The 113 miles of the Mahoning River and watershed occupies parts of eight counties from north east Ohio to west central Pennsylvania. During the 1920’s, steel mills were located along the river and used the river for cooling and as site for waste deposition from manufacturing runoff. Environmental regulations were not applied at this time, so when the steel mills closed in the 1960’s to 1970’s the contaminants remained. During and after the time of the steel mill boom, the Mahoning River was prone to flooding. These flooding events were mild to severe moving soils, sediment, debris and other material into the floodplains). It is hypothesized that metals deposited from the steel industry may have moved from their deposition point as a result of flooding thereby contaminating floodplains downstream. The objective of this research was to determine if the floodplains downstream and not used for the steel industry resulted in elevated metal concentrations as compared to Ohio background levels. Soil samples were taken at five different sites including Mill Creek Park, Ohio State Route 289, Girard shoreline, Girard shoreline forest, and Hillsville Road, PA. All five sites were located downstream and away from the old steel mills and were not developed or in regular use. After samples were taken, the soil was sieved, extracted for plant available metals (Mechlich III) and total metals (EPA Method 3050B) as well as soil texture (Bouyoucos method) and soil pH (1:1 soil:water).
Results/Conclusions
The metals that were of concern included lead, cadmium, copper, magnesium, nickel, lead, arsenic and zinc. Several of these metals are phytotoxic including Cu, Ni, and Zn, while Cd and Pb pose a risk through food chain transfer. All five sites had similar trends with concentrations higher in the top 6 inches, with the exception of Mill Creek Park in which the concentrations were higher in the lower 6 inches. In general, the further away from the shoreline, the lower the metals concentrations. The highest plant available content was found at Mill Creek area with Pb and Zn concentrations 50.7 mg/kg and 104.1 mg/kg respectively. Total metal levels were found at higher levels than most of the background levels for Ohio. Further investigations could confirm the source of the metals and if they pose an ecological hazard.