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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Effects of nanoplastics and microplastics on the growth of sediment-rooted macrophytes
Weert, S. van; Redondo Hasselerharm, P.E. ; Diepens, N.J. ; Koelmans, A.A. - \ 2019
Science of the Total Environment 654 (2019). - ISSN 0048-9697 - p. 1040 - 1047.
Plastic debris of all sizes has been detected in marine, terrestrial and freshwater habitats. Effects of plastic debris on macrophytes have hardly been studied, despite their importance in aquatic ecosystems. We provide the first experimental study exploring nano- and microplastic effects on the growth of sediment-rooted macrophytes. Myriophyllum spicatum and Elodea sp. were exposed to sediments amended with six doses of polystyrene (PS) nanoplastic (50–190 nm, up to 3% sediment dry weight) and PS microplastic (20–500 μm, up to 10% dry weight) under laboratory conditions. Both macrophyte species were tested for changes in root and shoot dry weight (DW), relative growth rate (RGR), shoot to root ratio (S:R), main shoot length and side shoot length. Microplastics did not produce consistent dose-effect relationships on the endpoints tested, except that main shoot length was reduced for M. spicatum with increasing microplastic concentration. Nanoplastic significantly reduced S:R for both macrophytes as a result of increased root biomass compared to shoot biomass. Nanoplastic also caused a decrease in M. spicatum main shoot length; however, shoot biomass was not affected. Elodea sp. side shoot length, root and shoot biomass and RGR were positively correlated to the nanoplastic concentration. All effects occurred at higher than environmentally realistic concentrations, suggesting no immediate implications for ecological risks. Our study did not aim for the elucidation of the exact mechanistic processes that cause the effects, however, particle size seems to play an important factor.
Origin and Processing Methods Slightly Affect Allergenic Characteristics of Cashew Nuts (Anacardium occidentale)
Reitsma, Marit ; Bastiaan-Net, Shanna ; Sijbrandij, Lutske ; Weert, Evelien de; Sforza, Stefano ; Gerth van Wijk, Roy ; Savelkoul, Huub F.J. ; Jong, Nicolette W. de; Wichers, Harry J. - \ 2018
Journal of Food Science 83 (2018)4. - ISSN 0022-1147 - p. 1153 - 1164.
2D electrophoresis - Anacardium occidentale - cashew - in vitro gastric digestion
The protein content and allergen composition was studied of cashews from 8 different origins (Benin, Brazil, Ghana, India, Ivory Coast, Mozambique, Tanzania, Vietnam), subjected to different in-shell heat treatments (steamed, fried, drum-roasted). On 2D electrophoresis, 9 isoforms of Ana o 1, 29 isoforms of Ana o 2 (11 of the acidic subunit, 18 of the basic subunit), and 8 isoforms of the large subunit of Ana o 3 were tentatively identified. Based on 1D and 2D electrophoresis, no difference in allergen content (Ana o 1, 2, 3) was detected between the cashews of different origins (P > 0.5), some small but significant differences were detected in allergen solubility between differently heated cashews. No major differences in N- and C-terminal microheterogeneity of Ana o 3 were detected between cashews of different origins. Between the different heat treatments, no difference was detected in glycation, pepsin digestibility, or IgE binding of the cashew proteins.
Geochemical and Microbiological Characteristics during in Situ Chemical Oxidation and in Situ Bioremediation at a Diesel Contaminated Site
Sutton, N.B. ; Kalisz, M. ; Krupanek, J. ; Marek, J. ; Grotenhuis, J.T.C. ; Smidt, H. ; Weert, J. de; Rijnaarts, H.H.M. ; Gaans, P. van; Keijzer, T. - \ 2014
Environmental Science and Technology 48 (2014)4. - ISSN 0013-936X - p. 2352 - 2360.
activated persulfate oxidation - soil organic-matter - fentons reagent - biodegradation - remediation - degradation - oxidants - ozonation - peroxide - minerals
While in situ chemical oxidation with persulfate has seen wide commercial application, investigations into the impacts on groundwater characteristics, microbial communities and soil structure are limited. To better understand the interactions of persulfate with the subsurface and to determine the compatibility with further bioremediation, a pilot scale treatment at a diesel-contaminated location was performed consisting of two persulfate injection events followed by a single nutrient amendment. Groundwater parameters measured throughout the 225 day experiment showed a significant decrease in pH and an increase in dissolved diesel and organic carbon within the treatment area. Molecular analysis of the microbial community size (16S rRNA gene) and alkane degradation capacity (alkB gene) by qPCR indicated a significant, yet temporary impact; while gene copy numbers initially decreased 1–2 orders of magnitude, they returned to baseline levels within 3 months of the first injection for both targets. Analysis of soil samples with sequential extraction showed irreversible oxidation of metal sulfides, thereby changing subsurface mineralogy and potentially mobilizing Fe, Cu, Pb, and Zn. Together, these results give insight into persulfate application in terms of risks and effective coupling with bioremediation.
With whom did you have sex? Evaluation of a partner notification training for STI professionals using motivational interviewing
Coul, E.L.M. Op de; Spijker, R. ; Aar, F. van; Weert, Y. van; Bruin, M. de - \ 2013
Patient Education and Counseling 93 (2013)3. - ISSN 0738-3991 - p. 596 - 603.
sexually-transmitted infections - enhance recall - contact - efficacy - behavior - health - hiv
Objective: To enhance partner notification (PN) practices in Dutch STI clinics, a PN training using motivational interviewing as core strategy was offered to STI professionals and evaluated. Methods: The effectiveness of PN training on professionals' attitude, self-efficacy, skills and behavior toward PN, was examined using within-subject and between-subject comparison. Before the training and at three months follow-up, a questionnaire was completed by the intervention group (n = 54) and a non-random control group (n = 37). Results: In the within-subject comparison, positive changes were observed in self-efficacy, skills, and PN behaviors (all p <.05), but not in attitudes toward PN. When we examined differences in change-scores between the intervention and control group, self-efficacy was no longer significant. Conclusion: The PN training significantly improved PN skills and -behavior, but had no effect on professionals' attitudes or self-efficacy toward PN. The selection of a convenience control sample seems to offer a more rigorous test of hypotheses than pre-post evaluation only. Practice implications: The beneficial effect of PN training of STI professionals seems to support a wider roll-out of the training to all STI clinics in the Netherlands, although effects on the number of partners notified and transmissions prevented need to be examined in future research. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
DiveLOp Flow-Cap: Ontwikkeling van een meetinstrument voor directe metingen van afvoergemiddelde concentraties en vrachten vanuit landbouwdrains en kassen naar het oppervlaktewater
Rozemeijer, J. ; Baan, B. ; Jonge, H. de; Roos-Klein Lankhorst, J. ; Harmsen, J. ; Jansen, S. ; Weert, J. de - \ 2013
Delft : Deltares - 79
drainage - waterverontreiniging - landbouw - glastuinbouw - monitoring - water pollution - agriculture - greenhouse horticulture
De waterkwaliteit in veel Nederlandse sloten en plassen laat nog te wensen over. Om de belangrijkste verontreinigingsbronnen op te kunnen sporen is het belangrijk vrachten vanuit landbouwdrains en lozingsbuizen te kunnen meten. Het doel van het project DiVeLOp (Directe metingen van Verontreinigingsvrachten vanuit Landbouwdrains en kassen naar het Oppervlaktewater) was dan ook een eenvoudig en robuust meetsysteem te ontwikkelen om vrachtenmetingen mogelijk te maken voor toepassing in waterschapsmonitoring, in het Landelijk Meetnet effecten Mestbeleid (LMM) en in de glastuinbouw
KASVERLICHTING Verbetering voedingswaarde en smaak van groenten en fruit, meer vitamine C
Weert, H. van; Labrie, C.W. ; Wageningen UR Glastuinbouw, - \ 2013
Limburgs Dagblad (2013). - p. 16 - 16.
Studie naar leds in tuinbouw
Weert, H. van; Wageningen UR Glastuinbouw, ; Labrie, C.W. - \ 2013
Eindhovens Dagblad (2013).
Bio-reduction of elemental sulfur to increase the gold recovery from enargite
Hol, A. ; Weijden, R.D. van der; Weert, G. van; Kondos, P. ; Buisman, C.J.N. - \ 2012
Hydrometallurgy 115-116 (2012). - ISSN 0304-386X - p. 93 - 97.
refractory ore - dissolution - oxidation - sulfide - ferrooxidans - concentrate - bacteria - kinetics - pyrite - zinc
The mineral enargite can be of interest to the mining industry as a copper and precious metal source. The mineral has a refractory character towards oxidation, which is attributed to the formation of elemental sulfur that seals off the mineral surface. In this study it was investigated whether elemental sulfur resulting from oxidation during industrial milling can be converted into hydrogen sulfide via bio-reduction. The removal of elemental sulfur in this process will clean the mineral surfaces for subsequent oxidation, prevent interference with the gold extraction process and reduce consumption of chemicals such as cyanide. HPLC analysis confirmed that indeed elemental sulfur was formed during industrial milling of an enargite-pyrite gold concentrate. Removal of elemental sulfur via bio-reduction was successful and improved the gold leachability from 48.9% to 69.6%. The combination of milling and bio-reduction was therefore concluded to be a possible route to liberate metals. Further research is necessary to investigate if the enargite to sulfur conversion can be improved to obtain economically satisfactory (> 90%) gold recoveries.
Degradation of 4-n-nonylphenol under nitrate reducing conditions
Weert, J.P.A. de; Vinas, M. ; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. ; Langenhoff, A.A.M. - \ 2011
Biodegradation 22 (2011)1. - ISSN 0923-9820 - p. 175 - 187.
anaerobic degradation - desulfobacterium-phenolicum - polychlorinated-biphenyls - nonionic surfactants - sewage-sludge - n-hexadecane - sp-nov - nonylphenol - biodegradation - 4-nonylphenol
Nonylphenol (NP) is an endocrine disruptor present as a pollutant in river sediment. Biodegradation of NP can reduce its toxicological risk. As sediments are mainly anaerobic, degradation of linear (4-n-NP) and branched nonylphenol (tNP) was studied under methanogenic, sulphate reducing and denitrifying conditions in NP polluted river sediment. Anaerobic bioconversion was observed only for linear NP under denitrifying conditions. The microbial population involved herein was further studied by enrichment and molecular characterization. The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity. This implies that different microorganisms are involved in the degradation of 4-n-NP in the sediment. The major degrading bacteria were most closely related to denitrifying hexadecane degraders and linear alkyl benzene sulphonate (LAS) degraders. The molecular structures of alkanes and LAS are similar to the linear chain of 4-n-NP, this might indicate that the biodegradation of linear NP under denitrifying conditions starts at the nonyl chain. Initiation of anaerobic NP degradation was further tested using phenol as a structure analogue. Phenol was chosen instead of an aliphatic analogue, because phenol is the common structure present in all NP isomers while the structure of the aliphatic chain differs per isomer. Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions.
Processing of Arsenopyritic Gold Concentrates by Partial Bio-Oxidation Followed by Bioreduction
Hol, A. ; Weijden, R.D. van der; Weert, G. van; Kondos, P. ; Buisman, C.J.N. - \ 2011
Environmental Science and Technology 45 (2011)15. - ISSN 0013-936X - p. 6316 - 6321.
sulfur - dissolution - bioreactor - mechanisms - reduction - oxidation - minerals - progress - removal - iron
Gold is commonly liberated from sulfide minerals by chemical and biological oxidation. Although these technologies are successful, they are costly and produce acidic waste streams. Removal of mineral-sulfur to overcome the mineralogical barrier could also be done by bioreduction, producing hydrogen sulfide (H2S). To make the sulfur within these minerals available for bioreduction, the use of partial bio-oxidation as a pretreatment to oxidize the sulfides to elemental sulfur was investigated in gas lift loop reactor experiments. Experiments at 35 °C using a refractory concentrate showed that at pH 2 arsenopyrite is preferentially partially oxidized over pyrite and that elemental sulfur can be subsequently converted into H2S at pH 5 via bioreduction using H2 gas. A single partial bio-oxidation/bioreduction treatment increased the gold recovery of the concentrate from 6% to 39%. As elemental sulfur seems to inhibit further oxidation by covering the mineral surface, several treatments may be required to reach a gold recovery >90%. Depending on the number of treatments this method could be an interesting alternative to bio-oxidation
Plant weert zich tegen belagers (André van der Wurff aan het woord tijdens bijeenkomst over gewasgezondheid)
Visser, P. ; Wurff, A.W.G. van der - \ 2011
Groenten en Fruit Actueel 2011 (2011)21. - ISSN 0925-9694 - p. 10 - 10.
Bio-reduction of sulfide minerals to recover invisible gold
Hol, A. - \ 2011
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Renata van der Weijden; J.P.A. de Weert. - S.l. : s.n. - ISBN 9789085859222 - 117
redoxreacties - pyriet - extractie - goud - redox reactions - pyrites - extraction - gold

Sulfide minerals, like pyrite and arsenopyrite, are of economical interest due to the presence of invisible gold locked inside these minerals. As fine grinding is often not sufficient to liberate the gold from these minerals, additional destruction techniques, based on chemical and biological oxidation processes, are required to access the gold via cyanidation. These techniques have proven to be successful to reach satisfactory gold recoveries, but operation costs are high and challenging waste streams (sulfuric acid) are produced. As an alternative to the oxidation methods in this thesis the bio-reduction of sulfide minerals was proposed and investigated. Bio-reduction, the use of hydrogen to convert mineral-sulfur to hydrogen sulfide, has as major advantage that the hydrogen sulfide can be recovered from the solution (to produce bio-sulfur) leaving a waste stream without diluted sulfuric acid. Furthermore, electrical energy will be saved. Theoretically, this more environmental friendly alternative should work, but no bio-reduction reaction was observed in practice. It appeared that sulfur/sulfate reducing bacteria were not able to use sulfur when fixed in the crystal lattice of pyrite and arsenopyriteat the selected conditions (pH 5, 35ºC). In order to make the mineral-sulfur bio-available for these bacteria the sulfur should first enter the solution. As alternative the combination between partial bio-oxidation and bio-reduction was therefore investigated. Partial bio-oxidation at pH 2 results in the formation of elemental sulfur, which can serve as a substrate at pH 5 for the sulfur/sulfate reducing bacteria. This combined method was found to be successful at 35°C, as the gold leachability of the used concentrate was increased from 6% to 39%. Optimization of this process is needed to reach gold recoveries >90% in 1 or 2 ox/red cycles, but when successful a new method (called the Paroxsul process) with a lower environmental impact, less costs, and application to a large number of minerals, is ready to be introduced to the precious metal industry.

The effect of anaerobic processes on the leachability of an arsenopyrite refractory ore
Hol, A. ; Weijden, R.D. van der; Weert, G. van; Kondos, P. ; Buisman, C.J.N. - \ 2011
Minerals Engineering 24 (2011)6. - ISSN 0892-6875 - p. 535 - 540.
arsenic speciation - oxidation - pyrite - gold - dissolution - reduction - minerals - sb2s3 - as2s3
Gold is commonly liberated from sulfide minerals via oxidative destruction techniques. To circumvent the formation of sulfuric acid and to reduce the amount of energy required for these processes two alternative anaerobic processes based on sulfate reducing bacteria are investigated for arsenopyrite in this study. The first alternative, “bio-reduction” is expected to alter the structure of arsenopyrite via reduction of the mineral-sulfur to hydrogen sulfide, yielding a sulfur depleted residue that probably contains the gold. The second alternative “anaerobic oxidation” focuses on the mineral-arsenic which under anaerobic conditions can be oxidized to arsenite and subsequently precipitates as orpiment, which may contain the gold. Both alternatives were investigated with gas lift loop reactor experiments performed at pH 5 and 35 °C. These experiments showed that sulfate reducers were able to reduce sulfate from the reactor fluid, but that they were not able to use arsenopyrite as an electron acceptor (bio-reduction) or donor (anaerobic oxidation) under the selected conditions. As a result the gold leachability of the ore concentrate was not improved. To make the mineral more accessible for the leach solution the solubilization of lattice constituents from arsenopyrite that can be biologically reduced/anaerobically oxidized, should be stimulated. In addition, the concentration of arsenite needs to be limited to preserve the activity of sulfate reducing bacteria
Eindrapportage 'Gezond ouder worden in Epe' 2006-2010
Vlaming, R. de; Lezwijn, J. ; Weert, L. de; Coenen, I. - \ 2010
Apeldoorn : GGD Gelre IJssel - 30 p.
Nonylphenol mass transfer from field-aged sediments and subsequent biodegradation in reactors mimicking different river conditions
Weert, J.P.A. de; Streminska, M.A. ; Hua, D. ; Grotenhuis, J.T.C. ; Langenhoff, A.A.M. ; Rijnaarts, H.H.M. - \ 2010
Journal of Soils and Sediments 10 (2010)1. - ISSN 1439-0108 - p. 77 - 88.
fresh-water - lakes - alkylphenols - desorption - kinetics - octylphenol - ecosystems - events
Sediments can function as secondary source for water pollution of aerobically biodegradable non-halogenated organic compounds, which are persistent in anaerobic sediments. The mass transfer of compounds from sediment to bulk water depends on hydraulic conditions. In this study, desorption, mass transfer and biodegradation are investigated under settled and resuspended sediment conditions for branched nonylphenol (NP), which was used as model compound for aerobically biodegradable and anaerobic persistent compounds. Continuous flow through reactor experiments were performed in duplicate with aged NP polluted sediment under sterile and non-sterile conditions to investigate the mass transfer and combined mass transfer and biodegradation. The mass transfer of NP from the sediment bed to the bulk water decreased from 5.1 +/- 0.6 mu g d(-1) to a stable value of 0.3 +/- 0.02 mu g d(-1). The desorbed NP in the non-sterile reactors was biodegraded in the first 20 days of the experiment. At the end of the settled sediment conditions, the biodegradation became very limited, and the mass transfer was comparable to the mass transfer under sterile conditions. Upon resuspension, the NP concentration in the bulk water increased instantaneously in all reactors with a factor of 100. This immediate, increased mass transfer of NP from the sediment was larger than the amount that can be biodegraded under optimal conditions. Under non-sterile conditions, a second increase in the mass transfer was observed. However, the amount of desorbing NP during this second increase in mass transfer can be biodegraded under optimal environmental conditions. NP desorbs continuously at low concentrations from the sediment bed into the bulk water, which can almost be completely biodegraded. Resuspension of NP-polluted sediment initially led to an increase in the desorbing NP concentrations and can be followed by a subsequent reduction of the concentrations due to biodegradation under environmental conditions where biodegradation of NP can occur.
Bio-reduction of pyrite investigated in a gas lift loop reactor
Hol, A. ; Weijden, R.D. van der; Weert, G. van; Kondos, P. ; Buisman, C.J.N. - \ 2010
International Journal of Mineral Processing 94 (2010)3-4. - ISSN 0301-7516 - p. 140 - 146.
bearing arsenian pyrite - gold - oxidation - bioreactor - minerals - progress - part
To liberate gold from refractory pyrite, oxidative destruction techniques that consume lots of energy and generate acidic waste streams are custom. As an alternative the “bio-reduction” of pyrite is proposed and investigated in this study. Bio-reduction is an anaerobic process based on sulfate/sulfur reducing bacteria which are thought to be able to use pyrite-sulfur as a possible electron acceptor. The conversion of pyrite-sulfur into hydrogen sulfide is advantageous because energy is saved and the generation of an acidic waste stream is prevented. In addition, the generated H2S can be used to produce elemental sulfur, or even gold lixiviants such as thiosulfate or bisulfide. Batch experiments under anaerobic conditions showed that two effects can inhibit bio-reduction; methane formation and sulfide accumulation. In a gas lift loop reactor operated at pH 5, temperature of 35 °C, and with continuous sulfide removal no evidence of pyrite bio-reduction was found. Though the sulfate reducing bacteria survived, they did not utilize pyrite-sulfur as an electron acceptor under the chosen conditions.
Aerobic nonylphenol degradation and nitro-nonylphenol formation by microbial cultures from sediments
Weert, J.P.A. de; Viñas, M. ; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. ; Langenhoff, A.A.M. - \ 2010
Applied Microbiology and Biotechnology 86 (2010)2. - ISSN 0175-7598 - p. 761 - 771.
sphingomonas-xenophaga bayram - sp strain ttnp3 - river sediment - nitrosomonas-europaea - ipso-substitution - p-nonylphenol - sewage-sludge - bisphenol-a - 4-nonylphenol - biodegradation
Nonylphenol (NP) is an estrogenic pollutant which is widely present in the aquatic environment. Biodegradation of NP can reduce the toxicological risk. In this study, aerobic biodegradation of NP in river sediment was investigated. The sediment used for the microcosm experiments was aged polluted with NP. The biodegradation of NP in the sediment occurred within 8 days with a lag phase of 2 days at 30°C. During the biodegradation, nitro-nonylphenol metabolites were formed, which were further degraded to unknown compounds. The attached nitro-group originated from the ammonium in the medium. Five subsequent transfers were performed from original sediment and yielded a final stable population. In this NP-degrading culture, the microorganisms possibly involved in the biotransformation of NP to nitro-nonylphenol were related to ammonium-oxidizing bacteria. Besides the degradation of NP via nitro-nonylphenol, bacteria related to phenol-degrading species, which degrade phenol via ring cleavage, are abundantly present
Preventie van eenzaamheid: hoe dragen beleid, praktijk en wetenschap hun steentje bij?
Haveman-Nies, A. ; Weert, L. de; Vlaming, R. de; Janssen, D. - \ 2009
Tijdschrift voor Gezondheidswetenschappen 87 (2009)3. - ISSN 1388-7491 - p. 54 - 54.
Fate of the estrogen nonylphenol in river sediment: availability, mass transfer and biodegradation
Weert, J.P.A. de - \ 2009
Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Alette Langenhoff; Tim Grotenhuis. - [S.l. : S.n. - ISBN 9789085854661 - 143
verontreinigde sedimenten - rivieren - bodemverontreiniging - verontreinigende stoffen - oestrogenen - waterorganismen - biodegradatie - aquatische toxicologie - bodemsanering - contaminated sediments - rivers - soil pollution - pollutants - oestrogens - aquatic organisms - biodegradation - aquatic toxicology - soil remediation
Veel riviersedimenten zijn in het verleden verontreinigd geraakt met estrogene verbindingen, die toxische effecten kunnen veroorzaken op aquatische organismen, zoals de vervrouwlijking van mannelijke vissen. Een van deze estrogene verbindingen is nonylfenol (NP). Nonylfenol is een organische verbinding die bestaat uit een fenolgroep met een lineaire of een vertakte keten van negen koolstofatomen. Voornamelijk mengsels van vertakte NP-isomeren komen voor als verontreiniging in het milieu. Sedimenten die verontreinigd zijn met NP kunnen functioneren als secundaire bron van verontreiniging van het rivierwater, waar het toxische effecten kan veroorzaken op aquatische organismen. Het risico van toxische effecten door NP, dat aanwezig is in het sediment, wordt bepaald door de beschikbaarheid van NP in het sediment, het massatransport vanuit het sediment naar het rivierwater en de mogelijkheid voor biologische afbraak van NP in het sediment of het rivierwater.
Degradation of 1,2-dichloroethane by microbial communities from river sediment at various redox conditions
Zaan, B.M. van der; Weert, J.P.A. de; Rijnaarts, H. ; Vos, W.M. de; Smidt, H. ; Gerritse, J. - \ 2009
Water Research 43 (2009)13. - ISSN 0043-1354 - p. 3207 - 3216.
rivieren - sediment - biodegradatie - redoxreacties - oxidatie - micro-organismen - anaërobe omstandigheden - elbe - rivers - sediment - biodegradation - redox reactions - oxidation - microorganisms - anaerobic conditions - river elbe - halogenated aliphatic-compounds - dichloroeliminans strain dca1 - reductive dechlorination - methanogenic bacteria - contaminated aquifer - chlorinated ethenes - pure cultures - sequence data - dehalogenation - groundwater
Insight into the pathways of biodegradation and external factors controlling their activity is essential in adequate environmental risk assessment of chlorinated aliphatic hydrocarbon pollution. This study focuses on biodegradation of 1,2-dichloroethane (1,2-DCA) in microcosms containing sediment sourced from the European rivers Ebro, Elbe and Danube. Biodegradation was studied under different redox conditions. Reductive dechlorination of 1,2-DCA was observed with Ebro and Danube sediment with chloroethane, or ethene, respectively, as the major dechlorination products. Different reductively dehalogenating micro-organisms (Dehalococcoides spp., Dehalobacter spp., Desulfitobacterium spp. and Sulfurospirillum spp.) were detected by 16S ribosomal RNA gene-targeted PCR and sequence analyses of 16S rRNA gene clone libraries showed that only 2-5 bacterial orders were represented in the microcosms. With Ebro and Danube sediment, indications for anaerobic oxidation of 1,2-DCA were obtained under denitrifying or iron-reducing conditions. No biodegradation of 1,2-DCA was observed in microcosms with Ebro sediment under the different tested redox conditions. This research shows that 1,2-DCA biodegradation capacity was present in different river sediments, but not in the water phase of the river systems and that biodegradation potential with associated microbial communities in river sediments varies with the geochemical properties of the sediments
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