Greenhouse Gas Emissions and Denitrification within Depressional Wetlands of the Southeastern US Coastal Plain in an Agricultural Landscape
Carolina Bays are depressional wetlands on the Coastal Plain of the southeastern United States. These wetlands are often the recipient of nutrient runoff from adjacent agricultural lands and there is potential for production of greenhouse gases during nitrification and denitrification processes occurring in the wetland sediments. Because of their saturated conditions, Carolina Bays may improve regional water quality through denitrification of soil nitrate. Three small bays in South Carolina were selected for denitrification and greenhouse gas analysis. A transect of four points was sampled within each Carolina Bay in May, July, September, and November over a two year period. Gas emissions were measured in-situ using a photoacoustic gas analyzer and soil samples were brought back to the lab for denitrification enzyme activity and microbial analysis. Emissions of nitrous oxide (N2O) averaged 1.8 mg m−2 d−1, with a median of 0.47 (with a range of below detectable limits to 9.414 mg m−2 d−1). Many measurement events of N2O were below detection and did not vary within the bays. The carbon dioxide emissions from Carolina Bays averaged 15.8 g m−2 d−1 and were largely controlled by temperature. Denitrification enzyme activity had a larger response to nitrate additions further into the bays. Gram + bacteria were also greater deeper into the bays, while Gram- and fungal populations were greater at the field/wetland interface. Manure application had some minor effects on DEA within the bays, but did not appear to increase gas emissions over the period measured.
KeywordsCarolina bays Denitrification PLFA DEA Photoacoustic gas analysis PAGA
The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned. We acknowledge the contributions of Ray Winnans and Katie Lewis for field, laboratory, and data analysis work for this study.
- Bouwman AF (1990) Exchange of greenhouse gases between terrestrial ecosystems and the atmosphere. Wiley, Chichester, UKGoogle Scholar
- Denver JM, Ator SW, Lang MW, Fisher TR, Gustafson AB, Fox R, Clune JW, McCarty GW (2014) Nitrate fate and transport through current and former depressional wetlands in an agricultural landscape, Choptank watershed, Maryland, United States. Journal of Soil and Water Conservation 69:1–16CrossRefGoogle Scholar
- Henderson SL, Dandie CE, Patten CL, Zebarth BJ, Burton DL, Trevors JT, Goyer C (2010) Changes in denitrifier abundance, denitrification gene mRNA levels, nitrous oxide emissions, and denitrification in anoxic soil microcosms amended with glucose and plant residues. Applied and Environmental Microbiology 76:2155–2164CrossRefPubMedPubMedCentralGoogle Scholar
- Miller JO, Hunt PG, Ducey TF, Glaz BS (2012) Denitrification and gas emissions from organic soils under different water table and flooding management. Transactions of the American Society of Agricultural and Biological Engineers 55:1793–1800Google Scholar
- Mosier A, Kroeze C, Nevison C, Oenema O, Seitzinger S, van Cleemput O (1998) Closing the global N2O budget: nitrous oxide emissions through the agricultural nitrogen cycle - OECD/IPCC/IEA phase II development of IPCC guidelines for national greenhouse gas inventory methodology. Nutrient Cycling in Agroecosystems 52:225–248CrossRefGoogle Scholar
- Newman MC, Schalles JF (1990) The water chemistry of Carolina bays: a regional study. Archive Hydrobiologie 118:147–168Google Scholar
- Ralston CW, Richter DD (1980) Identification of lower coastal plain sites of low soil fertility. Southern Journal of Applied Forestry 4:84–88Google Scholar
- Tiedje JM (1994) Denitrifier enzyme activity (DEA). In: Mickelson SH, Bigham JM (eds) Methods of soil analysis Part 2. 2nd ed. SSSA Book Series 5. SSSA Madison, WI, pp. 256–257Google Scholar