Uptake,translocation and fate of trichloroacetic acid in a Norway spruce/soil system

Trichloroacetic acid (TCA) is a secondary atmospheric pollutant formed by photooxidation of chlorinated solvents in the troposphere--it has, however, recently been ranked among natural organohalogens. Its herbicidal properties might be one of the factors adversely affecting forest health. TCA accumulates rapidly in conifer needles and influences the detoxification capacity in the trees. The aim of the investigations--a survey of which is briefly given here--was to elucidate the uptake, distribution and fate of TCA in Norway spruce. For this purpose young nursery-grown plants of Norway spruce (Picea abies (L.) Karst.) were exposed to [1,2-14C]TCA and the fate of the compound was followed in needles, wood, roots, soil and air with appropriate radio-indicator methods. As shown by radioactivity monitoring, the uptake of TCA from soil by roots proceeded most rapidly into current needles at the beginning of the TCA treatment and was redistributed at later dates so that TCA content in older needles increased. The only product of TCA metabolism/biodegradation found in the plant/soil-system was CO(2) (and corresponding assimilates). TCA biodegradation in soil depends on TCA concentration, soil humidity and other factors.     

Trichloroacetic acid in Norway spruce/soil-system. II. Distribution and degradation in the plant

Independently from its origin, trichloroacetic acid (TCA) as a phytotoxic substance affects coniferous trees. Its uptake, distribution and degradation were thus investigated in the Norway spruce/soil-system using 14C labeling. TCA is distributed in the tree mainly by the transpiration stream. As in soil, TCA seems to be degraded microbially, presumably by phyllosphere microorganisms in spruce needles. Indication of TCA biodegradation in trees is shown using both antibiotics and axenic plants.     

A stakeholder dialogue on European vulnerability

A stakeholder dialogue was embedded in the ATEAM project to facilitate the development and dissemination of its European-wide vulnerability assessment of global change impacts. Participating stakeholders were primarily ecosystem managers and policy advisers interested in potential impacts on ‘Agriculture’, ‘Forestry’, ‘Water’, ‘Carbon storage’, ‘Biodiversity’ and ‘Mountain environments’ sectors. First, stakeholder dialogue approaches to integrated assessment are introduced. Methodological considerations on stakeholder selection and dialogue implementation and evaluation follow. The dialogue content and process are evaluated from the perspectives of stakeholders and scientists. Its usefulness in the research process and the relevance of outcomes for stakeholders are particularly considered. The challenging compromises required to perform innovative research, which seeks to achieve both peer scientific credibility and societal relevance, are emphasized. Effective stakeholder dialogues play a substantial role in raising the visibility and meaningfulness of vulnerability assessments as critical means to improve awareness on global change and its potential worrying impacts on society. They further provide scientists with critical information on ecosystem management and sectoral adaptive capacity. These processes of mutual learning and knowledge exchange moreover foster a better understanding of the potential and limits of global change modelling and vulnerability assessment for policy and ecosystem management.

Ökologische, ökonomische und rechtliche umweltbewertung

This article provides information about a Series dealing with Integrated environmental assessment’ (IEA). We describe the development and the structure of a ‘Graduiertenkolleg’ (interdisciplinary course of study) which has been established in two phases at the University of Kiel from 1996–2002. The central terms ‘integration’, ‘environment’, and ‘assessment’ are discussed. Here, we take a special look at the chances and problems of interdisciplinary cooperation and communication (ecosystem research, jurisprudence, economics, social sciences) with regard to the general subject of IEA as a subject of research and schooling. Finally, we give a short review about the articles in the series.     

Reaction of spruce cells toward heavy metals and the influence of culture conditions

BACKGROUND: Plant cell cultures may serve as biosensors for the detection of heavy metals and other toxic substances. Standard culture media and protocols are frequently utilised, but in these media no care is usually taken to control the influence of hormones and nutrients on the reaction of the enzymes or m under consideration as parts of the sensor. The present paper investigates the influence of media composition on the reaction of spruce cells towards heavy metals. METHODS: Spruce cell cultures were grown in a standard medium, either i) alone, ii) containing 0.3% sucrose or iii) containing 3% sucrose and the hormones BAP and NAA. The cell cultures were then incubated in medium with fungal elicitor, H2O2, CdSO4 (50 to 500 microM), or, alternatively, with a standard heavy metal mixture containing 80 microM Na2HAsO4, 150 microM CdSO4 and 200 microM PbCl2. RESULTS: Depending on the nutrient status and hormone availability, large differences in glutathione contents and the GSH/GSSG ratio were observed. However, the cellular redox state seemed to remain more or less constant. Glutathione S-transferase activity was determined with four substrates, and high induction rates for the conjugation of three substrates were observed when hormones were omitted from the media. 1,2-epoxy-nitrophenoxy-propane conjugation was highest in starving cell in the presence of hormones, showing a transient GST induction, with highest rates occurring after 16 hrs following incubation; the induction effect was lost after 24 hrs. CONCLUSION: A medium containing 3% sucrose and both hormones (BAP and NAA) appears to be most favourable for cellular growth as well as the expression of a basis level of detoxification enzymes and antioxidants. With this combination, early responses towards heavy metals at low concentration can be monitored. RECOMMENDATIONS AND PERSPECTIVE: Plant cell cultures are valuable tools for the bioindication of heavy metals and toxic xenobiotics. If standard media and protocols are utilised, the influence of hormones and nutrients on the reaction of the biosensor have to be evaluated thoroughly.     

Trend der Schwermetall-Bioakkumulation 1990 bis 2005: Qualitätssicherung bei Probenahme, Analytik, geostatistischer Auswertung

Background, aim and scope Since 1990, the UN ECE Heavy Metals in Mosses Surveys provide data inventories of the atmospheric heavy metal bioaccumulation across national boundaries in Europe. The results prove how air pollution control in Germany and in all of Europe affected the bioaccumulation of metals in those ecosystems that are not directly influenced by nearby emission sources. This article focuses on the assessment of spatiotemporal patterns of the metal bioaccumulation in Germany since 1990. Furthermore, the spatial variance of the metal bioaccumulation is analysed with regard to sampling site-specific and regional land characteristics. Special focus hereby relies on the correlation of the metal concentration in mosses and in depositions. Hence, the moss surveys contribute to §?12 of the German Federal Nature Conservation Act as well as to the “Convention on Long-range Transboundary Air Pollution” (CLRTAP). Materials and methods The bioaccumulation of up to 40 trace elements in mosses was determined according to a European wide harmonised methodology. The according experimental protocol regulates the selection of sampling sites and moss species, the chemical analysis and quality control and the classification of the measured values for the mapping of spatial patterns. In Germany all sampling sites were described with regard to topographical and ecological criteria as well as other aspects seen as relevant in the mandatory guideline. Together with the measurements this metadata was combined with other information regarding emissions and land use in the surroundings of the sampling sites in the WebGIS MossMet. The spatial structure of the metal bioaccumulation was analysed and modeled by variogram analyses and then mapped by applying different kriging techniques. Furthermore, different multi-metal indices (MMI) were derived for both the sampling sites and raster maps with the help of percentile statistics: The MMI1990 aggregates the data for Cr, Cu, Fe, Ni, Pb, Ti, V and Zn determined in 1990. The MMI1995, MMI2000, MMI2005 furthermore include As, Cd, Hg and Sb for 1995, 2000 and 2005, respectively. Two other MMI allow for a time integrating view on the metal bioaccumulation in Germany: The MMI1990–2005 was calculated on behalf of all measured/geostatistically estimated data for Cr, Cu, Fe, Ni, Pb, Ti, V and Zn. Therefore the integrated assessment of the metal bioaccumulation in Germany from 1990 to 2005 is possible. The MMI1995–2005 furthermore includes the element-specific data of As, Cd, Hg and Sb therefore integrating 12 elements over the last three surveys. The statistical association of the metal bioaccumulation, site-specific characteristics as well as information on land use and emissions was analysed by bivariate correlation analysis and multivariate decision tree models (Classification and Regression Trees – CART, Chisquare Automatic Interaction Detection – CHAID). Results The results of the quality-controlled chemical analyses show a significant decrease of the metal bioaccumulation in Germany from 1990 to 2000. From 2000 to 2005 a further decrease can be stated for Hg, Pb and Ti. However, a significant increase for Cd, Cr, Cu, Sb and Zn can be observed. This especially holds true for Cr (+ 160?%) that almost reaches as high concentrations in mosses as in 1990. In 2005, the metal loads in mosses, except for Cr, show spatial distributions similar to those in 1990, 1995 and 2000. Hot spots are mostly found in the urbanised and industrially influenced Ruhr Area, the densely populated Rhine–Main region and in the industrially influenced regions of former East Germany (e.?g. Halle–Leipzig region). The spatial variance of the metal bioaccumulation can mainly be explained by site-specific (moss species, canopy drip effects) and site-surrounding (land use, depositions, emissions) characteristics. Discussion High Cr loads in mosses were also registered in other European countries like in Switzerland. Further investigation is therefore necessary to investigate whether this is due to different emission conditions or biogenic effects (e.?g. as a result of increasing nitrogen depositions). Compared to other environmental monitoring and modelling programmes the moss surveys registered increasing concentrations of toxic metal elements between 1990 and 2005. Contrary to deposition measurements that exhibit a higher temporal resolution the moss surveys provide measurement data on a wide range of elements. Some of these elements are important with regard to human-toxicological aspects (e.?g. Hg, Sb, As, Al, V). The standardised biomonitoring of atmospheric pollution by mosses is an important link between the technical acquisition of depositions and the accumulation in biological material. To claim that the element concentrations in mosses and in the deposition should correlate to a high degree is not appropriate since both approaches are physically related but are not identical. The degree of correlation thereby depends on the boundary conditions of the physical processes, like regional and site-specific meteorological conditions within the accumulation period, the vertical and horizontal vegetation structure or land use conditions. Conclusions The moss surveys contribute to the heavy metal and multi-component model of CLRTAP because they prove on different spatial scales how air pollution control influences the accumulation of emitted substances in environmental subjects of protection like vegetation. If environmental monitoring is seen as a continuous task and the applied methodology works well as an early warning system then environmental policy is enabled to act in preventative sense and to pursue unexpected developments. No other environmental monitoring programme provides such a wide range of ecotoxically relevant elements measured as spatially dense as the case for the moss surveys. The spatial distribution of environmental information is an essential criterion for their usability in terms of political measures for the federal states and the federation. Recommendations and perspectives The Heavy Metals in Mosses Surveys are a positive example for environmental monitoring activities reaching across three spatial and administrative levels: regional (e.?g. federal state or natural landscape), nationwide (e.?g. Germany) and continental (e.?g. Europe). In Germany the harmonised and quality-controlled moss data are made available via an internet-based webGIS portal. Therefore the moss data may easily be accessed for environmental monitoring purposes and the control of environmental political actions. Hence, the monitoring of Heavy Metals by Mosses Surveys is an important task among the European environmental observations, which should be continued in future for scientific and political reasons in its current extent.