Polycyclic Aromatic Hydrocarbons in Permian Coals of India: Source and Significance

Abstract

The organic matter entrapped in the sediments often retain their molecular structures for millions of years. These structures hold important clues to the origin, precursors and proxies for the sedimentary environment. The investigation on the Permian coals reveal pyrene, benzo[a] anthracene, fluoranthene, indeno [1,2,3-cd] pyrene, chrysene, triphenylene, benzo[a] pyrene, benzo[e] pyrene, perylene, benzo[ghi] perylene and coronene which offer a window to the geological episodes of the past. There are two categories of PAH in the sediments, one formed from biological molecules through diagenetic process and the second class formed due to the effect of heat and fire. PAH such as pyrene, benzo[a] anthracene, fluoranthene, indeno[1,2,3-cd] pyrene, benzo[a] pyrene, coronene and chrysene, are product of vegetation fire, these pyrogenic products may have been introduced into the paleomire by the riverine channels. The global fire in the end of Permian is well recorded in geological history which was followed by Permian-Triassic P/T mass extinction. These PAH possibly represent the vegetation fire during the Permian. The PAH are also environmentally sensitive as they are known to create health hazards causing cancer to humans. Therefore, coal extraction and utilization pose a major challenge in coal handling plants, thermal power plants, metallurgical industries and other coal based industries.