Denitrification of Nitrogen Released from Senescing Algal Biomass in Coastal Agricultural Headwater Streams

McMillan, Sara K.; Piehler, Michael F.; Thompson, Suzanne P.; Paerl, Hans W.

doi:10.2134/jeq2008.0438

Cited by 35 publications

(15 citation statements)

References 38 publications

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“…High standing stocks of labile C in the stream can then be released back to the stream in dissolved and particulate organic forms. These processes can be linked, as denitrification in hyporheic utilizes these C sources to fuel metabolism and reduce downstream nutrient transport (von Schiller et al ., ; McMillan et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Influence of Restoration Age and Riparian Vegetation on Reach‐Scale Nutrient Retention in Restored Urban Streams

McMillan

Tuttle

Jennings

et al. 2014

J American Water Resour Assoc

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In urban watersheds, stormwater inputs largely bypass the buffering capacity of riparian zones through direct inputs of drainage pipes and lowered groundwater tables. However, vegetation near the stream can still influence instream nutrient transformations via maintenance of streambank stability, input of woody debris, modulation of organic matter sources, and temperature regulation. Stream restoration seeks to mimic many of these functions by engineering channel complexity, grading stream banks to reconnect incised channels, and replanting lost riparian vegetation. The goal of this study was to quantify these effects by measuring nitrate and phosphate uptake in five restored streams in Charlotte and Raleigh, North Carolina, with a range of restoration ages. Using nutrient spiraling methods, uptake velocity of nitrate (0.02-3.56 mm/min) and phosphate (0.14-19.1 mm/min) was similar to other urban restored streams and higher than unimpacted forested streams with variability influenced by restoration age and geomorphology. Using a multiple linear regression approach, reach-scale phosphate uptake was greater in newly restored sites, which was attributed to assimilation by algal biofilms, whereas nitrate uptake was highest in older sites potentially due to greater channel stability and establishment of microbial communities. The patterns we observed highlight the influence of riparian vegetation on energy inputs (e.g., heat, organic matter) and thereby on nutrient retention.

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Section: Discussionmentioning

confidence: 97%

Influence of Restoration Age and Riparian Vegetation on Reach‐Scale Nutrient Retention in Restored Urban Streams

McMillan

Tuttle

Jennings

et al. 2014

J American Water Resour Assoc

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“…Increased dissolved organic C (DOC) availability fuels overall microbial activity and provides potentially limiting resources to the denitrification pathway. In particular, C and N released during senescence may fuel denitrification (McMillan et al, 2010) and maintain denitrifier microbial communities within plant beds. Farnsworth and Meyerson (2003) reported higher biomass turnover in cutgrass than cattail, an indication that more leaf input and breakdown probably occurs throughout the year in cutgrass stands.…”

Section: Discussionmentioning

confidence: 99%

Contrasting Nutrient Mitigation and Denitrification Potential of Agricultural Drainage Environments with Different Emergent Aquatic Macrophytes

2015

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Remediation of excess nitrogen (N) in agricultural runoff can be enhanced by establishing wetland vegetation, but the role of denitrification in N removal is not well understood in drainage ditches. We quantified differences in N retention during experimental runoff events followed by stagnant periods in mesocosms planted in three different vegetation treatments: unvegetated, cutgrass [ (L.) Sw.], and common cattail ( L.). We also quantified denitrification rates using membrane inlet mass spectrometry from intact cores extracted from each mesocosm treatment. All treatments retained 60% or more of NO-N loads during the 6-h experimental runoff event, but mesocosms planted with cutgrass had significantly higher (68%) retention than the cattail (60%) or unvegetated (61%) treatments. After the runoff event, mesocosms planted in cattail reduced NO-N concentrations by >95% within 24 h and cutgrass achieved similar reductions within 48 h, whereas reductions in the unvegetated mesocosms were significantly less (65%). Cores from cutgrass mesocosms had significantly higher average denitrification rates (5.93 mg m h), accounting for as much as 56% of the immobilized NO-N within 48 h, whereas denitrification rates were minimal in cores from the unvegetated (-0.19 mg m h) and cattail (0.2 mg m h) mesocosms. Our findings have implications for mitigating excess NO-N in agricultural runoff. While vegetated treatments removed excess NO-N from the water column at similar and significantly higher rates than unvegetated treatments, the high denitrification rates observed for cutgrass highlight the potential for permanent removal of excess N from agricultural runoff in vegetated ditches and wetlands.

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“…It is also likely that aboveground senescent vegetation in our mesocosms enhanced denitrification rates. Microbial biofilms on senescent plant stems and sediments can denitrify N retained by ditch plants and potentially contribute to coupled nitrification-denitrification during the breakdown process [47,48].…”

Section: The Role Of Denitrification In Net Nitrogen Retention In Vegmentioning

confidence: 99%

Vegetated Ditch Habitats Provide Net Nitrogen Sink and Phosphorus Storage Capacity in Agricultural Drainage Networks Despite Senescent Plant Leaching

Taylor

Moore

Speir

et al. 2020

Water

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The utility of vegetated ditch environments as nutrient sinks in agricultural watersheds is dependent in part on biogeochemical transformations that control plant uptake and release during decomposition. We investigated nitrogen (N) and phosphorus (P) uptake and release across four P enrichment treatments in ditch mesocosms planted with rice cutgrass (Leersia oryzoides) during the summer growing and winter decomposition seasons. Measured N retention and modeled denitrification rates did not vary, but P retention significantly increased with P enrichment. At the end of the growing season, root biomass stored significantly more N and P than aboveground stem and leaf biomass. Decomposition rates were low (<10% organic matter loss) and not affected by P enrichment. Nitrogen and P export during winter did not vary across the P enrichment gradient. Export accounted for <10% of observed summer N uptake (1363 mg m−2), with denitrification potentially accounting for at least 40% of retained N. In contrast, net P retention was dependent on enrichment; in unenriched mesocosms, P uptake and release were balanced (only 25% net retention), whereas net retention increased from 77% to 88% with increasing P enrichment. Our results indicate that vegetated ditch environments have significant potential to serve as denitrification sinks, while also storing excess P in agricultural watersheds.

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Denitrification of Nitrogen Released from Senescing Algal Biomass in Coastal Agricultural Headwater Streams

Cited by 35 publications

References 38 publications

Influence of Restoration Age and Riparian Vegetation on Reach‐Scale Nutrient Retention in Restored Urban Streams

Influence of Restoration Age and Riparian Vegetation on Reach‐Scale Nutrient Retention in Restored Urban Streams

Contrasting Nutrient Mitigation and Denitrification Potential of Agricultural Drainage Environments with Different Emergent Aquatic Macrophytes

Vegetated Ditch Habitats Provide Net Nitrogen Sink and Phosphorus Storage Capacity in Agricultural Drainage Networks Despite Senescent Plant Leaching

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