Newcomer et al. 2012 (Ecological Monographs) Organic C and Denitrification in Streams

The 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

Map showing the study region and our sampling sites.

<p>Sampling streams are indicated by heavy black lines, and samples sites are indicated by solid black circles. Other streams in this area are denoted by gray lines, and the light blues lines are 12-digit HUC watershed boundaries.</p

Nonmetric multidimensional scaling (NMDS) plot based on Bray-Curtis distances among the samples.

<p>Nonmetric multidimensional scaling (NMDS) plot based on Bray-Curtis distances among the samples.</p

Van Krevelen diagrams of refractory compounds a) ubiquitous for all samples in bacteria-only incubations; b) unique in F1 bacteria-only incubation; c) unique in F2 bacteria-only incubation; d) unique in P1 bacteria-only incubation; e) unique in P1 bacteria-only incubation; and f) ubiquitous for all samples in combined bacteria+light incubations.

<p>The light green solid line denotes the regression line through the minimum H/C and O/C values for formulas with AI_mod = 0.5 (i.e., the majority of aromatic molecules are plotted below the line) and the black solid line denotes the regression line for formulas with AI_mod = 0.67 (i.e., the majority of CAS molecules are below the line).</p

Comparing DOM diversity prior to versus after the incubations through a) compound number, and b) DOM formula similarities indicated by Jaccard similarity coefficients between T₀ vs. T₁₅ samples.

<p>Comparing DOM diversity prior to versus after the incubations through a) compound number, and b) DOM formula similarities indicated by Jaccard similarity coefficients between T₀ vs. T₁₅ samples.</p

Correlations between Jaccard similarity coefficients and absolute changes in the proportions of the five Krevelen classified groups in the bacteria-only incubations.

<p>Solid lines represent linear trend lines.</p

Van Krevelen diagrams for molecular series in F1 and P1 at T₀.

<p>The light green solid line denotes the regression line through the minimum H/C and O/C values for formulas with AI_mod = 0.5 (i.e., the majority of aromatic molecules are plotted below the line) and the black solid line denotes the regression line for formulas with AI_mod = 0.67 (i.e., the majority of CAS molecules are below the line).</p

a) Jaccard similarity coefficients of DOM formulas between different samples or incubation time points; b) Relative abundance (%total formulas) of aromatic formulas in T₀ samples.

<p>a) Jaccard similarity coefficients of DOM formulas between different samples or incubation time points; b) Relative abundance (%total formulas) of aromatic formulas in T₀ samples.</p

Effluent Organic Nitrogen (EON): Bioavailability and Photochemical and Salinity-Mediated Release

The goal of this study was to investigate three potential ways that the soluble organic nitrogen (N) fraction of wastewater treatment plant (WWTP) effluents, termed effluent organic N (EON), could contribute to coastal eutrophication - direct biological removal, photochemical release of labile compounds, and salinity-mediated release of ammonium (NH₄⁺). Effluents from two WWTPs were used in the experiments. For the bioassays, EON was added to water from four salinities (∼0 to 30) collected from the James River (VA) in August 2008, and then concentrations of N and phosphorus compounds were measured periodically over 48 h. Bioassay results, based on changes in DON concentrations, indicate that some fraction of the EON was removed and that the degree of EON removal varied between effluents and with salinity. Further, we caution that bioassay results should be interpreted within a broad context of detailed information on chemical characterization. EON from both WWTPs was also photoreactive, with labile NH₄⁺ and dissolved primary amines released during exposure to sunlight. We also present the first data that demonstrate that when EON is exposed to higher salinities, increasing amounts of NH₄⁺ are released, further facilitating EON use as effluent transits from freshwater through estuaries to the coast