Effect of a Water Treatment BMP on Nutrient Spiraling and Leaf Litter Breakdown in an Urban Stream

Alterations to stream conditions caused by urbanization can compromise valuable ecosystem services, such as nutrient attenuation and carbon processing. A best management practice (BMP) water facility was installed to restore an impaired urban stream in Columbus, GA. This study was conducted to determine the effect of this BMP on nutrient spiraling and leaf litter decomposition in a 2 km stretch of Weracoba Creek. I hypothesized the BMP would (1) reduce leaf mass loss over time and (2) interfere with nutrient concentrations and uptake lengths. I characterized leaf litter decomposition using tulip tree leaves {Liriodendron tulipifera) in 1mm mesh bags deployed upstream (1 site) and downstream (3 sites) of the BMP for 10 weeks (sampled bi-monthly, 3 replicates per site). I analyzed nitrate, phosphate, and nitrite concentrations bi-monthly (02/15/07-01/10/08) from three sub-surface grab samples taken at each of the four sites used in the leaf litter decomposition study. Leaf mass significantly declined over time, and was consistent across all four sites. Nitrate and nitrite concentrations remained consistent between pre- and post-construction, but phosphate increased during those periods. Nitrite showed consistently higher concentrations in the two upstream sites compared to the two downstream sites. Nitrate, phosphate, and nitrite uptake lengths remained unchanged pre- and post-implementation of the BMP. These results strongly suggest that the BMP had no positive effect on the two ecosystem services studied. Despite its impaired status, Weracoba Creek continues to provide some measure of services through leaf litter decomposition and nutrient retention