A geological perspective of plastic pollution

Abstract

The Anthropocene, the most recent geologic time division, marks humanity's profound impact on Earth. Amidst debates, the Anthropocene Working Group recommended its inclusion in the International Chronostratigraphic Chart (ICC). This period is characterized by the mid-20th century Great Acceleration Event Array (GAEA), which includes widespread presence of pollutants such as radionuclides, organochlorine pesticides, PCBs, and plastic production. The Anthropocene concept should raise public awareness of these threats, with plastic pollution being a primary concern. Plastics are now pervasive and serve as a marker for the Anthropocene Epoch or Age. Understanding their entry into the geological record requires considering the “Plastic Geological Cycle,” which encompasses extraction, production, use, disposal, degradation, fragmentation, accumulation, and lithification. This cycle reveals the transformation of plastics into new forms of pollution characteristic of the Anthropocene. With 91 % of discarded plastics never recycled, they accumulate in the environment and enter the geological record through processes like photodegradation, thermal stress, and biodegradation. The proposed Plasticene stage within the Anthropocene is defined by the post-World War II surge in plastic production and their incorporation into sedimentary processes and rocks. The study of plastics in the geologic record serves as a warning of their negative impacts and highlights the urgency of addressing plastic pollution for a sustainable future.