Potential role of microplastic in sediment as an indicator of Anthropocene

Earth has gradually deviated from the control of natural factors under the increasing force of human activities, thereby entering into a period that has become known as the “Anthropocene”. A series of indicators have been used to describe the characteristics of strata in this period, but man-made “novel materials”, which can directly indicate anthropogenic activities, were not valued as the proxies in previous studies. Microplastics (MPs), one of the most common man-made materials, are a potential indicator of human activities because of their widespread occurrence in the environment and their close relationship with almost aspects of human daily life. This paper reviews the literature on historical records of MPs in sediment cores, demonstrating that MPs can meet the basic requirements of an Anthropocene indicator. Plus, they have the advantage of being closely linked to human activities, thus reflecting changes in human society in multiple dimensions, and possess a persistent and stable signal. However, the complex processes of sedimentation, the differences in sources and transport way of MPs, and disturbances of the sedimentary environment bring uncertainty into the inversion of the temporal trend of MPs in sediments. For future studies on anthropogenic MPs, this paper provides guidelines on choosing a suitable study area, and specifically recommends alpine lake sediments as ideal research areas for Anthropocene research. The short transmission time, less local interference, stable sedimentary environment, and signals on large spatial scales of alpine lake sediments could favor to provide the continuous and high-resolution records of MPs in Anthropocene. • Global data of historical records of MPs in sediments were reviewed. • MPs had the potential to be the marker of the Anthropocene. • More studies should be focused on the processes of MPs from sources to sediments. • Alpine lakes are the ideal sites for studying the MPs in Anthropocene.