Redox conditions and a moderate anthropogenic impairment of groundwater quality reflected on the microbial functional traits in a volcanic aquifer

Abstract Groundwater is an important freshwater resource and hosts specialized microbial assemblages providing fundamental ecosystem services. The current knowledge on the role of aquatic microorganisms in subsurface ecosystems still limited. This work aimed to explore links between groundwater hydrogeochemical properties community traits a volcanic unconfined aquifer, moderately impacted by anthropic activities. main physical chemical parameters samples were analyzed, along with biomass (total cell counts, ATP-active concentration), potential metabolic activity, physiological profiles at level (Biolog ™ EcoPlates). results showed coexistence oxidizing reducing conditions across study area. We discriminated two groups oxidizing/reducing (Ox Red), each including subgroups different attributed contrasting levels anthropogenic impact for non-intensive agricultural practices waste disposal activities − Ox + ; Red +). Although was likely not affected changing redox, functional diversity changed significantly. In samples, community-level different, mainly owing utilization carboxylic acids > +) carbohydrates −). wider set organic substrates consumed communities, those less bioavailable (e.g., phenols). Significant differences also found , relative increase amino polymers amines active biomass. By reflecting local redox moderate impact, applied approach highlighted changes that imply direct repercussions biogeochemical cycling services provided microorganisms.