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Hill, Alan R.; Devito, K. J.; Campagnolo, Stefano; Sanmugadas, K.

doi:10.1023/a:1006476514038

Cited by 306 publications

(37 citation statements)

References 44 publications

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“…The denitrification rate is positively correlated with OM concentrations ([OM]) in stream ecosystems (Hill et al 2000;Inwood et al 2007). Our results in the riparian sediments are consistent with these results and suggest that [OC] affects denitrification rates in riparian sediments.…”

Section: Discussionsupporting

confidence: 89%

Factors Controlling Sediment Denitrification Rates in Grassland and Forest Streams

Kim¹

2014

Terr. Atmos. Ocean. Sci.

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Sediment denitrification is an important nitrate (NO 3 -) removal process from agricultural streams. The direct and indirect factors that control denitrification rates in tributary sediments can vary depending on the types of agricultural activities and vegetation. Our research investigated (1) tributary sediment denitrification rates in a grassland stream affected by pasture ecosystems and a forest stream affected by N fertilization; and (2) the environmental factors that determine denitrification rates in tributary sediments. The denitrification enzyme activity (DEA) in grassland stream sediments is positively correlated with precipitation likely due to the increased nutrient exchange rates between stream water and sediments, and was higher than in forest stream sediments, leading to a decrease in NO 3 -concentration ([NO 3 -]) in stream sediments. The DEA in riparian sediments was regulated by carbon concentrations and did not contribute to NO 3 -removal from the riparian sediment in grassland and forest streams. Thus, environmental factors affected by different types of agricultural activities and vegetation might regulate denitrification rates and in agricultural stream ecosystems.

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Section: Discussionsupporting

confidence: 89%

Factors Controlling Sediment Denitrification Rates in Grassland and Forest Streams

Kim¹

2014

Terr. Atmos. Ocean. Sci.

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“…The impacts of hydrochemical gradients on biogeochemical processes and soil development that we observed, however, are likely true to some extent in all wetland systems. Distinct horizontal gradients in pore-water chemistry with distance from a water source or in relation to multi-source mixing zones have been observed in riparian buffers (Duval and Hill 2007;Hill et al 2000;Vidon and Hill 2004), coastal wetlands (Bailey and Bedford 2003;Williams et al 2008), and expansive northern peatlands (Bubier 1995;Glaser et al 1997). Results from all of these studies emphasize the importance of explicitly relating plot-scaled biogeochemistry studies to local hydrologic settings.…”

Section: Discussionmentioning

confidence: 93%

Groundwater-induced redox-gradients control soil properties and phosphorus availability across four headwater wetlands, New York, USA

Boomer

Bedford

2008

Biogeochemistry

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Hydrochemical patterns across groundwater-fed wetlands, especially carbonate and redox gradients, can influence phosphorus (P) availability by controlling its distribution among different soil pools. We explored these linkages by comparing shallow (5-20 cm) soil properties along groundwater flowpaths in two rich fens, a marl fen, and a poor fen. Organic matter content, bulk density, and total elemental content varied more with depth to underlying drift materials than with water table fluctuation, but also were influenced by groundwater discharge, which stabilized water table elevations and controlled redox conditions. Total sulfur and calcium content increased where pore-water chemistry indicated active iron and sulfate reduction. Calcium mineral dynamics, however, did not appear to influence P availability: first, calcium carbonate (CaCO 3 ) accounted for \2% of the soil composition, except in the marl fen where it accounted for 20-25% of the soil composition. Second, Ca-bound P pools, determined from hydrochloric extraction of wet soil samples, accounted for \25% of the inorganic soil P pool. In contrast, iron-bound P determined from bicarbonate-buffered dithionite solution, accounted for 50-80% of the inorganic soil P, and increased where there was evidence of groundwater mixing, as did P release rates inferred from incubated anion resin bags. The total carbon and phosphorus content of organic-rich soils as well as available and labile P pools were strongly correlated with pore-water iron and alkalinity concentrations. Groundwater discharge and resulting hydrochemical gradients explained significant variation in soil composition and P availability across each site. Results highlight the importance of conducting biogeochemical studies in the context of a site's shallow geologic setting and suggest mechanisms supporting the diverse plant species unique to groundwater wetlands.

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“…This aspect needs to be evaluated in future studies. Various studies have shown that the extent and duration of contact time between wetland inflows and wetland sediment (Hill 1996;Cirmo and McDonnell 1997;Devito et al 2000;Hill et al 2000) can affect the extent of denitrification and hence the wetland capacity to remove NO 3 À . During high flow events, low removal is expected because high NO 3 À -containing water bypasses microbially active wetland sediments by flowing across the top of wetlands (Gold et al 2001;Burns and Nguyen 2002;Rutherford and Nguyen 2004).…”

Section: Preliminary Testing Of the Push-pull Technique Within A Confmentioning

confidence: 99%

Nitrous oxide generation, denitrification, and nitrate removal in a seepage wetland intercepting surface and subsurface flows from a grazed dairy catchment

Zaman¹,

Nguyen

Gold

et al. 2008

Soil Res.

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Abstract.Little is known about seepage wetlands, located within agricultural landscapes, with respect to removing nitrate (NO 3 À ) from agricultural catchments, mainly through gaseous emissions of nitrous oxide (N 2 O) and dinitrogen (N 2 ) via denitrification. These variables were quantified using a push-pull technique where we introduced a subsurface water plume spiked with 15 N-enriched NO 3 À and 2 conservative tracers [bromide (Br À ) and sulfur hexafluoride (SF 6 )] into each of 4 piezometers and extracted the plume from the same piezometers throughout a 48-h period. To minimise advective and dispersive flux, we placed each of these push-pull piezometers within a confined lysimeter (0.5 m diameter) installed around undisturbed wetland soil and vegetation. Although minimal dilution of the subsurface water plumes occurred, NO 3 À -N concentration dropped sharply in the first 4 h following dosing, such that NO 3 À -limiting conditions (<2 mg/L of NO 3 -N) for denitrification prevailed over the final 44 h of the experiment. Mean subsurface water NO 3 À removal rates during non-limiting conditions were 15.7 mg/L.day. Denitrification (based on the generation of isotopically enriched N 2 O plus N 2 ) accounted for only 7% (1.1 mg/L.day) of the observed groundwater NO 3 À removal, suggesting that other transformation processes, such as plant uptake, were responsible for most of the NO 3 À removal. Although considerable increases in 15 N-enriched N 2 O levels were initially observed following NO 3 À dosing, no net emissions were generated over the 48-h study. Our results suggest that this wetland may be a source of N 2 O emissions when NO 3 À concentrations are elevated (non-limited), but can readily remove N 2 O (function as a N 2 O sink) when NO 3 À levels are low. These results argue for the use of engineered bypass flow designs to regulate NO 3 À loading to wetland denitrification buffers during high flow events and thus enhance retention time and the potential for NO 3 À -limiting conditions and N 2 O removal. Although this type of management may reduce the full potential for wetland NO 3 À removal, it provides a balance between water quality goals and greenhouse gas emissions.

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Untitled

Cited by 306 publications

References 44 publications

Factors Controlling Sediment Denitrification Rates in Grassland and Forest Streams

Factors Controlling Sediment Denitrification Rates in Grassland and Forest Streams

Groundwater-induced redox-gradients control soil properties and phosphorus availability across four headwater wetlands, New York, USA

Nitrous oxide generation, denitrification, and nitrate removal in a seepage wetland intercepting surface and subsurface flows from a grazed dairy catchment

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