Stratigraphic diatom and chemical evidence for acid strip-mine lake recovery

Stratigraphic analyses of diatoms and chemical compounds in a sediment core were utilized to investigate the recovery of an acid strip-mine lake in southern Ohio. The chemical stratigraphy suggests that chemical recovery of the lake, defined as the rise and maintenance of water pH at values above 4.5, is a discrete process marked in the core by a sharp rise in the sediment concentrations of metals. The diatom data suggest that biological recovery may occur in stages, beginning at the sediment-water interface. As the lake ages, there is a transition from a community dominated by a single acidophilous species characteristic ofbbenthic habitats to a community composed of many planktonic, epiphytic, and benthic species of primarily alkaliphilous preference. Biological development is not directly correlated with the chemical recovery.