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Denitrification and Potential Nitrous Oxide and Carbon Dioxide Production in Brownfield Wetland Soils
Author(s) -
Palta Monica M.,
Ehrenfeld Joan G.,
Groffman Peter M.
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0392
Subject(s) - nitrous oxide , denitrification , environmental science , brownfield , carbon dioxide , wetland , soil water , environmental engineering , environmental chemistry , production (economics) , nitrogen , chemistry , soil science , ecology , civil engineering , organic chemistry , redevelopment , engineering , biology , macroeconomics , economics
Brownfields, previously developed sites that are derelict, vacant, or underused, are ubiquitous in urban areas. Wetlands on brownfields often retain rain and stormwater longer than the surrounding landscape because they are low‐lying; this increases the possibility for these areas to process waterborne contaminants from the urban environment. In the northeastern United States, atmospheric deposition of nitrate (NO 3 − ) is high. Denitrification, a microbial process common in wetlands, is a means of removing excess NO 3 − . Nitrogen gas is the desired end product of denitrification, but incomplete denitrification results in the production of N 2 O, a greenhouse gas. The goal of this study was to investigate the potential of brownfield wetlands to serve as sinks for inorganic nitrogen and sources of greenhouse gases. We examined limitations to denitrification and N 2 O production in brownfield wetland soils in New Jersey. Soil C:N ratios were high (18–40) and intact core denitrification (−0.78 to 11.6 μg N 2 O–N kg dry soil −1 d −1 ) and N mineralization (0.11–2.97 mg N kg dry soil −1 d −1 ) were low for all sites. However, soil NO 3 − increased during dry periods. Nitrate additions to soil slurries increased denitrification rates, whereas labile C additions did not, indicating that soil denitrifiers were nitrogen limited. Incubations indicated that the end product of denitrification was primarily N 2 O and not N 2 . These results indicate that brownfield wetlands can develop significant denitrification capacity, potentially causing NO 3 − limitation. They might be significant sinks for atmospheric NO 3 − but may also become a significant source of N 2 O if NO 3 − deposition were to increase.