Impervious surfaces in Texas have increased faster than any other states in the U.S. in the past few decades. Heavy metals run off generating from pavements, automobiles and oil spills are of great concern due to their negative impacts on habitats and human health. Conventional remedial methods recognize the hydrological factors mostly related to precipitation. Low impact development (LID), however, considers other constituents of the hydrological cycle. Understanding the ability of native vegetation in the removal of metals within the Edwards Aquifer is crucial. The six toxic heavy metals including cadmium, copper, lead, nickel, chromium, and zinc as well as two metals for monitoring purposes including iron and magnesium have been selected to monitor and evaluate the efficiency of the native vegetation in removing heavy metals. The stormwater samples are collected in 1 L bottles using the ISCO autosamplers located at the inflow and the outflow of the basin. The collected samples are then analyzed using ICP-OES. The results based on 11 rain events have indicated that retention basins can decrease the concentration of heavy metals to some extent. Iron was decreased in most cases, and zinc was decreased greatly if not entirely. Nickel and chromium, though very low concentrations were detected, were also decreased or removed. Copper in most cases showed lower concentration in the outflow. Magnesium and lead did not change significantly possibly due to the geological and structural characteristics of the basin. Cadmium was only detected in two events which its concentration was below the detection limit. This study verified the importance of the vegetation in the removal of heavy metals within the Edwards Aquifer zone. This study will also consider the microbial activities to further investigate the importance of LID.
