Coal dust in the Severn Estuary, southwestern UK

Abstract

Substantial amounts of coal dust attributable to mining occur in the recently accumulated muddy sediments of the Severn Estuary. The pollutant is most plentiful in the finest textured deposits, and in present-day (1985) intertidal mud is found to the general order of 1×10 9 grains kg −1 . The coal occurs to a similar degree in the muddy sediments accumulated from about 1945 to the present but declines rapidly in abundance in older deposits, a steady ‘background’ value of about 3×10 8 grains kg −1 obtaining in muds antedating circa 1845. A total of at least the order of 10 5–10 6 tonnes of coal dust may now be present in the estuarine fine sediments. Although the Severn Estuary taps several exposed coal-fields, most of the pollutant probably comes from the South Wales Coalfield, where production peaked in 1913, 30 years before the maximum of coal dust observed in the deposited sediments.