Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed ...

212 Pages·2005·3.74 MB·English

AECL EACL
CA0200116
AECL-12101
Review of Microbial Responses to Abiotic
Environmental Factors in the Context of the
Proposed Yucca Mountain Repository
Examen des reponses microbiennes aux facteurs
abiotiques dans le contexte du depot propose du
mont Yucca
A. Meike, S. Stroes-Gascoyne
October 2000 octobre
AECL EACL
REVIEW OF MICROBIAL RESPONSES TO ABIOTIC
ENVIRONMENTAL FACTORS IN THE CONTEXT OF THE
PROPOSED YUCCA MOUNTAIN REPOSITORY
by
A. Meike1 and S. Stroes-Gascoyne2
REPORT PREPARED FOR THE U.S. DEPARTMENT OF ENERGY,
YUCCA MOUNTAIN SITE, CHARACTERISTION OFFICE
UNDER AECL TECHNOLOGIES INC.
CONTRACT # DE-AC08-95-NV11784
'Lawrence Livermore National Laboratory
2Atomic Energy of Canada Limited
Whiteshell Laboratories
Engineered Barriers and Analysis Branch
Whiteshell Laboratories
Pinawa, Manitoba ROE 1L0
2000 October
AECL-12101
DISCLAIMER
This report was prepared as an account of work sponsored by an agency of the United States
Government. Neither the United States Government nor any agency thereof, nor any of their
employees, nor any of their contractors, subcontractors or their employees, makes any warranty,
express or implied, or assumes any legal liability or responsibility for the accuracy, completeness,
or any third party's use or the results of such use of any information, apparatus, product, or
process disclosed, or represents that its use would not infringe privately owned rights. Reference
herein to any specific commercial product, process, or service by trade name, trademark,
manufacturer, or otherwise, does not necessarily constitute or imply its endorsement,
recommendation, or favoring by the United States Government or any agency thereof or its
contractors or subcontractors. The views and opinions of authors expressed herein do not
necessarily state or reflect those of the United States Government or any agency thereof.
AECL EACL
EXAMEN DES REPONSES MICROBIENNES AUX FACTEURS ABIOTIQUES DANS
LE CONTEXTE DU DEPOT PROPOSE DU MONT YUCCA
A. Meike1 et S. Stroes-Gascoyne2
RAPPORT REDIGE POUR L'U.S. DEPARTMENT OF ENERGY,
SITE DU MONT YUCCA, BUREAU DE CARACTERISATION
EN VERTU DU CONTRAT D'AECL TECHNOLOGIES INC.
N° DE-AC08-95-NV11784
RESUME
Un atelier sur les activites microbiennes au mont Yucca (mai 1995, Lafayette, CA) a eu lieu dans
le but de compiler des renseignements sur tous les aspects pertinents de 1'activite microbienne
qui s'appliquent a un depot eventuel au mont Yucca. Les resultats de cet atelier ont suscite un
certain nombre de mesures visant a incorporer finalement les consequences du comportement
microbien dans les modeles devaluation des performances. Une de ces mesures etait d'elargir
une methode de modelisation existante pour englober les caracteristiques distinctives d'un depot
au mont Yucca (p. ex., conditions non saturees et charge thermique importante). En meme
temps, on a entrepris un certain nombre d'etudes experimentales ainsi que la compilation de
documentation pertinente pour etudier plus en profondeur les parametres physiques, chimiques et
biologiques qui auraient un effet sur l'activite microbienne dans des conditions semblables a
celles du mont Yucca. Cette recherche de documentation (terminee en 1996) est l'objet du
present document.
La documentation rassemblee peut etre divisee en quatre categories, 1) facteurs abiotiques,
2) dynamique de la communaute et aspects in situ, 3) nutriments et 4) transport des
radionucleides. La bibliographic complete (donnee a 1'annexe A) represente une ressource
considerable, mais est trop importante pour pouvoir etre traitee dans un seul document. Par
consequent, le rapport actuel est axe sur la premiere categorie, les facteurs abiotiques, et sur un
examen de ces facteurs afin de faciliter l'elaboration d'un modele pour le mont Yucca.
La premiere partie du rapport (chapitres 1 a 3) est un examen des etats microbiens generaux, des
phases et des criteres de proliferation, des conditions relatives a la «proliferation normale» et
d'autres types de proliferation, strategies de survie et mort de cellule. Elle contient
principalement des idees bien etablies en microbiologie. Les capacites microbiennes de survie et
d'adaptation aux modifications de 1'environnement sont examinees parce qu'un depot place au
mont Yucca aurait deux effets. En premier lieu, 1'environnement naturel serait perturbe par
1'excavation et la construction du depot et en second lieu, cet environnement modifie serait alors
perturbe par les dechets radioactifs eux-memes au cours de la duree de vie du depot (chaleur,
redistribution d'humidite et eventuellement radioactivite).
Dans la deuxieme partie (chapitres 4, 5 et 6), on traite des capacites microbiennes etablies dans la
premiere partie, dans un cadre propre au site qui contribuera a definir les limites de l'activite
microbienne prevue. L'evolution prevue d'un depot potentiel au mont Yucca ainsi que les
facteurs releves qui peuvent influer sur l'activite microbienne (c.-a-d. hautes temperatures,
changements du pH, dessiccation, changements de salinite et rayonnement) sont examines. On y
traite des previsions d'activite microbienne, dans la mesure du possible dans le contexte oii elle
contribue concretement aux decisions de conception pour le depot du mont Yucca envisage.
1 Lawrence Livermore National Laboratory
2Energie atomique du Canada limitee
Barrieres ouvragees et Analyse
Laboratoires de Whiteshell
Pinawa (Manitoba) ROE 1L0
Octobre 2000
AECL-12101
AECL EACL
REVIEW OF MICROBIAL RESPONSES TO ABIOTIC ENVIRONMENTAL FACTORS
IN THE CONTEXT OF THE PROPOSED YUCCA MOUNTAIN REPOSITORY
A. Meike1 and S. Stroes-Gascoyne2
REPORT PREPARED FOR THE U.S. DEPARTMENT OF ENERGY,
YUCCA MOUNTAIN SITE, CHARACTERISTION OFFICE
UNDER AECL TECHNOLOGIES INC.
CONTRACT # DE-AC08-95-NV11784
ABSTRACT
A workshop on Microbial Activities at Yucca Mountain (May 1995, Lafayette, CA) was held
with the intention to compile information on all pertinent aspects of microbial activity for
application to a potential repository at Yucca Mountain. The findings of this workshop set off a
number of efforts intended to eventually incorporate the impacts of microbial behaviour into
performance assessment models. One effort was to expand an existing modelling approach to
include the distinctive characteristics of a repository at Yucca Mountain (e.g., unsaturated
conditions and a significant thermal load). At the same time, a number of experimental studies
were initiated as well as a compilation of relevant literature to more thoroughly study the
physical, chemical and biological parameters that would affect microbial activity under Yucca
Mountain-like conditions. This literature search (completed in 1996) is the subject of the present
document.
The collected literature can be divided into four categories, 1) abiotic factors, 2) community
dynamics and in-situ considerations, 3) nutrient considerations and 4) transport of radionuclides.
The complete bibliography (included in Appendix A) represents a considerable resource, but is
too large to be discussed in one document. Therefore, the present report focuses on the first
category, abiotic factors, and a discussion of these factors in order to facilitate the development
of a model for Yucca Mountain.
The first part of the report (Chapters 1-3) is a review of general microbial states, phases and
requirements for growth, conditions for 'normal growth' and other types of growth, survival
strategies and cell death. It contains primarily well-established ideas in microbiology. Microbial
capabilities for survival and adaptation to environmental changes are examined because a
repository placed at Yucca Mountain would have two effects. First, the natural environment
would be perturbed by the excavation and construction of the repository and second, that
modified environment would then be perturbed by the radioactive waste itself during the lifetime
of the repository (heat, redistribution of moisture and possibly radioactivity.
Part Two (Chapters 4, 5 and 6) discusses the microbial capabilities established in part one, in a
site specific framework that will help define the limits of expected microbial activity. The
expected evolution of a potential repository at Yucca Mountain is reviewed as well as those
factors identified to be potential issues to microbial activity (i.e., high temperatures, changes in
pH, desiccation, salinity changes and radiation). Expectations for microbial activity, where
possible in the context of explicit input to design decisions for the proposed Yucca Mountain
Repository, are discussed.
'Lawrence Livermore National Laboratory
2Atomic Energy of Canada Limited
Engineered Barriers and Analysis Branch
Whiteshell Laboratories
Pinawa, Manitoba ROE 1L0
2000 October
AECL-12101
FOREWORD
The lack of sufficient data and understanding to build a model that could assess the significance,
or predict the influence, of microbial activity on physical and chemical properties of a nuclear
waste repository on par with existing abiotic models came into focus through a workshop of
microbiologists, geologists and Yucca Mountain Project engineers. This Workshop on Microbial
Activities at Yucca Mountain (May 1995, Lafayette, CA) was held with the intention to compile
information for application to a potential repository at Yucca Mountain (Horn and Meike 1995).
An assessment of the perturbations of the natural environment as a result of the presence of a
repository, the capabilities of the microbes with respect to affecting a repository's performance,
and the duration of time over which it would be necessary to determine the performance of a
repository, made it clear that a purely abiotic model would be incomplete. The findings of this
workshop set off a number of efforts intended to eventually incorporate the impacts of microbial
behaviour into performance assessment models for a proposed Yucca Mountain repository.
One effort was to expand an existing modelling approach (McKinley and Hagenlocher 1993) to
include the distinctive characteristics of a repository at Yucca Mountain, e.g., unsaturated
conditions and a significant thermal load. This resulted in the so-called TSPA Near Field Model
(TSPA 1998). At the same time, a number of experimental studies were undertaken (Meike et
al.1999, Chen et al. 1999), and a compilation of relevant literature (Appendix A of this report) to
more thoroughly study the physical, chemical and biological parameters that would affect
microbial activity under Yucca Mountain-like conditions. Both efforts were undertaken to
provide data that could further develop and strengthen the model.
The literature search, (Appendix A, by D. Haldeman, University of Nevada, Las Vegas 1996)
addressed a large number of significant factors elicited from the Workshop on Microbial Activity
at Yucca Mountain (Horn and Meike 1995):
1. Microbial growth and responses to environmental parameters - abiotic factors (growth
properties, pH, temperature, osmoregulation, desiccation, radiation, mutation).
2. Survival (general survival, dormancy, spores, resuscitation, viable versus non-culturable
organisms, cryptic growth, injury, stress proteins, bacterial size).
3. In-situ considerations on attachments (biofilms, polymers, polysaccharides) and
interactions (microbe-microbe, consortia, competition, colonization, succession).
4. Diversity of microbiota (general diversity, sulphate-reducing bacteria, anaerobes,
acetogens, microaerophiles, iron-reducing bacteria, autotrophs, hydrogen-oxidizing
bacteria, etc.) and the genetic methods for detecting and identifying microbes.
5. Nutrients and cycling.
continued...
6. Degradation of introduced materials (hydrocarbons (diesel exhaust), concrete, PVC,
rubber, bitumen, styrene, polysaccharaides, blasting residues, etc.).
7. Sorption/adhesion and migration: transport of metals and radionuclides.
A complete bibliography of all literature collected in 1996 from this search is given in
Appendix A. The bibliography represents a considerable resource; too large to present in one
document when it is combined with the necessary discussion. Therefore, the entire bibliography
is planned to be presented in four annotated units: 1) abiotic factors, 2) community dynamics
and in-situ considerations, 3) nutrient considerations and 4) transport of radionuclides. The
present document focuses on the first category, abiotic factors, and a discussion of these factors
in order to facilitate the development of a model for Yucca Mountain.
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