Early results from the pilot study suggested a reduction in nitrogen levels but also brought up a number of new questions that still need answers.
The grasses are dormant, their brown leaves poking the sky as they float in one of the frigid lily ponds in Lincoln’s Sunken Gardens, the 1.5-acre public garden at 27th Street and Capital Parkway.
During the summer, the garden contains 30,000 living plants, bright bursts of color layered upon layer on the pocket of land where koi fish swim in their ponds. It is here that Alexa Davis, graduate student with the School of Natural Resources, first anchored her floating treatment wetland, a collection of 12 Nebraska-native wetland sedges and milkweed “planted” in the holes of a buoyant rubber mat, the roots hanging down into the shallow water.
She set out to discover two things: whether the floating treatment wetland would reduce excess nutrients, such as nitrogen, from the water; and whether the plants can survive Nebraska’s harsh winter.
To answer the first, Davis collected and tested water samples from the middle of the two koi ponds — one a control site — and from the base of the fountain that feeds water into the two ponds. She needed measurements of temperature, as well as the water’s acidity, salinity and oxygen levels, and wanted to know what levels of E. coli, nitrogen and phosphorus were present.
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