Biodegradability of dissolved organic matter in Boom Clay pore water under nitrate-reducing conditions: Effect of additional C and P sources

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@article{478e9b68a3b0485e93ebea473cd56ff1,
title = "Biodegradability of dissolved organic matter in Boom Clay pore water under nitrate-reducing conditions: Effect of additional C and P sources",
abstract = "In Belgium, Boom Clay is considered a potential host rock for the deep geological disposal of nuclear waste such as Eurobitum, an intermediate-level nitrate-containing radioactive waste form. The presence of dissolved organic matter (DOM) in the Boom Clay may play an important role in the mobility of radionuclides due to complexation and/or reduction of redox-sensitive radionuclides. The biodegradation of this DOM could therefore affect the barrier function of the Boom Clay. Due to the presence of nitrate leaching from Eurobitum into the clay formation, the biodegradation of DOM by a nitrate-reducing population cannot be ruled out in the Boom Clay surrounding a Eurobitum repository. In this paper, the biodegradability of DOM in Boom Clay pore water (BCPW) under nitrate-reducing conditions was investigated in the presence or absence of additional nutrients (i.e., acetate and phosphate) expected to be present in the clay surrounding a Eurobitum repository. The results of these experiments indicate that microbial nitrate reduction and the related degradation of DOM are performed by a syntrophic microbial community but are characterised by very slow kinetics. Nitrate-reducing microorganisms seem to be (at least partially) dependent on fermentation products such as acetate provided by fermenting microorganisms. The observed slow biodegradation of DOM appears to be linked to the characteristics of Boom Clay DOM, rather than to a limitation of nutrients necessary for microbial growth. The addition of phosphate only boosts the microbial growth of certain microbial species but not the biodegradation of DOM. On the other hand, acetate significantly enhances the microbial degradation of DOM. This result can be attributed to the use of acetate as an efficient C source for certain DOM-degrading microbial species and/or as a co-substrate to stimulate DOM degradation.",
keywords = "Dissolved organic matter, Biodegradability, Nitrate, Acetate, Syntrophic microbial community",
author = "Nele Bleyen and Katrien Hendrix and Hugo Moors and Delphine Durce and Mirela Vasile and Elie Valcke",
note = "Score=10",
year = "2018",
month = "5",
day = "2",
doi = "10.1016/j.apgeochem.2018.02.005",
language = "English",
volume = "92",
pages = "45--58",
journal = "Applied Geochemistry",
issn = "0883-2927",
publisher = "Elsevier",

}

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TY - JOUR

T1 - Biodegradability of dissolved organic matter in Boom Clay pore water under nitrate-reducing conditions: Effect of additional C and P sources

AU - Bleyen, Nele

AU - Hendrix, Katrien

AU - Moors, Hugo

AU - Durce, Delphine

AU - Vasile, Mirela

AU - Valcke, Elie

N1 - Score=10

PY - 2018/5/2

Y1 - 2018/5/2

N2 - In Belgium, Boom Clay is considered a potential host rock for the deep geological disposal of nuclear waste such as Eurobitum, an intermediate-level nitrate-containing radioactive waste form. The presence of dissolved organic matter (DOM) in the Boom Clay may play an important role in the mobility of radionuclides due to complexation and/or reduction of redox-sensitive radionuclides. The biodegradation of this DOM could therefore affect the barrier function of the Boom Clay. Due to the presence of nitrate leaching from Eurobitum into the clay formation, the biodegradation of DOM by a nitrate-reducing population cannot be ruled out in the Boom Clay surrounding a Eurobitum repository. In this paper, the biodegradability of DOM in Boom Clay pore water (BCPW) under nitrate-reducing conditions was investigated in the presence or absence of additional nutrients (i.e., acetate and phosphate) expected to be present in the clay surrounding a Eurobitum repository. The results of these experiments indicate that microbial nitrate reduction and the related degradation of DOM are performed by a syntrophic microbial community but are characterised by very slow kinetics. Nitrate-reducing microorganisms seem to be (at least partially) dependent on fermentation products such as acetate provided by fermenting microorganisms. The observed slow biodegradation of DOM appears to be linked to the characteristics of Boom Clay DOM, rather than to a limitation of nutrients necessary for microbial growth. The addition of phosphate only boosts the microbial growth of certain microbial species but not the biodegradation of DOM. On the other hand, acetate significantly enhances the microbial degradation of DOM. This result can be attributed to the use of acetate as an efficient C source for certain DOM-degrading microbial species and/or as a co-substrate to stimulate DOM degradation.

AB - In Belgium, Boom Clay is considered a potential host rock for the deep geological disposal of nuclear waste such as Eurobitum, an intermediate-level nitrate-containing radioactive waste form. The presence of dissolved organic matter (DOM) in the Boom Clay may play an important role in the mobility of radionuclides due to complexation and/or reduction of redox-sensitive radionuclides. The biodegradation of this DOM could therefore affect the barrier function of the Boom Clay. Due to the presence of nitrate leaching from Eurobitum into the clay formation, the biodegradation of DOM by a nitrate-reducing population cannot be ruled out in the Boom Clay surrounding a Eurobitum repository. In this paper, the biodegradability of DOM in Boom Clay pore water (BCPW) under nitrate-reducing conditions was investigated in the presence or absence of additional nutrients (i.e., acetate and phosphate) expected to be present in the clay surrounding a Eurobitum repository. The results of these experiments indicate that microbial nitrate reduction and the related degradation of DOM are performed by a syntrophic microbial community but are characterised by very slow kinetics. Nitrate-reducing microorganisms seem to be (at least partially) dependent on fermentation products such as acetate provided by fermenting microorganisms. The observed slow biodegradation of DOM appears to be linked to the characteristics of Boom Clay DOM, rather than to a limitation of nutrients necessary for microbial growth. The addition of phosphate only boosts the microbial growth of certain microbial species but not the biodegradation of DOM. On the other hand, acetate significantly enhances the microbial degradation of DOM. This result can be attributed to the use of acetate as an efficient C source for certain DOM-degrading microbial species and/or as a co-substrate to stimulate DOM degradation.

KW - Dissolved organic matter

KW - Biodegradability

KW - Nitrate

KW - Acetate

KW - Syntrophic microbial community

UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/34769431

U2 - 10.1016/j.apgeochem.2018.02.005

DO - 10.1016/j.apgeochem.2018.02.005

M3 - Article

VL - 92

SP - 45

EP - 58

JO - Applied Geochemistry

JF - Applied Geochemistry

SN - 0883-2927

ER -

ID: 5399009