Untersuchungen zum ökotoxikologischen Schädigungspotenzial und Erosionsrisiko von kontaminierten Sedimenten in staugeregelten Flüssen

Particle-bound pollutants accumulate in river-bottom sediments, a process which results in a significant decrease in the ecotoxicological availability of toxicants for the majority of aquatic organisms. Under normal hydrologic conditions, the release of contaminants from bottom sediments is usually of minor importance. In contrast, flood events may remobilize highly contaminated sediments via in-stream erosion. The objective of this study was to develop a combined ecotoxicological and hydraulic approach to elucidate the ecotoxicological implications associated with the risk of erosion of contaminated sediments. This integrated strategy was applied to the lock-regulated Neckar river in Southern Germany. Both the bottom-sediment cores and suspended matter from two intensive flood events were investigated. Sediment samples below an erosional unconformity showed a sharp increase in the ecotoxicological load. Moreover, it was found that major flood events (HQ₅ and higher) could possibly erode even very old, well-consolidated and highlycontaminated sediments. The suspended matter of the high discharge events investigated (return periods of 15 to 20 years) exerted significantly higher cytotoxicity and mutagenicity than a moderate flood with a 1-year return period. These findings support the conclusion that the observed ecotoxicological effects during major floods may at least in part be due to the in-stream erosion of highly contaminated bottom sediments.     

GIS-gestützte Analysen zur möglichen Gefährdung von Naturschutzgebieten durch den Anbau gentechnisch veränderter Kulturpflanzen

Background, Aim, and Scope The introduction of genetically modified plants (GMP) into the European agriculture primarily has been investigated in respect of economical aspects, its impacts on conventional crops, and direct or indirect effects on human health. Potential ecological impacts, especially their long term and large scale implications, were out of focus, usually. A special task is to protect the integrity of nature reserves. According to §?23 of the German Nature Protection Law (BNatSchG) nature reserves are to protect nature and landscape properties by preserving and developing existing as well as by re-establishing biotopes of wild and endangered species. According to §?34a of the BNatSchG the use of GMP has to be accompanied by an environmental impact analysis of possible risks like it has to be done in projects affecting the integrity of Flora-Fauna-Habitats (FFH) or European bird sanctuaries. Considering this, the joint research project “Recommendations for isolation distances concerning the cultivation of genetically modified plants in the neighbourhood of protected areas” which was promoted by the Federal Agency for Nature Conservation (BfN) aimed at describing possible risks for biocoenoses in conservation areas that could be caused by the cultivation of GMP in their vicinity and at evaluating measures which could mitigate or hinder negative effects. The article at hand concentrates on describing the implications which would emerge when introducing different isolation distances concerning the cultivation of herbicide resistant oil seed rape (HR-OSR) and insect resistant maize (B.?t.-maize) near protection areas. On the other hand, a methodology is introduced which was developed to classify the German nature reserves according to their potential endangerment by GMP cultivation and to minimise calculation efforts for modelling possible impacts. Materials and Methods In 2003, there were around 7,400 nature reserves which covered 3?% of the whole territory of Germany. A geographical information system (GIS) was used to integrate geometries of conservation areas, land use data (CORINE landcover), agricultural information on district level as well as a map of German ecoregions. At first, it was evaluated how much arable land for B.?t.-maize or HR-OSR cultivation would remain if introducing different isolation distances around nature reserves (NSG). Furthermore, the NSG were aggregated to several homogenous classes reflecting different levels of cultivation intensities in their vicinity and different geometric properties. This was realised calculating a geometric coefficient (GC) which describes the ratio of periphery and area of each NSG in order to abstract the risk of GMP invasion. The density of maize and rape cropping near the NSG was expressed by a cultivation coefficient (CC). According to regional agricultural surveys, this was calculated by adding up the area of maize and rape fields within a radius of 1,000?m (maize) and 4,000?m (rape), respectively, around the NSG. Results Considering an isolation distance of 1,000?m around the NSG, 90?% of the farmland in Germany would be available for GMP cultivation. 50?% would remain when establishing an isolation distance of 4,000 m. The combination of GC and CC resulted in a total of nine risk categories (RC) describing the potential risk of endangerment by GMP cultivation in the vicinity of NSG. Areas with highest risk were grouped in RC nine where the smallest NSG (+ GC) in the main cultivation areas of maize or corn (+ CC) were summarised. With a numerical proportion of 7?% those sites cover only 0.4?% of total area of all NSG. All nature reserves showing highest CC values had a total proportion of 60?%. Discussion The derivation of GC and CC was based on a hierarchical approach and was implemented by complex GIS procedures. This makes it easy to calculate additional values for different GMP, protection areas or isolation distances. The RC were useful for choosing representative modelling sites in order to minimise calculation efforts when modelling possible impacts of GMP cultivation in vicinity of nature reserves. Conclusions The assessment of isolation distances around protection areas should be performed for each area individually concerning the GMP specific effects and dispersal properties as well as the protected organisms and the main protection targets. Especially HR-OSR is critical because of its volunteers and hybridisation partners. Another main source of GMP dispersal into protection areas might be the contamination of conventional seeds with transgene OSR seeds. Recommendations and perspectives Before defining and applying particular measures in order to protect conservation areas from possible impacts due to GMP cultivation a political and societal discussion is necessary in order to assess which GMP induced impacts may be tolerated. This has to be supported by additional scientific studies based on empirical and estimated data evaluating possible dispersal distances of GM pollen and possible environmental impacts of released transgenes and their toxins. According to the EU Directive 2001/18/EC the cultivation of GMP should be accompanied by a case-specific monitoring and general surveillance, as well. It should be realised as soon as possible, since the release and the cultivation of GMP in Germany have been started, already. The monitoring should be complemented by the implementation of a web-based geoinformation system (WebGIS) which enables the compilation and evaluation of the data and relevant geodata.     

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.     

Identifizierung toxischer Verbindungen in Sedimenten: Ansätze zur Integration von Wirkung und Bioverfügbarkeit

Sediments play an important role for aquatic ecosystem functions. However, they also act as sink, storage and source of lipophilic toxicants and metals. Effect-directed analysis (EDA) is a powerful tool to identify compounds causing adverse effects. In order to avoid misinterpretations and biased prioritization bioavailability needs to be considered together with effects. Bioavailability is a complex process finally resulting in the transfer of a so far particle bound molecule to the target location within the organism where it causes an effect. In order to operationalize this concept for EDA it can be divided into several partial processes. These include desorption from sediments and thus bioaccessibility, equilibrium partitioning of desorbable compounds between sediment, water and organisms driven by activity, and toxicological bioavailability as a result of toxicokinetics including resorption, transport, metabolization and excretion. Bioaccessibility is based on desorption kinetics and can be simulated with mild extraction methods e.?g. using TENAX. Equilibrium partitioning can be simulated with partition-based dosing techniques. First results with these approaches indicate that consideration of bioavailability increases the significance of polar sediment-associated toxicants relative to classical non-polar contaminants such as polycyclic aromatic hydrocarbons.