Abstract, Live Poster Session (BACK)

A Comparative Study Analyzing Water Quality in a Microcosm Iron Cycler System and a Constructed Stream Restoration System in Rock Creek Park, Washington, DC  (Click to view poster)


Anita Alexander
Environmental Science & Technology
College of Agriculture and Natural Resources
University of Maryland, College Park, MD

Anita Alexander1, Harrison Scherr1, Shawn David1, Geoffrey Chan1, Derek Lam1, Peter May1,2
1Envioronmental Science and Technology Department, University of Maryland, College Park, MD 20740 USA
2Biohabitats, Baltimore, MD 21211 USA

This study is primarily a comparison of water quality data from repeated monitoring of a constructed iron cycling system in the ecological engineering laboratory at the Environmental Science and Technology Department at the University of Maryland, as well as monitoring data and observations from a constructed headwater stream restoration site in Rock Creek Park, Washington, D.C.  The lab based system intentionally cycled oxidized iron through a constructed microcosm while the stream restoration site unintentionally created a naturally occurring condition whereby iron oxidizing bacteria produced a rust colored iron floc throughout some sections of the site but not others. The water quality parameters that were tested were ferric and ferrous iron, dissolved oxygen concentration, dissolved oxygen percent saturation, pH, oxygen reduction potential, temperature and turbidity.  The focus of this study was on iron oxidation and reduction. The ability of saturated soils to oxidize ferrous forms of iron, converting them to the insoluble ferric form was mimicked in our constructed iron cycling microcosm.  Ferrous iron levels were tested and the output water supply would show higher levels than the input water supply for a majority of the trials. Overall concentration of iron in the microcosm experiment varied, but iron was reduced in three out of twelve trials. A series of twenty-three pools were created as part of a novel headwater stream restoration effort at Rock Creek Park. The same water quality tests were conducted in each pool both onsite and in the lab. In general, there was a spike in both ferric and ferrous iron in the middle stretch of pools while lower levels of both iron forms were found in the upper and lower reaches of the stream. In addition, a comparison is made between the total nitrogen results collected from Rock Creek Park stream restoration site and the results found in other studies assessing the effectiveness of stream restoration on reducing nitrogen in downstream waters.