DOI: 10.5194/hess-22-4083-2018
论文题名: Nitrogen attenuation; dilution and recycling in the intertidal hyporheic zone of a subtropical estuary
作者: Lamontagne S. ; Cosme F. ; Minard A. ; Holloway A.
刊名: Hydrology and Earth System Sciences
ISSN: 1027-5606
出版年: 2018
卷: 22, 期: 7 起始页码: 4083
结束页码: 4096
语种: 英语
Scopus关键词: Aquifers
; Biogeochemistry
; Denitrification
; Estuaries
; Mixing
; Nitrogen
; Nitrogen removal
; Stream flow
; Tropics
; Wastewater treatment
; Biogeochemical process
; Ground water discharge
; Hyporheic exchange
; Intertidal sediments
; Isotopic fractionations
; Nitrogen attenuation
; Sub-tropical estuary
; Synthetic sources
; Groundwater resources
; aquifer
; denitrification
; dilution
; estuarine sediment
; estuary
; groundwater
; hyporheic zone
; intertidal environment
; isotopic fractionation
; nitrogen
; recycling
; subtropical region
; surface water
; Australia
英文摘要: Tidal estuarine channels have complex and dynamic interfaces controlled by upland groundwater discharge, waves, tides and channel velocities that also control biogeochemical processes within adjacent sediments. In an Australian subtropical estuary, discharging groundwater with elevated (> 300 mg N L-1) NH4 + and NO3 - concentrations had 80 % of the N attenuated at this interface, one of the highest N removal rates (> 100 mmol m-2 day-1) measured for intertidal sediments. The remaining N was also diluted by a factor of 2 or more by mixing with surface water before being discharged to the estuary. Most of the mixing occurred in a hyporheic zone in the upper 50 cm of the channel bed. However, groundwater entering this zone was already partially mixed (12 %-60 %) with surface water via tide-induced circulation. Below the hyporheic zone (50-125 cm below the channel bed), NO3 - concentrations declined slightly faster than NH4 + concentrations and δ15NNO3 and δ18ONO3 gradually increased, suggesting a co-occurrence of anammox and denitrification. In the hyporheic zone, δ15NNO3 continued to become enriched (consistent with either denitrification or anammox) but δ18ONO3 became more depleted (indicating some nitrification). A high δ15NNO3 (23-35) and a low δ18ONO3 (1.2 %-8.2 %) in all porewater samples indicated that the original synthetic nitrate pool (industrial NH4NO3; δ15N ∼ 0 %; δ18O ∼ 18 %-20 %) had turned over completely during transport in the aquifer before reaching the channel bed. Whilst porewater NO3 - was more δ18O depleted than its synthetic source, porewater δ18OH2O (-3.2 % to-1.8 %) was enriched by 1 %-4 % relative to rainfall-derived groundwater mixed with seawater. Isotopic fractionation from H2O uptake during the N cycle and H2O production during synthetic NO3 - reduction are the probable causes for this δ18OH2O enrichment. Whilst occurring at a smaller spatial scale than tide-induced circulation, hyporheic exchange can provide a similar magnitude of mixing and biogeochemical transformations for groundwater solutes discharging through intertidal zones. © 2018 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/163237
Appears in Collections: 气候变化与战略
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作者单位: Lamontagne, S., CSIRO Land and Water, PB 2, Glen Osmond, 5064, Australia; Cosme, F., Golder Ass., Richmond, VIC 3121, Australia; Minard, A., Golder Ass., Richmond, VIC 3121, Australia; Holloway, A., Golder Ass., St Leonards, NSW 2065, Australia
Recommended Citation:
Lamontagne S.,Cosme F.,Minard A.,et al. Nitrogen attenuation; dilution and recycling in the intertidal hyporheic zone of a subtropical estuary[J]. Hydrology and Earth System Sciences,2018-01-01,22(7)