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Oxidation of iron causes removal of phosphorus and arsenic from streamwater in groundwater-fed lowland catchments

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Abstract
The fate of iron (Fe) may affect that of phosphorus (P) and arsenic (As) in natural waters. This study addresses the removal of Fe, P, and As from streams in lowland catchments fed by reduced, Fe-rich groundwater (average: 20 mg Fe L-1). The concentrations of dissolved Fe (<0.45 mu m) in streams gradually decrease with increasing hydraulic residence time (travel time) of the water in the catchment. The removal of Fe from streamwater is governed by chemical reactions and hydrological processes: the oxidation of ferrous iron (Fe(II)) and the subsequent formation of particulate Fe oxyhydroxides proceeds as the water flows through the catchment into increasingly larger streams. The Fe removal exhibits first-order kinetics with a mean half-life of 12 h, a value in line with predictions by a kinetic model for Fe(II) oxidation. The Fe concentrations in streams vary seasonally: they are higher in winter than in summer, due to shorter hydraulic residence time and lower temperature in winter. The removal of P and As is much faster than that of Fe. The average concentrations of P and As in streams (42 mu g P L-1) and 1.4 mu g As L-1) are 1 order of magnitude below those in groundwater (393 mu g P L-1 and 17 mu g As L-1). This removal is attributed to fast sequestration by oxidizing Fe when the water enters oxic environments, possibly by adsorption on Fe oxyhydroxides or by formation of ferric phosphates. The average P and As concentrations in groundwater largely exceed local environmental limits for freshwater (140 mu g P L-1 and 3 mu g As L((-1)), but in streams, they are below these limits. Naturally occurring Fe in groundwater may alleviate the environmental risk associated with P and As in the receiving streams.
Keywords
FE(II) OXIDATION, NATURAL ORGANIC-MATTER, DIAGENETIC IRON, FRESH-WATER, SUSPENDED SEDIMENT, SURFACE-WATER, PHOSPHATE, SPECIATION, KINETICS, FIELD

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MLA
Baken, Stijn et al. “Oxidation of Iron Causes Removal of Phosphorus and Arsenic from Streamwater in Groundwater-fed Lowland Catchments.” ENVIRONMENTAL SCIENCE & TECHNOLOGY 49.5 (2015): 2886–2894. Print.
APA
Baken, S., Salaets, P., Desmet, N., Seuntjens, P., Vanlierde, E., & Smolders, E. (2015). Oxidation of iron causes removal of phosphorus and arsenic from streamwater in groundwater-fed lowland catchments. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 49(5), 2886–2894.
Chicago author-date
Baken, Stijn, Peter Salaets, Nele Desmet, Piet Seuntjens, Elin Vanlierde, and Erik Smolders. 2015. “Oxidation of Iron Causes Removal of Phosphorus and Arsenic from Streamwater in Groundwater-fed Lowland Catchments.” Environmental Science & Technology 49 (5): 2886–2894.
Chicago author-date (all authors)
Baken, Stijn, Peter Salaets, Nele Desmet, Piet Seuntjens, Elin Vanlierde, and Erik Smolders. 2015. “Oxidation of Iron Causes Removal of Phosphorus and Arsenic from Streamwater in Groundwater-fed Lowland Catchments.” Environmental Science & Technology 49 (5): 2886–2894.
Vancouver
1.
Baken S, Salaets P, Desmet N, Seuntjens P, Vanlierde E, Smolders E. Oxidation of iron causes removal of phosphorus and arsenic from streamwater in groundwater-fed lowland catchments. ENVIRONMENTAL SCIENCE & TECHNOLOGY. 2015;49(5):2886–94.
IEEE
[1]
S. Baken, P. Salaets, N. Desmet, P. Seuntjens, E. Vanlierde, and E. Smolders, “Oxidation of iron causes removal of phosphorus and arsenic from streamwater in groundwater-fed lowland catchments,” ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 49, no. 5, pp. 2886–2894, 2015.
@article{8047236,
  abstract     = {The fate of iron (Fe) may affect that of phosphorus (P) and arsenic (As) in natural waters. This study addresses the removal of Fe, P, and As from streams in lowland catchments fed by reduced, Fe-rich groundwater (average: 20 mg Fe L-1). The concentrations of dissolved Fe (<0.45 mu m) in streams gradually decrease with increasing hydraulic residence time (travel time) of the water in the catchment. The removal of Fe from streamwater is governed by chemical reactions and hydrological processes: the oxidation of ferrous iron (Fe(II)) and the subsequent formation of particulate Fe oxyhydroxides proceeds as the water flows through the catchment into increasingly larger streams. The Fe removal exhibits first-order kinetics with a mean half-life of 12 h, a value in line with predictions by a kinetic model for Fe(II) oxidation. The Fe concentrations in streams vary seasonally: they are higher in winter than in summer, due to shorter hydraulic residence time and lower temperature in winter. The removal of P and As is much faster than that of Fe. The average concentrations of P and As in streams (42 mu g P L-1) and 1.4 mu g As L-1) are 1 order of magnitude below those in groundwater (393 mu g P L-1 and 17 mu g As L-1). This removal is attributed to fast sequestration by oxidizing Fe when the water enters oxic environments, possibly by adsorption on Fe oxyhydroxides or by formation of ferric phosphates. The average P and As concentrations in groundwater largely exceed local environmental limits for freshwater (140 mu g P L-1 and 3 mu g As L((-1)), but in streams, they are below these limits. Naturally occurring Fe in groundwater may alleviate the environmental risk associated with P and As in the receiving streams.},
  author       = {Baken, Stijn and Salaets, Peter and Desmet, Nele and Seuntjens, Piet and Vanlierde, Elin and Smolders, Erik},
  issn         = {0013-936X},
  journal      = {ENVIRONMENTAL SCIENCE & TECHNOLOGY},
  keywords     = {FE(II) OXIDATION,NATURAL ORGANIC-MATTER,DIAGENETIC IRON,FRESH-WATER,SUSPENDED SEDIMENT,SURFACE-WATER,PHOSPHATE,SPECIATION,KINETICS,FIELD},
  language     = {eng},
  number       = {5},
  pages        = {2886--2894},
  title        = {Oxidation of iron causes removal of phosphorus and arsenic from streamwater in groundwater-fed lowland catchments},
  url          = {http://dx.doi.org/10.1021/es505834y},
  volume       = {49},
  year         = {2015},
}

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