Search

no abstract

The aim of this study was to quantify the effect of the pollutant, trifluoroacetate (TFA), on growth and photosynthesis of Phaseolus vulgaris (C-3) and Zea mays (C-4) in order to elucidate the physiological and biochemical basis of its inhibitory action. In whole plant studies, photosynthetic gas exchange, fast phase fluorescence kinetics and Rubisco activity were measured in parallel over a 14-day period in plants cultivated in a water culture system with NaTFA added at concentrations ranging from 0.625 to 160 mg l(-1). Although initial stimulation of some photosynthetic parameters was observed at low TEA concentrations early on in the experiment, marked inhibition occurred at higher concentrations. In general Z mays was affected more severely than P. vulgaris showing a large TFA-induced decrease in both apparent carboxylation efficiency (ACE) and in vitro Rubisco(ribulose-1,5-bisphosphate carboxylase/oxygenase: EC 4.1.1.39) activity. Analysis of photosynthetic gas exchange revealed that besides constraints on mesophyll processes suchas Rubisco activity, stomatal limitation also increased with increasing TEA concentration, especially in P vulgaris. In depth analysis of the fast phase fluorescence transients pointed at TFA-induced uncoupling of the oxygen evolving complex (OEC) and inhibition of electron transport beyond Q, including possible constraints on the reduction of end electron acceptors of photosystem I.

Trichloroacetic acid (TCA), a secondary atmospheric pollutant, is also formed in forest soil and thus ranked among natural organohalogens. The observed biooxidation of atmospheric tetrachloroethene (PER) to TCA in chloroplasts has led to the investigation of the mode of action of TCA in spruce needles, since TCA is also accumulated in the needles after its rapid uptake from soil by roots. Being phytotoxic, TCA considerably influences conifers by affecting their photosynthetic apparatus. We examined the transport of TCA from soil into chloroplasts in order to compare the effects of TCA on conifers from both sources, i.e. endogenously produced within chloroplasts or taken up by roots. The influence of TCA formed in chloroplasts was found to be much more adverse than that of "soil" TCA.

Artemisia lerchiana is a wormwood species of the Central Asian steppe regions, where it completely cover whole areas. For the first time it was possible to show through field experiments that C1/C2 halocarbons (VCHCs), such as chloroform (CHL), tetrachloroethene (PER) and hexachloroethane (HEX), can be taken up by test plants of the species A. lerchiana via the soil/root pathway and metabolised inter alia into trichloroacetic acid (TCA) under semi-aride conditions. At the same time, chlorophyll a fluorescence measurements carried out on the test plants revealed a phytotoxic influence on plant vitality (max. decline in vitality of 52% with application of CHL) and less efficient energy flows in the photosynthesis mechanism of the A. lerchiana test plants. The authors examine possible links between the simultaneous appearance of VCHCs and additional drought stress in the acceleration of desertification processes.

Die phytotoxisch wirkende Trichloressigsäure (TCA) wurde bis in die 1980er Jahre in Form von Natriumtrichloracetat (TCAA- Na) als Herbizid in der Land- und Forstwirtschaft eingesetzt. Mittlerweile ist die Verwendung von TCA als Herbizid aufgrund unerwünschter Nebenwirkungen auf Nutzpflanzen in den meisten europäischen Ländern und vielen weiteren Staaten der Erde untersagt. Tetrachlorethen (PER) gehört zur Stoffgruppe der leichtflüchtigen Chlorkohlenwasserstoffe (LCKW) und findet weltweit hauptsächlich als Entfettungs- und Reinigungsmittel in der metallverarbeitenden sowie chemischen Industrie Anwendung. Darüber hinaus kommen Altlasten, wie z.B. die im Landkreis Bitterfeld (Sachsen- Anhalt) gelegene Deponie Grube Antonie als anthropogene Flächenquelle von PER- Emissionen in Betracht. Die Grube Antonie verfügt über ein sehr großes Inventar sowohl an LCKW als auch an TCA und ist u.a. von Pioniergehölzen, wie der Birke (Betula pendula ROTH), besiedelt. PER wird unter bestimmten physikochemischen Bedingungen in der Atmosphäre zu TCA abgebaut. Darüber hinaus ist mittlerweile bekannt, daß PER nach stomatärer bzw. cuticulärer Resorption in der Blatt- bzw. Nadelmatrix von Pflanzen in Anwesenheit von reaktiven Sauerstoffspezies (ROS) u.a. zu phytotoxischer TCA metabolisiert werden kann. Aufgrund dieser biogenen TCA- Bildung wird PER auch in Verbindung mit neuartigen Waldschäden gebracht. Sowohl regionale als auch weltweit durchgeführte Untersuchungen zeigten, daß besonders Nadelgehölze, wie die Kiefer (Pinus sylvestris L.) z.T. hohe TCA- Gehalte in den Nadeln akkumulieren. Während in den letzten Jahren der Kenntnisstand hinsichtlich der natürlichen und anthropogenen TCA- Quellen immer mehr zunahm, ist über die schädigende Wirkung von TCA sowie ihrer Präcursoren (wie z.B. PER) auf Wild- und Forstpflanzen bisher nur wenig bekannt. Das Ziel der vorliegenden Arbeit bestand darin, anhand von ökotoxikologischen Untersuchungen sowie pflanzenphysiologischen (Chl a - Fluoreszenz), den

[1] It is shown for the first time that the volatile highly chlorinated C2 hydrocarbons (VCHCs) trichloroethene (TRI; C2HCl3), tetrachloroethene (PER; C2Cl4) and methyl chloroform (MC; C2H3Cl3), but also C1 hydrocarbons tetrachloromethane and chloroform can be naturally formed in the sediment of salt lakes (ssl). Archaic halobacteria appear to play a key role in the microbial formation involved. TRI, PER and MC can be transformed into trichloroacetic acid (TCA) in the atmosphere. TRI and PER can also be metabolised into TCA following uptake by plants. Already considerably phytotoxic by itself, TCA's phytotoxicity is exacerbated if the vegetation concerned is simultaneously exposed to drought-stress. TRI and PER, emitted by these newly identified natural sources, can accelerate desertification in semi-arid and arid climate zones in consequence of the destabilisation of vegetation by its phytotoxic metabolite TCA.

During the past five decades, the expansion of deserts has accelerated in many regions of the earth including sub-Saharan Africa. Both climatic changes and the over-exploitation of natural resources in these regions have been considered to be responsible for this phenomenon. Recent data, however, revealed an additional factor that may contribute to desertification through degradation of the vegetation in the areas concerned. This factor is the organic compound trichloroacetic acid (TCA; CCl3COOH), that has its origin in an enhanced presence of several C2-chlorohydrocarbons (C2-CHCs) in the atmosphere. In the present study the burden on the vegetation resulting from C2-CHCs pollutants was assessed by sampling the concentration of TCA in pine needles along a 600-km air pollution gradient, ranging from highly industrialized areas in Gauteng to rural areas in the eastern part of South Africa. Parallel measurement of the TCA content of pine needles and their vitality over an air pollution gradient ranging from Potchefstroom eastwards towards Sasolburg and further south in the direction of Heilbron, revealed a decline in the TCA content of the needles with increasing distance from Sasolburg in the Vaal Triangle, a 'hot spot' of anthropogenic air pollution in South Africa. An inverse correlation was found between TCA content and the photosynthetic functioning of the pine needles. Studies in South Africa and Russia have shown that large vegetation fires lead to a substantial increase in the C2-chlorohydrocarbon content of needles of pine trees growing in the lee of the fire zone. We also discuss the distinctive air transport patterns over southern Africa of pollutants such as perchlorethene and their phytotoxic decomposition product TCA, and their possible role as an additional stress factor in the degradation of vegetation, so enhancing desertification

One of the issues provided for by the 1993 existing substances regulation (793/93/EEC) is the assessment of the environmental risk emanating from waste materials. One such material is the highly volatile substance perchloroethene (PER; TECE). PER is produced in large quantities all over the world by the chemical industry. There are many industrial processes in which PER escapes into the environment, especially the atmosphere. It has since been proven that after entering plants via the air/leaf pathway, airborne PER can be metabolised into the phytotoxic substance trichloroacetic acid. However our own studies detected relatively high levels of TCA in environmental compartments in regions far away from industry which cannot be explained by the anthropogenic input of airborne substances into the relevant ecosystems. This indicates that natural PER emittents also exist and must be identified, in order to find out more about the global spread of PER.This paper reports on the findings of related fieldwork in the Kalmykian Steppe. This area of steppe in southern Russia spans an area extending west-to-east from the Black Sea and the Caspian Sea and north-to-south between the Greater Caucasus and Volgograd. The main aim of the experiments in the Kalmykian Steppe was to study water from lakes, rivers and springs with differing levels of salinity. The concentrations of the chlorinated hydrocarbons (VCHCs) chloroform (CHCl3), tetrachloromethane (CCl4), 1,1,1-trichloroethane (1,1,1-C2H3Cl3), trichloroethene (TRI; C2HCl3), tetrachloroethene (PER; C2Cl4) and TCA in these waters were measured, along with the levels of cations and anions and the pH-value of the waters. The measurements indicate that in particular water from salt lakes located in semiarid/arid areas of the study region must be considered as new types of natural emittents of PER and other chlorinated hydrocarbons as well as trichloroacetic acid. Furthermore, attention is drawn to ecological impacts resulting from the

There has been an accelerated expansion of deserts in the past five decades. Recent data reveal that the atmogenically formed organic compound, trichloroacetic acid (TCA) is a contributory factor in addition to anthropogenic and natural sources. The aim of this study was to use TCA as an indicator for the possible occurrence of C2-chloroacetic acids; to assess the burden on the vegetation by using pine needles as a bio-indicator system and to deliberate on the possible role of TCA in the dynamics of the vegetation in southern Africa. Field experiments conducted on pine trees and on C3 and C4 crop plants under controlled laboratory conditions, have revealed that plants could be influenced positively or negatively by TCA. To obtain an integrated assessment of the pollution emission over a time span of at least one year, two-year-old pine needles of different Pinus species were used as a bio-indicator for TCA pollution at different measuring sites. The data of our investigation clearly indicate that areas exist in South Africa where the vegetation is burdened by ecotoxicologically relevant TCA contents comparable to those in central Europe and southern Russia where TCA was shown to play a role in the destabilisation of the steppe vegetation.

Trichloroacetic acid (TCA, CCl3COOH) is a phytotoxic chemical. Although TCA salts and derivates were once used as herbicides to combat perennial grasses and weeds, they have since been banned because of their indiscriminate herbicidal effects on woody plant species. However, TCA can also be formed in the atmosphere. For instance, the high-volatile C-2-chlorohydrocarbons tetrachloroethene (TECE, C2Cl4) and 1,1,1-trichloroethane (TCE, CCl3CH3) can react under oxidative conditions in the atmosphere to form TCA and other substances. The ongoing industrialisation of Southeast Asia, South Africa and South America means that use of TECE as solvents in the metal and textile industries of these regions in the southern hemisphere can be expected to rise. The increasing emissions of this substance-together with the rise in the atmospheric oxidation potential caused by urban activities, slash and burn agriculture and forest fires in the southern hemisphere-could lead to a greater input/formation of TCA in the vegetation located in the lee of these emission sources. By means of biomonitoring studies, the input/formation of TCA in vegetation was detected at various locations in South America, North America, Africa, and Europe.

We present a modeling study investigating the influence of climate conditions and solar radiation intensity on gas-phase trichloroacetic acid (TCA) formation. As part of the ECCA-project (Ecotoxicological Risk in the Caspian Catchment Area), this modeling study uses climate data specific for the two individual climate regimes, namely "Kalmykia" and "Kola Peninsula". A third regime has also been included in this study, namely "Central Europe", which serves as a reference to somehow more moderate climate conditions. The simulations have been performed with a box modeling package (SBOX, photoRACM), which uses Regional Atmospheric Chemistry Mechanism (RACM) as its chemistry scheme. For this model a mechanism supplement has been developed including the reaction pathways of methyl chloroform photooxidation. The investigations are completed by a detailed sensitivity study addressing the impact of temperature and relative humidity. Atmospheric OH and HO2 concentrations and the NOx/HO2 ratio were identified as the governing quantities controlling the TCA formation trough methyl chloroform oxidation in the gas phase. Model calculations show a TCA production rate ranging between almost zero and 6.5 x 10(3) molecules cm(-3) day(-1) depending on location and season. In the Kalmykia regime the model predicts mean TCA production rates of 1.3x10(-4) and 5.4 x 10(-5) mug m(-3) year(-1) for the urban and rural environment, respectively. From the comparison of model calculations with measured TCA burdens in the soil ranging between 130 mug m(-3) and 1750 mug m(-3) we conclude that TCA formation through methyl chloroform photooxidation in the gas-phase is probably not the principal atmospheric TCA source in this region.

Trichloroacetic acid (TCA; CCl3COOH) is a phytotoxic chemical. Although TCA salts and derivatives were once deployed as herbicides against perennial grasses and weeds, their use has since been banned because of their indiscriminate herbicidal effects on woody plant species. However, TCA can also be formed in the atmosphere. For instance, high-volatile C2-chlorohydrocarbons tetrachloroethene (TECE, C2Cl4) and 1,1,1-trichloroethane (TCE, CCl3CH3) can react to TCA and other substances under oxidative conditions here. Owing to further industrialisation of Southeast Asia, South Africa and South America, a rise can be expected in the use of TECE as solvents in the metal and textile industries of these regions in the southern hemisphere (SH). The increasing emissions of this substance—together with the rise in the atmospheric oxidation potential caused by urban activities, slash and burn agriculture and forest fires in the SH—will result in the increased input/formation of TCA in the vegetation located on the lee side of these emission sources. By means of biomonitoring studies, inputs/formation of TCA related to the climatic conditions were detected at various locations in South America, Africa, and Europe.

During 1997-1999, in the territory of European Russia, several series of measurements of trichlo-roacetic acid (TCA) in vegetation and of minor gases in the atmosphere were performed. The latter determine the oxidizing ability of the atmosphere. It was assumed that anthropogenic emissions of chlorinated C2 hydro-carbons in central Europe and Russia may lead to the formation of toxic TCA, which, in climatically unfavor-able regions, may cause the destruction of vegetation. A large number of pine needle samples were collected. An analysis of these samples allowed the detection of several localities characterized by a significant content of TCA in vegetation. Observations of the variability of the contents of minor gaseous impurities in surface air allowed us to assume TCA generation over these areas and to make some assumptions on the sources of TCA precursors. Numerical simulation of oxidation processes and of the rates of TCA generation made it possible to explain the characteristic features of the processes occurring over such regions as Kalmykiya, central Russia, and the Kola Peninsula, which are strongly affected by anthropogenic pollution.

no abstract

Field studies were performed to investigate the time-dependent accumulation behaviour of some persistent organic pollutants (POPs) in pine needles (Pinus sylvestris) of different ages (4, 16 and 22 months old) under the influence of different emission sources. Measurements were made on needles from 5 trees at each of 7 sites located 1-2 km from potential local emitters of different types in Germany. The partitioning between the wax layer and the inner needle fraction did not depend on exposure time for all compounds. By contrast, for all five PAHs [polycyclic aromatic hydrocarbons] and two PCBs ([polychlorinated biphenyls], PCB 28 and 52) examined the compound concentration increased distinctly with needle age. For the other organochlorines (HCH isomers, DDX and higher chlorinated PCBs), bioconcentration was not affected by needle age. The discussion includes consideration of the particle-bound compound portion, of octanol-air partitioning as a thermodynamic parameter for bioconcentration from air, and metabolism.

Systematic investigations were performed to study the dependence of the extraction efficiency of persistent organic pollutants (POPs), including chlorobenzenes, HCH isomers, DDX, PCB congeners, and PAHs, on the accelerated solvent extraction (ASE) operating variables solvent and temperature. Mixed soil samples from two locations with considerable differences in soil properties and contamination in the Leipzig−Halle region (Germany) were used. The objective was to optimize ASE for the extraction of POPs from real soil samples and to improve on the results achieved with Soxhlet extraction (SOX). Solvents with differing polarities were tested. Quadruple and triple determinations were performed on the two soils, respectively, between 20 and 180 °C in 20 °C steps. All the results were compared with those obtained by SOX, as well as, in some cases during preliminary studies, by ultrasonic extraction (USE). In ASE, the optimum conditions proved to be two extraction steps at 80 and 140 °C (average RSD 10.7%) with three static cycles (extraction time 35 min) using toluene as solvent and at a pressure of 15 MPa. Owing to the superior analyte/matrix separation by ASE, in many cases for real soil samples analytical values better by up to 1 order of magnitude or even more were obtained compared to SOX results.

German reunification in 1990 resulted in economic and social upheavals in all of the newly-formed German states. One typical example is the Leipzig–Halle–Bitterfeld region, where many of the industrial plants were fully or partly demolished for economic and technical reasons. Additionally, changes in the political climate led to the closure of a number of major military bases. Despite generally improved environmental standards, dismantling was sometimes accompanied by substantial emissions of chlorinated insecticides and other persistent organic pollutants, as is highlighted for the first time in the present paper. Our analyses are based on a regional biomonitoring net covering 7500 km2 in the Leipzig–Halle–Bitterfeld area during the time period 1990-93. The results enable increased concentrations of airborne contaminants to be attributed to processes linked to the economic upheaval of this time.

The main sources of pollution discharge into the Caspian Sea are metal and oil processing plants in the catchment areas of the Ural and Volga rivers, as well as the coastal and offshore oil industry in the countries bordering the sea. The high evaporation from the surface of this largest inland sea introduces highly volatile C2-chlorohydrocarbons into the atmosphere. Subsequent reactions with OH radicals and other oxidants results in the formation of secondary pollutants, such as phytotoxic trichloroacetic acid (TCA), which are then delivered by the air or rain into the neighbouring ecosystems of various vegetation zones. Biomonitoring investigations in the catchment area of the Caspian Sea have revealed that differences in pollution levels in the southern Russian area between the Black Sea and the Caspian Sea, resulting from TCA originating in the atmosphere, are attributable to climatic conditions and the geographical position of the measuring sites.

Se han analizado los patrones de emisión de metales pesados aéreos utilizando las hojas aciculares de los pinos de tres diferentes especies de pinos en las áreas del Gran Mendoza, Argentina y Leipzig-Halle, Alemania. Se tomaron muestras de hojas de pinos de uno a dos años de vida en Alemania en enero-febrero de 1992, y en Argentina en abril-mayo de 1994. Los resultados analizados y discutidos de los componentes principales muestran tanto similitudes como claras diferencias entre los patrones de emisión, las cuales se deben tanto a condiciones naturales como a factores antrópicos.

Heavy metal content of agricultural topsoils has been experimentally determined at 14 areas in the German Leipzig–Halle–Bitterfeld region covering ca. 3700 km2. For most of the locations and elements, the contamination levels are comparable to those of other agricultural sites in Germany and Europe. Application of a sequential extraction technique revealed relatively low contamination levels in the mobile fractions, which indicates a correspondingly low degree of bioavailability of the heavy metals under the current milieu conditions. In contrast, acidification of the soil due to a drastic decrease in the deposition of calciferous fly ash would lead to a significantly increased ecotoxicological hazard potential, as is analyzed by a probabilistic distribution method that quantifies the overlap of normalized exposure and effect data. The discussion includes recommendations for further improvement of risk assessment schemes addressing soil contamination.

The present project involved extensive studies on the air pollution situation and interactions between organic as well as inorganic air pollutant levels and the vegetation in three east German states. Seven monitoring sites with different emission profiles were selected in Saxony-Anhalt, one typically polluted site in Saxony, and two less polluted sites in Mecklenburg-Western Pomerania. The following emitter types were found to exhibit consistent pollutant patterns: landfills receiving chloroorganic special wastes; hard-coal-fuelled firing installations; commercial charcoal plants; industry; industry - car traffic - domestic fuel combustion; car trafficIm Verlauf der Projektarbeiten wurden an sieben durch unterschiedliche Emittententypen belasteten Standorten in Sachsen-Anhalt, einem typisch belasteten Standort in Sachsen und an zwei weniger belasteten Standorten in Mecklenburg/Vorpommern umfangreiche Untersuchungen zur Immissionssituation und der Wechselwirkung der luftgetragenen anorganischen und organischen Schadstofffracht mit der Vegetation durchgefuehrt. Dabei konnten fuer folgende Emittenten charakteristische Schadstoffmuster ermittelt werden: - Deponien mit chlororganischem Sondermuell - Feuerungsanlagen fuer Steinkohle - Gewerbliche Anlagen zur Herstellung von Holzkohle - Industrie -Industrie/Kfz-Verkehr/Hausbrand - Kfz-Verkehr.