Water Resources Research Act Program

Details for Project ID 2006MD135B

Chemical and Biological Impacts of Zinc and Road Salt from Road Runoff Entering Stormwater Retention Ponds

Institute: Maryland
Year Established: 2006 Start Date: 2006-03-01 End Date: 2007-02-28
Total Federal Funds: $15,120 Total Non-Federal Funds: $63,894

Principal Investigators: Ryan Casey, Edward Landa, Steven Lev, Joel Snodgrass

Project Summary: Highway runoff has the potential to negatively impact receiving systems due to elevated levels of constituents such as deicing salts, organic compounds, nutrients, and metals. Several studies have demonstrated that road runoff contributes large quantities of Zn to the environment, much of which is derived from tire particulate matter. Roadway runoff, including Zn, has been implicated in causing adverse effects in aquatic organisms. Retention ponds attract and are utilized by a wide range of wildlife species, therefore deposition of metal-bearing vehicular wear particles may result in significant exposures of biota to elevated levels of Zn. Additionally, accumulation of Zn by biota inhabiting ponds (e.g., larval amphibians and fish) may result in trophic transfer of Zn out of ponds as semiaquatic wildlife (e.g., wading birds, waterfowl) feed on pond organisms that accumulate significant quantities of Zn. At this point, neither the magnitude nor the effects of such exposures are clearly known. Recent research has also demonstrated that road salt applications are resulting in increased salinization of freshwater systems throughout the year with potential toxicity occurring in sensitive organisms. In the first year of this project, our laboratory found that extremely high salt concentrations (up to 17,000 mg Cl- L-1) persisted through the summer in this retention pond and that lower (though still elevated) levels of salinity resulted in 100% mortality for wood frogs (Rana sylvatica). Additional work in our laboratory has demonstrated that Zn in pond sediments is relatively unavailable compared to Zn in road runoff entering the pond. Runoff can contribute substantial loads of Zn in single storm with up to 40% of the Zn in the truly dissolved phase. This aqueous phase is the most relevant toxicologically. The proposed research will continue the efforts currently underway (quantifying Zn in roadway runoff, characterization of roadway particulate matter) while adding two new objectives. The first objective is to determine the storage of Zn in stormwater ponds throughout the Red Run watershed and compare that storage to fluxes of Zn out of the watershed in surface water. This will allow us to assess the watershed-level impacts of stormwater management strategies on control of Zn export from this region. Secondly, we will quantify the salinization of retention ponds throughout the Red Run watershed to assess their contribution to regional salinity increases. We will evaluate both water column salinity as well as that in shallow groundwater that could be discharging into adjacent surface waters.