@article{hinckley_etheridge_peralta_2019, title={Storm Event Nitrogen Dynamics in Waterfowl Impoundments}, volume={230}, ISSN={["1573-2932"]}, DOI={10.1007/s11270-019-4332-5}, abstractNote={Waterfowl impoundments are hydrologically managed to provide food and habitat for migratory birds and have the potential to export nitrogen during drawdown. The goal of this study was to describe how nitrate, ammonium, and dissolved organic nitrogen dynamics varied under two different management schemes during storm events. This was made possible through monitoring the three forms of nitrogen at a high frequency (30 min) in a moist-soil managed (MSM) impoundment and seasonally flooded agricultural impoundment (Ag) for 17 months. Substantial differences in nitrogen dynamics between sites were observed when the sites were not flooded, while similar dynamics were observed during the winter flooding period. When the Ag site was drained, storm events mobilized nitrate (average 0.3 mg L−1; increase 0.8 mg L−1) and ammonium (average 0.4 mg L−1; increase 0.2 mg L−1). Under drained conditions in the MSM impoundment, rainfall reduced ammonium (average 0.5 mg L−1; decrease 0.1 mg L−1). Storms stimulated what appeared to be coupled nitrification-denitrification in both impoundments when flooded and ammonium concentrations were elevated. A surprising result of this work was observed at the Ag site, where elevated nitrate (0.5 mg L−1) was measured during high water levels when anoxic conditions were expected to support denitrification. Although water management schemes were found to be important for controlling nitrogen dynamics, other factors, such as carbon quality, require further research. This study demonstrates a high variability between storm events and the large influence of hydrologic management schemes on nitrogen dynamics during storm events.}, number={12}, journal={WATER AIR AND SOIL POLLUTION}, author={Hinckley, B. R. and Etheridge, J. R. and Peralta, A. L.}, year={2019}, month={Dec} }
 @article{hinckley_etheridge_peralta_2020, title={Wetland Conditions Differentially Influence Nitrogen Processing within Waterfowl Impoundments}, volume={40}, ISSN={["1943-6246"]}, DOI={10.1007/s13157-019-01246-8}, number={5}, journal={WETLANDS}, author={Hinckley, Brian R. and Etheridge, J. Randall and Peralta, Ariane L.}, year={2020}, month={Oct}, pages={1117–1131} }
 @article{granlund_rankinen_etheridge_seuri_lehtoranta_2015, title={Ecological recycling agriculture can reduce inorganic nitrogen losses - model results from three Finnish catchments}, volume={133}, journal={Agricultural Systems}, author={Granlund, K. and Rankinen, K. and Etheridge, R. and Seuri, P. and Lehtoranta, J.}, year={2015}, pages={167–176} }
 @article{osburn_mikan_etheridge_burchell_birgand_2015, title={Seasonal variation in the quality of dissolved and particulate organic matter exchanged between a salt marsh and its adjacent estuary}, volume={120}, ISSN={2169-8953}, url={http://dx.doi.org/10.1002/2014JG002897}, DOI={10.1002/2014jg002897}, abstractNote={AbstractFluorescence was used to examine the quality of dissolved and particulate organic matter (DOM and POM) exchanging between a tidal creek in a created salt marsh and its adjacent estuary in eastern North Carolina, USA. Samples from the creek were collected hourly over four tidal cycles in May, July, August, and October 2011. Absorbance and fluorescence of chromophoric DOM (CDOM) and of base‐extracted POM (BEPOM) served as the tracers for organic matter quality while dissolved organic carbon (DOC) and base‐extracted particulate organic carbon (BEPOC) were used to compute fluxes. Fluorescence was modeled using parallel factor analysis (PARAFAC) and principle components analysis (PCA) of the PARAFAC results. Of nine PARAFAC components (C) modeled, C3 represented recalcitrant DOM and C4 represented fresher soil‐derived source DOM. Component 1 represented detrital POM, and C6 represented planktonic POM. Based on mass balance, recalcitrant DOC export was 86 g C m−2 yr−1 and labile DOC export was 49 g C m−2 yr−1; no planktonic DOC was exported. The marsh also exported 41 g C m−2 yr−1 of detrital terrestrial POC, which likely originated from lands adjacent to the North River estuary. Planktonic POC export from the marsh was 6 g C m−2 yr−1. Assuming the exported organic matter was oxidized to CO2 and scaled up to global salt marsh area, respiration of salt marsh DOC and POC transported to estuaries could amount to a global CO2 flux of 11 Tg C yr−1, roughly 4% of the recently estimated CO2 release for marshes and estuaries globally.}, number={7}, journal={Journal of Geophysical Research: Biogeosciences}, publisher={American Geophysical Union (AGU)}, author={Osburn, Christopher L. and Mikan, Molly P. and Etheridge, J. Randall and Burchell, Michael R. and Birgand, François}, year={2015}, month={Jul}, pages={1430–1449} }
 @article{etheridge_birgand_burchell_2015, title={Quantifying nutrient and suspended solids fluxes in a constructed tidal marsh following rainfall: The value of capturing the rapid changes in flow and concentrations}, volume={78}, ISSN={0925-8574}, url={http://dx.doi.org/10.1016/j.ecoleng.2014.05.021}, DOI={10.1016/j.ecoleng.2014.05.021}, abstractNote={Coastal tidal wetlands are perceived to provide nutrient dissipation services and serve as the final buffer between excess nutrient loads coming from nearby upland watersheds and sensitive estuarine waters. The construction and restoration of tidal marshes has the potential to benefit coastal waters. However, the water quality services of tidal wetlands have yet to be established with any certainty. This is in part due to the difficulty of monitoring these systems where flow and concentrations vary widely with tidal ebb and flood along with rainfall events mobilizing nutrients in pulses from upstream watersheds. In this article, we show over a period of 10 days following a rainfall event, the value of high temporal resolution data to characterize the complex nutrient and flow dynamics and to reliably calculate material balances in a created coastal marsh in North Carolina. Ultraviolet–visible spectrometers were used to obtain 15-min concentration data for nitrate, total Kjeldahl nitrogen, dissolved organic carbon, total suspended solids, phosphate, and total phosphorus. Our results show that a pulse of nitrate moved through the marsh from upstream agricultural production following the rainfall event and 25% (13 kg of 53 kg) of the nitrate was retained in the marsh over a period of 10 days. No other material showed a clear pulse from the upstream agricultural production. The marsh acted as a sink for total suspended solids (40 kg) and had near neutral mass balances for dissolved organic carbon, total Kjeldahl nitrogen, total phosphorus, and phosphate. Subsequent simulations indicated that different and erroneous results would have been obtained from 2-, 6- or 12-h sampling intervals. These results demonstrate, even on a short term basis, why high-frequency data acquisition is necessary in these tidal marsh systems to truly quantify their impact on water quality ecosystem services.}, journal={Ecological Engineering}, publisher={Elsevier BV}, author={Etheridge, J. Randall and Birgand, François and Burchell, Michael R., II}, year={2015}, month={May}, pages={41–52} }