Gold particles from Kamchatka: A brief look at gold biogeochemical cycling in a distinct environment

Kamchatka is a peninsula located on the far eastern side of Russia and is a geologically active region within the Pacific Ring of Fire. Placer gold particles were obtained from a stream located in the Yelizovsky District and were compared to particles from regions at similar latitudes. Russian gold particle surface textures and morphologies were characterised optically and using electron microscopy, and bacteria occurring on the surface of particles were inferred from detected amplicon sequence variants (ASVs). The gold particles contained remarkably variable gold surface textures with an average 70% of surface area containing clay-filled concavities. Particle morphologies, interpreted from axis ratios, suggested that these particles were transported from primary sources. Proteobacteria constituted 60% of all the detected ASVs from the particles. Within this phylum, Gammaproteobacteria was the most dominant class. This study contributes to the understanding of gold biogeochemical cycling in a distinct bioclimatic environment.