Influence of hydrological connectivity of riverine wetlands on nitrogen removal via denitrification

Racchetti, Erica; Bartoli, Marco; Soana, Elisa; Longhi, Daniele; Christian, Robert R.; Pinardi, Monica; Viaroli, Pierluigi

doi:10.1007/s10533-010-9477-7

Cited by 100 publications

(80 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The concentration series conducted in our 15 Nlabeling experiments allowed us to assess the simultaneous occurrence of anammox and denitrification as potential N 2 -producing processes (RisgaardPetersen et al 2003, Trimmer et al 2006, Racchetti et al 2011). Since genuine 28 N 2 production was constant and independent of the concentrations of added labeled nitrate, anammox did not appear to contribute significantly to N 2 production (Trimmer et al 2006).…”

Section: Denitrification and Dnra Rates Under Hy No And Nob Conditionsmentioning

confidence: 99%

Effect of reoxygenation and Marenzelleria spp. bioturbation on Baltic Sea sediment metabolism

Bonaglia

Bartoli²,

Gunnarsson³

et al. 2013

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

Nutrient reduction and the improvement of bottom water oxygen concentrations are thought to be key factors in the recovery of eutrophic aquatic ecosystems. The effects of reoxygenation and bioturbation of natural hypoxic sediments in the Baltic Sea were studied using a mesocosm experiment. Anoxic sediment box cores were collected from 100 m depth in Kanholmsfjärden (Stockholm Archipelago) and maintained in flow-through mesocosms with 3 treatments: (1) hypoxic: supplied with hypoxic water; (2) 3− and H 4 SiO 4 , and rates of nitrate ammonification (DNRA), denitrification and anammox were determined. Phosphate was taken up by the sediment in all treatments, and the uptake was highest in the normoxic treatment with Marenzelleria. Normoxic conditions stimulated the denitrification rate by a factor of 5. Denitrification efficiency was highest under normoxia (50%), intermediate in bioturbated sediments (16%), and very low in hypoxic sediments (4%). The shift from hypoxic to normoxic conditions resulted in a significantly higher retention of NH 4 + , H 4 SiO 4 and Mn 2+ in the sediment, but the bioturbation by Marenzelleria reversed this effect. Results from our study suggest that bioturbation by Marenzelleria stimulates the exchange of solutes between sediment and bottom water through irrigation and enhances bacterial sulfate reduction in the burrow walls. The latter may have a toxic effect on nitrifying bacteria, which, in turn, suppresses denitrification rates.

show abstract

Section: Denitrification and Dnra Rates Under Hy No And Nob Conditionsmentioning

confidence: 99%

Effect of reoxygenation and Marenzelleria spp. bioturbation on Baltic Sea sediment metabolism

Bonaglia

Bartoli²,

Gunnarsson³

et al. 2013

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…This method allows to split total denitrification (D TOT ) into denitrification of nitrate diffusing to the anoxic sediment from the water column (D W ) and denitrification of nitrate produced within the sediment due to nitrification (D N ). Details on analytical methods and calculations are reported in Racchetti et al (2011).…”

Section: Export Of N From the Basinmentioning

confidence: 99%

Nitrogen balance and fate in a heavily impacted watershed (Oglio River, Northern Italy): in quest of the missing sources and sinks

et al. 2012

Self Cite

View full text Add to dashboard Cite

Abstract. We present data from a comprehensive investigation carried out from 2007 to 2010, focussing on nitrogen pollution in the Oglio River basin (3800 km 2 , Po Plain, Northern Italy). Nitrogen mass balances, computed for the whole basin with 2000 and 2008 data, suggest a large N surplus in this area, over 40 000 t N yr −1 , and increasing between 2000 and 2008. Calculations indicate a very large impact of animal husbandry and agricultural activities in this watershed, with livestock manure and synthetic fertilizers contributing 85 % of total N inputs (about 100 000 t N yr −1 ) and largely exceeding crop uptake and other N losses (about 60 000 t N yr −1 ). Nitrogen from domestic and industrial origin is estimated as about 5800 and 7200 t N yr −1 , respectively, although these loads are overestimated, as denitrification in treatment plants is not considered; nonetheless, they represent a minor term of the N budget. Annual export of nitrogen from the basin, calculated from flow data and water chemistry at the mouth of the Oglio River, is estimated at 13 000 t N yr −1 , and represents a relatively small fraction of N inputs and surplus (∼12 % and 34 %, respectively). After considering N sinks in crop uptake, soil denitrification and volatilization, a large excess remains unaccounted (∼26 000 t N yr −1 ) in unknown temporary or permanent N sinks. Nitrogen removal via denitrification was evaluated in the Oglio riverbed with stable isotope techniques (δ 15 N and δ 18 O in nitrate). The downstream final segment of the river displays an enriched nitrate stable isotope composition but calculations suggest a N removal corresponding to at most 20 % of the unaccounted for N amount. Denitrification was also evaluated in riverine wetlands with the isotope pairing technique. Areal rates are elevated but overall N removal is low (about 1 % of the missing N amount), due to small wetland surfaces and limited lateral connectivity. The secondary drainage channel network has a much higher potential for nitrogen removal via denitrification, due to its great linear development, estimated in over 12 500 km, and its capillary distribution in the watershed. In particular, we estimated a maximum N loss up to 8500 t N yr −1 , which represents up to 33 % of the unaccounted for N amount in the basin. Overall, denitrification in surface aquatic habitats within this basin can be responsible for the permanent removal of about 12 000 t N yr −1 ; but the fate of some 14 000 t remains unknown. Available data on nitrate concentration in wells suggest that in the central part of the watershed groundwater accumulates nitrogen. Simultaneously, we provide evidences that part of the stored nitrate can be substantially recycled via springs and can pollute surface waters via rivergroundwater interactions. This probably explains the ten fold increase of nitrate concentration in a reach of the Oglio River where no point pollutions sources are present.

show abstract

“…Racchetti et al [46] reported sediment denitrification rates in several riverine wetlands of the Oglio River basin, measured seasonally by means of isotope pairing technique. Denitrification rates were up to two orders of magnitude higher in perifluvial wetlands hydraulically connected to the NO , average value 400 kg N ha À1 year À1 ) than those measured in hydraulically isolated sites.…”

Section: N Removal In Aquatic Environments Within the Lower Oglio Rivmentioning

confidence: 99%

Soil Budget, Net Export, and Potential Sinks of Nitrogen in the Lower Oglio River Watershed (Northern Italy)

Soana

Racchetti

Laini

et al. 2011

CLEAN Soil Air Water

Self Cite

View full text Add to dashboard Cite

A nitrogen mass balance, realized for the lower Oglio River basin (Po River Plain, northern Italy), suggested an elevated impact of agricultural activities in this watershed. Livestock manure, synthetic fertilizers, biological fixation, atmospheric deposition, and wastewater sludge contributed 51,34,12,2, and 1% of total N (TN) . About 34% of the N surplus was exported annually from the basin while the remaining amount (about 26 800 t N year À1) underwent other unaccounted for processes within the watershed.The relevance of nitrogen removal via denitrification in aquatic compartments within the watershed was evaluated. Denitrification in the secondary drainage network can represent a relevant nitrogen sink due to great linear extension (over 12 500 km), with estimated nitrogen loss up to 8500 t N year À1 . Denitrification in the riverbed and in perifluvial wetlands have the potential to remove only a small fraction of the nitrogen surplus (<3%). Evidence suggests the relevance of groundwater as a site of nitrogen accumulation. IntroductionIncreased reactive nitrogen (N) input to the biosphere by human activities has resulted in the gradual saturation of the N buffering capacity of terrestrial areas and augmented N loads toward surface and ground waters. Reactive N is now accumulating in the environment at all spatial scales, from local to global [1,2]. Farming activity is one of the primary causes for the current high N loads, as an unbalance between livestock manure production and agricultural lands for spreading causes an available N pool generally exceeding the crop requirements and the soil's metabolic capacity [3,4]. The control of N inputs to aquatic systems is of general public interest due to their known ecosystemic consequences, namely eutrophication [5][6][7] and the potential toxicity risks posed by a high nitrate (NO À 3 ) concentration in water resources [8,9]. Rivers are particularly critical because they link terrestrial and coastal ecosystems, and aggregate stressors occurring at the landscape scale. Human-driven alterations such as channelization, impoundment, water withdrawals, reduction of perifluvial vegetation, and wetlands have enhanced soil erosion and runoff processes, affected the biogeochemistry of riparian and in-stream zones and reduced the efficiency of the river network in mitigating N excess [10][11][12].Worldwide N budgets estimate that, on a long-term basis, up to $75% of the N load generated within catchments is generally retained within the basin and not exported via river discharge [2,13]. The ratio between exported and generated N can be considered an integrated measure of the watershed metabolic capacity toward N. The retained N is the result of several processes, among which some are well studied (i.e., crop uptake) while others are scarcely investigated (i.e., denitrification in lotic ecosystems, N storage in soils, and percolation to groundwater) and represent large unknown terms in N budgets [14]. Even if denitrification is accepted as the major sink of N excess in the...

show abstract

Influence of hydrological connectivity of riverine wetlands on nitrogen removal via denitrification

Cited by 100 publications

References 58 publications

Effect of reoxygenation and Marenzelleria spp. bioturbation on Baltic Sea sediment metabolism

Effect of reoxygenation and Marenzelleria spp. bioturbation on Baltic Sea sediment metabolism

Nitrogen balance and fate in a heavily impacted watershed (Oglio River, Northern Italy): in quest of the missing sources and sinks

Soil Budget, Net Export, and Potential Sinks of Nitrogen in the Lower Oglio River Watershed (Northern Italy)

Contact Info

Product

Resources

About