Quantifying water quantity, quality, and zinc mobilization in a bioretention area in the Piedmont of Georgia

Abstract

A bioretention area installed in the Piedmont of Georgia on the University of Georgia, Athens campus was monitored from January 2011 to December 2012 to quantify hydrologic benefits, water quality improvements, and zinc transport through the bioretention media. The bioretention area demonstrated an excellent ability to provide extended 24 hour storage for each storm and reduce peak runoff volumes from 6-93%. Water quality reductions ranged from 60-98% for total suspended solids, biochemical oxygen demand, ammonium-nitrogen, and zinc were reported. However, increases in nitrate-nitrogen were seen over the entire course of the study and is attributed to the compost in the filter bed of the bioretention area. Influent zinc accumulation within the bioretention media could not be established due to preexisting zinc discovered within the compost used for the fill material. Influent zinc concentrations were directly related to influent TSS but outflow zinc was found to be Zn2+ released from the bioretentoin fill material.