MICROBIAL COMMUNITY STUDY LINKED TO BIOGEOCHEMISTRY: INSIGHTS INTO MANGANESE CYCLING IN A DRINKING WATER RESERVOIR

Reservoir water quality, especially with respect to Mn and Fe concentrations, is closely tied to redox conditions like oxygen availability, which in turn is influenced by thermal stratification. Warmer surface temperatures and elongated stratification periods have been demonstrated for bodies of standing waters, including the Wahnbach Reservoir (Germany). Increasing levels of dissolved Mn trouble raw water treatment. Sediment may function as a sink or source for Mn. As microorganisms play a crucial role here, we investigated sediment for Mn compounds as well as Mn oxidizers and Mn reducers. Mn-reducing activities were more pronounced and selective cultures enriched phylogenetically highly diverse microorganisms including members of the genera Azospira, Rhodoferax, Bacillus, Aeromonas, Anaeromyxobacter, Geothrix, and Methanosarcina. Extensive long-term monitoring unveils biogeochemical processes in the water column. To link these processes to key microorganisms and their metabolisms, the water column and surface sediments were sampled at three sites in the reservoir monthly for one year (2022/2023). 16S rRNA amplicon sequencing was performed. Data analysis will primarily focus on Mn dynamics and putative Mn metabolizing microorganisms in relation to the availability of O₂, organic carbon, N and P nutrients. In addition, the interplay with other anaerobic respiration processes such as Fe(III) reduction, sulfate reduction, and methanogenesis will be investigated. Gained knowledge can offer valuable insights to guide future water quality management strategies.

Primary Presenter: Lea Hahn, University of Koblenz (leahahn@uni-koblenz.de)

Authors:

Lea Hahn, University of Koblenz  (leahahn@uni-koblenz.de)

Gabriele Packroff, Wahnbach Reservoir Association  (gabriele.packroff@wahnbach.de)

Jutta Meier, University of Koblenz  (jmeier@uni-koblenz.de)

Werner Manz, University of Koblenz  (manz@uni-koblenz.de)