Megan Lord-Hoyle, Royal
Military College of Canada, Kingston,
Ontario, Canada
abstract
Ashish K. Sahu, University
of Massachusetts, Amherst,
MA
abstract
Christina
L. Stauber,
University of
Massachusetts, Amherst,
MA
abstract
Megan
Lord-Hoyle:
Bioaccessibility: Improving
Risk Assessments for Contaminated Sites
Megan Lord-Hoyle,
Environmental Sciences Group, Royal Military College of
Canada, Kingston, Ontario, K7K 7B4, Canada, Tel:
613-541-6000 ext. 6922, Fax: 613-541-6596, Email: Megan.Lord-Hoyle@rmc.ca
Louise Meunier, Environmental Sciences Group,
Royal Military College of Canada, Kingston, Ontario, K7K
7B4, Canada
Ken Reimer, Environmental Sciences Group, Royal Military
College of Canada, Kingston, Ontario, K7K 7B4, Canada
Chris Ollson, Jacques Whitford Environment Limited, 2781
Lancaster Road, Ottawa, Ontario, Canada
Iris Koch, Environmental Sciences Group, Royal Military
College of Canada, Kingston, Ontario, K7K 7B4, Canada
Regulations and guidelines
for contaminated site remediation in Canada are currently
based on the total concentration of the target substance
in a particular substrate (soil, sediments or water).
Contaminants in soil, however, maybe be tightly bound and
thus there is a growing trend to consider bioavailability
– the fraction of a substance that is absorbed by the
organism – in determining suitable risk based endpoints
for site remediation in Canada. Bioavailability is usually
measured by using in vivo methodologies, which tend to be expensive and time
consuming; bioaccessibility measurements using simulated
gastrointestinal conditions to estimate the soluble
fraction of a substance are increasing in desirability for
incorporation into risk assessment. Bioaccessibility
measurements can be carried out with a simple extraction
procedure and hence are more accessible, less expensive
and quicker than in
vivo studies to estimate bioavailability. For these
measurements to be meaningful, however, it is important to
compare bioaccessibility to in
vivo bioavailability results and determine their
accuracy. This talk will focus on the development of
bioaccessibility methods for arsenic and nickel,
validation of the results using soils that have been
subjected to in vivo
testing, as well as the effect of more realistic exposure
scenarios on risk assessment outcomes. It will also
provide insight into the acceptance of the
bioaccessibility results by Canadian regulators. It will
conclude with a description of activities of
Bioaccessibility Research Canada (BARC) – a newly formed
network of parties interested in furthering the
development and implementation of bioaccessibility in
Canada.
Ashish
K. Sahu:
Perchlorate
Reduction in a Packed Bed Bioreactor Using Elemental
Sulfur
Ashish
K Sahu,
University of Massachusetts, 18 Marston Hall, Department
of Civil and Environmental Engineering, Amherst, MA,
01003, Tel: 413-577-3229, Fax: 413-545-2202, Email: aksahu@acad.umass.edu
Sarina
J. Ergas, University of Massachusetts, 18 Marston Hall,
Department of Civil and Environmental Engineering,
Amherst, MA, 01003, Tel: 413-545-3224, Fax: 413-545-2202,
Email: ergas@ecs.umass.edu
Perchlorate
release in groundwater has affected water supplies to
approximately 15 million people in the US and has
primarily occurred in association with manufacturing of
missiles, rockets, fireworks and industrial processes.
Presently, perchlorate contamination has been recorded in
drinking water in 38 US states[1].
The Commonwealth of Massachusetts has proposed limits on
perchlorate of 1 mg/L
because of adverse effects to the thyroid[2].
Although perchlorate is on the EPA contaminant list, no
standards have been set so far.
Various
researchers and have found that perchlorate can be used as
an electron acceptor in anaerobic microbial metabolism2.
A variety of electron donors including H2,
ethanol, acetate and sugar derivatives have been
investigated for perchlorate removal using both mixed and
pure cultures.
This
study investigated a novel process for treatment of
perchlorate contaminated water using elemental sulfur as
an electron donor. A
microbial culture capable of coupling sulfur oxidation
with perchlorate reduction was enriched from a
denitrifying wastewater inoculum under anaerobic
conditions. Microbial biomass was added to flasks
containing elemental sulfur, crushed oyster shell and 5
mg/L ClO4- . An initial
acclimatization period of approximately 15 days was
observed, after which perchlorate was reduced to below
detection limits (500ppb).
Subsequently,
the cultures were inoculated into an upflow bioreactor
packed with elemental sulfur and crushed oyster shell
media. Groundwater containing ~5 mg/L of ClO4-
was continuously fed to the column at an initial hydraulic
retention time (HRT) of 53 hours. HRT was optimized to 13
hour over the first three months of operation.
Intermittent recirculation resulted in faster degradation
of perchlorate, possibly due to more uniform distribution
of the biomass through the column. The column is presently
being operated with low levels of perchlorate (100 ppb)
and with other co-contaminants, which shall be discussed
at the meeting.
[1]
MADEP 2005. The
Occurrence and Sources of Perchlorate in Massachusetts
.Draft report
URL: http://www.mass.gov/dep
[2]
Edward, T. U. 1999. Perchlorate
in the Environment. Kluwer Academic/Plenum
publishers, NewYork, NY.
Christina L. Stauber:
The
Use of Local Carbon Sources in Encouraging Acid Mine
Drainage Bioremediation
Christina
L. Stauber,
University of Massachusetts Amherst, Department of Civil
and Environmental Engineering, Marston 18, Amherst, MA
01003. Tel:
413-532-3416, Email:
cstauber@student.umass.edu
Sarina
J. Ergas, University of Massachusetts Amherst, Department
of Civil and Environmental, Engineering, Marston 18,
Amherst, MA 01003, Tel: 413-545-3424, Fax: 413-545-2202,
Email: ergas@ecs.umass.edu
Jonathan R. Lloyd, The University of Manchester, School of
Earth, Atmospheric and Environmental Sciences, Manchester
M13 9PL, Tel: (0161) 275 7155, Fax: (0161) 306 9361,
Email: Jon.Lloyd@manchester.ac.uk
Acid
Mine Drainage (AMD), occurring at abandoned mines, is a
water problem characterized by low pH and high levels of
metals. Factors
aiding in the bioremediation of AMD are currently being
studied by an interdisciplinary group at UMass Amherst,
focusing around the Davis Mine, located in Rowe,
Massachusetts. Natural
attenuation of the AMD has been observed at Davis Mine, as
evidenced by a rise in pH and reduction of sulfate and
iron in the stream bed.
A prior microcosm study indicated that local carbon
sources, such as algae, could be useful in encouraging the
attenuation by acid tolerant anaerobic bacteria.
To
further investigate the effects local carbon sources have
on AMD bioremediation, a second microcosm study is being
conducted at the University of Manchester in England.
Samples were taken from two sites: Mam Tor, an
ancient land slip located in Derbyshire, England, and
Parys Mountain, an abandoned copper mine in Anglesey,
Wales. While
natural attenuation is occurring at Mam Tor, Parys
Mountain is characterized by low pH levels of around 2,
very high metal contents in the stream water, and little
natural attenuation.
Local
algae, wood chips, and glycerol were added to the sediment
and water samples taken from the Mam Tor and Parys
Mountain sites in a microcosm study.
Geochemical
parameters linked to the microbial reduction of sulfate
and Fe(III) were studied including
changes
in pH, oxidation reduction potential (ORP), Fe(II), and
sulfate. Both
wood chips and algae have been found to be promising
carbon sources, encouraging a rise in pH and a reduction
of Fe(II) more quickly than glycerol.
Quick responses were observed in the Mam Tor
samples, while the Parys samples were delayed due to
harsher conditions. Local
materials provide an interesting, sustainable source of
carbon for microbial reduction of Fe(II) and sulfate and
attenuation of AMD.
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