Plant Establishment and Water Quality Changes in a Constructed Wetland Designed to Treat Agricultural Runoff

Abstract

A variety of constructed wetlands are used to treat agricultural runoff. Research was carried out on a small pond located on private property in Fairfield Township,Columbiana County, Ohio. The pond receives runoff from two small streams that drain a small cattle farm and surrounding crop land. The excess of nutrients in the pond is causing heavy growth of duckweed and algae. A constructed wetland was built to remove nutrients from the pond inflow to improve as a means of improving the water quality and making the pond more aesthetically appealing. Pre-wetland construction and post construction water quality sampling and analyses were conducted to evaluate the effectiveness of the wetland in improving water quality. Water Quality parameters included: biochemical oxygen demand, total solids, total suspended solids, Escherichia coli (E. coli), coliform, dissolved oxygen and temperature. Local wetland plant species were transplanted from two established wetland sites to populate the new constructed wetland. A plant count was performed to determine the percent growth and proliferation of the wetland plants. Statistical analysis of the pre and post wetland construction water testing results showed a significant decrease in total suspended solids in 2011 from 2010. The boxplot tests showed decreases of the average number in total suspended solids, total solids,biochemical oxygen demand, E. coli, and coliform bacteria. An increase in dissolved oxygen and temperature was also shown in the SPSS boxplot tests. The univariate test between temperature and dissolved oxygen showed a slight significance between the two parameters. The total percent growth rate for both of the wetland cells was found to be 2900%, with cattails being the dominate species.