despite an exposure to hot spots of 5000 ppm at the beginning of the accidental release, no visible toxic effects were observed on the biological components such as plants, algae, molluscs, and fish. The effects of the physical components in the defluoridation showed a significant role in the control the accidental release of fluoride in the aquatic system.

A tracer method to study unidirectional fluxes of lithium. Application to frog skin.

We describe a new tracer method to measure unidirectional fluxes of Li+ despite the lack of any utilizable radioisotope of lithium. This method uses the purified stable isotopes, 6Li and 7Li, detected with an ion-probe microanalyser. The accuracy is comparable to that obtained for other ions (e.g., Na+) with radiotracers. The method has been applied to frog skin with both faces bathed in a 20% lithium/80% sodium medium. Sodium and lithium unidirectional fluxes have been measured simultaneously. The results are consistent with lithium being actively pumped, the outflux of lithium being, however, much larger than that of sodium.

Cortical Air Spaces (Aerenchyma) in Roots of Corn Subjected to Oxygen Stress: STRUCTURE AND INFLUENCE ON UPTAKE AND TRANSLOCATION OF RUBIDIUM IONS.

When the seminal root system of 14-day-old corn (Zea mays cv. Dekalb 202) was subjected to O(2) stress, nodal roots with well developed cortical air spaces (aerenchyma) grew into the deoxygenated solution. Microscopic examination showed that there was extensive breakdown of cells in the midcortex of these roots, while the stele, endodermis, and inner layer of cortical cells remained complete, as did the outer layers of the cortex and the epidermis. Occasional files of intact cells, and the wall residues of collapsed cells, crossed the space between inner and outer cortex. Experiments with short, intact root segments with and without air spaces showed that in the presence of O(2) the ability to absorb and translocate (86)Rb(+), per unit volume or length of root, was little affected by cortical degeneration. The distribution across root sections of recently supplied strontium and rubidium, determined by electron microprobe analysis, indicated that in roots with air spaces the strands of wall residues bridging the cortex could be involved in maintaining the conduction of ions from the outer cortex up to the endodermis.

[Lithium exchange in from epithelium: determination of unidirectional flux using the stable isotopes 6Li and 7Li in an ionic analyzer]. / Echanges de lithium de l'épithélium de Grenouille: détermination des flux unidirectionnels à l'aide des isotopes STABLES 6Li et 7Li et d'un analyseur ionique.

The use of the stable isotopes 6 and 7 of lithium, and detection with the ionic analyser, allow the measurement of unidirectional transepithelial Li-fluxes, between "external" and "internal" solutions which both contain 80% Na and 20% Li. Efflux was found to be bigger than influx. An important lag-phase on the curve, reveals the interference of a Li-compartment, with a high capacity, in the epithelium itself.