Potential rates and environmental controls of denitrification and nitrous oxide production in a temperate urbanized estuary

Abstract

tial rates and environmental controls of denitrification and nitrous oxide production in a temperate urbanized estuary.Marine Environmental Research, Elsevier, 2010, 70 (5) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The Douro estuary (NW Portugal) suffers from both problems: freshwater input of 19 nitrate and organic load from untreated wastewater discharges. To assess how these 20 factors might control sediment denitrification, a 12-month survey was designed. 21Denitrification potential and nitrous oxide (N 2 O) production were measured at different 22 locations using the slurry acetylene blockage technique. Denitrification rate ranged from 23 0.4 to 38 nmol N g -1 h -1 , increasing towards the river mouth following an urban 24 pollution gradient. N 2 O production, a powerful greenhouse gas implicated on the 25 destruction of the ozone layer, was significantly related with sediment organic matter 26 and accounted for 0.5 -47 % of the N gases produced. Additional enrichment 27 experiments were consistent with the results found in the environment, showing that 28 sediments from the upper less urban stretch of the estuary, mostly sandy, respond 29

Sources and sinks of methane and nitrous oxide in the subtropical Brisbane River estuary, South East Queensland, Australia

“…Wastewater discharges into waterways are identified as external point sources contributing to high GHG concentrations, especially for N 2 O (De Angelis and Scranton 1993; Toyoda et al 2009;Beaulieu et al 2010;Teixeira et al 2010). Elevated GHG concentrations in Oxley Creek could be due to the effluent discharged from the Oxley WWTP.…”

“…However, it is often difficult to quantify the gases and identify the estuarine sources and sinks where contributions from the water column and sediments (Law et al 1992;Hovland et al 1993;Bange 2006;Zhang et al 2008), freshwater streams (Ferron et al 2007;Call et al 2015), and sewage discharges need to be considered (De Angelis and Scranton 1993;Toyoda et al 2009;Beaulieu et al 2010;Teixeira et al 2010). Methane concentrations and emissions are found to be high in estuaries and streams surrounded by forests, agricultural land and peatlands (De Angelis and Lilley 1987;Jones and Mulholland 1998;Hope et al 2001;Dawson et al 2004;Kristensen et al 2008).…”

Mimicking floodplain reconnection and disconnection using <sup>15</sup>N mesocosm incubations

“…3), implying that denitrification was more efficient. N 2 O production has been related to high organic sediment content and eutrophic environments (Kenny et al, 2004;Sloth et al, 1995;Teixeira et al, 2010), which are the conditions found at both sites. However, when riverine water was added to the disconnected site (i.e.…”

“…We predicted that, due to the high supply of carbon and anoxic conditions in the disconnected sediments, the disconnected site would be nitrate-limited, as has been demonstrated in different riverine sediments (Forshay and Stanley, 2005;Hill et al, 2000;Silvennoinen et al, 2008), streams (Smith et al, 2006), constructed wetlands (Scott et al, 2008) and estuaries (Teixeira et al, 2010). Therefore, by increasing the nitrate concentration in the water column of the disconnected site, which is high in organic carbon, we expected to measure a corresponding increase in denitrification.…”

Incongruous variation of denitrifying bacterial communities as soil N level rises in Canadian canola fields

“…Nitrogen fertilization has been shown to affect N denitrification in soils, mainly via its effect on the nitrates (Teixeira et al, 2010). However, this has not been researched at gene levels in the past.…”