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In an exemplary incubation study with an anaerobic sediment sampled at an oxbow of the river Lahn in Germany (50°18056.8700N; 7°37041.2500E) and contaminated by former mining activity, a novel meso profiling and sampling system (messy) is presented. Messy enables a low invasive, automated sampling of pore water profiles across the sediment water interface (SWI), down to ~20 cm depth with a spacial resolution of 1 cm. In parallel to the pore water sampling it measures physicochemical sediment parameters such as redox potential and pH value. In an incubation experiment of 151 days the ability of the setup was proven to address several different aspects relevant for fresh water and marine sediment studies: (i) The influence of mechanical disturbance and oxygen induced acidification on the mobility of 13 metals and metalloids (Cd, Co, Cu, Fe, Mn, Mo, Ni, Sb, U, V, Zn) was quantified based on 11 profiles. The analytes were quantified by inductively coupled plasma-mass spectrometry. Three groups of elements were identified with respect to the release into the pore water and the overlying water under different experimental conditions. (ii) The capability to investigate the impacts of changing physicochemical sediment properties on arsenic and antimony (III/V) speciation is shown. (iii) An approach to obtain information on size fractionation effects and to address the colloidal pore water fractions (0.45 mm e16 mm) was successfully conducted for the elements Ag, As, Cu, Fe and Mn.
Sediment water interfaces (SWIs) are often characterized by steep biogeochemical gradients determining the fate of inorganic and organic substances. Important transport processes at the SWI are sedimentation and resuspension of particulate matter and fluxes of dissolved materials. A microprofiling and micro sampling system (missy), enabling high resolution measurements of sediment parameters in parallel to a direct sampling of sediment pore waters (SPWs), was combined with two fractionation approaches (ultrafiltration (UF) and cloud point extraction (CPE)) to differentiate between colloidal and dissolved fractions at a millimeter scale. An inductively coupled plasma-quadrupole mass spectrometry method established for volumes of 300 μL enabled the combination of the high resolution fractionation with multi-element analyzes. UF and CPE comparably indicated that manganese is predominantly present in dissolved fractions of SPW profiles. Differences found for cobalt and iron showed that the results obtained by size-dependent UF and micelle-mediated CPE do not necessarily coincide, probably due to different fractionation mechanisms. Both methods were identified as suitable for investigating fraction-related element concentrations in SPW along sediment depth profiles at a millimeter scale. The two approaches are discussed with regard to their advantages, limitations, potential sources of errors, further improvements, and potential future applications.
Today, basic requirements for construction works include the protection of human health and of the environment. In the tension area between economic demands, circular flow economy and environmental safety, a link between the results from standardized leaching tests and the respective environmental quality standards must be created. To derive maximum release limits of metals and metalloids for armourstones in hydraulic engineering, this link is accomplished via a simple model approach. By treating natural materials and industrial by-products the same way, the article delivers an overview on the recent regulative situation in Europe as well as describes and discusses an innovative approach to derive maximum release limits for monolithic construction products in hydraulic engineering on a conceptual level. On a practical level, a list of test parameters is derived by connecting an extensive dataset (seven armourstone materials with five repetitions and 31 elements tested with the worldwide applied dynamic surface leaching test) with surface water quality standards and predicted no effect concentrations. Finally, the leaching tests results are compared with the envisaged maximum release limits, offering a direct comparison between natural materials and industrial by-products.
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The spatial high resolution of a microprofiling system was combined with the multi element capability of ICP-MS to enable a better understanding of element distributions and related processes across environmental boundary layers. A combination of a microprofiling system with a new micro filtration probe head connected to a pump and a fraction collector (microprofiling and micro sampling system, missy) is presented. This enables for the first time a direct, dynamic, and high resolution automatic sampling of small water volumes (<500 μL) from depth profiles of water saturated matrices (e.g., sediments, soils, biofilms). Different membrane cut-offs are available, and resolutions of a few (matrices with a high physical resistance) to a submillimeter scale (matrices with low physical resistance) can be achieved. In this Article, (i) the modular setups of two missys are presented; (ii) it is demonstrated how the micro probe heads are manufactured; (iii) background concentrations and recoveries of the system as well as (iv) exemplary results of a sediment water interface are delivered. On the basis of this, potentials, possible sources of errors, and future applications of the new missy are discussed.
Validated and easily applicable analytical tools are required to develop and implement regulatory frameworks and an appropriate risk assessment for engineered nanoparticles (ENPs). Concerning metal-based ENPs, two main aspects are the quantification of the absolute mass concentration and of the “dissolved” fraction in, e.g., (eco)toxicity and environmental studies. To provide information on preparative aspects and on potential uncertainties, preferably simple off-line methods were compared to determine (1) the total concentration of suspensions of five metal-based ENP materials (Ag, TiO2, CeO2, ZnO, and Au; two sizes), and (2) six methods to quantify the “dissolved” fraction of an Ag ENP suspension. Focusing on inductively coupled plasma–mass spectrometry, the total concentration of the ENP suspensions was determined by direct measurement, after acidification and after microwave-assisted digestion. Except for Au 10 nm, the total concentrations determined by direct measurements were clearly lower than those measured after digestion (between 61.1 % for Au 200 nm and 93.7 % for ZnO). In general, acidified suspensions delivered better recoveries from 89.3 % (ZnO) to 99.3 % (Ag). For the quantification of dissolved fractions two filtration methods (ultrafiltration and tangential flow filtration), centrifugation and ion selective electrode were mainly appropriate with certain limitations, while dialysis and cloud point extraction cannot be recommended. With respect to precision, time consumption, applicability, as well as to economic demands, ultrafiltration in combination with microwave digestion was identified as best practice. Figure A Multi-method approach to identify best practice for ICP-MS based off-line characterization of ENP suspensions. Electronic supplementary material The online version of this article (doi:10.1007/s00216-013-7480-2) contains supplementary material, which is available to authorized users.
- Oct 2018
Each year thousands of square meters geotextiles are used in hydraulic engineering and other construction sectors. The short article summarizes a BfG report on how to manage used geotextiles in the future and provides an alternative pathway to soil deposits/landfilling.
Welcome to the final conference of the COST Action ES1205. The most important aim of our Action was to create a pan-European network and, glancing at the book of abstracts – I can say – we were successful. The majority of contributions you will find here were influenced by our activities. The foundations of this Action however, must certainly be the projects funded on a national or international basis, that we all ran. The “safe” place provided between open minded partners, in the same working areas, that stretched beyond international borders was a genuine success of the last four years. It was a great pleasure to be part of a fast growing network (150 members from 28 countries) and to be able to provide support via the COST idea. This was most of all the removal of national barriers within our working area (from my understanding). My feeling is that our Action was always driven by altruism, and not in the context that Noam Chomsky addressed by saying “Those in power always present themselves as being altruistic, disinterested, and generous.”1. This tendency always leads to fragmentation, and although correct for many parts of our society and also sciences, I believe this Action was different. I sincerely hope you never felt like underdogs, especially not the early career scientists, and that you agree with my reflection. Our Action was always guided by mutual respect, a profound scientific interest, and by the will to follow the interests of our members. I like to thank all members of ES1205 that made this project a “living organism” and my special thanks go to the working group chairs and vice chairs: Ralf Kaegi, Michael Burkhardt, Yann Sivry, Björn Meermann, Frank von der Kammer, Ailbhe Macken, and Arno Gutleb; to our brilliant STSM manager Rute Domingos, and to our manager for the early stage researchers interests Maria Petala. Second to none was the effort the University of Salento put into our activities, and I would like to say thank you to Luciana Dini and her team as well as to the COST office team, especially to Deniz Karaca. Finally this conference would never have happened if Susana Loureiro and her team, together with the scientific committee (Rute Domingos, Susana Loureiro, Ailbhe Macken, Karen Tiede, Geert Cornelis, Christoph Pagnout, Tommaso Serchi, Yann Sivry) had not taken the responsibility to organise the event, for which I am grateful. It was my pleasure working together with you. Lars Duester Chair of ES1205
Fig A and B show the results of two armourstone surveys performed by the BfG. Table A and Fig C basic information on the DSLT is presented. Information on chemicals and materials used in the study as well as on analyzes performed is given on page fou. Fig D shows the stepwise reduction of the initial parameter list. The full DSLT dataset with seven stones is presented in Tables B-H. All calculations (releasemax and releasemin) are based on the TS. In Table I conductivity and pH values are presented. Table J compares the nine days MRLs with the DSLT results. An overview on the evaluation of the blank criteria is given in Tables K and L. Figs I-R show the log/log graphs for CUS1-3, Granite, Granodiorite, Greywacke, Basalt, Karbon Quartzite and LDS. A chapter on “DSLT practical considerations and potential improvements of potential following technical specification” is also given. (PDF)
- Sep 2016
Optimal supply of trace elements (TE) is a prerequisite for microbial growth and activity in anaerobic digestion (AD) bioprocesses. However, the required concentrations and ratios of essential TE for AD biotechnologies strongly depend on prevailing operating conditions as well as feedstock composition. Furthermore, TE in AD bioreactors undergo complex physico-chemical reactions and may be present as free ions, complex bound or as precipitates depending on pH, or on the presence of sulfur compounds or organic macromolecules. To overcome TE deficiency various commercial mineral products are typically applied to AD processes. The addition of heavy metals poses the risk of overdosing operating systems, which may be toxic to microbial consortia and ultimately the environment. Adequate supplementation, therefore, requires not only appropriate knowledge about the composition, but also on the speciation and bioavailability of TE. However, very little is yet fully understood on this specific issue. Evaluations of TE typically only include the measurement of total TE concentrations but do not consider the chemical forms in which TE exist. Thus detailed information on bioavailability and potential toxicity cannot be provided. This review provides an overview of the state-of-the-art in approaches to determine bioavailable TE in anaerobic bioprocesses, including sequential fractionation and speciation techniques. Critical aspects and considerations, including with respect to sampling and analytical procedures, as well as mathematical modelling, are examined. The approaches discussed in this review are based on our experiences and on previously published studies in the context of the ‘COST Action 1302: European Network on Ecological Roles of Trace Metals in Anaerobic Biotechnologies'.
Coacervate-based techniques are intensively used in environmental analytical chemistry to enrich and extract different kinds of analytes. Most methods focus on the total content or the speciation of inorganic and organic substances. Size fractionation is less commonly addressed. Within coacervate-based techniques, cloud point extraction (CPE) is characterized by a phase separation of non-ionic surfactants dispersed in an aqueous solution when the respective cloud point temperature is exceeded. In this context, the feature article raises the following question: May CPE in future studies serve as a key tool (i) to enrich and extract nanoparticles (NPs) from complex environmental matrices prior to analyses and (ii) to preserve the colloidal status of unstable environmental samples? With respect to engineered NPs, a significant gap between environmental concentrations and size- and element-specific analytical capabilities is still visible. CPE may support efforts to overcome this “concentration gap” via the analyte enrichment. In addition, most environmental colloidal systems are known to be unstable, dynamic, and sensitive to changes of the environmental conditions during sampling and sample preparation. This delivers a so far unsolved “sample preparation dilemma” in the analytical process. The authors are of the opinion that CPE-based methods have the potential to preserve the colloidal status of these instable samples. Focusing on NPs, this feature article aims to support the discussion on the creation of a convention called the “CPE extractable fraction” by connecting current knowledge on CPE mechanisms and on available applications, via the uncertainties visible and modeling approaches available, with potential future benefits from CPE protocols.
Women's on Sportster Street Easy Slip platform presentation, Session: Metals in the Environment: Fate, Speciation and Bioavailability in Water, Soil and Sediment (II)
PICO presentation in Session HS9.6 - Aquatic interfaces: advancing understanding through inter-disciplinary research; 2 minutes oral presentation + viewing and discussion
- Apr 2016
Stoffeinträge in Gewässer finden generell sowohl über direkte Zuflüsse aus Nebengewässern und Gerinnen, als auch diffus z. B. über Oberflächen und über die Grundwasserpassage statt. Im urbanen Raum werden über den Niederschlagsabfluss von Siedlungs- und Verkehrsflächen vielfältige anthropogene Stoffe mit hoher zeitlicher und räumlicher Variabilität in die Oberflächengewässer und das Grundwasser eingetragen. Die Nutzungen der Flächen haben unmittelbaren Einfluss auf die Stoffgemenge und die Konzentrationen der verschiedenen Stoffe. Als bedeutsame Ausgangsflächen für diffuse Stoffeinträge in Gewässer werden im urbanen Raum Freiflächen, überbaute Flächen und Verkehrsflächen unterschieden. Der vorliegende DWA-Themenband beschreibt und bewertet die Stoffeinträge von diesen Flächen differenziert nach primären Stoffquellen und Eintragspfaden. Die Emissionen können sich hinsichtlich der Stoff- und Konzentrationsmuster, dem allgemeinen Verteilungsverhalten, der Eintragsmenge, sowie durch Pfad- und regionalspezifische Besonderheiten unterscheiden. Mit dem Themenband bietet die DWA einen Überblick über wesentliche Stoffgruppen und Eintragspfade unter urbanen Nutzungen. Dies soll einen langfristigen und nachhaltigen Gewässerschutz fachlich unterstützen. Der Themenband richtet sich an Experten und Entscheider, die mit Planungen und wasserwirtschaftlichen Lösungen, speziell im urbanen Raum befasst sind, und bietet auf dieser Grundlage einen Diskussionsbeitrag zu diesem Thema.
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- Anne-Lena Fabricius
- Jingfu Liu
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- Muhammad Faizan Nazar
The workshop is organized within the frame of the COST Action ES1205: Transfer of engineered nanomaterials from wastewater treatment & stormwater to rivers (http://www.es1205.eu/). Since the production and application of Engineered NanoMaterials (ENMs) to daily life’s fields within the EU are known to increase, the release of ENMs into the aquatic environment is expected. Hence, it is crucial to understand the processes determining the behavior of ENMs and to develop viable regulations. As a basis, validated and easily implementable methods are required. CPE is one promising tool for separation and concentration in ENM analyses in complex environmental matrices. The workshop is hosted by working group 1 of the Action (http://www.es1205.eu/workinggroups/wg1-fate/). The scope of the workshop is to bring together scientists from different disciplines and to address benefits and challenges of the method in a comprehensive manner. A balance of 60 % presentations and 40 % discussion is envisaged. Interested scientists are encouraged to send an informal abstract (max. 1 page Arial, 12 pt, full justification) to email@example.com till 2015/12/15. Per presentation, a time slot of 20 minutes is available. Potential topics: Environmental analytical chemistry, physical chemistry, toxicology, process engineering. Please feel free to submit your own ideas. Travel costs support is available from ES1205 for up to 5 presenters from COST countries (http://www.cost.eu/about_cost/cost_countries).
Bioaccumulation, the accumulation of a chemical in an organism relative to its level in the ambient medium, is of major environmental concern. Thus, monitoring chemical concentrations in biota are widely and increasingly used for assessing the chemical status of aquatic ecosystems. In this paper, various scientific and regulatory aspects of bioaccumulation in aquatic systems and the relevant critical issues are discussed. Monitoring chemical concentrations in biota can be used for compliance checking with regulatory directives, for identification of chemical sources or event-related environmental risk assessment. Assessing bioaccumulation in the field is challenging since many factors have to be considered that can affect the accumulation of a chemical in an organism. Passive sampling can complement biota monitoring since samplers with standardised partition properties can be used over a wide temporal and geographical range. Bioaccumulation is also assessed for regulation of chemicals of environmental concern whereby mainly data from laboratory studies on fish bioaccumulation are used. Field data can, however, provide additional important information for regulators. Strategies for bioaccumulation assessment still need to be harmonised for different regulations and groups of chemicals. To create awareness for critical issues and to mutually benefit from technical expertise and scientific findings, communication between risk assessment and monitoring communities needs to be improved. Scientists can support the establishment of new monitoring programs for bioaccumulation, e.g. in the frame of the amended European Environmental Quality Standard Directive.
Besides the leaching behaviour of a construction material under standardised test-specific conditions with laboratory water, for some construction materials it is advisable to test their environmental behaviour also under close to end use conditions. The envisaged end use combined with the product characteristics (e.g., mineral phases) is decisive for the choice of environmental factors that may change the release of substance that potentially cause adverse environmental effects (e.g., fertilisation or ecotoxicity). At the moment an experimental link is missing between mono-factorial standardised test systems and none standardised complex incubation experiments such as mesocosms which are closer to environmental conditions. Multi-factorial batch experiments may have the potential to close the gap. To verify this, batch experiments with copper slag were performed which is used as armour stones in hydraulic engineering. Design of Experiments (DoE) was applied to evaluate the impact of pH, ionic strength, temperature and sediment content on the release of As, Cu, Mo, Ni, Pb, Sb and Zn. The study shows that release and sediment-eluent partitioning of metal(loid)s are impacted by interactions between the studied factors. Under the prevalent test conditions sediment acts as a sink enhancing most strongly the release of elements from the material.
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Der Kurzbericht umfasst acht Projektteile, die direkt oder indirekt (z. B. Kapitel 6) mit dem gewässerchemischen Verhalten von Kupferschlacke (Produktbezeichnung: Eisensilikatge-stein, kurz: CUS) in Zusammenhang stehen. Die Umweltverträglichkeit von CUS wurde im Rahmen eines gemeinsamen Untersuchungsprogramms zwischen dem Hersteller Aurubis/Peute und der BfG untersucht. Außerhalb des Projektes wurden einige zusätzliche Arbeiten von der BfG durchgeführt, welche nicht Bestandteil der Vereinbarungen des gemeinsamen Untersuchungsprogrammes waren. Diese Untersuchungen bilden die Basis dieses Kurzberichtes.
To assess the fate and behaviour of metal(loid)s in aquatic systems as well as (potential) impacts on associated biota, a comprehensive investigation of different aspects including, e.g., mobility, transformation, transport processes, availability and bioaccumulation, is needed. Since the mobility and toxicity of substances depend on their speciation, the investigation under close to environmental conditions is inevitable to understand key mechanisms and processes that govern “in situ” changes. Standardised methods and test systems, for e.g., construction materials in hydraulic engineering, provide the possibility to obtain comparable results. However, results from these tests may only be linked via sophisticated assessment procedures to environmental quality standards. How, e.g. construction materials investigated under standardised laboratory conditions perform under environmentally relevant conditions (e.g., low redox in contact with sediments) is seldom addressed. Standardised test systems are, with few exceptions (e.g., OECD 308 ), not designed to deliver information on the transformation and fate of substances. To address these questions, complex laboratory tests systems are needed. The presentation will deliver an overview on different non-standardised experimental setups applicable to study the transformation and fate of metal(loid)s in sediments and the overlaying water bodies. Furthermore, a method comparison will be given and pros and cons will be figured out. Exemplary, methods suitable to address the speciation of metal(loid)s under close to natural or field conditions will be presented, including e.g., Diffusive Gradient in Thin Films (DGT ), sediment Peeper , the Sediment or Fauna Incubation Experiment (SOFIE ), microprofiling and micro sampling system (Missy ) or various (commercially available) mesocosm systems. 1. Ericson, J.F., Environmental Science & Technology, 2007. 41(16): p. 5803-5811. 2. W. Davison, G.F., M. Harper, P. Teasdale, H. Zhang in In Situ Monitoring of Aquatic Systems, J. Buffle, Horvai, G., Editor. 2000, John Wiley & Sons. 3. Lewandowski, J., K. Ruter, and M. Hupfer, Environmental Science & Technology, 2002. 36(9): p. 2039-2047. 4. Vink, J.P.M. Environmental Science & Technology, 2002. 36(23): p. 5130-5138. 5. Fabricius, A.-L., et al., A new micro profiling and micro sampling system for water saturated environmental boundary layer. In prep. 6. Duester, L., et al., J. Anal. At. Spectrom., 2011: p. DOI:10.1039/C0JA00149J.
Constructed wetlands are used to treat diluted and undiluted wastewater. A basic understanding on the fate and transformation of several engineered nano materials (ENMs) in the sewer system and wastewater treatment plants (WWTPs) is already available. However, little is known about fate and potential transformations of ENMs in constructed wetlands. Since the biogeochemical conditions and retention times are significantly different in the two waste water treatment systems, a mechanistic understanding on the transformation and transport of ENMs in constructed wetlands is required. Especially, in order to address removal efficiencies and a potential enrichment in certain wetland compartments.
The European COoperation in Science and Technology (COST) Action ES1205 on the transfer of Engineered Nano materials from wastewater Treatment and stormwatEr to Rivers (ENTER) aims to create and to maintain a trans European network among scientists. This perspective article delivers a brief overview on the status quo at the beginning of the project by addressing the following aspects on engineered nano materials (ENMs) in the urban systems: i) ENMs that need to be considered on a European level; ii) uncertainties on production-volume estimations; iii) fate of selected ENMs during waste water transport and treatment; iv) analytical strategies for ENM analysis; v) ecotoxicity of ENMs, and vi) future needs. These six step stones deliver the derivation of the position of the ES1205 network at the beginning of the projects runtime, by defining six fundamental aspects that should be considered in future discussions on risk evaluation of ENMs in urban water systems.
KEYNOTE The presentation will provide a broad overview on metal and metalloid emerging pollutants 1 which are used in "new" industrial applications as well as on organic compounds/particles that are under discussion to induce adverse environmental effects in close to nature and constructed wetlands. The release scenarios and factors that impact the environmental fate and transformation of potential pollutants will be addressed within the presentation (figure. 1). Figure 1: The four central themes and connecting links of the presentation. I. "NEW" METAL(LOID)S At a first glance and compared to the magnitude of man-made organic compounds that show a potential to cause adverse environmental effects, inorganic compounds seem to have a lower innovation potential in industrial application. This impression may change as soon as one begins to think about speciation, fractionation 2 and the availability of metals or metalloids (metal(loid)s). Hence, for some metal(loid)s the occurrence of: 1. "new" metal(loid) organic species, 2. "new" fractions, e.g., nanoparticles, 3. or less commonly used metals in "new" industrial/medical applications, is connected with certain concerns. 1 Emerging pollutants: A substance currently not included in routine environmental monitoring programmes and which may be candidate for future legislation due to its adverse effects and / or persistency (http://www.norman-network.net/index_php.php?module=public/others/glossary#e_pollute). 2 Chemical species: Chemical elements: specific form of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure. Fractionation: Process of classification of an analyte or a group of analytes from a certain sample according to physical (e.g., size, solubility) or chemical (e.g., bonding, reactivity) properties (Templeton, Ariese et al. 2000).
Long-term leaching experiments are crucial to estimate the potential release of dangerous substances from construction materials. The application of Diffuse Gradients in Thin film (DGT) in static-batch experiments was tested to study the long-term release of metal(loid)s from construction materials for hydraulic engineering, for half a year. Long-term release experiments are essential to improve calculations of the life-time release for this materials. DGTs in batch experiments were found to be a space and labour efficient application, which enabled (i) to study, in a non-invasive manner, the total release of nine metal(loid)s for half a year, (ii) to differentiate between release mechanisms and (iii) to study mechanisms which were contrary to the release or caused experimental artefacts in the batch experiments. For copper slag (test material) it was found that eight metal(loid)s were released over the whole time period of 184 d. Cu, Ni and Pb were found to be released, predominantly caused by (the) weathering of sulphide minerals. Only for Zn a surface depletion mechanism was identified. The results from the long-term batch experiments deliver new information on the release of metal(loid)s during the life cycle of construction materials with regard to river basin management objectives.
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Engineered nanoparticles (ENPs) show new and interesting properties leading to an increased use in various application fields and have entered our daily environment (e.g., functionalized clothing, cosmetics, food, medicine). Though on the one hand nanotechnology plays a substantial role in societies' daily life, on the other the presence and behavior of ENPs in organisms and the environment is still unclear to a large extent. Furthermore, comprehensive legislative regulation is still missing. For adequate regulation a clear definition of ENPs is needed. A definition recommendation was released in 2011 by the European Commission (EC) on the basis of size and number of ENPs present within a defined size range. However, straightforward analytical techniques which easily provide information allowing for a decision (based on the EC definition) on the presence and concentration of ENPs in a given sample do not exist yet. A promising tool, offering fraction-related size information on the one hand and allowing for element-specific detection on the other is the coupling of asymmetric flow-field-flow-fractionation (AF4) with inductively coupled plasma-mass spectrometry (ICP-MS). In this work, a new strategy for quantifying silver nanoparticle (AgNP) size fractions (30 nm +/- 2.1 nm, 75 nm +/- 3.9 nm) after base-line AF4 separation relying on on-line ICP-MS detection combined with "post-channel" species-unspecific on-line isotope dilution (on-line ID) was successfully developed. A limit of detection (LOD) of 0.5 [small mu ]g Ag L-1 and a limit of quantification (LOQ) of 1.6 [small mu ]g Ag L-1 were achieved by the approach applied. The recovery values for the smaller size-fraction (30 nm) were in the range of 31-41% while for the larger size-fraction (75 nm) in the range of 75-78%. The overall reproducibility (RSDs, peak areas) was in between 3.4-5.4%. Validation of the on-line ID approach was achieved via off-line fraction collection and total silver determination afterwards; a bias of 2.9-16.4% between both approaches was observed indicating that the on-line ID approach is working properly. To the best of the authors' knowledge, this is the first time that species-unspecific (post-channel) on-line ID was combined with AF4/ICP-SF-MS for fraction-related quantification of AgNPs.
Construction materials are tested worldwide for a potential release of dangerous substances to prevent adverse effects on humans and biota. It is crucial to identify and understand the processes which are decisive for the release of hazardous substances. The current study compares the results of different test methods. Taking copper slag as model material, the influence of material particle size, eluant composition and ionic strength was tested. Ionic strength and salinity significantly influenced the release of metal(loid)s in the water phase. Furthermore, it was elucidated that colloids can cause methodological artefacts. The available specific surface area exhibited a positive correlation with the release of hazardous substances. The specific surface areas of materials were determined by the Brunauer, Emmett and Teller model (BET) and four other methods. The aluminium foil method showed the best results with regard to the statistical uncertainty, compared to a 3D laser scanning method. With help of the roughness factor λ it is possible to compare the results from surface area measurements with different material particle sizes (0-250 mm). This comparability offers the potential to match the release of metal(loid)s from laboratory studies with field applications and catchment area calculations/modelling, based on the release per m(2).
Engineered inorganic nanoparticles (EINP) are expected to pass the wastewater-river-topsoil-groundwater pathway. Despite their increasing release, the processes governing the EINP aging and the changes in functionality in the environment are up to now largely unknown. The objective of the interdisciplinary research unit INTERNANO funded by the German Research Foundation (DFG) is to identify the processes relevant for the fate of EINP and EINP-associated pollutants in the interfacial zone between aquatic and terrestrial ecosystems. The research unit consists of six subprojects and combines knowledge from aquatic and terrestrial sciences as well as from microbiology, ecotoxicology, physicochemistry, soil chemistry and soil physics. For the identification of key processes we will consider compartment specific flow conditions, physicochemistry and biological activity. Situations representative for a floodplain system are simulated using micromodels (μm scale) as well as incubation, soil column and joint laboratory stream microcosm experiments. These results will be transferred to a joint aquatic-terrestrial model system on EINP aging, transport and functioning across the aquatic-terrestrial transition zone. EINP isolation and characterization will be carried out via a combination of chromatographic, light scattering and microscopic methods including dynamic light scattering, elemental analysis, hydrodynamic radius chromatography, field flow fractionation as well as atomic force microscopy, Raman microscopy, dynamic light scattering methods and electron microscopy. INTERNANO generates fundamental aquatic-terrestrial process knowledge, which will help to evaluate the environmental significance of the EINP at aquatic-terrestrial interfaces. Therefore, INTERNANO serves as a qualitative basis to predict the environmental impact of EINP contamination.
- Jul 2011
The energy stored in coarse particulate organic matter, e.g. leaf litter, is released to aquatic ecosystems by breakdown processes involving microorganisms and leaf shredding invertebrates. The palatability of leaves and thus the feeding of shredders on leaf material are highly influenced by microorganisms. However, implications in the colonization of leaves by microorganisms (=conditioning) caused by chemical stressors are rarely studied. Our laboratory experiments, therefore, investigated for the first time effects of a fungicide on the conditioning process of leaf material by means of food-choice experiments using Gammarus fossarum (Crustacea: Amphipoda). Additionally, microbial analyses were conducted to facilitate the mechanistic understanding of the observed behavior. Gammarids significantly preferred control leaf discs over those conditioned in presence of the fungicide tebuconazole at concentrations of 50 and 500 μg/L. Besides the decrease of fungal biomass with increasing fungicide concentration, also the leaf associated fungal community composition showed that species preferred by gammarids, such as Alatospora acumunata, Clavariopsis aquatica, or Flagellospora curvula, were more frequent in the control. Tetracladium marchalianum, however, which is rejected by gammarids, was abundant in all treatments suggesting an increasing importance of this species for the lower leaf palatability--as other more palatable fungal species were almost absent--in the fungicide treatments. Hence, the food-choice behavior of G. fossarum seems to be a suitable indicator for alterations in leaf associated microbial communities, especially fungal species composition, caused by chemical stressors. Finally, this or similar test systems may be a reasonable supplement to the environmental risk assessment of chemicals in order to achieve its protection goals, as on the one hand, indirect effects may occur far below concentrations known to affect gammarids directly, and on the other hand, the observed shifts in leaf associated microbial communities may have perpetuating implications in leaf shredding invertebrates.
The production and use of nanoparticles (NP) has steadily increased within the last decade; however, knowledge about risks of NP to human health and ecosystems is still scarce. Common knowledge concerning NP effects on freshwater organisms is largely limited to standard short-term (≤48 h) toxicity tests, which lack both NP fate characterization and an understanding of the mechanisms underlying toxicity. Employing slightly longer exposure times (72 to 96 h), we found that suspensions of nanosized (∼100 nm initial mean diameter) titanium dioxide (nTiO(2)) led to toxicity in Daphnia magna at nominal concentrations of 3.8 (72-h EC(50)) and 0.73 mg/L (96-h EC(50)). However, nTiO(2) disappeared quickly from the ISO-medium water phase, resulting in toxicity levels as low as 0.24 mg/L (96-h EC(50)) based on measured concentrations. Moreover, we showed that nTiO(2) (∼100 nm) is significantly more toxic than non-nanosized TiO(2) (∼200 nm) prepared from the same stock suspension. Most importantly, we hypothesized a mechanistic chain of events for nTiO(2) toxicity in D. magna that involves the coating of the organism surface with nTiO(2) combined with a molting disruption. Neonate D. magna (≤6 h) exposed to 2 mg/L nTiO(2) exhibited a "biological surface coating" that disappeared within 36 h, during which the first molting was successfully managed by 100% of the exposed organisms. Continued exposure up to 96 h led to a renewed formation of the surface coating and significantly reduced the molting rate to 10%, resulting in 90% mortality. Because coating of aquatic organisms by manmade NP might be ubiquitous in nature, this form of physical NP toxicity might result in widespread negative impacts on environmental health.
The pore water transport of antimony and titanium, applied as nanoparticles (NPs), was studied by spiking stable suspensions of two different nanomaterials on the surface of an undisturbed floodplain soil. For preparation of stable dispersions, two different strategies were followed. (i) Comparable to those used in industrial applications: titanium dioxide nanoparticles, with an average diameter of 99 nm, were prepared by high-energy ball milling in water, whereas for (ii) antimony trioxide (Sb(2)O(3); average diameter 121 nm) a dispersing agent (sodium salt of poly[(naphthaleneformaldehyde)sulfonate] (pNFS) in water) was used. The upper 17 cm of a floodplain soil (river Rhine, Germany) was sampled using the minimally invasive sediment or fauna incubation experiment (SOFIE® two compartment cell; 3 l volume each), which preserved the pore system of the soil. The cells were equipped with 450 and 100 nm filter probes at different depths providing a non-invasive sampling of the pore water. The pore water was sampled at different times (T = 0, 24, 48, 96 and 196 h) and analysed by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Sb and Ti were transported via the pore water of the floodplain soil to a depth of 14 cm, corresponding to the maximum cell depth. The highest Sb concentration in the pore water was detected after 24 h at a depth of 5.5-8 cm. Although the spiked concentration was higher for Ti than for Sb, the total Ti concentration in the pore water of the spiked cell was lower. This indicates a stronger agglomeration of TiO(2) NPs or a more intensive interaction of Ti with the solid matrix and a faster transport of Sb towards deeper soil layers. The results show that metal(loid)s from metal oxide NPs are transported in the soil pore water and, hence, have the potential to act as the source of contamination of deeper soil layers after soil surface contamination.
- Lars DuesterBoris Hilfiger Tommy Lw Tommy Black Hilfiger q1RIwnxCE
- Denis Rakcheev
- Julia V. Bayer
- Gabriele E Schaumann
The demand to quantify the elemental composition of very small sample amounts and/or of samples which form artefacts during conventional sample preparations is increasing. Example applications are the quantification of engineered metal(loid) based nanomaterials in environmental samples, e.g. (i) the direct analyses of engineered nanoparticle (ENP) suspensions showing broad particle size distributions which are not suitable to be applied via the spray chamber in ICP-MS analyses, (ii) measurements of single invertebrates and tissue of selected organs which were exposed to ENPs, and (iii) whole plants or plant parts e.g. from Lemna sp. The use of imaging based high resolution methods like atomic force microscopy or environmental scanning electron microscopy creates the need to quantify the elemental composition of the visualised objects as directly and exactly as possible, at very low limits of detection. With this study the authors present a method/concept for the multi-element quantification of analytes from ENPs in complex matrices with different degrees of complexity by graphite furnace electrothermal vaporisation coupled to inductively coupled plasma quadrupole mass spectrometry equipped with collision/reaction cell (GF-ETV-ICP-QMS).
The alkylation of metalloids through the transfer of methyl groups is an important factor in the biogeochemical cycling of elements like arsenic and antimony. In the environment, many different organic and inorganic forms of these elements can therefore be found in soils, sediments or organisms. Studies that compare the ecotoxicity of these different chemical species however are rare. Therefore, this study aimed to generate toxicity data on two scarcely studied organic compounds of arsenic and antimony, as well as to compare their toxicity to the inorganic species, which are studied so far to a higher extent, in order to improve the environmental effect assessment of these elements. To this purpose, bioassays were performed in which three different aquatic organisms (the floating water plants Lemna minor and Wolffia arrhiza and the green alga Selenastrum capricornutum) were exposed to a concentration series of 3 different arsenic species (sodium arsenite — As(III), sodium arsenate — As(V), and monomethylarsonous diiodide — MMAs(III)) and three different antimony species (antimony potassium tartrate hydrate — Sb(III), potassium hexahydroxoantimonate — Sb(V), trimethylantimony(V) bromide — TMSb(V). The observed effect concentrations demonstrated that the inorganic (III)- and (V)-valent species of arsenic were clearly more toxic than the corresponding antimony species. The highest overall toxicity has been shown by MMAs(III) followed by the inorganic As(III). The highest toxicity of the three tested antimony species has been observed for TMSb(V). The observed differences in effect levels stress the importance once more that speciation must not be ignored in toxicity studies.
Das ökotoxikologisch relevante Halbmetall Arsen (As) ist in einigen Gebieten Deutschlands im Boden bis weit über die Hintergrundwerte angereichert. Zu den betroffenen Standorten zählen Niederungsböden, die durch Kontakt mit As-haltigem Grundwasser natürlicherweise erhöhte Gehalte zeigen, und Auenböden, in denen belastete Sedimente die Quelle des As darstellen. Ziel dieser Studie war es, die Gefahr einer Mobilisierung des As aus den betroffenen Böden abzuschätzen. Aufgrund der Redoxsensitivität des As lag dabei der Schwerpunkt auf der Untersuchung der As-Löslichkeit unter oxischen und unter anoxischen Bedingungen. Je zwei Standorte in den Bundesländern Baden-Württemberg, Bayern, Niedersachen, Nordrhein-Westfalen, Sachsen und Sachsen-Anhalt wurden ausgewählt. Dazu gehörten sechs Niederungsböden (Gleye und Niedermoore) sowie sechs Auenböden (Tschernitza, Vega, Auengleye) mit As-Gehalten von 3 bis 3.100 mg kg-1. Die Bodenproben wurden in eine oxisch und eine anoxisch behandelte Teilprobe getrennt und auf Bindungsformen des As analysiert. Zudem wurde die Redox- und As-Lösungsdynamik in den Oberböden während 41tägiger Wassersättigung in Laborsäulen untersucht. Zur Validierung der im Labor erzielten Ergebnisse wurden Daten zweier Langzeitstudien zur As-Bodenlösungsdynamik im Freiland vergleichend herangezogen. Die oxische und anoxische Probenbehandlung ergab für Böden, die zur Zeit der Probenentnahme nicht vernässt waren, keine signifikanten Unterschiede im löslichen und leicht austauschbaren As. Gefriertrocknung führte vermutlich aufgrund einer Oberflächenvergrößerung zu einer erhöhten Extrahierbarkeit des As. Der dominierende Prozess der As-Immobilisierung in den Böden ist die Okklusion in amorphen sowie in Niederungsböden zudem in kristallinen Fe-(Hydr)oxiden. Erhöhte PO4-extrahierbare Anteile deuten auf eine höhere Mobilisierbarkeit des As in den Auenböden hin. Schon unter oxidierenden bis schwach reduzierenden Bedingungen nach 24 h Wassersättigung in den Säulen wurden die Prüfwerte der Bundes-Bodenschutzverordnung für den Transferpfad Boden- Grundwasser in vielen Bodenlösungen überschritten. Engere Beziehungen der Lösungskonzentrationen zeigten sich zum SO4- als zum NO3-löslichen As. Unter reduzierenden Bedingungen fand eine starke As-Freisetzung in die Bodenlösung mit Konzentrationen bis zu 38 mg L-1 As statt, wobei offensichtlich im Verlauf von 41 Tagen zunächst nur das an den Oberflächen aufgelöster Fe-(Hydr)oxide sorbierte As freigesetzt wurde. Die Freilandversuche bestätigen diese mit einem schnellen Absinken des Redoxpotenzials verbundene As-Mobilisierung bei Wassersättigung redoximorpher Oberböden. Die im Vergleich zum Freiland deutlich erhöhte As-Löslichkeit im Laborversuch ist vermutlich auf höhere Bodentemperaturen und Störung der Bodenstruktur zurückzuführen. Das unter oxischen Bedingungen austauschbare und das unter anoxischen Bedingungen freigesetzte As zeigen den engsten Zusammenhang zum As-Gehalt des Bodens bezogen auf das dithionitlösliche Fe (As/Fed). Aus dieser positiven Korrelation ergibt sich eine geringere As-Löslichkeit in den Niederungsböden, in denen die Beziehung zwischen As-Belastung und Fe-(Hydr)oxidgehalt enger ist als in einigen Auenböden. Zwar geht die Freisetzung von As in allen Proben mit einer Freisetzung von Fe einher, das Fe/As-Verhältnis variiert jedoch zwischen den verschiedenen Bödenlösungen deutlich. In den meisten Bodenlösungen sollte ein Kontakt mit O2 zu einer nahezu vollständigen, in einigen Auenböden und den Niedermooren jedoch aufgrund niedriger Fe/As-Verhältnisse nur zu einer unvollständigen Ausfällung des As mit Fe-Hydroxiden führen. Die Ergebnisse zeigen, dass unter den Bodeneigenschaften vor allem die Vergesellschaftung von As und Fe-(Hydr)oxiden bei einer Gefahrenabschätzung zu berücksichtigen ist. Ein problematischer Transfer von As in Nutzpflanzen tritt offenbar nur kleinräumig bei einer speziellen Vegetationszusammensetzung im Grünland auf. Zu untersuchen bleibt eine potenzielle Anreicherung von Arsen vor allem in Grundwässern und Oberflächengewässern der Flussauen. Zukünftige Arbeiten sollten den Einfluss der Bodentemperatur sowie der mikrobiellen Aktivität auf die an der As-Dynamik beteiligten Redoxprozesse untersuchen.
In this study, the speciation of arsenic (As) and antimony (Sb) across a water-sediment interface and the formation of mono-, di-, and trimethylated species overtime in a microfiltered pore water solution were examined. We used an experimental technique, known as the sediment or fauna incubation experiment (SOFIE), which enables the determination of chemical speciation across redox zones in undisturbed systems. Five different incubation experiments were run: Over a 76 day incubation period, pore water was sampled and speciated 5 times. These experiments revealed the complete methylated species pattern for arsenic and antimony in the microfiltered sediment pore water. This constitutes the first report of methylated As and Sb species in a true pore water solution of sediments. Predominant organic species were dimethylantimony (DMSb up to 2.7 microg/L) and dimethylarsenic (DMAs up to 4.3 microg/L) followed by monomethylated species (MMAs and MMSb). These data (i) indicate that methylation significantly influences the translocation of As and Sb in sediments, (ii) demonstrate good agreement between the occurrence of methylantimony and the occurrence of methylarsenic in the pore water, (iii) reveal that As transformation in sediments is faster than Sb transformation but is more susceptible to disturbances from acidification, and (iv) regarding the translocation of these elements and antimony in particular, methylation is clearly a relevant, and perhaps as yet underestimated, factor.
The methylated antimony and arsenic species content of sediments derived from a sedimentation bowl of the river Ruhr were monitored over a 12 month period. The most prevalent species detected were monomethylarsenic (MMAs) and monomethylantimony (MMSb). The methylantimony and methylarsenic species concentration was found to be directly correlated to the winter spate. As the biological activity in the water body is generally low at this time of the year, it may be concluded that the concentration maxima in winter originated from the translocation of soil- and sediment particles to the river by heavy rains and the melting of snow. A second maximum in Spring/early Summer was observed for the methylarsenic species, and specifically the dimethylarsenic species (DMAs); this occurred in parallel to the algal bloom. A change in the methylarsenic speciation pattern was observed between April, May and June, with DMAs replacing MMAs as the dominant methylarsenic species. For methylated antimony species no seasonal variation in the species pattern was detected. Taken together these data strongly indicate a higher degree of transformation of arsenic compared to antimony in the Ruhr river system in spring and can be taken as a record for a biogeochemical different behaviour of these two elements which are often treated as equivalent in environmental studies.
The aim of this study was to determine to what extent particle size determines the occurrence of organometal(loid) compounds of the elements As, Sb, Sn and Te in freshwater sediments. In addition, the anthropogenic impact upon the distribution through differing usage of freshwater habitats was examined vis-à-vis flowing water, fish farms and a maturation pond for the bio-treatment of wastewater. All habitats sampled were located in the basin of the river Ruhr, Germany. In addition to the detection of high concentrations of total metal(loid) content of As, Sb, Sn and Te in the maturation pond sediments, this habitat also possessed the highest concentration of organometal(loid) species. Interestingly, the concentration of monomethylated metal(loid)s was up to 100-fold higher than those of higher methylated species of the same element. A maximum of 28 µg kg−1 MMAs, 18 µg kg−1 MMSb and 8 µg kg−1 MMSn per dry weight was detected. A similar tendency was noted for all other freshwater habitats tested. In contrast to methylated arsenic (arsenic containing pesticides are banned in Germany) and antimony species, there is no doubt that the alkyltin species detected, e.g. MBSn and DBSn, are of anthropogenic origin since biogenesis of these species does not occur. Alkyltins are, however, known to enter the environment in a continuous and diffuse manner via discharge to sewage and air. In samples from the maturation pond concentrations of up to 86 and 11 µg kg−1 per dry weight were detected for MBSn and DBSn, respectively. The detection of methylated arsenic and antimony species indicates that biotransformation of these elements is occurring in freshwater habitats. Irrespective of the usage and (anthropogenic) demands on the freshwater habitats tested, the highest concentration of organometal(loid) species was always detected in the sediment fractions that contained the highest concentration of humic substances and comprised up to 40% clays and silt particles (<63 µm). Owing to their high surface area to volume ratios these particles possess a high binding capacity for metal(loid) ions and are attractive microhabitats for microorganisms. The resulting microcosmos therefore has a high potential for the biomethylation of metal(loid)s. At this point in time it is not fully clear whether the high concentrations of organometal(loid) species detected in the clay/silt fraction are produced in situ by microbial biotransformation of bound metal(loid) ions or whether, as is the case for inorganic ions, the organometal(loid) species are translocated to this fraction and bound. Regardless of the mechanism, the accumulation of organometal(loid) species in clay/silt fraction means that these species are held in contact with the interstitial water and are therefore highly bioavailable, with potentially toxic consequences for aquatic organisms. Copyright © 2007 John Wiley & Sons, Ltd.
Methylated species of antimony, arsenic and tin were examined in urban soils of the Ruhr basin, near the cities of Duisburg and Essen, Germany. The main aim of this study was to investigate the occurrence of mono-, di- and trimethylated species of these elements in urban soils. The influence of historical and present land use upon the species content was examined. The distribution of inorganic As, Sb and Sn and their methylated species along the profile depth was investigated. As, Sb and Sn speciation was performed by pH-gradient hydride generation purge and trap gas chromatography, followed by inductively-coupled plasma mass spectrometry (HG-PT-GC/ICP-MS). Species' structures were confirmed by GC-EI/MS-ICP-MS. Monomethylated Sb and As were the dominant species detected: the concentration of these metal(loid) species varied between <0.07-56 microg kg(-1) per dry mass. All dimethylated species and monomethyltin concentrations were between <0.01-7.6 microg kg(-1) per dry mass, and for the trimethylated species of all examined elements, concentrations between <0.001-0.63 microg kg(-1) per dry mass were detected. The highest organometal(loid) concentrations were observed in agricultural soils and garden soils; lower concentrations were found in the soils of abandoned industrial sites (wasteland, primary forest and grassland) and a flood plain soil of the Rhine. This result can be ascribed to both the cultivation and the increased biological activity of the agricultural soils, and the generally higher contamination, the disturbed structure and the artificial substrates (deposits from industrial sources) of the abandoned industrial soils. Due to periodical sedimentation, the flood plain profile was the only one where no depth dependence of organometal(loid) species concentration was detected. The other soil profiles showed a decrease of species content with increasing depth; this was particularly noticeable in soils with a clear change from a horizon with an organic character towards a mineral horizon, i.e. decreasing vitality from profile top to bottom. It is not as yet clear whether the organometal(loid) species are formed in the mineral horizons of the profiles or whether they are displaced from the organic, biologically-active horizons towards the mineral horizons. Field studies revealed that soil parameters like pH, water content or temperature did not correlate significantly with the degree of biomethylation observed. In contrast to the lower in vitro biomethylation efficiency of Sb vs. As in microbial incubations, we consistently detected higher proportions of transformed Sb compounds in situ in soil samples. These data may indicate a need to re-examine the currently accepted model of Sb biogeochemical cycling in the real environment.
Die Konzentrationen methylierter As- und Sb-Verbindungen (MAs- und MSb-Verbingungen) in Böden und Sedimenten (93 Proben) liegen im Bereich von 10 - 10 μg/kg. Die dominierenden Spezies sind Monomethylarsen (MMAs), Dimethylarsen (DMAs) und Monomethylantimon (MMSb) sowie Dimethylantimon) DMSb. Die höchsten Konzentrationen treten in Böden und Sedimenten auf, welche entweder eine deutliche Förderung der Bodenbiologie erfahren (z.B. Äcker) oder eine starke Belastung mit anorganischem As und Sb zeigen (z.B. Spülteich der Bleierzgewinnung). Standorte, welche keiner direkten anthropogenen Kontamination mit As und Sb unterliegen traten Konzentrationen < 20 μg/kg auf. Für das Vorkommen von MAs und MSb im Feststoffanteil von Böden und Sedimenten, als auch in echter Lösung des Sedimentporenwassers (Mikrofiltration), liegt ein statistisch signifikanter Zusammenhang vor. Im Gegensatz zu den MAs-Spezies erfahren die MSb-Spezies im Frühjahr in einem Ackerboden eine Speziesmuster Verschiebung hin zum DMSb. Der Gehalt an MSb-Spezies in sedimentbürtigen Schwebstoffen der Ruhr steht in einer direkten Beziehung zum Winterhochwasser und ist am deutlichsten durch die Verlagerung von Sediment- und Bodenmaterial aus dem Einzugsgebiet der Ruhr (Niederschläge und Schneeschmelze) beeinflusst. MAs Spezies in den schwebstoffbürtigen Sedimenten zeigen die stärkste Beeinflussung durch die Frühjahrsalgenblüte. Dies ist ein Beleg der besseren Metabolisierung von As im Vergleich zu Sb durch Süßwasseralgen. In verschiedenen Inkubationsexperimenten, unter anderem mit dem Sediment Or Fauna Incubation Experiment (SOFIE®, EU-patent 1018200 / 02077121.8), wird das gesamte Muster an methylierten As und Sb Spezies (mono-, di-, trimethyl-,) im 0,1 μm filtrierten Porenwasser belegt (im Bereich von 1 μg/l). Dies ist der erste Nachweis dieser Spezies in echter Lösung des Porenwassers und unterstreicht die Umweltrelevanz des Methylierungsprozesses bei der Verlagerung der Metalloide. Die Methylierung erfolgt für beide Elemente sowohl aerob, als auch anaerob. Im Gegensatz zu den Speziesmustern im Feststoffanteil, sind die Muster in den Porenwässern der Inkubationsversuche eindeutig durch das Auftreten zweifach methylierter Spezies dominiert. Neben der signifikanten Korrelation zwischen MAs und MSb im Porenwasser und im Feststoffanteil, wird ein statistischer Zusammenhang zwischen der Sb Konzentration der einen Probenentnahme und der MSb Konzentration der darauf folgenden Probenentnahme belegt. Dies legt den zeitlichen Rahmen zwischen der höchsten Verlagerbarkeit/Verfügbarkeit der anorganischen Spezies bis zu der Verlagerung der methylierten Spezies auf 10 - 20 Tage fest. Weitere Zusammenhänge zwischen dem Auftreten von Sb-Spezies im Porenwasser und Begleitparametern waren nicht zu belegen. Für As wird ein Zusammenhang zwischen dem As(III) Gehalt und dem Gehalt an MMAs dokumentiert. Das parallele Auftreten von As(III) und MMAs in echter Lösung des Porenwassers zeigt, dass ein zählbarerer Anteil der beiden Spezies nicht einer weiteren Umwandlung durch eine Methylierung unterworfen ist, sondern von den Organismen unter nativen Bedingungen an die Umgebung abgegeben wird. Auch hier spricht die gute Übereinstimmung mit den Zeitpunkten der höchsten biologischen Aktivität gegen eine maßgebliche anorganische Umwandlung der Spezies. Für eine Beurteilung der Umweltrelevanz der im Screening- und Laborversuchsteil ermittelten Konzentrationen an MAs und MSb, wurden Selenastrum capricornutum, Wolffia arrhiza und Lemna minor mit As- und Sb-Spezies belastet. Als Merkmal für die Schädigung der Organismen wurde für die Grünalge die Reduktion der photochemischen Effizienz des PSII genutzt und für die höheren Pflanzen die Reduktion des Wachstums über die Anzahl der Fronds. Die höchste Toxizität zeigten As(III) und MMAs(III). Die beiden As-Spezies zeigen EC-Werte im Bereich von 1 mg/l. Die EC-Werte von TMSb(V) und As(V) sind im Bereich von 10 - 10 mg/l. Sb(III), Sb(V), MMA(V), DMAs(V) und TMAs(V) zeigen EC-Werte deutlich über 10 mg/l. Für As(III) muss von einer Unterbewertung der Toxizität ausgegangen werden, da eine 50 %ige Oxidation des As(III) nach ~ 5 Tagen, unter den herrschenden Versuchsbedingungen, erfolgte. Deutlich höher in der Umweltrelevanz als die akute Toxizität ist eine Verlagerung methylierter As- und Sb- Verbindungen in echter Lösung (0,1 μm filtriert) über das Porenwasser zu beurteilen. Für Antimon traten im filtrierten Porenwasser und dem Freiwasser in 15 von 63 Fällen prozentuale Anteile der MSb am Sb > 10% auf. Dies lag für MAs- Spezies in 6 von Fällen 55 vor. Somit kommt der Methylierung insbesondere bei der Verlagerung des Antimons in Böden und Sedimenten eine wesentliche Rolle zu.
Gabriele E Schaumann
- Universität Koblenz-Landau
All co-authors (50)
Awards & Achievements (1)
Award · Aug 2007
International Conference on Environmental Science and Technology: Young Scientist Paper Award