(523c) Electrochemical Sensors for Microbial Activities in Benthic Sediments: A Sentry for Lacustrine P Biogeochemistry
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
Topical Conference: Sensors
Applications in Chemical Sensors
Wednesday, November 18, 2020 - 8:30am to 8:45am
A series of laboratory and field experiments was conducted to identify electrochemical signatures associated with a variety of microbiological activities occurring in Lake Erie sediments. Our technique makes use of zero-resistance ammetry (ZRA) measurements, which we have previously used to diagnose microbiological activities. The approach uses inexpensive materials, demands little power, and can interrogate microbial activities at small spatial scales. The ZRA approach detects internal PO43- loading (the release of PO43-, as âdissolved reactive phosphorousâ from sediments), which can contribute to harmful algal blooms (HABs). Microbial degradation of algal biomass and microbially-induced mineralogical transformations can profoundly influence the PO43- concentration in the water column, and therefore, the potential for HABs despite adequate management of external PO43- loading. Thus, microbial metabolism in PO43--loaded benthic sediments represents a remnant threat to induce or contribute to HABs well into the future. Microbiological activities induce redox gradients in sediments, depending on the predominant terminal electron accepting process. Most notable from the standpoint of PO43- flux is the anaerobic reductive solubilization of Fe(III) (hydr)oxide phases by Fe(III) reducing bacteria (FeRB), which releases PO43- that was previously adsorbed to those phases. However, microbial activity can induce a variety of other chemical conditions that enhance or limit PO43- solubility (e.g. Fe(II) oxidation, organic carbon mineralization, acid production, primary productivity). ZRA-based monitoring can determine extents and types of microbial metabolism in the sediments, be exploited for long-term stewardship of Lake Erie sediments, and serve as an âearly-warning systemâ for internal PO43- loading events.
This presentation describes our newly-developed, ZRA-based technique for monitoring sediment activity and internal PO43- loads. We believe that this will eventually be an âearly warning systemâ for internal PO43--supported HABs.