U.S. Water News Online
MUSCATINE, Iowa -- University of Iowa researchers are using
100-year-old freshwater clams to provide fresh insights about waste
``Mollusks are very long-lived, some upward of 100 years old,''
said Larry Weber, associate director of IIHR-Hydroscience &
Engineering, formerly known as the Iowa Institute of Hydraulic
Research. ``Because, as adults, they are stationary, they are a very
good indicator of what's been happening at that point in the river.
``What we've learned in the last 18 months is that this is a lot
more complicated than we knew and that there's a lot left to be
The study looks at how the discharge from sewage treatment plants
is contaminating the Upper Mississippi River.
Ongoing research in Pool 16 of the river -- a 26-mile stretch
between Davenport and Muscatine -- is beginning to yield data on how
threatened and endangered species of mollusks have responded over
time to barge traffic, recreational boat use, ag chemical runoff and
pollutants from upstream sewage and industrial wastewater discharges
into the river.
``One factor is that what's happening in this pool is impacted by
things going on hundreds of miles upstream,'' Weber said. ``And the
changes that are showing up today could be the result of things that
happened 30 or 40 years ago.''
Weber said it's been estimated that every drop of water from the
Mississippi River watershed passes through at least four wastewater
treatment plants en route to the Gulf of Mexico.
``Whether that's true, I can't say, but one of the things we're
doing is taking live mussels back to the lab and developing protocols
for testing their tissues for different levels of fragrance chemicals
that are added to soaps, laundry detergents, deodorants and
perfumes,'' he said. ``These chemicals enter the Mississippi in
wastewater effluent, and we're looking at their toxicity in mussel
Seven fragrance chemicals are widely used, said Keri Hornbuckle,
an environmental engineer and an associate professor in Iowa's
College of Engineering's department of civil and environmental
``They've been found in the water of the Great Lakes and in the
air above the Great Lakes,'' Hornbuckle said. ``We're looking for
them in the Mississippi. Specifically, we're studying their
concentration in the water and in the mussels and working to
determine their toxicity in larval and juvenile mussels.''
Among the project's goals is providing guidance for conservation
and restoration of freshwater mussel populations.
Historically, 50 species of the bivalve mollusks populated the
Upper Mississippi River. Only 30 have recently been observed,
including 17 classified in Iowa as endangered, threatened or
The study is being conducted along with the U.S. Geological
Survey. Iowa's $45,000-a-year mussel project is one of a growing list
of studies based at the school's new Lucille A. Carver Mississippi
River Environmental Research Station five miles east of Muscatine on
The station, which was completed last year, is the only
university-affiliated research center on the Mississippi River. It is
used by the school as a field laboratory by undergraduate and
graduate students studying environmental hydraulics.
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