Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

Beaulieu, Jake J.; Smolenski, Ryszard T.; Nietch, Christopher T.; Townsend‐Small, Amy; Elovitz, Michael S.; Schubauer‐Berigan, Joseph P.

doi:10.4319/lo.2014.59.2.0495

Cited by 61 publications

(48 citation statements)

References 35 publications

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“…In the dry season, less runoff is generated; second, runoff nitrate generated from croplands in the upper parts of the landscape can be intercepted by paddy fields in the lower parts [ Yan et al ., ]; and third, runoff nitrate resides for a longer time in the ponds, reservoirs, and streams due to a lack of water exchange. Consequently, longer residence time allows more nitrate to be denitrified and/or deposited into the sediments [ Beaulieu et al ., ; Yan et al ., ]. Li et al [] reported that up to 52.1% of TN in runoff underwent denitrification in the pond‐stream continuum in this region.…”

Section: Discussionmentioning

confidence: 99%

Nitrate source apportionment using a combined dual isotope, chemical and bacterial property, and Bayesian model approach in river systems

Xia

Zhang

et al. 2017

JGR Biogeosciences

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Nitrate (NO3−) pollution is a serious problem worldwide, particularly in countries with intensive agricultural and population activities. Previous studies have used δ15N‐NO3− and δ18O‐NO3− to determine the NO3− sources in rivers. However, this approach is subject to substantial uncertainties and limitations because of the numerous NO3− sources, the wide isotopic ranges, and the existing isotopic fractionations. In this study, we outline a combined procedure for improving the determination of NO3− sources in a paddy agriculture‐urban gradient watershed in eastern China. First, the main sources of NO3− in the Qinhuai River were examined by the dual‐isotope biplot approach, in which we narrowed the isotope ranges using site‐specific isotopic results. Next, the bacterial groups and chemical properties of the river water were analyzed to verify these sources. Finally, we introduced a Bayesian model to apportion the spatiotemporal variations of the NO3− sources. Denitrification was first incorporated into the Bayesian model because denitrification plays an important role in the nitrogen pathway. The results showed that fertilizer contributed large amounts of NO3− to the surface water in traditional agricultural regions, whereas manure effluents were the dominant NO3− source in intensified agricultural regions, especially during the wet seasons. Sewage effluents were important in all three land uses and exhibited great differences between the dry season and the wet season. This combined analysis quantitatively delineates the proportion of NO3− sources from paddy agriculture to urban river water for both dry and wet seasons and incorporates isotopic fractionation and uncertainties in the source compositions.

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Section: Discussionmentioning

confidence: 99%

Nitrate source apportionment using a combined dual isotope, chemical and bacterial property, and Bayesian model approach in river systems

Xia

Zhang

et al. 2017

JGR Biogeosciences

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“…This pattern persisted until lake turnover in the fall. A similar pattern was also observed in EFR during the summers of 2012 [ Beaulieu et al ., ] and 2014 (J. J. Beaulieu, unpublished data, 2013), indicating that denitrification in the hypolimnion of this agricultural reservoir consistently transitions from a net N 2 O source to a sink in response to falling NO 2.3 availability during the period of thermal stratification.…”

Section: Discussionmentioning

confidence: 99%

Controls on nitrous oxide production and consumption in reservoirs of the Ohio River Basin

2015

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Aquatic ecosystems are a globally significant source of nitrous oxide (N 2 O), a potent greenhouse gas, but estimates are largely based on studies conducted in streams and rivers with relatively less known about N 2 O dynamics in reservoirs. Due to long water residence times and high nitrogen (N) loading rates, reservoirs support substantial N processing and therefore may be particularly important sites of N 2 O production. Predicting N 2 O emissions from reservoirs is difficult due to complex interactions between microbial N processing in the oxygen-poor hypolimnion and oxygen-rich epilimnion. Here we present the results of a survey of N 2 O depth profiles in 20 reservoirs draining a broad range of land use conditions in four states in the U.S. Nitrous oxide was supersaturated in the epilimnion of 80% of the reservoirs and was undersaturated in only one, indicating that reservoirs in this region are generally a source of N 2 O to the atmosphere. Nitrous oxide was undersaturated in the hypolimnion of 10 reservoirs, supersaturated in 9, and transitioned from supersaturation to undersaturation in 1 reservoir that was monitored periodically from midsummer to fall. All reservoirs with a mean hypolimnion nitrate concentration less than 50 μg N L À1 showed evidence of net N 2 O consumption in the hypolimnion. All reservoirs sampled during lake turnover supported N 2 O production throughout the water column. These results indicate that N 2 O dynamics in reservoirs differ widely both among systems and through time but can be predicted based on N and oxygen availability and degree of thermal stratification.

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“…The lake, which was built in 1978 [10] and is used for flood control, water supply, recreation, and as a wildlife habitat [8] [14], is estimated to have generated more than thirty million US dollars in visitor expenditures and to have prevented more than seventy million US dollars in flood damages since its impoundment [9]. The mean depth of Harsha Lake is 13.1 m with the maximum water depth of 34 m and a water depth more than 8 m in most areas [15].…”

Section: Methodsmentioning

confidence: 99%

“…William H. Harsha Lake or Harsha Lake, a multi-use reservoir and primary drinking water source in southwest OH, has experienced an increase in HAB frequency and intensity over the past several decades. Previously, there have been extensive investigations on the chemical contaminants and nutrients of this lake, such as denitrification [8], total organic carbon concentrations [9] and pesticides [10]. Recently, HABs and associated toxins are a major water-quality issue not only in Lake Erie, but also in the other inland lakes in Ohio.…”

Section: Introductionmentioning

confidence: 99%

Community Structures of Phytoplankton with Emphasis on Toxic Cyanobacteria in an Ohio Inland Lake during Bloom Season

Chen

Allen

2017

JWARP

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The community structures of phytoplankton are important factors and indicators of lake water quality. Harmful algal blooms severely impact water supply, recreational activities and wildlife habitat. This study aimed to examine the phytoplankton composition and variations using microscopy, and identify harmful Cyanobacteria in weekly samples taken from four sites at Harsha Lake in southwest Ohio. Over the course of the summer in 2015, the phytoplankton of Harsha Lake consisted mainly of 13 taxa belonging to Bacillariophyta, Chlorophyta, Cryptophyta, Cyanobacteria, Dinophyta and Euglenophyta. Their significant successions started with Bacillariophyta and/or Chlorophyta, then bloomed with Cyanobacteria and ended with Chlorophyta and/or Dinophyta. Cyanobacteria members: Microcystis, Planktothrix, Dolichospermum, Aphanizomenon, Cylindrospermopsis, and Oscillatoria from the Cyanophyceae were identified to be dominant genera. These organisms varied spatially and temporally in similar patterns along with the variations of nutrients and formed the summer bloom with the total biomasses ranging from 0.01 to 114.89 mg L−1 with mean of 22.88 mg L−1. M. aeruginosa and P. rubescens were revealed as the microcystin producers, while A. circinalis and Aphanizomenon sp. were identified as a saxitoxin producer through cloning and sequencing PCR products of mcyA, mcyE and sxtA genes. The biomasses of phytoplankton, Cyanobacteria and Microcystis were positively correlated to nutrients, especially to total nitrogen. The total ELISA measurement for microcystin positively correlated with Cyanobacteria (R2 = 0.66, P < 0.0001), Microcystis (R2 = 0.64, P < 0.0001) and phytoplankton (R2 = 0.59, P < 0.0001). The basic information on the occurrence and biomasses of Cyanobacteria and total phytoplankton, and the analysis for toxic species, which were the first report for the inland water in Ohio, USA, will document the succession patterns of phytoplankton and toxin production over a season and provide data to predict risk occurrence to both human and ecological factors.

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Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

Cited by 61 publications

References 35 publications

Nitrate source apportionment using a combined dual isotope, chemical and bacterial property, and Bayesian model approach in river systems

Nitrate source apportionment using a combined dual isotope, chemical and bacterial property, and Bayesian model approach in river systems

Controls on nitrous oxide production and consumption in reservoirs of the Ohio River Basin

Community Structures of Phytoplankton with Emphasis on Toxic Cyanobacteria in an Ohio Inland Lake during Bloom Season

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