Freshwater mussels are used in assessing comprehensive aquatic health because they are hypersensitive to their environments. Although the rivers of the United States support the most diverse fauna in the world, freshwater mussel populations have been rapidly declining across the country. The diversity in the mussel populations in Big Walnut Creek, which runs through central Ohio, has been found to decrease in the middle stretch; however, the reasons for the decline are not understood. One possibility is that anthropogenic activities, such as the presence of a major metropolitan airport, are affecting the sediment chemistry. In order to determine if metals in the substrate are affecting mussels, the identities and concentrations of the metals must first be determined.<br/>Sediment samples and pseudofeces (the finer material that has filtered through the mussel) were taken from nine locations via grab sampling along Big Walnut Creek, and then digested using EPA method 3050B. Following digestion, samples were analyzed using Microwave Plasma - Atomic Emission Spectroscopy (MP-AES) for several metals, including lead, zinc, chromium, cadmium, nickel, molybdenum, manganese, calcium, aluminum, and potassium. These metals were chosen because they may be affected by the specific anthropogenic activities in the area surrounding Big Walnut Creek. A standard soil sample from the National Institute of Standards and Technology containing known amounts of select metals was also analyzed to optimize and validate the analytical method. Preliminary analysis shows that lead levels are statistically different at sites along Big Walnut Creek with the greatest concentrations of lead found further downstream (F(4, 13) = 2703.177, p &lt; 0.0005). The cadmium levels were also statistically different at sites along Big Walnut Creek (F(4, 13) = 6.223, p &lt; 0.005). However, the cadmium concentration was lowest the further downstream. Additionally, the levels of cadmium at all sites analyzed thus far are above the consensus-based threshold effect concentrations (TEC: the concentration below which harmful effects are likely to be observed) for cadmium, which is 0.596 mg/kg. The concentrations of lead in sediment exceed the TEC of 35.8 mg/kg at three sites. This presentation will detail the findings for all sediment metal levels along Big Walnut Creek and their relationship to its mussel populations.

Determination of metal concentrations in sediments of Big Walnut Creek

253rd National Meeting (2017)

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