Legacy of anthropogenic activity recorded in sediments by microtechnofossils and chemical markers

This overview presents comparison of common microtechnofossils with other geochemical markers that may have the great potential to be the anthropogenic signatures for recent and future sediment strata. The novel man-made products encompass spherical and spheroidal fly-ash particulates, microplastics, synthetic crystals, and more recently examined glass microspheres. Due to their low specific gravity and small size varying from a tiny fraction of millimeter to approximately 5 mm, microtechnofossils may be transported over a long distance from their primary or secondary sources by water and wind. Of these technogenic materials, among the most resistant to physical and chemical degradation are glass microbeads, and additionally synthetic crystals and some types of fly-ash particulates derived mostly from coal/oil combustion, metal ore smelting operations and cement/lime manufacturing. Nonetheless, synthetic glass microspheres have found exponentially growing applications as reflective ingredients in traffic-related paints and building facades, as well as in a variety of applications mostly as low-density fillers of many materials. In contrast to anthropogenic fly-ash and microplastic particles, glass microspheres resemble in many respects common detrital quartz grains. Moreover, like quartz, they are resistant to depositional and diagenetic processes, which is a prerequisite for future geologic archives preserving anthropogenic signals. These and other characteristics make glass microspheres a more widely used product in various fields thus assigning them to a new emerging and globally spreading chronostratigraphic marker of human-impacted sediments.