Interactions Between Water Flowpaths and Subsurface Biogeochemistry That Drive Solute Yields from Northern Peatland Catchments.

The routing of water and subsurface biogeochemical processes interact to affect solute yields from peatlands. Whether water flows along lateral, near-surface flowpaths or vertically through peats has profound implications for solute transport and budgets. Both water availability and biogeochemical cycling are expected to change with climatic warming which may fundamentally alter flowpaths and biogeochemical transformations. These changes may ultimately lead to shifts in the patterns and magnitudes of solute yields, ecosystem productivity, and carbon stabilization in northern peatlands. We assessed piezometric, hydraulic conductivity, chemical, and isotopic data to study how water movement, solute sources, and biogeochemical transformations vary across a gradient of peatland types in northern Minnesota. Using geochemical mixing analysis, we found that pathways along which water flows determined how, when, and where solutes, such as dissolved organic matter, were transported from northern peatlands to downgradient aquatic ecosystems.  Overall, we used this assessment to elucidate how subsurface processes in peatlands affect solute yields and to conceptualize how these yields may be affected by future climate change.