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Investigators: Dr. Allyson Tessin, Dr. David Costello, and Dr. Lauren Kinsman-Costello (College of Arts and Sciences)

Reactive iron (Fe) and manganese (Mn) in marine and lake sediments can play a critical role in modulating the benthic(seafloor)-pelagic (water column) coupling of biogeochemical cycles, acting as a control on the exchange of carbon, nutrients, and contaminants between the sediments and the water column.  Briefly, Fe and Mn (oyhydr)oxide minerals within the benthic environment can sorb and trap micro(Cu, Mo, Ni, Zn)- and macro(P)- nutrients. The availability of these nutrients in the water column can control primary productivity (Moore et al. 2013).  The availability, speciation, and stability of Fe and Mn phases within sediments will, therefore, play an important role in benthic fluxes of nutrients, potentially altering patterns of nutrient availability and limitation.

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Predication of future changes in internal nutrient cycling is particularly important within Lake Erie -- one of the five Great Lakes and closest to Â鶹´«Ã½ -- due to the occurrence of Harmful Algal Blooms (HABs) in the lake that are fueled by high nutrient contents.  While the importance of sedimentary Fe cycling for benthic fluxes has been recently highlighted within Lake Erie (Gibbons and Bridgeman 2020; Anderson et al. 2021), no effort have been made to investigate the stock of reactive Fe ad Mn within Great Lake sediment.  This where Dr. Tessin, Dr. Costello, and Dr. Kinsman-Costello's research will contribute to the knowledge base.  Their plan is:

1. To determine spatial patterns of Fe and Mn within near-surface sediments.

2. To evaluate the impact of the two elements' distribution on current benthic fluxes, across time and Lake Erie basins.

3. To assess nutrient limitation across Lake Erie.

4. To investigate the sensitivity of benthic processes to changing lake conditions, such as algal blooms, warming and other inputs.

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Lake Erie's bathymetry is the result of repeated glacial erosion and deposition over the past two million years. Dr. Tessin, Dr. Costello and Dr. Kinsman-Costello's work is particularly meaningful because Lake Erie provides vital resources, including fresh drinking water, fisheries and recreation, all of which are threatened by environmental degradation. This Seed Grant will aid the investigators and an undergraduate student who will support field work and laboratory analyses.

Sources:

• Anderson, H.S., T.H. Johengen, C.M. Godwin, H. Purcell, P.J. Alsip, S.A. Ruberg, and L.A. Mason. 2021. Continuous In Situ Nutrient Analyzers Pinpoint the Onset and Rate of Internal P Loading under Anoxia in Lake Erie’s Central Basin. ACS ES&T Water 1: 774–781. doi:10.1021/acsestwater.0c00138.
• Gibbons, K.J., and T.B. Bridgeman. 2020. Effect of temperature on phosphorus flux from anoxic western Lake Erie sediments. Water Research 182: 116022. doi:10.1016/j.watres.2020.116022.
• Moore, C.M., M.M. Mills, K.R. Arrigo, I. Berman-Frank, L. Bopp, P.W. Boyd, E.D. Galbraith, R.J. Geider, et al. 2013. Processes and patterns of oceanic nutrient limitation. Nature Geoscience 6: 701–710. doi:10.1038/ngeo1765.