Author: Stephanie Whitmore
Institution: Arkansas State University, Jonesboro, AR
Date: December 2010
An urban city can influence the aqueous geochemistry of the local streams and rivers. The City of Jonesboro, the largest city in northeast Arkansas, is a growing urban center surrounded by agriculture. Runoff from agriculturally dominated lands and industries can adversely impact local waterways through higher nutrient and metal inputs. We compared two local waterways, Big Creek and Lost Creek, as they were the largest creeks flowing through Craighead County and the City of Jonesboro, respectively. To measure the effects of an urban center on stream geochemistry, samples were collected from Big Creek (reference creek) and Lost Creek and were analyzed for: major ions, selected heavy metals, and trace metal toxicity during low flow and high flow. Even though Lost Creek is considered to be a tributary of Big Creek, a mass balance calculation determined that Big Creek is comprised of 63-73% of Lost Creek water. The EPA impairment designation for Lost Creek for toxic levels of copper, lead, and zinc persists after Big Creek and Lost Creek merge; however, as indicated by the calculated trace metal toxicity, several sites that show toxic levels are not covered in the impairment listing.