Dating a Sediment Core Using a Spheroidal Carbonaceous Particle Chronology

Abstract

Spheroidal carbonaceous particles (SCPs), a type of insoluble fly-ash, are produced from the incomplete combustion of fossil fuels and are deposited in lake sediments. They are not influenced by chemical or biological decomposition; therefore, they provide a baseline reference for ecosystem disturbance from atmospheric pollution deposition. We hypothesize that using SCPs will track anthropogenic inputs of atmospheric pollution; and that they can be used as a primary dating tool since different SCP concentrations in lake sediments archive the local historical occurrence of industrial fossil fuel combustion. Utilizing a method to date cores using a SCP chronology is significant to the historical environment reconstruction process since it fills in data gaps by describing historical variables. A sediment core was taken from the depositional basin of Mosquito Creek Reservoir (MCR), located in Trumbull County in the Mahoning Valley industrial region of Northeastern Ohio, using a 5-cm diameter piston corer. A chronology was constructed by comparing annual raw steel production in the Lower Mahoning River Basin to sediment SCP concentrations. A very strong, positive linear correlation (Pearson Product-Moment Correlation Coefficient: r = 0.83, N= 15 p < 0.001) between steel production and smoothed SCP (&#8805;6.25&#181;m) concentrations enables determination of a chronology and allows the opportunity for reservoir sediment cores from other similar industrial regions to be dated primarily by a SCP chronology instead of less precise alternatives. Metals were analyzed to supplement the chronology, but their concentrations were not strongly correlated to SCP concentrations or regional raw steel production. Therefore, metal concentrations in the MCR do not reflect regional atmospheric deposition.