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DENITRIFICATION AND NITROGEN DYNAMICS IN SEDIMENTS OF A MID-ATLANTIC INCISED STREAM DEPOSITED WITH DEEP LEGACY SEDIMENTS.
Citation:
Forshay, Ken, P. Mayer, A. McElmurry, A. Kent, J. Koval, Bart Faulkner, D. Merritts, J. Weitzman, AND R. Walter. DENITRIFICATION AND NITROGEN DYNAMICS IN SEDIMENTS OF A MID-ATLANTIC INCISED STREAM DEPOSITED WITH DEEP LEGACY SEDIMENTS. Presented at EPA Region 3 Legacy Sediment Workshop - Franklin and Marshall College.
Impact/Purpose:
Provide information to managers and scientists on nitrogen dynamics in legacy sediment related to stream restoration. Improve water quality, habitat, and inform management decisions on stream restoration. As part of SHC N management task 3.3.1.10
Description:
Excess legacy sediments deposited in former impounded streams frequently bury Holocene pre-settlement wetlands, decrease in-situ nitrogen removal, and increase nitrogen transport downstream, particularly where deep incised channels limit sediment-water interactions. This has prompted efforts in the mid-Atlantic region to remove legacy sediments and restore floodplain wetlands. As part of an ongoing research project, we measured the denitrification rates and limiting nutrients (carbon and/or nitrate) of incised bank sediment and soil core strata that represent the historic buried wetland and legacy sediment strata at Big Spring Run to describe the current denitrification and provide insight into potential denitrification capacity of the site. Our results show that buried pre-settlement hydric soils support significantly greater denitrification potential than buried accumulated legacy sediments and exposed sediments support significantly greater denitrification potential than buried sediments. Organic carbon limits denitrification potential in the deposited legacy sediments while hydric sediments of incised banks are not limited by carbon, even after centuries of burial. These denitrification rates help identify geomorphic structures where sediment and water interactions will support enhanced denitrification and aid in future restoration activities in the region.