Effect of lead on growth and nitrate assimilation of Vigna radiata (L.) Wilczek seedlings in a salt affected environment

The inhibition of seedling growth and nitrate reductase activity in 5 d old Vigna radiata (L.) Wilczek cv. Pusa Baisakhi in the presence of 1.0 mM lead acetate increased drastically, if NaCl (6 and 12 EC) was also present in the nutrient media along with the metal salt. Correspondingly higher endogenous Na+ levels were accumulated in the roots and leaves of seedlings in presence of the two stresses. On the other hand, the levels of endogenous lead get reduced in presence of NaCl in both the roots and leaves. Roots accumulated more Pb2+ and Na+ than the leaves. The two stresses affect more drastically in the additive or even synergistic manner during the early growth phase of the seedlings.     

Nitrous oxide emission from an agricultural field: Comparison between measurements by flux chamber and micrometerological techniques

The soil in a drained fjord area, reclaimed for arable farming, produced N₂O mainly at 75–105 cm depth, just above the ground water level. Surface emissions of N₂O were measured from discrete small areas by closed and open-flow chamber methods, using gas chromatographic analysis and over larger areas by integrative methods: flux gradient (analysis by FTIR), conditional sampling (analysis by TDLAS), and eddy covariance (analysis by TDLAS). The mean emission of N₂O as determined by chamber procedures during a 9-day campaign was 162–202 μg N₂ONm⁻²h⁻¹ from a wheat stubble and 328–467 μg N₂ONm⁻² h⁻¹ from a carrot field. The integrative approaches gave N₂O emissions of 149–495 μg N₂ONm⁻² h⁻¹, i.e. a range similar to those determined with the chamber methods. Wind direction affected the comparison of chamber and integrative methods because of patchiness of the N₂O emission over the area. When a uniform area with a single type of vegetation had a dominant effect on the N₂O gradient at the sampling mast, the temporal variation in N₂O emission determined by the flux gradient/FTIR method and chamber methods was very similar, with differences of only 18% or less in mean N₂O emission, well below the variation encountered with the chamber methods themselves. A detailed comparison of FTIR gradient and chamber data taking into account the precise emission footprint showed good agreement. It is concluded that there was no bias between the different approaches used to measure the N₂O emission and that the precision of the measurements was determined by the spatial variability of the N₂O emission at the site and the variability inherent in the individual techniques. These results confirm that measurements of N₂O emissions from different ecosystems obtained by the different methods can be meaningfully compared.     

Monoterpene patterns of different tissues and plant parts of Norway spruce (Picea abies L. Karst.)

Norway spruce saplings (Picea abies L. Karst.) were exposed for five years to controlled concentrations of ozone and/or sulphur dioxide in open-top chambers. The monoterpenes of needles, twigs (bark and wood), bark and buds harvested from these trees were qualitatively and quantitatively analysed by combined gas chromatography-mass spectrometry. Different tissues and plant parts, showed notable differences in their percentage distribution. However, comparison of the monoterpene patterns of corresponding plant material obtained from trees which had been exposed to different fumigation regimes showed no significant effects of these pollutants.     

Effect of environmental factors on pheromone trap catches of (Hubner)

Prediction models relating pheromone trap catches of (H) with several onvironmental factors are worked out. It is expected that those models will help overcome indiscriminate use of pesticides.     

Comparison of methods for the extraction and determination of polychlorinated biphenyls in shiphull antifoulings

A method is presented for the determination of PCBs in chlorinated rubber antifoulings. In ten different brands, no PCB concentrations above 0.5 mg kg^?1 were found.     

Verteilung und Abnahme von bodennahem Ozon in st?dtischen und l?ndlichen Regionen

Zusammenfassung  Eine Zusammenstellung der Ozon-Me?werte der Luftme?stationnetze in Hessen und NRW ergab für die Jahresmittelwerte von 1990–1998 im Durchschnitt eine schwache Abnahme der Ozonkonzentrationen. Dabei lagen die Jahresmittelwerte der Ozonkonzentrationen über Waldstationen doppelt so hoch wie über Stadtstationen. Die Ozonkonzentrationen verhalten sich im regionalen Vergleich umgekehrt proportional zur Verkehrsdichte. In der Zahl der überschreitungen der gesetzlich festgelegten Grenzwerte von ≥180 μg Ozon/m³ pro Jahr lagen die Waldstationen mit dem 2–3 fachen Wert über den Stadtstationen. Lediglich die j?hrlichen Maximalwerte der stündlich gemessenen Ozonwerte n?hern sich einander. Die hohen Ozonwerte über den Waldstationen stehen im Zusammenhang mit den niedrigen Konzentrationen von NOx. Nachts reduziert sich das Ozon über den Waldstationen durch Rückreaktion mit vergleichsweise geringen Konzentrationen von NO nur bis ca. 50%, w?hrend der Ozongehalt über Stadtstationen bis nahe Null absinkt. Dieser Vorgang über den Stadtstationen wird auch durch Photolyse des in hohen Konzentrationen vorliegenden NO₂ und die dadurch erfolgende erh?hte Bildung von Ozon w?hrend des Tages nicht wieder kompensiert. Für die hier dargestellten Ergebnisse gibt es prinzipiell keine Unterschiede zwischen den Ozonverh?ltnissen in Hessen und NRW.      

Mechanism and kinetic model for the decolorization of the azo dye Reactive Black 5 by hydrogen peroxide and UV radiation

A kinetic model for the decolorization of C.I. Reactive Black 5 by the combination of hydrogen peroxide and UV radiation was developed based on experimental results and known chemical and photochemical reactions. The observed kinetic reaction coefficient was determined and correlated as a function of hydrogen peroxide concentration and UV intensity. The validity of the rate expression was tested experimentally in a parameterization study. The decolorization rate follows pseudo-first order kinetics with respect to dye concentration. The rate increases linearly with UV intensity and nonlinearly with increasing hydrogen peroxide concentration, going from a linear relationship at low H(2)O(2) concentrations to a maximum as hydrogen peroxide concentration continues to increase. The decolorization rate expression derived from the proposed reaction mechanism was reconciled with that used for correlating the experimental data.     

Lowered birth weight among infants born to women with a high intake of fish contaminated with persistent organochlorine compounds

In Sweden fatty fish from the Baltic Sea (at the Swedish east coast) constitute the main exposure route for persistent organochlorine compounds (POC). The present study assessed reproductive outcomes among fishermen's sisters from the Swedish east coast, who were shown to had had a relatively high consumption of contaminated fish in early life. For relevant comparison, we used a similar cohort from the Swedish west coast, where the contamination of fish is considerable less. The east coast cohort women had an increased risk of having an infant with low birth weight (LBW; <2500 g) as compared with the west coast cohort women (odds ratio (OR) 1.6. 95% confidence interval 1.1-2.3). The results strengthen the hypothesized association between exposure to POC during childhood and adolescence and an increased risk for LBW.