Nitrate removal in two relict oxbow urban wetlands: a 15N mass-balance approach

Denitrification and Nitrous Oxide Emissions in Annual Croplands, Perennial Grass Buffers, and Restored Perennial Grasslands

“…Similar to our results, Hill et al (2000) observed a significant increase in denitrification after in situ additions of labile C in a riparian zone. With regard to denitrification, these results suggest perennial filter strips function similarly to riparian buffer zones (Lowrance et al, 1984;Matheson et al, 2002) and wetlands (Harrison et al, 2012). Consistent with previous research, results from the 15 N and C 2 H 2 denitrification measurements were well correlated (Myrold, 1990).…”

“…Although DNRA may be an important NO 3 − -N sink (Fazzolari et al, 1998), DNRA represents a very short-term sink because the NH 4 + product is subject to nitrification. Plant uptake can be a significant NO 3 − -N sink in the riparian zone (Peterjohn and Correll, 1984;Hefting et al, 2005;Harrison et al, 2012), but plants represent a relatively finite N pool that can be rapidly remineralized after senescence (Reddy and Patrick, 1984). In contrast to these relatively small or short-term NO 3 − -N sinks, denitrification is thought to be the major process responsible for NO 3 − -N removal when plant uptake is low (Haycock and Pinay, 1993).…”

Influence of emergent vegetation on nitrate cycling in sediments of a groundwater-fed river

“…Other than reduction through denitrification, biotic uptake of NO 3 -by plants during the growing season could have been substantial. Harrison et al (2012) observed NO 3 -uptake by plants from 42 to 63 % during the plant growth season in relic oxbow-wetlands dominated by emergent vegetation. Dissimilatory nitrate reduction to ammonium (DNRA) could be an additional sink for pore water nitrate loss beneath VS (Kelso et al 1997); however, the potential for NO 3 -loss through DNRA was of minimal importance compared to denitrification in the un-vegetated sediments of River Leith .…”

“…The overall role of emergent vegetation, particularly Sparganium spp., in NO 3 -attenuation need consideration while evaluating options for nutrient management and restoration of biogeochemical functions rendered by riverine ecosystems. Further studies on quantifying plant mediated NO 3 -reduction processes in riverine sediments, particularly denitrification relative to plants uptake, both during growing and non-growing seasons, are recommended (Borin and Salvato 2012;Harrison et al 2012).…”

“…Nitrogen cascading into riverine sediments from upwelling groundwater, may be attenuated in the hyporheic zone through immobilization (sorption, and plant and microbial uptake) (Howard-Williams et al 1982;Clarke 2002;Strauss and Lamberti 2002), and through reduction to N 2 gas by denitrification before the reactive N joins river flows (Pretty et al 2006;Krause et al 2009;Trimmer et al 2009;Stelzer et al 2011;Forshay and Dodson 2011;Harrison et al 2012). In addition to research looking at the influence of classic geomorphic features of rivers on nutrient cycling in riverine sediments, a number of researchers have also noted the importance of evaluating the influence of different vegetation types on nutrient cycling including those growing in riverbeds (Templer et al 1996;Wigand et al 2001;Clarke and Wharton 2001;Groffman et al 2005;Trimmer et al 2009;Lefebvre et al 2006;Forshay and Dodson 2011).…”