ENVIRONMENTAL HISTORY AS RECORDED IN THE SEDIMENTS OF LAKE ISAAC IN MIDDLEBURG HEIGHTS, OHIO

Lake sediment can provide information on past environmental change to a lake system that is useful for present-day and future environmental planning. In this study, sediment cores up to 2 m long were collected from Lake Isaac in Middleburg Heights, Ohio in order to study past environmental change. The core lithology was visually described, and measured for loss-on-ignition, sediment magnetic parameters and heavy metal concentration. The sediment is comprised of 3 main lithologic units: a basal peat, a black and grey mud, and an upper organic-rich black and green-brown mud. The basal peat lithologic unit has a low dry bulk density (0.13g/cc), low ferrimagnetic content (2.3*10^-5 SI units), low Pb concentration (32.5μg/g) and high organic content (48%). These results coupled with the fact that Lake Isaac does not appear on any maps before 1951 indicate that Lake Isaac was once a wetland environment. Overlying the basal peat is black and grey mud having a high dry bulk density (0.39g/cc), low organic content (18%), high ferrimagnetic content (8.7*10^-5 SI units) and moderate Pb content (57.4μg/g). This mud lithology indicates a change from a wetland to an open water lake environment in the 1940s, as the lake does not appear on any maps as late as 1937 but first appears on a 1951 map. During this time the village of Middleburg Heights had increased suburban development. The uppermost black and green/brown organic mud has a moderate dry bulk density (0.19g/cc), moderate organic content (26%), high ferrimagnetic content (9.3*10^-5 SI units) and high Pb content (up to 321μg/g) that declines toward the core top. Increased anthropogenic activity in the Lake Isaac area caused the increase in heavy metal concentrations and the passing of environmental legislation may explain the decline towards the top of the core. Knowing the past environmental change from Lake Isaac sediment can be useful to environmental managers when planning for the future of the lake and the surrounding area by providing a reference to the original environment.