Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Monitoring vooroeververdediging Oosterschelde en Westerschelde 2014
Tangelder, M. ; Heuvel-Greve, M.J. van den; Kluijver, M. de; Glorius, S.T. ; Jansen, H.M. - \ 2015
Yerseke : IMARES (Rapport / IMARES C102/15) - 141
oeverbescherming van rivieren - dijken - steenwerk - staal - aquatische ecosystemen - biota - metalen - ecotoxicologie - oosterschelde - westerschelde - nederland - riverbank protection - dykes - stonework - steel - aquatic ecosystems - metals - ecotoxicology - eastern scheldt - western scheldt - netherlands
Rijkswaterstaat bestort de vooroevers voor de dijken in de Ooster- en Westerschelde om de waterveiligheid te kunnen blijven waarborgen. Voor deze bestortingen wordt gebruik gemaakt van staalslakken, breukstenen en zeegrind. Om de gevolgen van het bestorten voor het plaatselijke onderwaterleven inzichtelijk te maken wordt monitoring uitgevoerd door IMARES in opdracht van Rijkswaterstaat. Hierbij wordt onderzoek gedaan naar hard substraat soorten (planten en dieren gevestigd op de harde oever), zacht substraat soorten (dieren die in het sediment op de vooroever leven) en mogelijke uitloging van zware metalen vanuit de vooroeverbestorting naar planten en dieren
Gehaltes aan zware metalen in biota op stort- en referentielocaties in de Oosterschelde & Westerschelde : data rapport 2014
Jansen, H.M. ; Glorius, S.T. ; Tangelder, M. ; Heuvel-Greve, M.J. van den - \ 2015
Yerseke : IMARES (Rapport / IMARES C079/15) - 91
oeverbescherming van rivieren - zware metalen - sintels - metalen - verontreiniging - oosterschelde - westerschelde - monitoring - aquatische ecologie - ecotoxicologie - riverbank protection - heavy metals - slags - metals - pollution - eastern scheldt - western scheldt - aquatic ecology - ecotoxicology
Om erosie van de oevers en geulwanden tegen te gaan, is er in 2008 (pilot) en 2009 (structureel) begonnen om ‘bestortingen’ uit te voeren om de oevers te beschermen. Deze bestortingen zijn uitgevoerd met staalslakken (SS) en breukstenen (BS). Om met zekerheid vast te kunnen stellen dat als gevolg van deze bestortingen geen negatieve effecten optreden op het mariene milieu is een monitoringsprogramma ingevoerd om inzicht te krijgen in gehalten aan zware metalen in aanwezige biota meerdere jaren na het aanbrengen van vooroeververdediging. Dit rapport beschrijft de resultaten van de metaalanalyses in biota bemonsterd op verschillende locaties in de Oosterschelde en Westerschelde.
Leaching of inorganic contaminants towards groundwater : impact assessment of the Dutch Soil Quality Decree on Groundwater
Spijker, J. ; Groenenberg, J.E. ; Comans, R.N.J. ; Dijkstra, J.J. - \ 2013
Bilthoven : RIVM - 201
grondwaterverontreiniging - bodemverontreiniging - uitspoelen - metalen - halfmetalen - verontreinigende stoffen - modelleren - anorganische verbindingen - groundwater pollution - soil pollution - leaching - metals - semimetals - pollutants - modeling - inorganic compounds
Dit rapport beschrijft de opzet, evaluatie en resultaten van een modellering van uitloging van metalen en metalloïden uit bodems naar het grondwater. Deze studie had de volgende doelen: 1. het bepalen van representatieve concentraties van metalen en metalloïden in het ondiepe (eerste meter) grondwater; 2. het bepalen van representatieve waarden voor bodemparameters, die de uitloging van metalen en metalloïden bepalen, zoals reactiviteit van opgelost organische koolstof, gehalten aan oxiden en reactiviteit van metalen en metalloïden; 3. het verbeteren van het bestaande modelinstrumentarium voor het modelleren van de uitloging van metalen en metalloïden uit de bodem, inclusief de onzekerheid van deze modellen.
Simultaneous sulfate reduction and metal precipitation in an inverse fluidized bed reactor
Villa Gomez, D.K. - \ 2013
Wageningen University. Promotor(en): Piet Lens, co-promotor(en): Karel Keesman. - [S.l.] : S.n. - ISBN 9789461737410 - 194
wervelbedden - uitrusting - sulfaatreductie - chemische precipitatie - metalen - fluidized beds - equipment - sulfate reduction - chemical precipitation - metals
The impact of metal transport processes on bioavailability of free and complex metal ions in methanogenic granular sludge
Bartacek, J. ; Fermoso, F.G. ; Vergeldt, F. ; Gerkema, E. ; Maca, J. ; As, H. van; Lens, P.N.L. - \ 2012
Water Science and Technology 65 (2012)10. - ISSN 0273-1223 - p. 1875 - 1881.
afvalwaterbehandeling - bioreactoren - anaërobe omstandigheden - korrelslib - biologische beschikbaarheid - metalen - toxiciteit - kernspintomografie - waste water treatment - bioreactors - anaerobic conditions - granular sludge - bioavailability - metals - toxicity - magnetic resonance imaging - magnetic-resonance - dynamics - immobilization - biofilm - nickel
Bioavailability of metals in anaerobic granular sludge has been extensively studied, because it can have a major effect on metal limitation and metal toxicity to microorganisms present in the sludge. Bioavailability of metals can be manipulated by bonding to complexing molecules such as ethylenediaminetetraacetate (EDTA) or diethylenetriaminepentaacetate (DTPA). It has been shown that although the stimulating effect of the complexed metal species (e.g. [CoEDTA]2-) is very fast, it is not sustainable when applied to metal-limited continuously operated reactors. The present paper describes transport phenomena taking place inside single methanogenic granules when the granules are exposed to various metal species. This was done using magnetic resonance imaging (MRI). The MRI results were subsequently related to technological observations such as changes in methanogenic activity upon cobalt injection into cobalt-limited up-flow anaerobic sludge blanket (UASB) reactors. It was shown that transport of complexed metal species is fast (minutes to tens of minutes) and complexed metal can therefore quickly reach the entire volume of the granule. Free metal species tend to interact with the granular matrix resulting in slower transport (tens of minutes to hours) but higher final metal concentrations.
Evaluation of models for metal partitioning and speciation in soils and their use in risk assessment
Groenenberg, J.E. - \ 2011
Wageningen University. Promotor(en): Rob Comans; Wim de Vries. - [S.l. : S.n. - ISBN 9789085858485 - 218
toxicologie - metalen - bodemchemie - risicoschatting - transportprocessen - geochemie - bodemoplossing - organisch bodemmateriaal - modellen - toxicology - metals - soil chemistry - risk assessment - transport processes - geochemistry - soil solution - soil organic matter - models
In this thesis models were developed and evaluated which describe metal partitioning and speciation in soils. Both partition-relations and multisurface models were developed and evaluated on their performance for a large set of elements
Metal supplementation to anaerobic granular sludge bed reactors: an environmental engineering approach
Gonzalez Fermoso, F. - \ 2008
Wageningen University. Promotor(en): Jules van Lier; Piet Lens. - S.l. : S.n. - ISBN 9789085048787 - 247
rioolslib - anaërobe omstandigheden - bioreactoren - metalen - supplementen - sewage sludge - anaerobic conditions - bioreactors - metals - supplements
The objective of this research is the optimization of essential metal dosing in upflow anaerobic sludge bed (UASB) reactors used for methanogenic wastewater treatment. Optimization of essential metal dosing in UASB reactors is a compromise between achieving the maximal biological activity of the biomass present in the reactor, while minimizing the costs of the supplied metal and the metal losses into the environment. The fate of metals in the anaerobic granular sludge is studied. The boundary conditions to keep a stable reactor operation are evaluated: Nutrient deficiency due to lack of essential metals versus toxicity in case of their excess. Finally, metal dosing strategies are evaluated. It is shown that the metal addition to UASB reactors and the methanogenic activity are related and, more important, this relation can be quantified
Sulfate reduction under acidic conditions for selective model recovery
Bijmans, M.F.M. - \ 2008
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Piet Lens. - [S.l.] : S.n. - ISBN 9789085049258 - 156
sulfaat - redoxreacties - zuurgraad - metalen - terugwinning - afvalwaterbehandeling - bioreactoren - nikkel - ijzer - sulfaatreductie - sulfate - redox reactions - acidity - metals - recovery - waste water treatment - bioreactors - nickel - iron - sulfate reduction
Dit proefschrift heeft als doel om processen te ontwikkelen voor selectieve metaal herwinning uit afvalwater and processtromen die meerdere metalen bevatten, door gebruik te maken van sulfaat reductie onder zure omstandigheden
Trace metals in floodplain lake sediments : SEM/AVS as indicator of bioavailability and ecological effects
Griethuysen, C. van - \ 2006
Wageningen University. Promotor(en): Bart Koelmans. - [S.l. ] : S.n. - ISBN 9085043654 - 223
sporenelementen - metalen - stroomvlakten - meren - sediment - verontreinigende stoffen - waterverontreiniging - methodologie - ecologie - risicoschatting - waterkwaliteit - nederland - land van maas en waal - trace elements - metals - floodplains - lakes - pollutants - water pollution - methodology - ecology - risk assessment - water quality - netherlands
This thesis addresses the geochemical aspects of AVS (Acid Volatile Sulfide) and SEM (Simultaneously Extracted Metals) in floodplain lake sediment, its spatial distribution in floodplain lakes and dynamics over time, the link with effects on single species (bioassays), as well as the impact of excess SEM on the in situ benthic community, in one consistent methodological approach. Using this approach the SEM-AVS concept is thus evaluated on various levels from geochemical through ecotoxicology towards ecology. Furthermore, the aspect of spatial and temporal variability is addressed. For the case studies in the field, several floodplain lakes located in the floodplain area Afferdensche and Deestsche Waarden along the Waal branche of the Rhine were selected. Occasionally, this selection was extended towards other floodplain lakes along the Rhine branches. The main goal of this research is a) to explore the actual risks of trace metals to benthic communities in floodplain systems and b) to evaluate the SEM-AVS concept as a tool to assess bioavailable concentrations of trace metals in dynamic floodplain sediment
Dynamic speciation analysis and bioavailability of metals in aquatic systems
Leeuwen, H.P. van; Town, R.M. ; Buffle, J. ; Cleven, R.F.M.J. ; Davison, W. ; Puy, J. ; Riemsdijk, W.H. van; Sigg, L. - \ 2005
Environmental Science and Technology 39 (2005)22. - ISSN 0013-936X - p. 8545 - 8556.
chemische speciatie - metalen - risicoschatting - biologische beschikbaarheid - waterbodems - chemical speciation - metals - risk assessment - bioavailability - water bottoms - in-situ measurements - deposition potential sscp - anodic-stripping voltammetry - permeation liquid-membrane - association dissociation kinetics - integrated microelectrode arrays - ion-selective electrodes - lower detection limit - biotic ligand model - natural-w
Dynamic metal speciation analysis in aquatic ecosystems is emerging as a powerful basis for development of predictions of bioavailability and reliable risk assessment strategies. A given speciation sensor is characterized by an effective time scale or kinetic window that defines the measurable metal species via their labilities. Here we review the current state of the art for the theory and application of dynamic speciation sensors. We show that a common dynamic interpretation framework, based on rigorous flux expressions incorporating the relevant diffusion and reaction steps, is applicable for a suite of sensors that span a range of time scales. Interpolation from a kinetic spectrum of speciation data is proposed as a practical strategy for addressing questions of bioavailability. Case studies illustrate the practical significance of knowledge on the dynamic features of metal complex species in relation to biouptake, and highlight the limitations of equilibrium-based models.
Trace metal dynamics in methanol fed anaerobic granular sludge bed reactors
Zandvoort, M.H. - \ 2005
Wageningen University. Promotor(en): Gatze Lettinga, co-promotor(en): Piet Lens. - Wageningen : - ISBN 9085041465 - 208
anaërobe behandeling - rioolslib - metalen - sporenelementen - milieuafbraak - anaerobic treatment - sewage sludge - metals - trace elements - environmental degradation
Trace metals are essential for anaerobic microorganisms, because they are present as cofactor in many of their enzymes. Therefore anaerobic wastewater treatment systems using these microorganisms to perform biological conversions are dependent on these metals for their (optimal) performance. In practice these metals are supplied to the influent when they are absent or insufficiently present in the wastewater. This supply is generally not very rational. However, such a rational metal supply is desired in order to reduce the costs, to minimize the introduction into the environment and to maximize the biological activity. To achieve this insight, in the trace metal dynamics in anaerobic granular sludge bed reactors is required. This thesis therefore focuses on the retention, accumulation and release of trace metals in anaerobic granular sludge and the factors affecting these processes. Further the impact of metal presence/absence and dosing on the anaerobic conversion of methanol was addressed
The preparation of four biological reference materials for QUASIMEME
Leeuwen, S.P.J. van; Pieters, H. ; Boer, J. de - \ 2004
IJmuiden : RIVO (Report / RIVO-Netherlands Institute for Fisheries Research C058/04) - 18
verontreinigende stoffen - besmetters - organische verontreinigende stoffen - mossels - makrelen - marien milieu - metalen - pollutants - contaminants - organic pollutants - mussels - mackerels - marine environment - metals
Four biological materials have been prepared for use in QUASIMEME interlaboratory studies including a shrimp sample for metal analysis (QM01-1) and two mussel (QO01-3 and QO02-2) and one mackerel sample (QO02-1) for organic contaminant analysis.
Mission Report Mauritania: Consultancy on Implementation of a Shellfish Quality monitoring Programme
Poelman, M. - \ 2004
IJmuiden : RIVO (Internal report / RIVO 04.016) - 16
schaaldieren - schaal- en schelpdierenvisserij - kokkels - venus - venerupis - vistoxinen - toxinen - fytoplankton - metalen - polycyclische aromatische koolwaterstoffen - monitoring - kwaliteit - kwaliteitsnormen - europese unie - mauritanië - shellfish - shellfish fisheries - clams - fish toxins - toxins - phytoplankton - metals - polycyclic aromatic hydrocarbons - quality - quality standards - european union - mauritania
Mauritania has several commercially interesting shellfish species, such as Venus verrucosa, Venus rosalina and Venerupis dura , in her coastal waters. In order to comply with the European standards and to export these shellfish to the European market a shellfish monitoring programme for parameters such as marine phycotoxins, toxic phytoplankton, metals, Polycyclic Aromatic Hydrocarbons (PAH), metals, physical parameters, and microbiology should be set up. Therefore a mission to Mauritania took place in order to evaluate the needs and make an inventory of the lacking items with respect to a monitoring programme. IMROP (Institut Mauritanien des Recherches Océanographiques et de Pêche), DVIS (Département de Valorisation et Inspection Sanitaire) was visited for these purposes. In order to set up an adequate monitoring system legislation should be written, a monitoring programme should be designed, an Internal Quality system should be set up, and various analyses should be implemented. The implementation of these requires the input of expert knowledge and training possibilities. The needs for a successful implementation of a monitoring programme are therefore depicted in the report.
Biological recovery of metals, sulfur and water in the mining and metallurgical industry
Weijma, J. ; Copini, C.F.M. ; Buisman, C.J.N. ; Schultz, C.E. - \ 2002
In: Water Recycling and Recovery in Industry / Lens, P.N.L., Hulshoff Pol, L.W., Wilderer, P., Asano, T., London, UK : IWA Publishing - ISBN 9781843390053 - p. 605 - 622.
terugwinning - metalen - zwavel - bodemschatten - hulpbronnenbehoud - biologische technieken - biologische behandeling - mijnbouw - metallurgie - recovery - metals - sulfur - mineral resources - resource conservation - biological techniques - biological treatment - mining - metallurgy
Metals of particular interest in acid mine drainage and industrial wastewaters include copper, zinc, cadmium, arsenic, manganese, aluminum, lead, nickel, silver, mercury, chromium, uranium and iron, in a concentration that can range from 106 to 102 g/l. The composition of such wastewater reflects the particular combination of heavy metals and production process. Presently, removal by precipitation as metal hydroxide is the most widely used treatment method for water contaminated with heavy metals. This is because of the simplicity and the low costs of this method. For the same reasons, sulfate removal is mostly accomplished by precipitation with Ca2+, added as lime. However, more stringent legislation in future and an increasing scarcity of resources creates a need for heavy metal and sulfate removal technologies with a better performance. Thus, treatment processes should aim to recover valuable metals and other possible resources from waste streams such as sulfur compounds and process water. The biological reduction of sulfate to sulfide is catalysed by bacteria
Herziening LAC-signaalwaarden: op weg naar bodem-specifieke normen?
Römkens, P.F.A.M. ; Vries, W. de - \ 2001
Bodem 11 (2001)3. - ISSN 0925-1650 - p. 104 - 106.
bodem - kwaliteit - gewaskwaliteit - kwaliteitsnormen - voedselveiligheid - bodemgiftigheid - voedselkwaliteit - metalen - opname (uptake) - biologische beschikbaarheid - bodemchemie - opnamemechanismen - gewassen - methodologie - bodemverontreiniging - zware metalen - bodemkwaliteit - landbouw - milieu - soil - quality - crop quality - soil pollution - heavy metals - quality standards - food safety - soil toxicity - food quality - metals - uptake - bioavailability - soil chemistry - uptake mechanisms - crops - methodology - soil quality
De huidige LAC-signaalwaarden voor bodemkwaliteit (gehalten aan schadelijke stoffen in de bodem waarbij normen voor gewaskwaliteit worden overschreden) zijn slechts beperkt geschikt voor een locatie-specifieke risico-inschatting m.b.t. zware metalen en arseen. Een overzicht en evaluatie van gebruikte en in ontwikkeling zijnde methodieken voor de schatting van metaalgehalten in gewassen, en perspectieven voor een betere methode voor het bepalen van de locatie-secifieke bodemkwaliteit
Metal stress in free-living nematodes
Hamelijnck-Arts, M.S.J. - \ 2001
Wageningen University. Promotor(en): Jaap Bakker; Jan Kammenga. - S.l. : S.n. - ISBN 9789058085337 - 104
vrijlevende nematoden - metalen - toxicologie - merkers - heat shock eiwitten - stress - free living nematodes - metals - toxicology - markers - heat shock proteins
Terrestrial invertebrates offer meaningful targets for assessing the potential adverse effects of chemicals on soil ecosystems. Invertebrates play a major role in the functioning of the soil ecosystem by enhancing the soil structure, mineralization and the decomposition of organic material, and because of their role in the foodweb. The most dominant group of terrestrial invertebrates, in fact of all multicellular organisms on earth, are nematodes, also called threadworms or roundworms. Nematodes are usually small (0.2-2 mm), transparent and present in almost every habitat on earth. In soil, they usually occur in high abundances and the nematode community comprises a considerable species diversity (Sohlenius, 1980). Nematodes belonging to the terrestrial bacterial feeders inhabit the interstitual water of soil particles (Houx and Aben, 1993). Therefore, they are subjected directly to the dissolved fraction of contaminants in soils, apart from being subjected indirectly via the foodsource. After extraction from the soil, many of these terrestrial bacterivorous nematodes can easily be reared in the laboratory in growth media or on agar plates with bacteria as foodsource.</p><p><em>Plectus acuminatus</em> (Nematoda, Torquentia, Plectidae) Bastian 1865 is an example of such a free-living terrestrial bacterivorous nematode species, easy to rear in the laboratory. This species has an egg-to-egg period of approximately 3 weeks and a life span of about 3 months at 20°C. <em>P. acuminatus</em> appeared to be a suitable species for toxicity tests (Kammenga <em>et al.</em> , 1996) and is ubiquitous in the moderate regions of the world (e.g. in soils in the Netherlands (Bongers, 1988) and the UK (Arts, unpublished)).</p><p><em>Caenorhabditis elegans</em> (Nematoda, Secernentea, Rhabditidae) Maupas 1899 is another example of a free-living terrestrial bacterivorous nematode species. It is the most investigated nematode species in laboratory experiments that exists. <em>C. elegans</em> strain N2 has originally been extracted from soil from the area of Bristol, UK, but has not been found in Dutch soils yet. It has been reared and maintained in the laboratory for decades. <em>C. elegans</em> is homozygous and doesn't suffer from any inbreed depression. Its life-cycle is very short with an egg-to-egg period of nearly 3 days and a total life span of about 20 days at 20<FONT FACE="Symbol">°</font>C (Wood, 1988). Therefore, this nematode species is very suitable to study life-cycle traits and to perform multi-generation experiments.</p><p>The purpose of this thesis is to evaluate metal stress in free-living terrestrial bacterivorous nematodes by measuring the response on the one hand at a very low organisational level (biomarker response) and on the other hand at a high organisational level (fitness consequences at the population level after consecutive generations). The biomarker response can predict effects of toxicants on cellular function, which might lead to changes in the physiology and/or histology of an organism. These changes possibly exert effects on life-cycle traits, which could lead to changes in fitness, which might eventually lead to extinction of the population.</p><p>Biomarkers are changes at the molecular, biochemical or cellular level in organisms following exposure to pollutants (Peakall and Shugart, 1992; Deplegde and Fossi, 1994) and are usually the first detectable responses to environmental perturbation. Because these alterations underlie all effects at higher organisational levels, they can be helpful tools in ecotoxicological risk assessment.</p><p>If we select as biomarker cellular and biochemical events which are intimately involved in protecting and defending the cell from environmental insults, we have ideal candidates for biomarkers of exposure and possibly of effect (Sanders, 1990). Cells dramatically alter their gene expression in response to environmental stress, attempting to protect themselves from damage and to repair existing damage (Schlesinger <em>et al.</em> , 1982). This response is called the cellular stress response. Changes in gene expression associated with the stress response are extremely rapid and result in the induced synthesis and accumulation of stress proteins. One group of stress proteins are the heat shock proteins (hsps), first discovered upon heat exposure but later found to be induced by a wide variety of chemical, physical and biological stressors (e.g. listed in Nover, 1991 and Sanders, 1993).Hsps possibly all function as molecular chaperones (Ellis, 1987), for one, facilitating the synthesis, folding, assembly and intracellular transport of many proteins, reducing protein denaturation and aggregation and aiding in protein renaturation (e.g. Ellis and van der Vies, 1991; Parsell and Lindquist, 1993). The common signal elicited by all hsp-inducing stressors involves an abnormally high concentration of damaged/aggregated proteins within cells, a phenomenon generally referred to as 'proteotoxicity' (Hightower, 1993). Hsp biomarkers give an integrated response summarizing the total proteotoxic damage caused within the target organism or organism tissue.</p><p>Each hsp is the member of a multigene family, regulated by different promotors and coding for closely related protein isoforms (Lindquist, 1986). Based on their molecular weight, hsps can be classified into different families (Sanders, 1993). The family of 55-65 kDa is called chaperonin. The members of this family have thus far been found in eubacteria and in eukaryotic cells, almost exclusively in organelles which are probably of endosymbiotic origin (mitochondria, chloroplasts) (Hemmingsen <em>et al.</em> , 1988) designated hsp60, stress-60, cpn60, GroEL ( <em>E. coli</em> ) or RuSBP (Rubisco Subunit Binding Protein (chloroplast)). Hsp60 is a nucleus-encoded, constitutively expressed protein. Under stressfull conditions, the hsp60 expression can be dramatically increased. Together with the ubiquitous hsp70 family, which is the most highly conserved and the largest of all the hsp families, the hsp60 family has great potential as a biomarker for general stress (Sanders, 1990).</p><p>Therefore, both the hsp70 and hsp60 response were qualitatively analyzed in the nematode <em>P. acuminatus</em> (see chapter 2) in order to select the most sensitive hsp-biomarker to increasing metal concentrations. The hsp70 and hsp60 responses were studied following exposure to heat, to copper chloride and to cadmium chloride. Mini two-dimensional polyacrylamide gel electrophoresis was used for protein separation. Poly- and monoclonal antibodies raised against hsp70 or hsp60 in various organisms were used to detect the respective hsps by immunoblotting. Both hsp60 and hsp70 could be identified after exposure of the nematodes to heat, indicating the broad cross reactivity among species to the antibodies used. The induction of hsp60 in <em>P. acuminatus</em> was related to increased concentrations of cadmium and copper chloride. For copper chloride, the induction of hsp60 was 3 orders of magnitude more sensitive than was the EC20 for reproduction; for cadmium chloride, the hsp60 induction was 2 orders of magnitude more sensitive. The hsp70 response in <em>P. acuminatus</em> was also elevated after exposure of the nematodes to cadmium and copper chloride, but this response was relatively weak compared to the hsp60 response. Therefore, it was concluded that the hsp60 response may be suitable as a potential biomarker to metal stress in <em>P. acuminatus</em> .</p><p>The hsp60 response in <em>P. acuminatus</em> has been further investigated quantitatively in the laboratory, at the protein level as well as at the mRNA level after exposure to various metals (see chapter 3). The mRNA response may be more sensitive and reproducible compared to the protein response and was therefore worth considering. Both the hsp60 protein and mRNA response were measured after 24 hours of exposure to either zinc chloride (0-550<FONT FACE="Symbol">m</font>M) or copper chloride (0-59<FONT FACE="Symbol">m</font>M), the protein response also after 24 hours of exposure to cadmium chloride (0-109<FONT FACE="Symbol">m</font>M). Furthermore, we identified hsp60 in <em>P. acuminatus</em> by elucidating its full-length mRNA sequence and deduced amino acid translation and comparing this to other known sequences. After exposure of the nematodes to zinc chloride, a significant optimum curve was found for the hsp60 response at the protein level, with a maximum induction of over 8 fold the control response at a concentration of 291<FONT FACE="Symbol">m</font>M zinc chloride. Most likely, the hsp60 response increased until the ability of the heat shock system to react to increasing metal concentrations reached its climax, after which a further increase in metal concentrations resulted in a decline of the hsp60 level, which might be interpreted as a result of pathological tissue damage as described by Eckwert <em>et al</em> . (1997) concerning the hsp70 response in the isopod species <em>Oniscus asellus</em> . A significant hsp60 increase at the protein level was also detected with increasing copper chloride concentrations, but the maximum hsp60 induction was not reached within the investigated copper concentration range. When the nematodes were exposed to cadmium chloride, no significant trend was observed. At the mRNA level, in <em>P. acuminatus</em> no considerable hsp60 induction was obtained when compared to control levels and to the protein levels at the investigated metal concentration range after 24 hours of exposure. Though the variability at the hsp60 protein level in <em>P. acuminatus</em> was much higher compared to the hsp60 mRNA level, the increase upon metal exposure was much higher at the protein level and occurred at higher metal concentrations. Therefore, the hsp60 protein response in <em>P. acuminatus</em> may have more potential as a biomarker for metal stress than the hsp60 mRNA response.</p><p>In chapter 4, the application of the hsp60 protein response in <em>P. acuminatus</em> as a biomarker for metal pollution is evaluated in an in situ bio-assay in a field experiment along a metal gradient near Avonmouth, UK. Because it is impossible to determine nematodes to the species level without killing or at least heavily stressing them, <em>P. acuminatus</em> specimens were transplanted into six field sites along the metal gradient and the hsp60 protein response was measured. The response appeared to be significantly higher in the nematodes transplanted into the field site with the lowest metal concentrations compared to the other field sites. The responses of the nematodes in the other field sites did not significantly differ from each other. It can be concluded that the hsp60 response in <em>P. acuminatus</em> alone was not a suitable biomarker for heavily contaminated soils. However, this biomarker had indicative value when related to other biomarker responses measured simultaneously in the same field sites (e.g. the hsp70 response in the isopod species <em>O. asellus</em> and <em>Porcellio scaber</em> ). Furthermore, it might be a suitable biomarker for less heavily contaminated soils. This would have to be investigated in field experiments, because laboratory experiments provide no alternative.</p><p>From this thesis it can be concluded that the hsp60 response in <em>P. acuminatus</em> could be used as a biomarker for metal exposure, but with the following limitations:</p><OL><LI>An increase of the hsp60 response in the nematode indicates the presence of a proteotoxic stress factor. To identify this stress factor, additional measurements would have to be performed, e.g. chemical analyses, the application of biomarkers which identify specific stressors.</LI><LI>The hsp60 response in <em>P. acuminatus</em> is only elevated within a restricted and relatively low concentration range of the metal(s). No elevation of the response means that the stressor level is either too low or too high. The hsp60 response should always be related to other biomarker responses in order to interpret the response. This is not only important in case no elevation is measured, but also to determine where the hsp60 response should be located compared to the maximum induction value, indicating whether the response is increasing or already quenching.</LI></OL><p>The outcome of short-term toxicity studies, such as the hsp responses described in this thesis, may not be used for predicting long-term demographic effects. Because effects at the population level are mediated through effects on fitness, the change in fitness under metal stress in a multi-generation experiment is studied using the nematode <em>C. elegans</em> (chapter 5). The strong advantage of testing multiple generations instead of one generation is the detection of possible trade-off mechanisms among life-history traits and fitness consequences, thus eliciting the probable course of the final consequences of chronic metal stress on the existence of the population. A life-history model of <em>C. elegans</em> was developed to calculate fitness maximisation in populations exposed to cadmium chloride during multiple generations. It was shown that the maximum fitness of <em>C. elegans</em> depended strongly on the trade-off between sperm maturation time and juvenile development. Once <em>C. elegans</em> was exposed to cadmium chloride, fitness decreased during the first generation. After exposure of consecutive generations, fitness increased slightly but significantly compared to the first exposed generation, while various life-cycle traits were strongly affected. The life-history modelling of <em>C. elegans</em> showed that cadmium chloride decreased fitness by impairment of juvenile development. The sperm maturation time remained constant. After long-term exposure of multiple generations, <em>C. elegans</em> counteracted the effect on juveniles by growing faster and increasing reproduction and fitness. This chapter illustrates that the combination of detailed knowledge of the life-cycle and life-history modelling provides insight into the underlying mechanisms of toxicant induced life-cycle changes and fitness consequences.</p>
Conversion of methanogenic substrates in anaerobic reactors : metals, mass transport, and toxicity
Gonzalez-Gil, G. - \ 2000
Agricultural University. Promotor(en): G. Lettinga; R. Kleerebezem. - S.l. : S.n. - ISBN 9789058081896 - 157
anaërobe behandeling - methaan - slib - toxiciteit - metalen - anaerobic treatment - methane - sludges - toxicity - metals
<p>The EGSB systems represents an attractive option to extend further the use of anaerobic technology for wastewater treatment, particularly with respect to waste streams originating from chemical industries. Frequently chemical waste streams are unbalanced with respect to nutrients and/or micronutrients and furthermore these streams may contain toxic-biodegradable compounds. To reduce toxicity high recycle ratios may be applied as in the case of EGSB reactors however, this at the same time may adversely affect the substrate conversion rates due to mass transport limitations. These aspects were considered in this research. The main objectives of the work described in the thesis were to assess the kinetic impact of (i) nickel and cobalt limitations on the methanogenic degradation of methanol, (ii) the relative importance of mass transport phenomena in methanogenic granular sludge, and (iii) to characterize the toxicity and biodegradation of formaldehyde in the anaerobic conversion of methanogenic substrates. Particularly in the case of anaerobic systems, the ubiquitous presence of sulfides resulting from sulfate reduction and organic matter mineralization will lead to strong metal precipitation as metal sulfides. These precipitated metals are not directly available for the biomass. It is shown here that precipitation-dissolution kinetics of metal sulfides may play a key role in the bioavailability of essential metals.</p><p>We furthermore showed that nutrient limitations can be overcome if the essential metals are added continuously at a proper rate so that their availability in solution can fulfill the requirement for biomass activity and growth. The metal dosing rates utilized range from 0.05 to 0.2μmol/h corresponding to metal to methanol ratios of 0.1-0.4 (μmol/g methanol-COD) and these values agree well with the calculated metal requirements based on the biomass yield and Ni and Co content of methylotrophic methanogens ( <em>Methanosarcina</em> sp.) grown on methanol. With respect to mass transport phenomena, it was found that at liquid upflow velocities exceeding 1 m/h liquid-film (external) mass transfer limitations normally can be neglected for acetate degrading methanogenic granular sludge. On the contrary, a clear increase in apparent K <sub>S</sub> -value was found at increasing mean granule diameters. Herewith we have clearly shown that anaerobic biofilms can be internally transport limited. In addition we also demonstrated that substrate transport in the biofilm can be described by diffusion, and that there was no evidence of convective flow due to biogas production in the anaerobic granules. Regarding formaldehyde conversion and toxicity, we demonstrated that methanogenesis from formaldehyde mainly occurred after intermediate formation of methanol and formate.</p><p>Furthermore it was shown that the characteristics of formaldehyde toxicity were independent of the methanotrophic substrate used (methanol or acetate). Formaldehyde toxicity was in part reversible since once the formaldehyde concentration was extremely low or virtually removed from the system, the methane production rate was partially recovered. Since the degree of this recovery was not complete, we conclude that formaldehyde toxicity was also irreversible. The irreversible toxicity likely can be attributed to biomass formaldehyde-related decay. Independent of the mode of formaldehyde addition (slug or continuous), a certain amount of formaldehyde irrevocably reduced the methane production rate to a certain extent, hence the irreversible toxicity was dependent on the total amount of formaldehyde added to the system. This finding suggest that in order to treat formaldehyde containing waste streams a balance between formaldehyde-related decay and biomass growth should be attained. We furthermore showed that the biomass diversity may play a key role in the outcome of toxicity tests. Therefore we recommend that metabolic characterization of methanogenic sludge should be an integral component of toxicity studies and we describe a newly developed methodology that can be used for that purpose.</p>
Electrochemical metal speciation in natural and model polyelectrolyte systems
Hoop, M.A.G.T. van den - \ 1994
Agricultural University. Promotor(en): J. Lyklema, co-promotor(en): H.P. van Leeuwen. - S.l. : Van den Hoop - ISBN 9789054852179 - 131
metalen - elektrolyten - chemische speciatie - elektrochemie - dubbelzouten - metals - electrolytes - chemical speciation - electrochemistry - double salts
<p>The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules. In <em>chapter 1</em> a general introduction is given to (i) metal speciation in aquatic systems, (ii) (bio)polyelectrolytes and their counterion distributions and (iii) electrochemical methods emphasizing their apllication to metal speciation.<p><em>Chapter 2</em> deals with the conductometric: measurement of counterion association with macromolecules. First, we have surveyed theoretical developments concerning ion association for purely electrostatic interaction and as reflected in the conductivities of polyelectrolyte solutions. It will be shown that for the salt free case, the distribution of monovalent counterions can be obtained from plots of the molar conductivity of the polyelectrolyte solution versus the molar conductivity of the monovalent counterion, so-called Eisenberg plots. Experimental results for various alkali polymethacrylate concentrations show that the fraction of conductometrically- free monovalent counterions is in close agreement with theoretical predictions, which are based on a two-state appoach. Furthermore, for linear polyelectrolytes a recently proposed model for the case of counterion condensation in systems with ionic mixtures is presented. Finally, the treatment of conductometric data for polyelectrolyte solutions with either one type of counterion or mixtures of two types of counterions in terms of free and bound fractions is discussed.<p>In <em>chapter 3</em> we describe a voltammetric methodology for the analysis of labile homogeneous heavy metal-ligand complexes in terms of a stability <em>K</em> . The method takes into account the difference between the diffusion coefficients of the free and bound metal. Since the relationship between voltammetric current and mass transport properties under stripping voltammetric conditions is not yet well esthablished, we propose a relationship between the experimentally obtained current and the mean diffusion coefficient of the metal-complex system. A sensitivity analysis of this expression for different parameters, such as the stability and the ratio of the diffusion coefficients of the bound and free metal is performed.<p>Natural complexing agents are often heterogeneous with regard to their affinity to metal ions. Therefore, we will discuss the evaluation of the heterogeneity of these complexes from voltammetric data for various metal-to-ligand ratios. For the case of a large excess of ligand over the metal atom concentration, the stability of the metal-complex system may be obtained independently from the potential shift. For this an equation is given similar to the classical one derived by DeFord and Hume. Finally, we present an experimental procedure based on adding ligand to the solution of the metal and measuring its voltammetric characteristics. The procedure takes into account (i) possible adsorption of metal ions to elements of the equipement and (ii) measuring all protolysis of the polyacids involved.<p>The characteristic features of applying the two electrochemical techniques conductometry and voltammetry to the study of ion binding by polyelectrolytes are discussed and compared in <em>chapter 4.</em> Analysis of data on K <sup><font size="-2">+</font></SUP>/Zn(II)/polyacrylate and K <sup><font size="-2">+</font></SUP>/Zn(II)/polymethacrylate systems illustrates a certain complementary of the two methodologies. Conductometry primarily measures the Zn(II)/K <sup><font size="-2">+</font></SUP>exchange ratio. Voltammetry measures the Zn(II)/polyion binding strength; its dependence on the (excess) K <sup><font size="-2">+</font></SUP>concentration also yields information on the Zn(II)/K <sup><font size="-2">+</font></SUP>exchange ratio. The different results seem to be fairly coherent.<p>Experimental conductometric and voltammetric speciation data of metal-synthetic polyacid systems are presented and discussed in <em>chapter 5.</em> The competitive binding of monovalent and divalent counterions has been studied by the conductometric procedure described in chapter 2 for aqueous solutions of alkali metal polymethacrylates in the presence of Ca(NO <sub><font size="-2">3</font></sub> ) <sub><font size="-2">2</font></sub> and Mg(NO <sub><font size="-2">3</font></sub> ) <sub><font size="-2">2</font></sub> . The experimentally obtained fractions of conductometrically free counterions are compared with theoretical values computed according to a new thermodynamic model described in the same chapter. For the systems studied, the fractions of free monovalent and divalent counterions can be fairly well described by the theory. In fact, the results support the assumption that under the present conditions the conductometrically obtained distribution parameters <em>f <sub><font size="-2">1</font></sub></em> and <em>f <sub><font size="-2">2</font></sub></em> approximate the equilibrium fractions of free monovalent and divalent counterions. The experimentally obtained M <sup><font size="-2">+</font></SUP>/M <sup><font size="-2">2+</font></SUP>exchange ratios agree well with the theoretical ones. Similar experiments have been performed for the Zn(II)/polyacrylate and Zn(II)/polymethacrylate systems. It seems that, compared to Ca <sup><font size="-2">2+</font></SUP>and Mg <sup><font size="-2">2+</font></SUP>ions, the Zn(II)-ions are bound more strongly. This could be due to some specific binding of Zn(II)-ions. Since the theoretical model does not incorporate this mechanisme, the experimental results do not agree well with the theoretical ones.<p>Furthermore, <em>chapter 5</em> collects the results of a systematic study of the stripping voltammetric behaviour of Zn(II)- and Cd(II)-ions in polyacrylate and polymethacrylate solutions. All metal- ligand complexes involved apprear to be voltammetrically labile over the whole range of metal-to- ligand ratios under the various experimental conditions employed. Hence, the voltammetric data could be analyzed in terms of a stability <em>K</em> according to the methodology presented in chapter 3. The first set of experiments is concerned with the influence of the molar mass of the polyacrylate anion on the stability. Analysis of the data in terms of a mean diffusion coefficient, which decreases with increasing molecular mass, yields a consistent picture with molar mass- independent complex stabilities. The speciation of Zn(II) in such a polyelectrolyte system varies with the concentration of carboxylate groups, but it is invariant with the polyionic molar mass. Secondly, the competition between monovalent (K <sup><font size="-2">+</font></SUP>) and divalent (Zn(II) and Cd(II)) counterions has been investigated by varying the concentration of electroinactive supporting electrolyte. The results show that the stability of the heavy metal/polymethacrylate complex decreases with increasing KNO <sub><font size="-2">3</font></sub> concentration. This effect is largely due to the reduction of the electrostatic component of the metal/polyanion interaction, which is generally the case for polyelectrolytes with high charge densities. For the Zn(II)/polymethacrylate system, a comparison with conductometric data representing the competitive behaviour of monovalent and divalent counterions has been made in chapter 4. The influence of the polyelectrolyte charge density of the polymethacrylic acid on the stability <em>K</em> has been studied by varying the degree of neutralization of the polyanion. For the Zn(II)/PMA complexes, the stability increases approximately linearly with increasing degree of neutralization, i.e. with increasing polyionic charge density. This is in accordance with the general polyelectrolytic feature that counterion binding is stronger with higher polyionic charge density. Finally, for later comparison with natural complexing agents, the chemical homogeneity of the macromolecules involved has been verified by varying the total metal ion concentration for a given polyelectrolyte concentration. The results indeed confirm that the Zn(II)/polymethacrylate and Cd(II)/polymethacrylate complexes have a homogeneous energy distribution. This is in line with expectation, since these macromolecules consist of only one repeating chemical binding site, i.e. the carboxylate group.<p>Chapter 6 deals with the pretreatment and characterization of humic material. The pretreatment procedure is used to purify the humic material in such a way that (i) the molecules are soluble under the experimental conditions employed in chapter 7, (ii) the amount of impurities is minimized and (iii) the resulting humic material is transferred into the acid form. Furthermore, a fractionation method based on the solubility of the humic substances is described. The humic material is characterized in terms of (i) the amount of chargeable groups by means of conductometric titration and (ii) molar mass distribution by flow field-flow-fractionation. It will be shown that although the fractionation by varying pH results in samples with different molar masses, the separation is far from ideal.<p>As was done with the synthetic polyacids, experiments have been performed for natural occuring polyelectrolytes. Conductometric and voltammetric results forvarious metal humic acid systems are presented in chapter 7. Solutions of humic acids were conductometrically titrated with potassium, sodium, lithium, calcium and barium hydroxide solutions. The results have been analyzed in terms of fractions of free and bound metal. The conductance properties of humic acids are basically different from those of a linear polyelectrolyte such as polymethacrylate. A marked difference was observed between the shapes of the curves for alkali metal hydroxides and those for alkaline earth metal hydroxides. It appears that monovalent cations are hardly bound by the humate polyion, whereas divalent counterions show a strong interaction. The latter feature may be fruitfully utilized in quantitative analysis.<p>The association of the heavy metals zinc(II) and cadmium(II) with humic acid samples has been furthere studied by differential pulse anodic stripping voltammetry (i) for various concentrations of supporting electrolyte (KNO <sub><font size="-2">3</font></sub> and Ca(NO <sub><font size="-2">3</font></sub> ) <sub><font size="-2">2</font></sub> ), (ii) for different degrees of neutralization of the humate polyion, (iii) for different metal-to-ligand ratios and (iv) for different fractions of the humic acid. Under the experimental conditions employed, all heavy metal/humate complexes have been found to be voltammetrically labile over the whole range of metal-to-ligand ratios. Hence, the stability <em>(K)</em> of the complex could be computed taking into account the difference between the diffusion coefficients of the free and bound metal. The dependence of <em>K</em> on the concentration of 1-1 electrolyte (KNO <sub><font size="-2">3</font></sub> ) is of comparable extent for various metal-humate complexes, but significantly smaller than in the case of the highly charged linear polyelectrolyte polymethacrylic acid. For the humic acid systems, it has been concluded that the relatively weak dependency of <em>K</em> on the salt concentration mainly reflects screening effects. The influence of the concentration of 2-1 electrolyte (Ca(NO <sub><font size="-2">3</font></sub> ) <sub><font size="-2">2</font></sub> ) on the stability of the heavy metal/humate complex is more pronounced than for the corresponding case of 1-1 electrolyte. By taking into account the association of calcium with the humate polyion, the stability of the heavy metal/humate complex was found to be more or less constant over the range of Ca(NO <sub><font size="-2">3</font></sub> ) <sub><font size="-2">2</font></sub> concentrations studied and comparable to the stability of the corresponding complex in the absence of calcium.<p>The stability of the heavy metal/humate complex has been found to increase with increasing degree of neutralization, i.e. with increasing charge density of the humate polyion. It seemed that the increase of <em>K</em> is less pronounced for higher values of α <sub><font size="-2">n</font></sub> . This observation could not be interpreted from an electrostatic point of view, and is in fact a further indication that the binding of heavy metals with the humate polyion is mainly governed by the chemical characteristics of the humic acid. The chemical heterogeneity of the humic acids was investigated by varying the metal-to-ligand ratio for different total concentrations of the heavy metals but in a range of comparable ligand concentrations. The results show that the stability <em>K</em> of the heavy metal/humate complex decreases with increasing total metal ion concentration, reflecting a certain chemical heterogeneity of the humic acid. For various heavy metal/fractionated humate complexes, the stability <em>K</em> was found to be comparable to the <em>K</em> value for the corresponding unfractionated humic acid system. This means that the distribution of functional groups is more or less the same for different molar masses of the humic acid.<p>For the present metal/humate complexes, the general conclusion is that the distribution of counterions over the free and bound states is mainly governed by the chemical heterogeneity of the humate polyion.
The influence of the form of nitrogen nutrition on uptake and distribution of cadmium in lettuce varieties.
Florijn, P.J. ; Nelemans, J.A. ; Beusichem, M.L. van - \ 1992
Journal of Plant Nutrition 15 (1992). - ISSN 0190-4167 - p. 2405 - 2416.
assimilatie - cadmium - cultivars - groeikamers - lactuca sativa - slasoorten - vloeibare kunstmeststoffen - metalen - stikstof - rassen (taxonomisch) - bodemaciditeit - bodem ph - rassen (planten) - assimilation - growth chambers - lettuces - liquid fertilizers - metals - nitrogen - races - soil acidity - soil ph - varieties
Detectie van verschillende metalen met grafietoven atoom absorptie spectrometrie en Zeeman achtergrond correctie
Wolters, T.C. ; Tuinstra, L.G.M.Th. - \ 1991
Wageningen : RIKILT (Rapport / RIKILT 91.13) - 26
metalen - grafiet - vuurhaarden - atomaire absorptiespectrometrie - metals - graphite - furnaces - atomic absorption spectrometry
Doel van het onderzoek is om vast te stellen wat de optimale verassings- en atomisatietemperaturen van aluminium, cadmium, chroom, cobalt, koper, lood en nikkel. Daarnaast is de herhaalbaarheid vastgesteld van het injectiesysteem bij verschillende injectievolumina en bij meervoudige injecties.
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