Now, a study proves that gardens are more than just a pretty place. The study, by researchers at Illinois State University, demonstrates that such constructed gardens can have a measurable and positive impact on water quality.
Floating gardens are essentially platforms built and wrapped in coconut husks (椰子壳), and filled in with native plantings. As plants grow, they extend their roots into the water. On the North Branch of the Chicago River, non-profit Urban Rivers and its partners are developing a mile-long floating eco-park called the Wild Mile. The re-development of this former industrial canal is Urban Rivers' important project. As part of the park, floating gardens, attached to shore, are being fixed.
The primary aim of the floating gardens is beautification. But the Illinois State team, from the University's Department of Geology, Geography, and the Environment, saw an ideal setup for a controlled experiment. "We joined it because it's the perfect opportunity to see if there's an influence on water quality," explains lead author Abigail Heath.
The study is novel: previous studies have explored floating gardens' influence on water quality over time, primarily in wastewater treatment ponds, but not over space, in moving water. The project also matches well with Urban Rivers' broader goals. "The city is interested in bettering water quality," says Phil Nicodemus, Urban Rivers' Director of Research. "Happily, Illinois State took part in it later."
Could this small human-made park improve water quality? An average of data collected over the course of the study shows middle but definitive improvement. For example, nitrogen (氮) dropped from 4.69 milligrams per liter in surface water to 4.43 milligrams per liter, a drop of about 1 percent.
"Despite how small this garden was, there was measurable improvement in water quality from upstream to downstream," notes Heath. She and her colleagues see this as a model for how large floating gardens should be to help improve water in similar settings. "Even this tiny garden makes a difference," she says.
