Merritt was born in Stanford, California and later moved to Boulder. After going to high school in New Hampshire he received a BA from Colorado College and began working as a malt quality chemist at MillerCoors in Golden Colorado. Since then he lived in Maine where he taught high school chemistry and outside of Boston working for Pfizer on monoclonal antibodies. He chose to return to grad school to better understand analytical systems and deepen his understanding of the analytical methods he worked with at MillerCoors and Pfizer.
Soil Organic Matter Before and After Permafrost Thaw
Merritt is studying the composition of organic matter adsorbed to minerals and in porewater in the Stordalen mire in Abisko, Sweden. The Stordalen mire is a location of interest because it is a thawing permafrost peatlands and permafrost peatlands contain 25% of the carbon in the atmosphere. Due to the quantity of carbon stored in this type of peatland, thawing and other disturbances as a result of climate change have the potential to release a tremendous amount of CO2 and CH4 into the atmosphere. Stordalen mire was also chosen as a field site because it is an actively thawing permafrost that has been a research site for the Swedish Polar Research Secretariat since the 1970s.
In Stordalen there is a high abundance of iron mineral sorbed soil organic matter in the palsa present above the intact permafrost. As the permafrost thaws and the palsa collapses into bog and subsequently fen the soil becomes anoxic and conditions become more reductive, resulting in the release of the iron mineral associated OM through reductive dissolution. This potentially created a large influx of bioavailable carbon into anoxic pore water which could result in large releases of CH4 or CO2. Additionally as the dissolved organic matter moves through the surface water systems into ponds and lakes it is exposed to and potentially transformed by exposure to new vegetation, resulting in shifted bioavailability and nutrient composition in those aqueous systems. Increased nutrient leaching from thawing soil and transformation of those nutrients by downstream vegetation systems can affect the surface water systems and potentially downstream drinking water. Therefore understanding how thawing affects the surface water moving out of these permafrost systems affects both immediate downstream water quality and elucidates the degree of mineralization of previously frozen soil organic matter. In turn this will improve scientist’s ability to predict future carbon release and inform climate change models.
Merritt is working with Monique Patzner and using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterize the OM from samples they collected during a summer 2019 field campaign.
Anna L. Hermes, Merritt N. Logan, Brett A. Poulin, Amy M. McKenna, Todd E. Dawson, Thomas Borch, and Eve-Lyn S. Hinckley. Agricultural Sulfur Applications Alter the Quantity and Composition of Dissolved Organic Matter from Field-to-Watershed Scales. Environmental Science & Technology 2023 57 (27), 10019-10029. DOI: 10.1021/acs.est.3c01347
Patzner, M.S., Logan, M., McKenna, A.M., Robert B. Young, Zhou, Z., Joss, H., Mueller, C.W., Hoeschen, C., Scholten, T., Straub, D., Kleindienst, S., Borch, T., Kappler, A., Byrce, C. Microbial iron cycling during palsa hillslope collapse promotes greenhouse gas emissions before complete permafrost thaw. Commun Earth Environ 3, 76 2022. https://doi.org/10.1038/s43247-022-00407-8
William Bahureksa, Malak M. Tfaily, Rene M. Boiteau, Robert B. Young, Merritt N. Logan, Amy M. McKenna, and Thomas Borch Environmental Science & Technology 2021 55 (14), 9637-9656. https://pubs.acs.org/doi/10.1021/acs.est.1c01135