Ökotoxikologische Wirkungen von Teeröl-imprägnierten Holzpfählen

Aim and Scope

This study was aimed at evaluating environmental effects of tar-oil impregnated (tanalized) tree stakes using simple and efficient biotests to obtain results of its ecological impacts during the tar-oil breakdown in the stake.

Results

1. Soil respiration was measured in-situ as an indication of soil microbial activity in two field trials. Soil respiration was measured in a 20 year-old apple orchard at various distances from the tar-oil impregnated tree stakes and also on soil mixed with chippings from pine stakes with tar-oil impregnation of different ages.
2. Cress germination tests were employed to evaluate tar-oil phytotoxicity in a field and laboratory trial. Cress was seeded close to tree stakes in the same 20 year-old apple orchard and germination rates related to tar oil-impregnation. Cress was also seeded in trays in sand mixed with pine chippings from stakes with tar-oil impregnation of different ages.
3. The portion of the carcinogenic benzoapyrene (BaP) ranged between 0.0015% in freshly tar-oil impregnated to 0.4% in tar-oil impregnated 20-year old trees stakes, i.e. irrespective of the overall PAK concentration and its degradation.
4. Kinetic analysis using DIXON plots showed a 50% breakdown of overall PAHs after ca. 2.7 years, i.e. km or Ki values of less than 3 years.

Conclusion

Germination tests of cress and endogenous seeds as well as soil respiration proved sensible indicators of the phytotoxicity and ecotoxicity of tar-oil impregnated tree stakes in fruit orchards. Soil respiration proved particularly sensitive to tar-oil ageing. Its combination with kinetic inhibition models resulted in parameters suitable for the interpretation of results.     

Umweltschäden durch Heizöl nach Hochwasserereignissen

Background Due to high safety measures in production, transport and storage of fuel oil it rarely occurs, that fuel oil will be released in the environment. One exception of this experience was the fuel oil releases of private fuel oil tanks during the “century flood” 2002 in Germany. By order of IWO (Institut für wirtschaftliche Oelheizung e.?V.), the authors investigated the environmental behaviour of fuel oil after flood incidents. Aim Due to the fast spreading of the fuel oil on water surfaces and the contamination of huge areas one expects large environmental harm. For appraisal the behaviour of fuel oil in water and soil must be studied in detail as well as the effect on high and low developed animals and plants, on water organisms and on the flora and fauna of soil. From the valuation of the environmental harm official measures and measures of precaution and safety by manufacturer and user of private fuel oil installations can be derived. Main features For considering the various aspects the authors studied the extensive analyses of the special measuring programme of Saxony-Anhalt, used interviews of concerned persons (private persons and officials), aerial photos, extensive study of literature including eco-toxicological investigations, experiences of more than 70-years applications of fuel oil in plant protection and practical experiences at large field redevelopment of oil damages following averages and accidents. The authors valuated on the base of results of analyses and on own calculations. Results The release of fuel oil in the air is no particular problem because about 40?% of the oil fast evaporate and will be decomposed to carbon dioxide and water. In addition to the evaporation a characteristic behaviour is fast spreading of the fuel oil on the water surface to very thin layers. For a typical coloured oil layer e.?g. one cubic meter of oil is spread on a water surface of about 3?km², this corresponds to 3?ml/m² surface and contaminates the soil after drying up with about 3?µg/kg soil some orders less than the natural content of hydrocarbons in soil. Because of the absorption capacity of soil and the microbial decomposition by everywhere existing hydrocarbons decomposing micro-organisms the oil infiltrates only a few centimetre and will be decomposed in a few months, so that ground water detriments not arise practically. By measurements a few months after fuel oil release in the flood 2002 oil components in the soil could not be detected. Discussion Acute injuries of micro-flora and -fauna in soil and water by fuel oil cannot be excluded from the first. Thus the limiting values of injuries for some water organisms are below 1?mg/l. According to the special measuring programme at the flood 2002 in Saxony-Anhalt however the measured values were mostly wide below of this limit. In detail the spreading and evaporation of fuel oil on water surfaces, the propagation and decomposition of fuel oil in soil will be described. A quantitative valuation of fuel oil distribution in a real flood incident will be given. Conclusions Particular measures of redevelopment of soil for fuel oil release after flood incidents are not necessary normally. Even at the redevelopment after transport damages or at devastated sites with essential higher oil contaminations of soil in comparison to fuel oil release after flood incidents high decomposition rates are obtained by normal soil improving measures supporting the natural micro-organisms in reducing the hydrocarbon concentration for 70–90?% after a few months. Perspectives With the described results a realistic valuation of the environmental harm of fuel oil release after flood incidents could be given. From this qualified measures can be derived for official decisions and precautionary and reliable activities at fuel oil installations of flood endangered areas.     

Qualität und Verwertungsmöglichkeiten von Holzaschen aus naturbelassenen Hölzern

Background, aim and scope The increasing use of wood for generating heat and electricity requires that more and more fuels be obtained directly or indirectly from the forest. Sound, sustainable recycling management calls for the return of any generated wood ash back to the forest to make use of the nutrients it contains. Similarly, recycling this ash in other locations such as agricultural land or private gardens can serve equally well as fertilizer. At the same time, it is critical that no accumulated pollutants be introduced into the nutrient loop. Wood ash that is heavily laden with such pollutants must not be considered for recycling. As part of this research project, commissioned by the Ministry for the Environment and Conservation, Agriculture and Consumer Protection of the State of North Rhine-Westphalia in Germany (MUNLV), ash samples of 209 wood-fired appliances generating between 10 and 4000?kW of heat performance were taken from throughout the federal state of North Rhine-Westphalia. Untreated wood, either forested or scrap, was used as the sole fuel for these appliances. Materials and methods All course ash and fly ash samples were analyzed to determine their composition of main nutrients, heavy metals, and the elements Fe, Cl, Si, Al and Na. The purpose of this analysis was to evaluate the suitability of this wood ash for reintroduction to forest soils or as fertilizer in other types of soil. Results The majority of the wood ash samples in this study contained sufficiently high amounts of nutrients to match the requirement for stand-alone fertilizers (PK-fertilizer, potash fertilizer). However, the heavy metal content was highly variable, with a mean content high enough to prohibit them from being classified per se as PK- or potash fertilizer for agricultural land. Due to the high quantities of cadmium, application of this ash to garden soils would likewise be ill-advised. Discussion On forest soils German law permits application of a mixture of potash fertilizer containing, at most, 30?% wood ash (course ash). Because of the high amounts of cadmium and copper, wood ash from our samples can only comprise a maximum of 28?% when added to typically used potash fertilizers. Higher percentage of wood ash would exceed the cut-off value established by the German Fertilizer Ordinance (Düngemittelverordnung – DüMV). Conclusions The application of wood ash on agricultural land and in private gardens is, rightfully so, highly regulated by law. However, the rules governing application of wood ash in the forest are much more lax. Determination of heavy metal content in wood ash cannot be used to determine compliance with DüMV standards because of the high content and fluctuating nature of heavy metals found. Recommendations and perspectives Presently an alternative approach for classifying the ecologic risk of wood ash recycling is being developed.     

Biozide in Gebäudefassaden – ökotoxikologische Effekte, Auswaschung und Belastungsabschätzung für Gewässer

Background, aim and scope Sources of organic micropollutants occuring in surface waters are often unknown. Regarding environmental risk assessments for surface waters, construction materials have as till now, not been given much consideration, although biocides used as preservatives are known to reach urban storm water runoff. The study focused on biocides for facades coatings and aimed (1) to determine ecotoxicological effect values, (2) to quantify the leaching behaviour and (3) to assess the environmental risk for surface waters using a dynamic transport model. Materials and methods Eight biocides used in resin based facade coatings were investigated. Some biocides are substances known as pesticides for agricultural purposes like diuron, carbendazim and terbutryn. Ecotoxicological effect values for aquatic organisms were determined for every biocide. Leaching of four biocides from a render under UV-irradiation has been investigated in the laboratory including the influence of varying temperatures. Using 80 irrigation intervals over 28 days, facade runoff was sampled and followed by biocide chemical analysis. The total losses were calculated based on the concentration patterns. These data were used for modelling the transport of cybutryn from facades to surface waters. Biocide specific effect values and leaching characteristics have been taken into consideration. Results Acute and chronic effect values as well as predicted no effect concentrations for the investigated biocides indicate their high potential to affect aquatic organisms. The leaching of four biocides (diuron, terbutryn, cybutryn, carbendazim) from the facade render under the experimental conditions delivers high concentrations in the beginning followed by an exponential decrease. Rising temperature increased the concentration of biocides in the runoff. The total losses were between 7?% and 29?% depending on the substances. More than half of the losses occur in the runoff within the first 15 min of runoff from a 60 min irrigation cycle. The modelling result for cybutryn underlines its high environmental risk for small surface waters. Discussion The leaching of the biocides, their potential ecotoxic effects and persistence show clearly that the environmental risk for surface waters and soils seems to be high for certain biocides; whereas for others the risk seems to be significantly lower. With respect water quality criteria, polluted facades runoff has to be diluted before runoff can enter the discharge. Diuron and carbendazim are however also used as pesticides and preservatives for other materials and cybutryn is also used as an antifouling agent. All pathways have to be evaluated in order to identify relevant sources and to act more efficiently with respect to water and soil protection. Conclusions Concentrations with high environmental risk are expected at new facades, especially at facades with thermal insulation. With the given low predicted no effect concentrations in a range of a few ng/L and large amounts of biocides applied in paints and renders, the environmental risk for common biocides used in facade coatings has to be investigated in laboratory and field scale. It seems plausible that source control measures as the most efficient and sustainable precautionary principle need to be evaluated. Recommendations and perspectives Biocides and additives applied in construction materials have to be taken into consideration as relevant sources when evaluating the quality of storm water runoff, discharge into urban areas and the impact to soil and surface waters. A sustainable construction material management and storm water management are required. It is expected that ongoing laboratory and field studies with exterior paints, renders and flat sheets for waterproofing containing biocides and additives will give further insight into their environmental impact.     

Mikrobiologisch-ökotoxikologische Bodenuntersuchungen von zwei zur Unkrautbekämpfung mit hohen Dosierungen eingesetzten Fettsäure-Herbiziden

Goal and Scope

Products based on fatty acids (including acetic acid) are known in plant protection since more than 100 years to control several harmful organisms. In the following decades, however, they lost their importance due to the rapid development of ‘modern’ chemical pesticides. In the meantime some trials were run to control weeds with relatively high doses. The knowledge on its ecotoxic effects on soil microorganisms as a part of the soil fertility, however, is still incomplete.

Methods

Under laboratory conditions two agricultural soils were treated with different dosages of two products based on acetic acid and pelargonic acid (=nonanoic acid) as well as with a biocidal reference compound (e.g. dinitrophenol herbicide). The applied dosages were related to the concentrations in soil reached after simulated penetration of practical field amounts into upper soil layers. In some cases green manuring was simulated by adding lucerne meal to the soil. During the incubation for several weeks biomass-related microbial activities (dehydrogenase activity, substrate-induced shortterm respiration) as well as the mineralization of carbon and nitrogen (including nitrification) were measured.

Results and Conclusion

As compared to ‘normal’ pesticides (e.g. the reference compound) the effects of both test substances on soil microorganisms showed different behaviour. Nearly none of the effects typical for strongly biocidal compounds, namely a dose-related inhibition of microbial biomass combined with a stimulated mineralization (especially of nitrogen), occurred with the fatty acid products. Depending on the marked input of organic carbon by the higher dosages of fatty acid products and their rapid decomposition, especially of acetic acid, an increase of biomass-related parameters and of carbon mineralization combined with a reduction of the available nitrate content (e.g biological nitrogen immobilization) occurred for several weeks. By combining the results of the soil with that of lucerne meal-amended soil ‘real effects’ can be distinguished from those depending on the decomposition of the introduced carbon. In comparison with the strongly biocidal reference compound the two fatty acid products not only caused little microbiological-ecotoxicological impacts on the soil, but often stimulated important microbiological parameters for some time.

Recommendation and Perspective

As result of the trials we recommend an extended microbiological-ecotoxicological test spectrum especially for those plant protection products (pesticides) which should be applied at high dosages or if they contain higher amounts of well decomposable organic substances. This is necessary to distinguish dose-related enhanced biocidal activities induced by biocidal effects (including the subsequent mineralization of the killed microorganisms) from ‘real’ stimulations directly produced by the substrate.     

Einfache Versuchsanordnung zur Gewinnung gewässerökologisch relevanter daten

Important parameters relevant to waters such as bioelimination, mineralisation, toxicity of activated sludge and the inhibition of nitrifiers can be determined in a very short time by means of simple trickling filters. Based on such test results we can assess the behaviour of substances, products and components of waste water in sewage purification plants. The trickling filters enable us to obtain persistent hydrophilic and hydrophobic metabolites which can be used for tests relevant to ecotoxicology.     

Ableitung ökotoxikologisch begründeter Bodenqualitätskriterien am Beispiel Arsen

Background

A vast amount of data on the concentration of substances in soils is being generated in environmental monitoring programmes. This data has to be assessed in terms of effects on terrestrial biota. Benchmarks for such an assessment have been missing up to now. This gap has been filled by the development of a concept for the derivation of ecotoxicologically based soil quality criteria (SQC) and the application of this concept to environmentally relevant substances.

Objectives

The derivation method was applied to arsenic. The derivation process was described in detail from the compilation of data regarding effects on microbial processes, plants, and soil invertebrates to the formulation of a recommendation for an SQC.

Methods

The conceptual framework for the derivation of ecotoxicologically based SQC was developed after reviewing national and international concepts for the assessment of the effects of substances on terrestrial communities. For the assessment of arsenic effects, all relevant biotic processes and trophic levels have been taken into account. Moreover, soil characteristics that may affect the toxicity to biota have been reviewed.

Results

Effects of arsenic on biota may occur at soil background concentrations or slightly above. There are only a few studies in which the influence of soil characteristics, such as soil pH, soil texture, and soil organic carbon, on the effects of arsenic has been investigated systematically. That is why the SQC was oriented on soil background concentrations for sandy soils (5 mg As/kg soil dw). A comparison of the SQC derived in this work with ecotoxicologically based soilquality values from Canada, Denmark, the Netherlands, and the United States shows an average value of 16 mg As/kg, with a range between 5 and 34 mg/kg. The variations in the soil quality values are mainly due to differences in the derivation approaches.

Conclusions and Outlook

The concept applied is considered suitable for the derivation of SQC designed to protect terrestrial communities against direct effects of substances in soils. Therefore, its use is planned to derive SQC for other environmentally relevant substances. In addition to compensation factors, statistical methods should be taken into account to compensate for risks which cannot be quantified. Furthermore, there is the need for an assessment of indirect effects of soil contaminants on birds and mammals.     

Partikelentfernung in der Trinkwasseraufbereitung: Problematiken und Lösungsansätze

The drinking water treatment plant (WTP) in Irsch-Treves is one of the WTPs operated by the Public Utility Company of Treves (SWT) responsible for supplying the city of Treves with drinking water. This treatment plant has been responsible for the treatment of raw, soft water from the oligotrophic reservoir Riveris since 1958. The main functions of the WTP are the removal of particulate matter, manganese, iron, aluminium and organic material, especially humic substances. The removal of particulate matter such as bacteria, other microorganisms and plankton is very important to ensure a microbiologically and hygienically stable drinking water. Insufficient removal of particulate manganese may lead to manganese scaling in the supply system and, in extreme conditions, may lead to a brown-coloured drinking water. The so called Multi-Barrier-System is being used in the entire water treatment process. Under this system, great importance is given to the monitoring of the catchment area, the inflows, and the reservoirs. After a preliminary and subsequent sedimentation and biological treatment in the preliminary and in the main reservoirs respectively, the raw water is finally treated through flocculation filtration over the rapid multi-layer sand filters in the WTP Irsch. With this approach, only a rigid application of the above mentioned steps and the application of the latest recognized technology to maintain the supply system can best guarantee a constant supply of clean drinking water. Online particle count in raw water and in drinking water is one of the main quality control measures applied in the WTP Irsch. The conventional flocculation filtration is not always able to fulfil the increasing quality demands for drinking water, especially during adverse raw water quality conditions. This is the reason why more and more membrane filtration units are currently being installed in completely new plants, as substitutes in conventional plants, or for upgrade purposes. The SWT is currently planning an enlargement and upgrade of the WTP Irsch, integrating ultrafiltration, which was successfully tested in a pilot study. The upgrade of the elimination of particulate matter is one of the most important targets, after the enlargement and upgrade of the plant.     

Konzentrationen von Schwermetallen in Bodenlösungen aus bayerischen Wäldern

Goal and Methods

During two years, soil solution samples were collected at 18 forest sites with low anthropogenic heavy metal loads in Bavaria using ceramic suction cups. The collected samples were analysed for pH, conductivity, dissolved organic compounds, and the trace elements Al, Cr, Fe, Mn, Ni, Cu, Zn, Cd, Ba, and Pb.

Results

In addition to initial interference effects caused by the installation of suctions cups, time series were characterised by seasonal variations. The results obtained for the replicated suction cups were comparable for every individual area with standard deviations of 20 to 25 percent. With increasing soil depth, the pH of the soil solution increases specifically at those sites (up to 2.5 pH units) where the topsoils have been acidified. On the other hand, concentrations of all trace elements investigated — excepted of Al and Mn — are not influenced by the soil depth. The forest stand has no significant additional effect on trace element concentrations. Contents of Al, Mn, and Zn are correlated with low pH-values in the soil solution, whereas the mobilisation of Ba is mainly caused by ion exchange. Complexes of trace elements and dissolved organic matter were only detected for Cu at one site. Element concentrations in the soil solution are not significantly influenced by the contents of aqua regia soluble portions in the soil matter. Only very high qua soluble portions increase the concentrations in the soil solution. The overall heavy metal concentrations determined in soil solutions are low compared with different limiting and threshold values, respectively.

Conclusions

Trace element concentrations in soil solutions are mainly influenced by the soil properties themselves. The contribution of the forest stand is negligible. Therefore, from the ecotoxicologic point of view, the risk of leaching heavy metals contaminating the groundwater is not significant for the investigated forest sites and without any respect to silviculture practices.     

Mikrobiologisch-ökotoxikologische Bodenuntersuchungen von zwei im Pflanzenschutz eingesetzten Öl-Präparaten

Goal and Scope

Since many years mineral and plant oils have been applied with relatively high doses to control noxious insects in sevral agricultural and horticultural crops. In addition they have also been used with low doses as adjuvants (additives) together with herbicides to improve their efficacy. Their ecotoxicological effets on soil microorganisms as an important part of the soil fertility, however, have been insufficiently investigated.

Methods

Under laboratory conditions two agricultural soils were treated with a rapeseed oil and a paraffin oil as well as in some cases with biocidal reference compounds (e.g. dinitrophenol herbicides). The applied dosage were related to the concentrations in soil reached after simulated penetration of practical field amounts into upper soil layers. In some cases green manuring was simulated by adding lucerne meal to the soil. During incubation for several weeks biomass-related microbial activities (dehydrogenase activity, substrate-induced short-term respiration) as well as the mineralization of carbon and nitrogen (including nitrification) were measured. In addition some combinations of these activities were investigated.

Results and Conclusion

As compared to ‘normal’ pesticides both oil products differed in their effects on soil microorganisms. Those effects typical for strongly biocidal compounds including plant protection products, namely a dose-related inhibition of microbial biomass and stimulated mineralization (especially of nitrogen) failed with the tested oily compounds. Depending on the high input of organic carbon by these oils and their rapid decomposition a dose-dependent increase of biomass-related parameters and of the carbon mineralization occurred especially with the high doses, whereas the nitrogen mineralization was reduced or even the available nitrate content was nearly eliminated for some time by microbiological immobilization. In comparison with the reference products the two oil preparations caused only little microbiological-ecotoxicological impacts on the soil and even some stimulations of important microbial soil parameters when tested with the extended test system (including the dosages used).

Recommendation and Perspective

As a result of these investigations and of the existing literature we recommend an extension of the test spectrum for those formulated preparations and adjuvants which should be applied at high dosages or if they contain higher amounts of well decomposable organic substances. This is necessary to distinguish dose-related enhanced activities induced by biocidal effects and the subsequent mineralization of this death material (=indirect effects) from ‘real’ stimulations directly produced by the substrate.     

Screening zur Mobilisierbarkeit von Kupfer aus Böden und Schlämmen

In the presented paper, the pHstat-procedure is compared with four simple extraction procedures. These procedures make use of the following extraction solutions: distilled water (based on DIN 38414 part 4, DIN-S4), 1 mol/L ammonium nitrate, 1 mol/L ammonium acetate at pH 7.0 and 1 mol/L sodium acetate at pH 5.0, respectively. The extraction procedures were applied to 10 different soil samples and 2 sludges. The DIN-S4-procedure shows the lowest amounts of mobilized copper. The highest parts are extracted by sodium acetate solution. For the procedures investigated, the mobilized amounts extracted by ammonium acetate solution are most comparable with those of the pHstat-procedure. The simple sodium acetate procedure is useful for screening to select significant samples from a large number of soils. Thus, the high effort caused by the pHstat-procedure can be reduced to a minimum through the application of this screening procedure. The application of this screening, however, is difficult for samples containing large parts of organic compounds, e.g. sewage sludge. These samples show a different extracting behaviour.     

Einschätzung der Konzentrationsprofile polyzyklischer aromatischer Kohlenwasserstoffe (PAK) in Böden des Biosphärenreservates Spreewald

To work out background values, the information of concentration profiles of PAHs in soils of uncontaminated territories is indispensable. This investigation shows PAH concentrations of different soil samples like agricultural soils, grassland, forest and litter from the biosphere reserve in Spreewald, Germany. The mean values of the soil samples are about 460 μg Σ-PAK/kg d.m. A top value of 7.2 mg Σ-PAK/kg d.m. shows a sample of a flooded grassland area. The relation of the concentrations in the litter, forest, grassland and agricultural soil samples is about 5∶3∶2∶1. Compared to the other samples, the litter samples contain a higher amount of low molecular PAHs. Increasing distance to the former power plants Lübbenau and Vetschau (brown coal) lead to decreasing PAH contents in the soil samples of forests from 2190.9 after 4 km to 294.8 Σ-PAK/kg d.m. after 16 km. In comparison to results obtained in Nordrhein-Westfalen and Bayern, the PAH measurements indicate Spreewald to be an uncontaminated and rural area.     

Löwenzahn Taraxacum officinale Web. als (städtischer) Bioindikator

Investigations of the dandelion, Taraxacum officinale Web. in Poland, Romania and Germany showed that the species concentrates various elements dependent on the intensity of the pollutants. In this study, we followed up the question of whether T. officinale enriches pollutants by the atmospheric deposition on the leaves or via the soil. Therefore, samples from at least 10 plants and a soil sample at 57 sample sites were collected from a grid of 500 m × 500 m. In addition to the analysis of the total soil sample, the (mobile) ion pool of the soil (DIN V 19739) was analysed. The elements Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, K, Mg, Mn, Mo, Na, Ni, Rb, Sr, Ti, Tl, V, and Zn were determined through the use of spectrometry with inductive coupled plasma (ICP-MS and ICP-OES). The results are compared with the element concentrations of washed and unwashed leaf samples in T. officinale. We could only find two direct correlations (Ti and Zn) between the element content, of the entire soil samples, but 14 correlations (As, Ba, Cd, Cu, Ga, K, Mn, Mo, Na, Ni, Rb, Ti, Tl und Zn) between the ion pool of the soil and the washed samples. The grid point data interpolation by ArcInfo showed a similar distribution pattern for the unwashed leaf elements Al, Ce, Fe, Ti and V (r≥0.75). The elements Al, Ce, Fe, Ti, and V are washed out at the same ratio. Thus, although the concentration of these elements were significantly reduced by the washing procedure, the correlations were not influenced. The admissibility of the grid point data interpolation for a distribution map of the town area was investigated, as well. It is shown that the element content varies with the land use (meadow, field, rural areas), the sampling point and the local pollutants. However, none of the discussed elements, Al, Ce, Fe, Ti, and V, is significantly influenced by the land use. The data allows one to make the conclusion that the elements of Al, Ce, Fe, Ti and V are dependent on the dry and wet deposition on the leaves of T. officinale. These elements are taken up not only by the roots, but also by the surface of the leaves. This is evident because there is no correlation between one of these elements in the leaves and the ion pool of the soil.     

Veränderungen des NO/NO2-Verhältnisses in Nordrhein-Westfalen (1984–2004) und mögliche Ursachen

Objective and Background

The nitrogen oxides NO and NO₂ and, in particular, their ratio (NO/NO₂), play important roles in the radical-system of the atmospheric boundary layer. There were various indications upon a dropping NO/NO₂-ratio in citiex over the last years, however, no proof has been given yet Especially in densely populated areas such as the federal state of North Rhine-Westphalia (NRW), such a change can have significant influences upon various atmospheric reactions. The objective of this investigation was to prove the existence of a systematic change of the NO/NO₂-ratio, to describe the development of NO_x over the past 2 decades at different locations and to determine the causes for this development.

Methods

To detect changes of the NO/NO₂-ratio we processed the data of 11 continuously operating air quality stations of the State Environment Agency (LUA NRW) with time series reaching back up to 20 years. We investigated rural stations, stations in the urban background and heavily traffic influenced locations. It was possible to calculate and assess the NO/NO₂-ratio under consideration of the fast reaction of ozone with NO. There were clear indications towards existing trends and they could be determined as statistically significant using the nonparametric Mann-Kendall Test. The analysis of possible causes for the change of the NO/NO₂-ratio focused upon the change of the global radiation, the change of the patterns of the atmosphetic circulation, and the frequency of cyclones and anticyclones meteorological conditions in Central Europe, the introduction of automotive catalytic converters, and the development of the atmospheric oxidation-capacity.

Results and conclusions

The results are indicating a decline of the ratio at traffic-influenced stations with a statistical significance over 95%. The negative trend can also be detected at most urban background stations. It was problematic to perform the trend-analysis of the rural background station in the Egge-Mountains because of the fragmentary character of the dataset. Regional differences in the development of the NO/NO₂-ratio indicate towards various causes. Crucial for the situation at the rural areas are the changed trajectories of cyclones and anticyclones as well as the decline of the atmospheric oxidation-capacity, while the traffic plays another important role at urban stations. The negative trend at the traffic-stations was intensified by the introduction of catalytic converters, which lead to a reduction in emissions of NO_x

Recommendations and prospects

The significance of the NO/NO₂-ratio for the oxidation capacity of the atmosphere shows the necessity to further monitor this development. Previous investigations detected a decline in total NO_x without examining the relative development of the two nitrogen oxides towards each other. Gaining insight into the local differences of this ratio helps to allocate sources and to develop understanding of the atmospheric processes.     

Persistente organische Schadstoffe in Böden, Gewässern und in Firn der Region nördliches Piringebirge (Bulgarien)

Systematic environmental screenings are still the exception in South-Eastern Europe. Especially, there is a decisive lack of information concerning the occurrence and behaviour of xenobiotic and toxic compounds like volatile-and non volatile halogenated organics, suppressed by the surrogate AOX, synthetic chelating agents, pesticides, like DDT as well as chlorate in the biosphere. The analysis of soils, waters and firns of a representative area in Bulgaria, the Pirin mountains, indicate a relatively low back ground pollution. The accumulation of the xenobiotics in this high mountain region is recognised to be low. Nevertheless, traces of pesticides and chelating agents like EDTA and NTA in ice (firns) and soils were found. The surrogate AOX should be a parameter, suitable for routine environmental screenings of such areas.