Bacterially facilitated rock-coating formation as a component of the geochemical budget in cold climates: An example from Kärkevagge, Swedish Lapland

• Rock coatings from Kärkevagge, Sweden are colonized by diverse bacterial communities.
• Bacterial scavenging and concentrating facilitate rock-coating formation.
• Coating formation serves as a cation sink in the drainage basin.
• Bacteria influence the overall geochemical budgets in cold climates.

Environmental microbiology and advances in molecular techniques have been a driving force in advancing the understanding of microbial communities in previously understudied environments. Though it is widely accepted that biological and geological processes are closely linked, the importance of microbes in geomorphological processes has been understated. Microbes interact with the environment, playing a significant role in nutrient cycling, ion mobilization, and metal scavenging and concentration. Although in some of these areas understanding is expanding, the role of microbes in geochemical budgets in cold climates has been largely ignored. To investigate one such case of microbial influence, we focus on rock-coating development in the glacially eroded valley, Kärkevagge, in arctic-alpine Sweden. This bacterial diversity study shows evidence of a link between microbe–mineral interactions and key processes in the formation of diverse geochemical rock coatings. Here, we present a study of the bacterial role in metal scavenging and coating formation as a component of the geochemical budget of the valley.