Data from: Influence of natural and novel organic carbon sources on denitrification in forest, degraded urban, and restored streams

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Organic carbon is important in regulating ecosystem function, and its source and abundance may be altered by urbanization. We investigated shifts in organic carbon quantity and quality associated with urbanization and ecosystem restoration, and its potential effects on denitrification at the riparian–stream interface. Field measurements of streamwater chemistry, organic carbon characterization, and laboratory-based denitrification experiments were completed at two forested, two restored, and two unrestored urban streams at the Baltimore Long-Term Ecological Research site, Maryland, USA. Dissolved organic carbon (DOC) and nitrate loads increased with runoff according to a power-law function that varied across sites. Stable isotopes and molar C:N ratios suggested that stream particulate organic matter (POM) was a mixture of periphyton, leaves, and grass that varied across site types. Stable-isotope signatures and lipid biomarker analyses of sediments showed that terrestrial organic carbon sources in streams varied as a result of riparian vegetation. Laboratory experiments indicated that organic carbon amendments significantly increased rates of denitrification (35.1 ± 9.4 ng N·[g dry sediment]−1·h−1; mean ± SE) more than nitrate amendments (10.4 ± 4.0 ng N·[g dry sediment]−1·h−1) across streamflow conditions and sites. Denitrification experiments with naturally occurring carbon sources showed that denitrification was significantly higher with grass clippings from home lawns (1244 ± 331 ng N·g dry sediment−1·h−1), and overall unrestored urban sites showed significantly higher denitrification rates than restored and forest sites. We found that urbanization influences organic carbon sources and quality in streams, which can have substantial downstream impacts on ecosystem services such as denitrification.,Newcomer et al. 2012 (Ecological Monographs) Organic C and Denitrification in StreamsThe file “Newcomer et al. 2012 (Ecological Monographs) Organic C and Denitrification in Streams.xlsx” provides original data from the manuscript. The worksheets are named to correspond with the figures in the manuscript. “Figure 4” has field measurements of nitrate and DOC loads (g ha-1 day-1) and runoff (mm day-1). We measured discharge at Spring Branch and discharge was downloaded from USGS gaging stations at the other sites. “Figure 5” was created using discharge (cfs) downloaded from USGS gaging stations and dividing it by watershed area to get runoff (mm day-1). “Figure 6” has field measurements of mean C:N molar ratios for leaves, periphyton, grass, sediment, and stream particulate organic matter (POM). “Figure 7” has field measurements of 15N and 13C stable isotope signatures for leaves, periphyton, grass, sediment, and stream POM. “Figure 8” has laboratory measurements of denitrification potentials associated with glucose versus nitrate amendments. “Figure 9” has laboratory measurements of denitrification potentials associated with the use of leaves, periphyton, and grass as a carbon source.,



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