ASSESSING WATERSHED CHANGE AND SEDIMENT GEOCHEMISTRY IN A RIVERINE WATER-SOURCE RESERVOIR

Changes in land use, water demand and basin morphometry alter sources of inputs and subsequent water quality in many reservoirs. This study used a sediment core to investigate the legacy of watershed scale anthropogenic impacts to better understand reservoir response these changes. Meander Creek Reservoir (MCR) was formed when Meander Creek was dammed in 1932 and is the primary potable drinking water source for around 300,000 in the Youngstown-Warren, Ohio region. A 144 cm sediment core was collected from MCR in 2005, and an additional 27 cm core was collected in 2016 to update sediment geochemistry after zebra mussels were identified in the reservoir. Both cores were extruded at 1.12 cm sections. All samples (153 total) were nitric acid digested then analyzed using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Elements analyzed include: aluminum, antimony, arsenic, boron, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, mercury, molybdenum, nickel, phosphorus, potassium, selenium, silver, sodium, strontium, thallium, vanadium and zinc. Core chronology was established using a combination of core top, core bottom and two ¹³⁷Cs dates. Select results showed high concentrations of zinc, chromium and tin at the end of WWII, when population began to grow rapidly and land was quickly developed as the area industrialized, transporting material from the regional steel industry. A more recent increase in copper concentrations from 2000-2005 is likely due to the Mahoning County Sanitary District adding copper sulfate to the water to control microscopic algae. Overall, trends correspond with human activities in the region and reflect the fate of anthropogenic materials in MCR watershed.