426 results on '"metalen"'
Search Results
152. Sulfate reduction under acidic conditions for selective model recovery
- Author
-
Buisman, Cees, Lens, Piet, Bijmans, M.F.M., Buisman, Cees, Lens, Piet, and Bijmans, M.F.M.
- Abstract
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
- Published
- 2008
153. Metal supplementation to anaerobic granular sludge bed reactors: an environmental engineering approach
- Author
-
van Lier, Jules, Lens, Piet, Gonzalez Fermoso, F., van Lier, Jules, Lens, Piet, and Gonzalez Fermoso, F.
- Abstract
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
- Published
- 2008
154. Metalen in drinkwater
- Author
-
Groenendijk, M., Tielemans, M., Slaats, N., Groenendijk, M., Tielemans, M., and Slaats, N.
- Abstract
Het onderwerp 'risico op verontreiniging van drinkwater door metalen tijdens de productie en/of distributie' leeft, zo bleek ook weer tijdens het internationale congres METEAU in Antalya (Turkije), dat in het najaar van 2007 werd gehouden. Ongeveer 130 deelnemers uit 17 landen waren daar aanwezig om ervaringen uit te wisselen over metalen in drinkwater. Het congres werd georganiseerd met financiële steun van de Europese Unie. Vanuit Nederland waren vertegenwoordigers van DZH, Brabant Water, het ministerie van VROM en Kiwa Water Research aanwezig om een toelichting te geven op metalen in drinkwater, leidingmaterialen en het conditioneren van drinkwater met als doel om corrosie te voorkomen
- Published
- 2008
155. Eerste inventarisatie van gemeten concentraties lood, koper, nikkel en chroom in de drinkwater
- Author
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Slaats, N., Blokker, M., Versteegh, A., Slaats, N., Blokker, M., and Versteegh, A.
- Abstract
In 2004 zijn de Nederlandse waterbedrijven begonnen met het zogeheten Random Day Time bemonsteren van de metalen lood, koper, nikkel en chroom aan de tap. Om inzicht te krijgen in de voorkomende concentraties van deze metalen bij de consument heeft Kiwa Water Research de individuele meetwaarden geanalyseerd. Lood, koper en nikkel komen voor in concentraties die hoger zijn dan de geldende normwaarden voor de weekgemiddelden. Voor lood geldt dat dit voornamelijk het geval is in gebieden waarvan bekend is dat daar een relatief groot aantal panden met loden leidingen voorkomt. Het aantal meetwaarden voor koper en nikkel dat hoger ligt dan de normwaarde, bedraagt maximaal 0,8 procent. Daarnaast blijkt dat het begrip Random Day Time in de praktijk niet echt een meting willekeurig over de dag is. De resultaten die beschreven zijn in dit artikel, leveren stof voor de discussie over de invulling voor de monitoring van lood, koper, nikkel en chroom in drinkwater
- Published
- 2008
156. Worden in 2027 de doelen voor stoffen gehaald in rijkswateren?
- Author
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Engelbertink, R., Driesprong, A., Ven, K. van de, Roovaart, J. van den, Engelbertink, R., Driesprong, A., Ven, K. van de, and Roovaart, J. van den
- Abstract
Aan de hand van prognoses van binnenlandse emissies en buitenlandse vrachten zijn met de KRW-verkenner inschattingen gemaakt van de chemische toestand van rijkswateren in 2015 en 2030. 2030 staat representatief voor 2027, het uiterste jaar waarin de KRW doelbereik acceptabel acht. Dit project is in twee opzichten uniek: voor het eerst zijn op landelijke schaal zoete en zoute rijkswateren in één model gezet. Daarnaast is gebruik gemaakt van berekeningen van het voormalige Milieu- en NatuurPlanbureau in regionale wateren, die zijn doorvertaald naar concentraties in rijkswateren. Uit de analyses blijkt dat nutriëntengehalten bij uitvoering van huidig beleid al significant zullen afnemen ten opzichte van de huidige situatie. Voor tweederde van de zoete rijkswateren zijn daarmee de ecologische doelen voor 2027 binnen bereik. Aanvullende maatregelen hebben nauwelijks extra effect, behalve het op brede schaal inzetten van helofytenfilters en natuurvriendelijke oevers. Ook een variant waarbij alle buitenlandse en regionale wateren aan hun eigen gestelde doelstelling voldoen, levert nog extra reductie. Voor de stroomgebieden Maas en Schelde dalen in 2030 de gehalten van zink, cadmium en koper in rijkswater met respectievelijk 10, 20 en 25 procent. De gehalten voor PAK's dalen hier 15 tot 20 procent. In de stroomgebieden van Rijn en Eems dalen de gehalten van de overige stoffen minder hard
- Published
- 2008
157. Vergeten metalen in de Rijkswateren: meten we de goede stoffen?
- Author
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Osté, L., Epema, O., Schrap, M., Beek, M., Osté, L., Epema, O., Schrap, M., and Beek, M.
- Abstract
Metalen zijn belangrijke probleemstoffen in de Nederlandse oppervlaktewateren. Van veel metalen is de invloed op de waterkwaliteit onbekend. Inzicht in de niet-gangbare metalen is echter wel belangrijk, omdat het bereiken van een ‘goede ecologische toestand’ van de oppervlaktewateren in 2015, zoals de Kaderrichtlijn Water (KRW) voorschrijft, mede afhankelijk is van de chemische kwaliteit van het water. Rijkswaterstaat heeft gedurende een aantal jaren een veel breder pakket aan metalen gemeten. Op basis van concentraties in gefiltreerde watermonsters en toxiciteitsgegevens uit de literatuur is een eerste prioritering gemaakt van het milieurisico van metalen. De gemeten concentraties laten zien dat de Rijn voor de onbekendere metalen zeker niet schoner is dan de Maas. De Schelde bevat meestal de hoogste concentraties. De eindscores geven aan dat van de gangbare metalen alleen koper de top 5 haalt. De andere stoffen zijn strontium, selenium, boor en lithium
- Published
- 2008
158. Bodegraven, Oud Bodegraafseweg/Overtocht : inventariserend veldonderzoek door middel van proefsleuven
- Author
-
Habraken, J., Mousch, R. van, J. Habraken, R. van Mousch, and BAAC
- Subjects
bewoning ,prospectie ,Romeinse tijd ,Archaeology ,aardewerk ,Houtresten ,Middeleeuwen ,Nieuwe tijd ,Metalen ,archeologie ,Castella - Abstract
Lit.opg.
- Published
- 2004
159. Een archeologisch inventariserend veldonderzoek (IVO) door middel van boringen en proefsleuven bij het plangebied 't Slot Noord te Bergambacht, gemeente Bergambacht (Z.-H.)
- Author
-
Tuinstra, S.J., Vanden Borre, J., Bosma, K.L.B., Buitenhuis, Hijlke, Koopstra, C.G., S.J. Tuinstra, met bijdragen van J. Vanden Borre, K.L.B. Bosma, H. Buitenhuis & C.G. Koopstra, and Archaeological Research & Consultancy
- Subjects
prospectie ,Archaeology ,aardewerk ,Been ,Nieuwe tijd ,kastelen ,Metalen ,Late middeleeuwen ,archeologie - Abstract
Lit.opg.
- Published
- 2004
160. Transmission electron microscopy studies of interfaces in multi-component systems
- Author
-
Mogck, Stefan, de Hosson, Jeff, and Kooi, Bart
- Subjects
Grenslagen ,33.68 ,Oxiden ,Elektronenmicroscopie ,Ab initio berekeningen ,Proefschriften (vorm) ,Metalen - Abstract
In order to understand the bonding between metals and oxides, interfaces were studied with high-resolution transmission electron microscoy, analytical TEM' in-situ experiments down to an atomic scale and first-principles Density Functional Theory (DFT) calculations. It was possible to combine HRTEM observations with the analysis of the chemical composition within one monolayer at the metal-oxide interfaces. With in-situ experiments, a detailed visualization of order-disorder transitions on an atomic scale at metal-oxide interfaces could be realized. A computer code was developed to relate HRTEM observations to charge transfer (ionicity) and charge redistribution along metal- oxide interfaces. The interfaces of interest were fabricated by internal oxidation to obtain many small oxide precipitates inside a metal matrix. This method produces many clean interfaces for investigations in each sample and such internally oxidized samples are easy to prepare for transmission electron microscopy
- Published
- 2004
161. Archeologisch onderzoek bij Zorgcentrum Oldershove te Wehl, een vervolg
- Author
-
Prangsma, N.M., Bloo, S.B.C., Chijs, F.A. van der, Hoss, S., Reigersman-van Lidt de Jeude, W.F., N.M. Prangsma, met bijdragen van: S.B.C. Bloo ... [et al.], and ADC ArcheoProjecten
- Subjects
prospectie ,Romeinse tijd ,Archaeology ,aardewerk ,Ovens ,Bouwmaterialen ,nederzettingen ,Vroege Middeleeuwen ,slakken ,Metalen ,archeologie - Abstract
Lit.opg.
- Published
- 2004
162. Transmission electron microscopy studies of interfaces in multi-component systems
- Subjects
Grenslagen ,33.68 ,Oxiden ,Elektronenmicroscopie ,Ab initio berekeningen ,Proefschriften (vorm) ,Metalen - Abstract
In order to understand the bonding between metals and oxides, interfaces were studied with high-resolution transmission electron microscoy, analytical TEM' in-situ experiments down to an atomic scale and first-principles Density Functional Theory (DFT) calculations. It was possible to combine HRTEM observations with the analysis of the chemical composition within one monolayer at the metal-oxide interfaces. With in-situ experiments, a detailed visualization of order-disorder transitions on an atomic scale at metal-oxide interfaces could be realized. A computer code was developed to relate HRTEM observations to charge transfer (ionicity) and charge redistribution along metal- oxide interfaces. The interfaces of interest were fabricated by internal oxidation to obtain many small oxide precipitates inside a metal matrix. This method produces many clean interfaces for investigations in each sample and such internally oxidized samples are easy to prepare for transmission electron microscopy
- Published
- 2004
163. The preparation of four biological reference materials for QUASIMEME
- Subjects
marine environment ,organic pollutants ,metalen ,organische verontreinigende stoffen ,metals ,mossels ,RIVO Milieu en Voedselveiligheid ,makrelen ,mussels ,pollutants ,mackerels ,contaminants ,marien milieu ,besmetters ,verontreinigende stoffen - Abstract
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.
- Published
- 2004
164. Stress and dislocations in thin metal layers
- Subjects
Vervorming ,Dunne films ,Proefschriften (vorm) ,Plasticiteit ,Metalen - Abstract
According to experimental findings there are types of loading for which it is more difficult to plastically deform small metal structures than the corresponding massive metal. This occurs when at least one of the dimensions of the structure is at the micrometer scale or smaller. It is for instance the case of thin metal coatings: the thinner is the film, the more difficult it is to deform it plastically. This feature is in contrast with what expected on the basis of classical plasticity theories, which predict a size-independent mechanical response. In this thesis the size effect in thin films is studied by means of two-dimensional discrete dislocation plasticity. Plasticity is treated as the collective motion of edge dislocations on prescribed slip systems. The framework contains an intrinsic length scale- the dislocation Burgers vector- which is a necessary condition to capture a size effect. ... Zie: Summary
- Published
- 2004
165. Archeologisch onderzoek bij Zorgcentrum Oldershove te Wehl, een vervolg
- Subjects
prospectie ,Romeinse tijd ,Archaeology ,aardewerk ,Ovens ,Bouwmaterialen ,nederzettingen ,Vroege Middeleeuwen ,slakken ,Metalen ,archeologie - Abstract
Lit.opg.
- Published
- 2004
166. Een archeologisch inventariserend veldonderzoek (IVO) door middel van boringen en proefsleuven bij het plangebied 't Slot Noord te Bergambacht, gemeente Bergambacht (Z.-H.)
- Subjects
prospectie ,Archaeology ,aardewerk ,Been ,Nieuwe tijd ,kastelen ,Metalen ,Late middeleeuwen ,archeologie - Abstract
Lit.opg.
- Published
- 2004
167. Aanvullende archeologische inventarisatie 2 Westerhage te Rijnsburg
- Author
-
Huizer, J., Linden, B.A. van der, Plasmeijer, D.D.F., J. Huizer, B.A. van der Linden, D.D.F. Plasmeijer, and Synthegra
- Subjects
prospectie ,Archaeology ,aardewerk ,Nieuwe tijd ,Metalen ,archeologie - Abstract
Projectnr.: 173161.
- Published
- 2004
168. Mission Report Mauritania: Consultancy on Implementation of a Shellfish Quality monitoring Programme
- Author
-
Poelman, M.
- Subjects
vistoxinen ,metalen ,clams ,polycyclic aromatic hydrocarbons ,metals ,venus ,schaal- en schelpdierenvisserij ,fytoplankton ,toxinen ,kwaliteit ,Netherlands Institute for Fisheries Research ,european union ,shellfish fisheries ,toxins ,fish toxins ,polycyclische aromatische koolwaterstoffen ,europese unie ,mauritanië ,mauritania ,monitoring ,shellfish ,venerupis ,kwaliteitsnormen ,kokkels ,quality ,Rijksinstituut voor Visserijonderzoek ,phytoplankton ,schaaldieren ,quality standards - Abstract
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.
- Published
- 2004
169. The preparation of four biological reference materials for QUASIMEME
- Author
-
van Leeuwen, S.P.J., Pieters, H., and de Boer, J.
- Subjects
marine environment ,organic pollutants ,metalen ,organische verontreinigende stoffen ,metals ,mossels ,RIVO Milieu en Voedselveiligheid ,makrelen ,mussels ,pollutants ,mackerels ,contaminants ,marien milieu ,besmetters ,verontreinigende stoffen - Abstract
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.
- Published
- 2004
170. Stress and dislocations in thin metal layers
- Subjects
Vervorming ,Dunne films ,Proefschriften (vorm) ,Plasticiteit ,Metalen - Abstract
According to experimental findings there are types of loading for which it is more difficult to plastically deform small metal structures than the corresponding massive metal. This occurs when at least one of the dimensions of the structure is at the micrometer scale or smaller. It is for instance the case of thin metal coatings: the thinner is the film, the more difficult it is to deform it plastically. This feature is in contrast with what expected on the basis of classical plasticity theories, which predict a size-independent mechanical response. In this thesis the size effect in thin films is studied by means of two-dimensional discrete dislocation plasticity. Plasticity is treated as the collective motion of edge dislocations on prescribed slip systems. The framework contains an intrinsic length scale- the dislocation Burgers vector- which is a necessary condition to capture a size effect. ... Zie: Summary
- Published
- 2004
171. Stress and dislocations in thin metal layers
- Author
-
Nicola, Lucia, van der Giessen, Erik, and Faculty of Science and Engineering
- Subjects
Vervorming ,Dunne films ,Proefschriften (vorm) ,Plasticiteit ,Metalen - Abstract
According to experimental findings there are types of loading for which it is more difficult to plastically deform small metal structures than the corresponding massive metal. This occurs when at least one of the dimensions of the structure is at the micrometer scale or smaller. It is for instance the case of thin metal coatings: the thinner is the film, the more difficult it is to deform it plastically. This feature is in contrast with what expected on the basis of classical plasticity theories, which predict a size-independent mechanical response. In this thesis the size effect in thin films is studied by means of two-dimensional discrete dislocation plasticity. Plasticity is treated as the collective motion of edge dislocations on prescribed slip systems. The framework contains an intrinsic length scale- the dislocation Burgers vector- which is a necessary condition to capture a size effect. ... Zie: Summary
- Published
- 2004
172. Transmission electron microscopy studies of interfaces in multi-component systems
- Subjects
Grenslagen ,33.68 ,Oxiden ,Elektronenmicroscopie ,Ab initio berekeningen ,Proefschriften (vorm) ,Metalen - Abstract
In order to understand the bonding between metals and oxides, interfaces were studied with high-resolution transmission electron microscoy, analytical TEM' in-situ experiments down to an atomic scale and first-principles Density Functional Theory (DFT) calculations. It was possible to combine HRTEM observations with the analysis of the chemical composition within one monolayer at the metal-oxide interfaces. With in-situ experiments, a detailed visualization of order-disorder transitions on an atomic scale at metal-oxide interfaces could be realized. A computer code was developed to relate HRTEM observations to charge transfer (ionicity) and charge redistribution along metal- oxide interfaces. The interfaces of interest were fabricated by internal oxidation to obtain many small oxide precipitates inside a metal matrix. This method produces many clean interfaces for investigations in each sample and such internally oxidized samples are easy to prepare for transmission electron microscopy
- Published
- 2004
173. Mission Report Mauritania: Consultancy on Implementation of a Shellfish Quality monitoring Programme
- Subjects
vistoxinen ,metalen ,clams ,polycyclic aromatic hydrocarbons ,metals ,venus ,schaal- en schelpdierenvisserij ,fytoplankton ,toxinen ,kwaliteit ,Netherlands Institute for Fisheries Research ,european union ,shellfish fisheries ,toxins ,fish toxins ,polycyclische aromatische koolwaterstoffen ,europese unie ,mauritanië ,mauritania ,monitoring ,shellfish ,venerupis ,kwaliteitsnormen ,kokkels ,quality ,Rijksinstituut voor Visserijonderzoek ,phytoplankton ,schaaldieren ,quality standards - Abstract
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.
- Published
- 2004
174. Archeologisch onderzoek te Dronrijp, gemeente Menaldumadeel (Fr.)
- Subjects
IJzertijd ,bewoning ,Romeinse tijd ,Archaeology ,aardewerk ,Veeteelt ,Metalen ,archeologie ,terpen - Abstract
Lit.opg.
- Published
- 2003
175. Archeologisch onderzoek te Dronrijp, gemeente Menaldumadeel (Fr.)
- Author
-
Hielkema, J.B., Halici, H., Koopstra, C.G., Ufkes, A., Vos, P.C., J.B. Hielkema, met bijdragen van H. Halici ... [et al.], and Archaeological Research & Consultancy
- Subjects
IJzertijd ,bewoning ,Romeinse tijd ,Archaeology ,aardewerk ,Veeteelt ,Metalen ,archeologie ,terpen - Abstract
Lit.opg.
- Published
- 2003
176. Grauwsluiers en biobeschikbaarheid : hoog totaalgehalte, lage blootstelling aan metalen
- Author
-
Gestel, C.A.M. van and Gestel, C.A.M. van
- Abstract
Om een beeld te verkrijgen van het risico van verhoogde metaalgehalten in de Biesbosch, de Afferdense en Deestsche Waarden en de Ronde Venen, is op deze locaties nader onderzoek verricht naar de beschikbaarheid van metalen voor organismen
- Published
- 2006
177. Trace metals in floodplain lake sediments : SEM/AVS as indicator of bioavailability and ecological effects
- Author
-
Koelmans, Bart, van Griethuysen, C., Koelmans, Bart, and van Griethuysen, C.
- Abstract
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
- Published
- 2006
178. Biotic Ligand-modellen in lijn met KRW
- Author
-
Vijver, M., Peijnenburg, W., Koning, A. de, Vijver, M., Peijnenburg, W., and Koning, A. de
- Abstract
Recent is door onderzoekers het Biotic Ligand-model geïntroduceerd als alternatief voor de totaal opgeloste concentratie aan metalen. Het model (BLM) voorspelt de binding van het metaal aan aquatische organismen, rekening houdend met de verschijningsvorm van het metaal, binding van andere ionen aan het organisme en gevoeligheid van het organisme. Het gebruik van BLM maakt watertype-afhankelijke effectvoorspelling van metalen mogelijk. Een accurate effectvoorspelling geeft meer inzicht in hoe voldaan kan worden aan de KRW-eisen. Of de implementatie van deze nieuwe kennis een verfijning oplevert in de effectvoorspelling voor de Nederlandse oppervlaktewateren is hier uitgewerkt
- Published
- 2006
179. De waterhuishouding van Corus : 'herbezinning op watergebruik nodig' [thema proceswater]
- Author
-
Gast, M. and Gast, M.
- Abstract
Aanrijden op de Corusvestiging in IJmuiden, het vroegere Hoogovens, langs de zuidoever van het Noordzeekanaal, is telkens weer een belevenis: het silhouet van de diverse staalfabrieken, de pluimen van witte stoom, de brandende gasvlam, 's avonds de zee van lichtjes. Daarvoor het sluizencomplex aan de mond van het Noordzeekanaal met de bedrijvigheid op het water aan weerskanten. Een bedrijf dat zich bewust op die plek, direct aan de Noordzee, gevestigd heeft in verband met de aanvoer van grondstoffen, de afvoer van producten naar het achterland, - 85 procent van de afzet vindt plaats naar de Europese markt, inclusief Nederland -, èn de beschikbaarheid van water, veel water. Over de vraag wat Corus allemaal met water en afvalwater doet, welke zorgen het bedrijf op dit punt heeft en welke verwachtingen er voor de toekomst zijn, ditmaal niet een gesprek met één man, maar met drie: Antoine van Hoorn, seniorconsultant water en afvalwater van de afdeling Environmental Management, Pascal Bonte, manager demiwater en Mark de Haan, manager water, beide van de afdeling Energiebedrijf
- Published
- 2006
180. Dynamics of microstructures in metal sheets
- Subjects
Structuuranalyse ,51.50 ,Microstructuur ,Proefschriften (vorm) ,Microscopie ,Metalen - Published
- 2002
181. Biological recovery of metals, sulfur and water in the mining and metallurgical industry
- Subjects
inorganic chemicals ,WIMEK ,zwavel ,metallurgy ,biologische technieken ,metalen ,mijnbouw ,biological techniques ,metals ,mining ,metallurgie ,resource conservation ,recovery ,terugwinning ,sulfur ,biologische behandeling ,Environmental Technology ,Milieutechnologie ,biological treatment ,mineral resources ,bodemschatten ,hulpbronnenbehoud - Abstract
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
- Published
- 2002
182. IJsselstein Lage Dijk N210
- Author
-
Bulten, E.E.B., Bloo, S.B.C., Chijs, F.F.A. van der, Dijk, A.M. van, Dijk, J. van, Haaster, H. van, Hanraets, A.E.M., Kars, E.A.K., Nooijen, C., Rijn, P. van, Wiepking, C.G., Zijverden, Wilko K. van, E.E.B. Bulten, met bijdragen van S.B.C. Bloo ... [et al.], and Archeologisch Diensten Centrum
- Subjects
IJzertijd ,Archeobotanie ,Romeinse tijd ,Natuursteen ,Archaeology ,aardewerk ,archeozoologie ,nederzettingen ,Metalen ,archeologie - Abstract
Lit.opg.
- Published
- 2002
183. Aanvullende archeologische inventarisaties West Maas en Waal, 2001: bestemmingsplan De Ret, Beneden-Leeuwen
- Subjects
IJzertijd ,Houtskool ,prospectie ,Romeinse tijd ,Archaeology ,aardewerk ,Been ,nederzettingen ,Metalen ,archeologie - Abstract
Lit.opg. en verklarende woordenlijst.
- Published
- 2002
184. Het erfgoed van Eigenblok : bewoningssporen uit de Bronstijd te Geldermalsen
- Author
-
Jongste, P.F.B., Wijngaarden, G.J. van, Bloo, S.B.C., Brinkkemper, Otto, Cuijpers, A.F.G.M., Dijk, J. van, Gijn, Annelou van, Gijssel, K. van, Haaster, H. van, Hielkema, J.B., Kars, E.A.K., Kolen, J., Kroft, P. van der, Prangsma, N.M., Rijn, P. van, Robb, J.E., Schelvis, J., Schouten, W., Schreurs, J., medewerker, Smit, S., Verbauwen, E.C., Vermeeren, C., Verneau, S., Zijverden, Wilko K. van, Onder red. van P.F.B. Jongste en G.J. van Wijngaarden, met bijdragen van S.B.C. Bloo ... [et al.], and Rijksdienst voor het Oudheidkundig Bodemonderzoek
- Subjects
Steen ,Archeobotanie ,Archaeology ,aardewerk ,archeozoologie ,Fosfaatmethode ,nederzettingen ,Gebouwsporen ,Fysische antropologie ,Bronstijd ,Metalen ,archeologie - Abstract
Boventitel: Archeologie in de Betuweroute. - Ondertitel op voorpag.: nederzettingsterreinen uit de Bronstijd te Rumpt (gemeente Geldermalsen).
- Published
- 2002
185. Electrical spin injection in metallic mesoscopic spin valves
- Author
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Jedema, Friso, van Wees, Bart, and Physics of Nanodevices
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Elektronspin ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,Proefschriften (vorm) ,33.71 ,Metalen ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) - Published
- 2002
186. Electrical spin injection in metallic mesoscopic spin valves
- Subjects
Elektronspin ,Proefschriften (vorm) ,33.71 ,Metalen - Published
- 2002
187. Boeren, erven, graven : de boerengemeenschap van De Bogen bij Meteren (2450-1250 v. Chr.)
- Author
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Meijlink, B.H.F.M., Kranendonk, P., Bloo, S.B.C., Brokke, A.J., Butler, J.J., Dijk, J. van, Esser, E., Exaltus, R., Gijn, Annelou van, Haaster, H. van, Hänninen, K., Hielkema, J.B., Kars, E.A.K., Lammers-Keijsers, Niekus, Marcel J.L.Th., Robb, J.E., Schreurs, J., Smit, S., Ufkes, A., Verbauwen, E.C., Zeiler, Jørn T., Zijverden, Wilko K. van, Onder red. van B.H.F.M. Meijlink en P. Kranendonk, met bijdragen van S.B.C. Bloo ... [et al.], and Rijksdienst voor het Oudheidkundig Bodemonderzoek
- Subjects
bewoning ,Archeobotanie ,Natuursteen ,Neolithicum ,archeozoologie ,Fysische antropologie ,Vuursteen ,Begraving ,landbouw ,Archaeology ,aardewerk ,Bronstijd ,Metalen ,archeologie - Abstract
Boventitel: Archeologie in de Betuweroute.
- Published
- 2002
188. Dynamics of microstructures in metal sheets
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Structuuranalyse ,51.50 ,Microstructuur ,Proefschriften (vorm) ,Microscopie ,Metalen - Published
- 2002
189. Biological recovery of metals, sulfur and water in the mining and metallurgical industry
- Author
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Weijma, J., Copini, C.F.M., Buisman, C.J.N., and Schultz, C.E.
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inorganic chemicals ,WIMEK ,zwavel ,metallurgy ,biologische technieken ,metalen ,mijnbouw ,biological techniques ,metals ,mining ,metallurgie ,resource conservation ,recovery ,terugwinning ,sulfur ,biologische behandeling ,Environmental Technology ,Milieutechnologie ,biological treatment ,mineral resources ,bodemschatten ,hulpbronnenbehoud - Abstract
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
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- 2002
190. Aanvullende archeologische inventarisaties West Maas en Waal, 2001: bestemmingsplan De Ret, Beneden-Leeuwen
- Author
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Wilgen, L.R. van, L.R. van Wilgen, and SOB Research
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IJzertijd ,Houtskool ,prospectie ,Romeinse tijd ,Archaeology ,aardewerk ,Been ,nederzettingen ,Metalen ,Beneden-Leeuwen ,archeologie - Abstract
Lit.opg. en verklarende woordenlijst.
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- 2002
191. Boeren, erven, graven : de boerengemeenschap van De Bogen bij Meteren (2450-1250 v. Chr.)
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bewoning ,Archeobotanie ,Natuursteen ,Neolithicum ,archeozoologie ,Fysische antropologie ,Vuursteen ,Begraving ,landbouw ,Archaeology ,aardewerk ,Bronstijd ,Metalen ,archeologie - Abstract
Boventitel: Archeologie in de Betuweroute.
- Published
- 2002
192. Electrical spin injection in metallic mesoscopic spin valves
- Subjects
Elektronspin ,Proefschriften (vorm) ,33.71 ,Metalen - Published
- 2002
193. Aanvullend archeologisch onderzoek (AAO) van terpen in het gasleidingstracé Hemert-Arum, gemeente Wûnseradiel (Fr.)
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IJzertijd ,Archeobotanie ,Romeinse tijd ,Natuursteen ,Archaeology ,aardewerk ,Middeleeuwen ,Metalen ,fauna ,archeologie ,terpen - Abstract
Lit.opg.
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- 2002
194. IJsselstein Lage Dijk N210
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IJzertijd ,Archeobotanie ,Romeinse tijd ,Natuursteen ,Archaeology ,aardewerk ,archeozoologie ,nederzettingen ,Metalen ,archeologie - Abstract
Lit.opg.
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- 2002
195. Het erfgoed van Eigenblok : bewoningssporen uit de Bronstijd te Geldermalsen
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Steen ,Archeobotanie ,Archaeology ,aardewerk ,archeozoologie ,Fosfaatmethode ,nederzettingen ,Gebouwsporen ,Fysische antropologie ,Bronstijd ,Metalen ,archeologie - Abstract
Boventitel: Archeologie in de Betuweroute. - Ondertitel op voorpag.: nederzettingsterreinen uit de Bronstijd te Rumpt (gemeente Geldermalsen).
- Published
- 2002
196. Dynamics of microstructures in metal sheets: an orientation imaging microscopy study
- Author
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Balke, Peter and de Hosson, Jeff
- Subjects
Structuuranalyse ,51.50 ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,Microstructuur ,Proefschriften (vorm) ,Microscopie ,Metalen ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) - Published
- 2002
197. Aanvullend archeologisch onderzoek (AAO) van terpen in het gasleidingstracé Hemert-Arum, gemeente Wûnseradiel (Fr.)
- Author
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Dijkstra, Y., Halici, H., Koopstra, C.G., Niekus, Marcel J.L.Th., Roller, G.J. de, Y. Dijkstra, met bijdragen van H. Halici ... [et al.], and Archaeological Research & Consultancy
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IJzertijd ,Archeobotanie ,Romeinse tijd ,Natuursteen ,Archaeology ,aardewerk ,Middeleeuwen ,Metalen ,fauna ,archeologie ,terpen - Abstract
Lit.opg.
- Published
- 2002
198. Environmental Risk Limits for Nine Trace Elements
- Author
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SEC, Vlaardingen PLA van, Posthumus R, Posthuma-Doodeman CJAM, SEC, Vlaardingen PLA van, Posthumus R, and Posthuma-Doodeman CJAM
- Abstract
RIVM rapport:In dit rapport wordt een herziening van milieurisicogrenzen gepresenteerd voor de sporenelementen beryllium, vanadium, kobalt, selenium, molybdeen, tin, antimoon, barium en thallium. Er werd literatuuronderzoek uitgevoerd om de gegevenssets die in 1992 voor de normafleiding zijn gebruikt, aan te vullen. Er zijn milieurisicogrenzen afgeleid voor zoet water, grondwater, bodem en sediment. De herziene milieurisicogrenzen voor water en grondwater zijn in de meeste gevallen lager dan de bestaande waarden. Dit wordt veroorzaakt door het vinden van nieuwe informatie op het gebied van toxiciteit en door veranderingen in de methodologie die bij de afleiding van normen gebruikt wordt. De nieuw afgeleide risicogrenzen voor bodem zijn nu gebaseerd op toxiciteitsgegevens voor bodemorganismen, terwijl de bestaande waarden alle zijn berekend uit de risicogrenzen voor water, middels evenwichtspartitie. De risicogrenzen voor sediment zijn wel berekend met behulp van evenwichtspartitie bij gebrek aan toxiciteitsgegevens. In het algemeen zijn de nieuw afgeleide milieurisicogrenzen voor sediment weinig veranderd ten opzichte van de bestaande. Het gemiddelde van gemeten concentraties van beryllium, vanadium, kobalt en barium in zoet oppervlaktewater overschrijdt het maximaal toelaatbaar risiconiveau (MTR). Voor selenium en antimoon was dit niet het geval. Voor grondwater laat een kwalitatieve vergelijking zien dat het MTR wordt overschreden voor beryllium, vanadium, kobalt, selenium en barium, maar niet voor molybdeen, tin, antimoon en thallium. Voor de compartimenten bodem, sediment en zeewater werden geen meetgegevens gevonden., In this report, we present an update of environmental risk limits (ERLs), based on the literature, for nine trace elements, namely, beryllium (Be), vanadium (V), cobalt (Co), selenium (Se), molybdenum (Mo), tin (Sn), antimony (Sb), barium (Ba) and thallium (Tl). The updated ERLs, established for these elements in freshwater, groundwater, soil and sediment, are to supplement 1992 datasets for risk limit derivation. The updated ERLs for water and groundwater have turned out to be generally lower than existing limits as a result of both new information on toxicity and changes in the methodology used to derive risk limits. Risk limits derived for soil are now based on soil toxicity data for the elements investigated, whereas the existing values for soil were all based on ERLs for water using equilibrium partitioning (EqP). Due to lack of data, ERLs for sediment are still based on EqP and generally show minor changes when compared to existing limits. The maximum permissible concentration (MPC) in rivers and lakes in the Netherlands was found to be exceeded by average measured concentrations of Be, V, Co and Ba, but not of Se and Sb. A qualitative comparison shows that the MPC in groundwater is exceeded for Be, V, Co, Se and Ba concentrations but not for Mo, Sn, Sb and Tl concentrations, although some data on deeper groundwater are missing. No measurement data could be found for the soil, sediment and marine water compartments
- Published
- 2005
199. Trace metal dynamics in methanol fed anaerobic granular sludge bed reactors
- Author
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Lettinga, Gatze, Lens, Piet, Zandvoort, M.H., Lettinga, Gatze, Lens, Piet, and Zandvoort, M.H.
- Abstract
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
- Published
- 2005
200. Metal stress in free-living nematodes
- Subjects
metalen ,merkers ,markers ,metals ,toxicologie ,PE&RC ,vrijlevende nematoden ,stress ,heat shock eiwitten ,free living nematodes ,heat shock proteins ,Laboratory of Nematology ,Laboratorium voor Nematologie ,toxicology - Abstract
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.Plectus acuminatus (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. P. acuminatus appeared to be a suitable species for toxicity tests (Kammenga et al. , 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)).Caenorhabditis elegans (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. C. elegans 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. C. elegans 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°C (Wood, 1988). Therefore, this nematode species is very suitable to study life-cycle traits and to perform multi-generation experiments.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.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.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 et al. , 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.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 et al. , 1988) designated hsp60, stress-60, cpn60, GroEL ( E. coli ) 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).Therefore, both the hsp70 and hsp60 response were qualitatively analyzed in the nematode P. acuminatus (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 P. acuminatus 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 P. acuminatus 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 P. acuminatus .The hsp60 response in P. acuminatus 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 (0-550mM) or copper chloride (0-59mM), the protein response also after 24 hours of exposure to cadmium chloride (0-109mM). Furthermore, we identified hsp60 in P. acuminatus 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 291mM 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 et al . (1997) concerning the hsp70 response in the isopod species Oniscus asellus . 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 P. acuminatus 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 P. acuminatus 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 P. acuminatus may have more potential as a biomarker for metal stress than the hsp60 mRNA response.In chapter 4, the application of the hsp60 protein response in P. acuminatus 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, P. acuminatus 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 P. acuminatus 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 O. asellus and Porcellio scaber ). 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.From this thesis it can be concluded that the hsp60 response in P. acuminatus could be used as a biomarker for metal exposure, but with the following limitations: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.The hsp60 response in P. acuminatus 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.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 C. elegans (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 C. elegans was developed to calculate fitness maximisation in populations exposed to cadmium chloride during multiple generations. It was shown that the maximum fitness of C. elegans depended strongly on the trade-off between sperm maturation time and juvenile development. Once C. elegans 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 C. elegans showed that cadmium chloride decreased fitness by impairment of juvenile development. The sperm maturation time remained constant. After long-term exposure of multiple generations, C. elegans 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.
- Published
- 2001
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