@article{Parsons-2017-Sediment,
title = "Sediment phosphorus speciation and mobility under dynamic redox conditions",
author = "Parsons, Christopher T. and
Rezanezhad, Fereidoun and
O{'}Connell, David and
Cappellen, Philippe Van",
journal = "Biogeosciences, Volume 14, Issue 14",
volume = "14",
number = "14",
year = "2017",
publisher = "Copernicus GmbH",
url = "https://gwf-uwaterloo.github.io/gwf-publications/G17-29001",
doi = "10.5194/bg-14-3585-2017",
pages = "3585--3602",
abstract = "Abstract. Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O2) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N2), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous- and solid-phase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low ( ∼ 2.5 {\mbox{$\mu$}}M) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 {\%} of the released P accumulated in solution while the rest was redistributed between the MgCl2 and NaHCO3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 {\%} of sediment particulate P. Phosphatase activities up to 2.4 mmol h−1 kg−1 indicated the potential for rapid mineralization of organic P (Po), in particular during periods of aeration when the activity of phosphomonoesterases was 37 {\%} higher than under N2 sparging. The results emphasize that the magnitude and timing of internal P loading during periods of anoxia are dependent on both P redistribution within sediments and bottom-water nitrate concentrations.",
}
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<abstract>Abstract. Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O2) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N2), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous- and solid-phase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low ( ∼ 2.5 μM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl2 and NaHCO3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h−1 kg−1 indicated the potential for rapid mineralization of organic P (Po), in particular during periods of aeration when the activity of phosphomonoesterases was 37 % higher than under N2 sparging. The results emphasize that the magnitude and timing of internal P loading during periods of anoxia are dependent on both P redistribution within sediments and bottom-water nitrate concentrations.</abstract>
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%0 Journal Article
%T Sediment phosphorus speciation and mobility under dynamic redox conditions
%A Parsons, Christopher T.
%A Rezanezhad, Fereidoun
%A O’Connell, David
%A Cappellen, Philippe Van
%J Biogeosciences, Volume 14, Issue 14
%D 2017
%V 14
%N 14
%I Copernicus GmbH
%F Parsons-2017-Sediment
%X Abstract. Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O2) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N2), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous- and solid-phase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low ( ∼ 2.5 μM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl2 and NaHCO3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h−1 kg−1 indicated the potential for rapid mineralization of organic P (Po), in particular during periods of aeration when the activity of phosphomonoesterases was 37 % higher than under N2 sparging. The results emphasize that the magnitude and timing of internal P loading during periods of anoxia are dependent on both P redistribution within sediments and bottom-water nitrate concentrations.
%R 10.5194/bg-14-3585-2017
%U https://gwf-uwaterloo.github.io/gwf-publications/G17-29001
%U https://doi.org/10.5194/bg-14-3585-2017
%P 3585-3602
Markdown (Informal)
[Sediment phosphorus speciation and mobility under dynamic redox conditions](https://gwf-uwaterloo.github.io/gwf-publications/G17-29001) (Parsons et al., GWF 2017)
ACL
- Christopher T. Parsons, Fereidoun Rezanezhad, David O’Connell, and Philippe Van Cappellen. 2017. Sediment phosphorus speciation and mobility under dynamic redox conditions. Biogeosciences, Volume 14, Issue 14, 14(14):3585–3602.
