Floating islands are masses of floating aquatic plants with the rools hanging into the water column.  They function very similar to wetlands.  The hanging roots remove contaminants from the water through filtration and uptake of nutrients and contaminants into the plant's tissue.  Biofilms composed predominatly of bacteria are present on the root surfaces and aid in the removal of ammonium, nitrate, phosphate, and heavy metals.  While floating islands are relatively common in natural phenomena, the implememtation of man-made floating islands for improving water quality in only beginning to be considered a viable water treatment solution. 

 

The impletmention of floating islands in the tidal water zone of polluted Anacostia River helps improve water quality and aesthetics.