COAL CONSUMPTION: AN ANTHROPOGENIC LEGACY MEASURED BY MARINE ORGANISMS

Throughout human history, from the dawn of man to present day, burning thermal coal has been an essential part of life. Thermal coal was burned as an easy source for heat by early humans, and later on, as an easy source for power. With the First Industrial Revolution in Great Britain from 1760-1840, steam engines, powered by coal, saw an explosion of production and usage. Across the pond, in the U.S.A., as well as in the rest of continental Europe and in Japan, the Second Industrial Revolution from 1840-1914, saw further increases in the burning of coal in the manufacturing of goods. Although other fossil fuels saw increases as an energy source, coal remained king as the top used energy source.

Burning of coal – thermal and metallurgical – leads to the release of various chemicals and compounds including heavy metals such as selenium (Se). Se is required by many organisms to sustain life, however, in large doses Se is toxic. Tracking and monitoring the burning of thermal coal during the Industrial Revolutions are of vital importance to the well-being of both terrestrial and marine life forms. In brachiopods from 1926-1960 Se molar levels approximately doubled from 5.7 mmol to 11.9 mmol within the calcite shell. This steady increase in Se emissions was mitigated in the 1960s by the installation of thermal coal scrubbers. Their use helped reduce harmful emissions from the combustion of coal, while reducing soot and heavy metals being released into the atmosphere. This technological step is witnessed by a rapid decline in Se levels within brachiopod shells, which saw a decrease of approximately 9 mmol from the 1960s to the 1980s. With coal scrubbers successful in reducing emissions, this reduction in Se is to be expected. However, not every thermal coal-burning power plant incorporates the appropriate scrubbers. This increase in consumption to present day is mirrored in the Se levels within brachiopod shells, which have also seen an increase to approximately 9.2 mmol of Se. This clearly demonstrates the effectiveness of scrubbers in removing harmful contaminants such as Se and the great potential of marine invertebrates in tracing the industrial progression and its transgressions.

Our research has the potential to be an important tracer of thermal coal combustion, as well as a novel tracer and proxy of wildfires in the geologic past.