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Dr. Chris Marvin, Research Chemist, National Water Research Institute, Contaminant History of the Great Lakes
In the late 60s and early 70s, Environment
Canada undertook a program to evaluate the
contaminants found in sediments in Lakes
Superior, Huron, Erie, St. Clair and Ontario,
in recognition of the fact that pollutants in
the Great Lakes posed a serious threat to
wildlife, biodiversity and aquatic ecosystems.
Samples were taken and tested, and the
research was documented.
Several years ago, a colleague of Dr. Chris
Marvin discovered the archived sediment
samples. This was great news, because in the
ensuing years there were dramatic
improvements in the instruments used for
analysis. Most importantly, improved
instruments were able to detect with a higher
degree of accuracy and at lower
concentration. "With the existence of
archived samples," Dr. Marvin explains,
"we’ve been able to use advanced analytical
methods and technology to do a direct
comparison of these older samples with
current samples. This has helped overcome
the problems of comparing today’s data with
data that was documented using 30-years-old
technology."
The best news is that there have been
dramatic and definitive drops in almost all
contaminants. Most notable is the drop in
lead, attributed to its ban from use in
gasoline, mercury and PCBs.
Over the past 25 years, there has
also been a four-fold decrease in
PCBs in Lake Erie. And, there has
been a marked decline in a host of
metals, chlorinated organic
pollutants (including pesticides and DDT), as
well as dioxins and furans, both by-products
of chemical manufacturing.
Key factors contributing to the overall
decline in contaminant levels are the
Canada-United States Great Lakes Water
Quality Agreement and the Bi-National
Toxics Strategy, which have targeted
specific harmful compounds and encourages
the commitment of both the public and
private industry to more environmentally
responsible practices.
Today, the National Water Research Institute, in partnership
with the Ontario Region of Environment Canada, the Ontario Ministry of the
Environment, and the Department of Fisheries
and Oceans, continues to conduct sediment surveys
in the Great Lakes. In fact, after reviewing the
reports from the 60s and 70s, researchers decided
to sample at the same sampling stations given
their proximity to heavy industrial and urbanized areas, and to allow
comparison of data with previous surveys.
The research done by the Great Lakes
Sediment Assessment Program measures
the occurrence and spatial distribution of
toxic substances, and helps us understand the
role human activities play in releasing these
substances into the environment. It also
provides valuable information for developing
effective strategies to lessen the severity of
health risks.
The program’s primary goals are to discover
how best to identify and track the remaining
sources of contamination and accelerate their
elimination, and to perform focused
monitoring in order to track down the
localized sources of contamination. There are
also compounds that people haven’t heard
much about that need to be considered –
compounds like polybromated .ame
retardants which were introduced to replace
the banned PCBs.
"We have a good handle on the pollutants
we’ve been analyzing for 30 years," says
Dr. Marvin. "Now we are actively pursuing
emerging chemicals. We have to do
everything in our power to be one step
ahead."
The Canadian Council of the Ministers of
the Environment
(CCME) publishes the
Canadian Sediment
Quality Guidelines. These
are based on contaminant
levels to ensure the
protection of aquatic life.
"The guidelines indicate a
certain level of
environmental health. This
is the target at which we’re
aiming," says Dr. Marvin.
The program is also now
starting to put together
data from the federal and
provincial governments, the United States, as
well as programs from other agencies. "We
look at programs from other agencies such as fish populations and surface water
monitoring, and always consider what these
are telling us," says Dr. Marvin. "We can get
a far more complete picture and track the
progress towards elimination if we include
all the monitoring information out there.
Much progress has been achieved, but we are
committed to virtual elimination of persistent
toxic substances."
Ontario Region Success Stories
Great Lakes Success Stories
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