Determination of Metal Concentrations in Sediments of Big Walnut Creek

The freshwater mussel populations in the lower stretch of Big Walnut Creek in central Ohio have been found to vary along the run of the creek with the lowest population of mussels in the middle stretch. One possible cause for the decline is the presence of contaminants in the sediments of the creek. In this study, nine Sites along the creek were examined. At each Site, sediment samples from a pool region and two quadrants from where mussels were also studied (the area of interest) were collected, along with pseudo feces, which is the waste mussels produce as they filter water and sediment to find food. The concentrations of select metals in the sediments and pseudo feces were determined using acid extraction and analysis with microwave plasma-atomic emission spectroscopy. The concentrations of metals were found to vary along the creek, most notably in the cases of lead, zinc, calcium, and manganese. However, only calcium and zinc were found to be significantly correlated to the mussel populations. The concentration of calcium was found to positively correlate to mussel populations (r = 0.715, p = 0.03), while zinc was found to negatively correlate to mussel populations (r = -0.717, p = 0.03). Additionally, the metal levels in the area of interest were compared to those collected in the year 2000, and the overall quality of the sediments improved over the past two decades with only four occasions where a sampleexceeds the threshold effect concentration out of 45 total samples