Application of organic petrography as a forensic tool in environmental studies to investigate the source of coal pollution on beaches in Gijón (Northern Spain)

Abstract

Coal is one of the oldest and most widespread pollutants of natural environments such as marine coastal areas. The sources of this pollution are varied and mainly anthropogenic, one of which is handling coal in marine coal terminals and in bulk seaports. In coastal environments, there is also accidental coal pollution caused by accidents such as shipwrecks or sinking of bulk carriers and barges operating in port areas. One case of coal pollution is the beaches in Gijón on the Cantabrian coast in the north of Spain, which are intermittently covered to varying degrees by carbonaceous materials. To the north of Gijón there is a bulk seaport, El Musel, the largest bulk seaport in Spain where millions of tons of coal and other carbonaceous materials are handled annually. In January 1986 the Castillo de Salas bulk carrier sank with 100,000 tons of coal off the beaches of Gijón. For >34 years the true origin of the coal staining the beaches has been the subject of controversy at all levels of society. The aim of this study was to determine the main source of coal pollutants on the beaches. To that end, organic petrography was used to determine the mixtures of coal and other carbonaceous materials in sediments. The results indicate that the El Musel seaport is quantitatively the main source of coal pollution on the beaches and that coal from the sunken vessel reaches the beaches only during significant storms, heavy waves, and strong tides, which are common on the Cantabrian coast. Organic petrography emerged as a powerful forensic tool that can be applied to environmental investigations to determine the source of coal pollution, which is especially important in controversial cases.