John J. Griffin

Impact of fossil fuel combustion on the sediments of Lake Michigan

A study was conducted to determine the relationships between metal and mineral contents of the Lake Michigan sediments and fluxes of charcoal, whose morphologies and surface characteristics are indicative of different combustion processes. Sediments deposited during 1930-1968 showed increasing concentrations of chromium, nickel, iron, aluminum, zinc, cobalt, lead, cadamium, and copper. After 1968, these concentrations decreased slightly. A similar profile was found for total charcoal concentration.

Notes. Impact of fossil fuel combustion on sediments of Lake Michigan: a reprise.

The size distribution of charcoals in sediments of Lake Michigan reflects the onset of the industrial revolution and the increased intensities of fossil fuel combustion during the twentieth century. Prior to 1900 the less than 1-..mu..m fraction was dominant, and its source was primarily biomass burning. In the subsequent years coal and oil burning became evident with larger particles, especially greater than 32 ..mu..m, making larger contributions to the total charcoal concentrations. The input of the larger particles is a consequence of near fallout of particles from energy-producing plants near the lake.

Talc in atmospheric dusts.

The mineral talc has been observed in dusts recovered directly from the atmosphere and in the solid mineral phases of rain and snow. The talc, where detected, attains levels of the order of a per cent by weight in the solid phases. This talc probably arises from agricultural activity where the mineral is used as a carrier and diluent for pesticides. The amounts of talc found in atmospheric dusts appear to reflect a local introduction rather than a generalized global fallout.