U.S. Water News Online
MUSCATINE, Iowa -- University of Iowa researchers are using 100-year-old freshwater clams to provide fresh insights about waste water.
``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 known.''
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 populations.''
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 engineering.
``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 exterminated.
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 Highway 22.
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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