Overview

The health of many terrestrial and aquatic ecosystems is compromised by metal contamination, introduced either naturally through weathering of metal-laden bedrock or by way of anthropogenic activities.  While many metals are micronutrients required by plants and animals at low concentrations, at higher concentrations these same metals can be toxic, having potentially fatal effects.  The potential for metals to disrupt ecosystem health is reliant upon the metal’s speciation and structure, which may be controlled by a myriad of abiotic and biotic processes.  These processes include sorption to mineral and/or microbial surfaces, complexation with organic ligands (including microbial biofilms), co-precipitation in secondary mineral phases, and redox transformation induced abiotically or as an indirect or direct consequence of microbial metabolism.

The Hansel lab strives to understand the abiotic and biotic processes that govern the fate and biovailability of metals within both terrestrial and aquatic environments. Our research is at the interface of microbiology and geochemistry, utilizing a multidisciplinary approach to understand the link between microbial metabolism and metal redox chemistry.  We focus our research primarily on the cycling of Fe and Mn due to their ubiquity within the environment, importance for microbial respiration, and necessity for primary production.  Furthermore, considering that Fe and Mn (hydr)oxides are dominant controls on the cycles of numerous other organic (e.g. hydrocarbons) and inorganic (e.g. Cr, As) contaminants, manipulating the redox cycles of Fe and Mn is considered a promising means of environmental remediation.  Successful remediation, however, is reliant upon an enhanced understanding of the microorganisms and ensuing (a)biotic reactions that govern the Fe and Mn redox cycle – this is the ultimate goal of the Hansel lab.