Water Resources Research Act Program

Details for Project ID 2014DC161B

Geochemical characteristics of an urban river: detecting the influences of an urban landscape

Institute: District of Columbia
Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $15,000 Total Non-Federal Funds: $51,804

Principal Investigators: Stephen MacAvoy

Abstract: The Anacostia River is a major waterway, encompassing 440 km2, located in Washington, D.C. It is also one of the nation’s 10 most contaminated rivers, containing sewage, metals, polycyclic aromatic hydrocarbons (PAH), and polychlorinated biphenyls (PCB), and has been cited by the EPA as a "major area of concern" for the Chesapeake region (Maa 2008). The toxic chemicals in the river have had a deleterious effect on fishes, contributing to mortality and cancers among many of them (Pikney et al. 2004) . Although the presence of contaminants and nutrients has been well established, a more pervasive stress may be understudied; the changing aqueous chemistry associated with dissolution of concrete in this urban waterway. The literature bears multiple examples of the dramatic effects that impervious surfaces can have on watersheds. Those effects may be chemical as well as hydrological. Specifically, runoff from urban areas (where concrete is a major conglomerate rock) can lead to increased pH, conductivity, and modified ionic composition (Gaillardet et al. 1999; Gallo et al. 2013; Hasenmuller and Criss 2013; Wright et al. 2011). For example, a 2011 study examining the influence of concrete drainage systems on streams in Sydney, Australia found that, in comparison to reference streams, urban streams showed increases in alkalinity/buffering capacity and pH, as well as Na. Cl, and Ca. (Wright et al. 2011). Additionally, they suggest that significant amounts of Ca, HCO3, and K ions in urban streams could originate from contact with concrete drainage pipes (Wright et al. 2011). Also a critical issue for the river is nitrogen concentrations (nitrate and ammonium in particular). While urban streams generally have less nitrogen than agricultural streams, the Anacostia's can be high and should be monitored (MacAvoy et. al. 2009; Connor et al. in review). Clearly, the altered urban landscape can influence the geochemistry and nutrients of natural river systems; examining the geochemical controls of urban rivers could be an important factor in fully understanding how development impacts their health and biodiversity. Here we propose to collect geochemical and nutrient data from water column samples in order to identify controls on the Anacostia River, Washington DC, and compare that data to the more sub-urban/ex-urban Potomac River. The specific objectives of this research are 1) to determine concentrations of nutrients in this anthropogenically influenced river in the United State's capital, 2) characterize relationships among geochemical components to assess the importance of concrete versus natural geochemical controls.