Klaus Jung

Anthropogenic impacts on natural nitrogen isotope variations in Pinus sylvestris stands in an industrially polluted area.

Natural variations of the nitrogen isotopes 15N/14N (delta15N values) and the N concentrations of one-year-old needles from 7-12-year-old pine trees (Pinus sylvestris L.) were determined on 27 sites in the heavily polluted Leipzig-Halle region (former GDR). At three selected sites measurements were repeated over a period of 2 years. N concentrations and delta15N values in different needle age classes were compared at the three sites. The delta15N values of the N in the humus layer and the potential plant available N in the A(h) horizon of the local soil were determined. The 15N/14N isotope ratios (delta15N values) of one-year-old pine needles in the region of Leipzig-Halle were found to vary depending on their specific location by a factor of up to one order of magnitude (-9.6 per thousand to + 0.4 per thousand ). N concentrations in one-year-old pine needles varied between 0.71 and 1.38 mmol eq N g dw(-1). Pine stands with positive or slightly negative delta15N values and high N concentrations in one-year-old needles were concentrated around the cities of Leipzig and Halle and in the industrial areas. More negative delta15N values and lower N concentrations in one-year-old pine needles were found on sites at greater distances from the industrial agglomerations, mainly in the NE forested part. Site specific differences in the delta15N values of the N in the humus layer from three selected sites were similar to those found for the needles. No site specific differences, however, were found for the delta15N values of the water soluble nitrogen fraction from the mineral soil horizons of the same sites.

Analysis of arsenic species accumulation by plants and the influence on their nitrogen uptake

Terrestrial plants are able to accumulate arsenic to a substantial extent but survive the stress to differing degrees of vitality. The influence of arsenic on important energy and metabolic cycles does not yet have sufficient explanation. Parallel to the uptake and processing of arsenic species such as As(III) and As(V) by Silene vulgaris, the nitrogen uptake using a 15N tracer method was investigated. The results showed that the nitrogen uptake decreases with increasing arsenate concentrations applied to the plants. The reaction of the plants treated with arsenite changed from a depression at low arsenite concentrations to a strong increase with the largest quantity applied, exceeding the 15N-incorporation of the control plants. This behaviour underlines the divergent behaviour of the N-metabolism caused by both arsenic species. As(III) can be detoxified by complexation with peptides rich in SH-groups. As(V) acts as a phosphate analogue and interrupts diverse phosphorylation reactions.

Effects of heavy metals on the nitrogen metabolism of the aquatic moss Fontinalis antipyretica L. ex Hedw. A 15N tracer study.

The assessment of pollution in aquatic systems necessitates an accurate indication of toxicity of heavy metals for organisms and ecosystems. We used the stable nitrogen isotope15N to estimate the influence of the heavy metals Cd, Pb and Zn on the synthesis of nitrogen-containing fractions in the aquatic mossFontinalis antipyretica. This method permits conclusions concerning inhibitory effects of these heavy metals on the assimilation of nitrogen and the biosynthesis of amino acids and proteins. The moss was exposed to metal concentrations of 25–500 μM over a period of 5–10 days.15N abundance of exposed plants was compared with that of control plants. Similar to a loss of vitality determined using a fluorometric assay, a decrease of the15N abundance in the N fractions ofFontinalis antipyretica was measured in dependence on the metal concentration. Nevertheless, the individual inhibition by the distinct metals was different, so that the following order of toxicity was derived: Cd » Pb > Zn.

15N Metabolic test for the determination of phytotoxic effects of chemicals and contaminated environmental samples

A stable isotope15N-nitrogen test (ESIMA = Ecotoxicological Stable Isotope Metabolic Assay) was developed to assess biological effects and the potential toxicological hazard of chemicals and contaminated environmental samples on plant metabolism. The assay measures the effect of toxicants on the incorporation of a15N labelled tracer into the total nitrogen fraction (both the nonprotein and protein fraction) of plants. Segments ofPisum arvense epicotyls are used as test substrates because of their high metabolic activity. The plant material is incubated under standardised conditions for two hours; subsequently15N incorporation is analysed by determining the15N abundance (15N atom-%) in the epicotyl segments.The effects of toxicants are evaluated by comparing the15N incorporation rates of control tissue and epicotyl segments exposed to individual chemicals or complex environmental samples. The specificity and sensitivity of effects as indicated by ESIMA were compared with effects as measured by two established ecotoxicological bioassays, the pollen tube growth test using pollen ofNicotiana sylvestris and the bacterial luminescence inhibition test using pollen ofPhotobacterium phosphoreum. The results of the study clearly indicate the suitability of ESIMA for assessing toxic impacts on plant nitrogen metabolism.

Effects of trichloroacetic acid on the nitrogen metabolism of Pinus sylvestris--a 13C/15N tracer study.

Trichloroacetic acid (TCA) can be found in various environmental compartments like air, rain and plants all over the world. It is assumed that TCA is an atmospheric degradation product of volatile chloroorganic hydrocarbons. The herbicide effect of TCA in higher concentrations is well known, but not much is known about the phytotoxic effects in environmentally relevant concentrations. It can be shown in this study by using the 13C/15N stable isotope tracer technique that [13C]TCA is taken up by roots of two-year-old seedlings of Pinus sylvestris L. and transported into the needles. At the same time the effect of the substance on nitrogen metabolism can be analyzed by measuring the incorporation of 15NO3- into different nitrogen fractions of the plant. The more [13C]TCA incorporation, the higher the synthesis of 15N labelled amino acids and proteins is. These effects on the nitrogen metabolism are probably based on the activation of stress- and detoxification metabolism. It has to be assumed that there is an influence on N metabolism of Pinus sylvestris caused by the deposition of environmentally relevant TCA concentrations.

Deponiesickerwässer: Bestimmung zytotoxischer Wirkungen mit dem Pollenschlauchwachstumstest

ZusammenfassungFür die Risikobewertung von Umweltproben ist es notwendig, Screening-Verfahren zum schnellen und sensitiven Nachweis toxischer Wirkungen einzusetzen. Wir stellen am Beispiel von Sickerwässern einer Deponie der Industrieregion Leipzig-Halle ein einfaches Testverfahren vor, das geeignet ist, die Zytotoxizität wäßriger Proben abzuschätzen. Die Methode, die als Pollenschlauchwachstumstest (Pollen Tube Growth Test, PTG-Test) bekannt ist, wird wie folgt angewendet: Pollen der Tabakpflanze (Nicotiana sylvestris Spegazz. & Comes) werden in einem Kulturmedium für 18 Stunden zusammen mit Deponiesickerwasser inkubiert. Die gewachsenen Pollenschläuche werden mit Alzianblau gefärbt, die Menge der produzierten Pollenschläuche photometrisch quantifiziert und die Hemmung des Pollenschlauchwachstums im Vergleich zu unbehandelten Kontrollansätzen berechnet. Der Test zeichnet sich durch eine hohe Sensitivität gegenüber den unterschiedlich belasteten, gepufferten Sickerwässern (pH 6,3 bis 7,0) aus und zeigt eine gute Übereinstimmung mit dem Leuchtbakterientest. Aus unseren Ergebnissen kann gefolgert werden, daß der PTG-Test für eine toxikologische Bewertung wäßriger Umweltproben geeignet ist.AbstractFor risk assessment of environmental samples, rapid and sensitive screening assays for detection of toxic potencies are required. Using leachates from waste deposites in the industrial region Leipzig-Halle (Germany) as an example, we present a simple test procedure suitable for the detection of cytotoxic effects of samples. This method, the pollen tube growth test (PTG), works as follows: Pollen of tobacco (Nicotiana sylvestris Spegazz, & Comes) are suspended in mixtures of growth medium and buffered (pH 6,3 to 7,0) dumping ground leachates. After an 18h-incubation period, growth of pollen tubes is quantified by staining with Alcian blue and subsequent measurment of optical density in a photometer. Sample induced inhibition of pollen tube growth is calculated in relation to controls maintained in pure growth medium. The PTG test shows high sensitivity towards leachates of different chemical composition, and it shows good agreement with assay results from luminescent bacteria tests. We conclude that the PTG test is well suited to assess the hazardous potential of aqueous environmental samples.

Biomonitoring — Eine Methode der Umweltanalytik

ZusammenfassungDer Beitrag gibt anhand von ausgewählten Bioindikationsmethoden einen Einblick in Forschungs- und Entwicklungsarbeiten zum Biomonitoring am Institut für Biochemie der Martin-Luther-Universität Halle-Wittenberg und an der Sektion Chemische Ökotoxikologie des Umweltforschungszentrums Leipzig-Halle. Er vermittelt einen Eindruck von der Leistungsfähigkeit der hier auf biochemischer Ebene an Flechten und Flechtenalgen sowie an Kiefernnadeln für die Bioindikationsmerkmale „energy charge”, antioxidative Systeme, natürliche Isotopenvariation (N15/N14) und Enzymen des N-Metabolismus entwickelten und erprobten Methoden. Im einzelnen werden Ergebnisse zum Nachweis von Dosis-Wirkungs-Beziehungen und zur Erfassung der räumlichen Differenzierung von Immissionswirkungen vorgestellt.