GROWTH PERFORMANCE AND NUTRIENT RETENTION POTENTIAL OF TWO AQUATIC PLANT SPECIES IN ARTIFICIAL FLOATING ISLANDS

Nutrient pollution is considered one of America’s most widespread, costly, and challenging environmental problems. Artificial Floating Islands (AFIs), a phytoremediation technology, has been proven as an efficient, environmental-friendly, and cost-effective strategy to address this issue. However, most previous studies of AFIs were done in controlled conditions at mesocosm experiments. In addition, limited information exists on the use of AFIs as a nutrient remediation/prevention strategy in Ohio. This study aims to fill these gaps. We are currently undertaking a combination of mesocosm and natural experiment to assess the nutrient-removal efficiency of AFI systems in the Milliron Research Wetlands (at the Ohio State University Mansfield campus), and establish a performance baseline for two native aquatic plant species, Carex comosa and Eleocharis palustris.

In this study, 18 AFIs, 6 planted with Carex comosa, 6 with Eleocharis palustris, and 6 have no plants, were deployed in a section of the Milliron Research Wetlands. Physical and chemical parameters were monitored bi-weekly. The AFI systems were constructed using PVC pipes to provide buoyance, EVA foam mats as platforms, and nylon nets to cover the system. Each AFI unit had eight luffa sponges, inserted in the foam mat, to hold aquatic plant seedlings, keep the moisture of roots, and enlarge the surface area for bacterial biofilm development. Since nutrient removal from the wetland is affected by numerous natural processes, a mesocosm experiment was set up to assist the quantification of nutrient removal due specifically to the presence of AFIs. The mesocosm experiment mimicked the natural experiment at the wetland and contained 12 equal-size tanks containing water pumped directly from the wetland, 3 of which had AFIs with Carex comosa, 3 had Eleocharis palustris, 3 had no plants, and 3 contained just water from the wetland. Physical and chemical measurements (as well as sample collections) were performed weekly in the tanks. Water in the tanks was exchanged bi-weekly. Preliminary results showed that the AFI systems quickly developed large root systems and extensive bacterial biofilms. The growth performance and nutrient retention potential of the two tested aquatic plant species were investigated in this study.