The behaviour of dissolved phosphate during mixing in the Beaulieu Estuary and its relation to that of iron and other elements
The behaviour of dissolved phosphate during mixing in the Beaulieu Estuary and its relation to that of iron and other elements
Ultrafiltration of River Beaulieu water indicated that 50to 85% of the reactive dissolved phosphate occurred, in association with, onaverage, more than 93% of the dissolved iron, in the colloidal fraction ofmolecular weight > 105. Dissolved organic carbon mostly occurred(~65%) in the molecular weight range < 103, with > 5%associated with iron colloids in the high molecular weight range (> 105).Dissolved silicon was almost wholly in true solution.
During mixing in the Beaulieu Estuary, extensive removalof dissolved iron was observed with 90–95% removal in the salinity range 0–15°/ooand almost complete removal as the salinity approached about 20°/oo. The extentof removal of iron appeared to be influenced by the amount of DOC in the riverwater. In contrast, the DOC behaved essentially conservatively except for onesurvey in which there was an apparent removal of 20% relative to the riverwater concentration.
Dissolved silicon showed conservative behaviour in owsurvey but on other occasions there was evidence of removal, generally in therange 10–25% but up to an apparent 70% in another survey. It is suggested thatthis large-scale apparent removal may reflect uncertainties in interpretation.
The behaviour of phosphate in the Beaulieu Estuary wascomplex. An initial increase in concentration with increasing salinity, whichcommonly occurred, may be due to desorption from river-borne suspended solids.After this stage, some removal was usually observed, probably associated withthe process of iron removal. The pattern of behaviour of phosphate wasirregular, however, and it is possible that mobilization from bottom sediments ledto changes not directly related to the mixing of the river and sea waterend-members.
Laboratory experimental studies were carried out on theinteraction of dissolved phosphate with estuarine sedimentary material. Maximumadsorption of phosphate in river water occurred between pH 3–6; adsorption wasdecreased in more saline water, supporting the view that desorption may occurin the early stages of estuarine mixing. There was a marked reduction in thecapacity of suspended solids to adsorb phosphate when iron coatings wereremoved from the particles. Removal of organic matter also tended to decrease theadsorption capacity of the sediment.
University of Southampton
Umnuay, Gullaya
9c5499d4-db0a-42b4-9b61-6337d911fbfe
1980
Umnuay, Gullaya
9c5499d4-db0a-42b4-9b61-6337d911fbfe
Burton, J.P.
12f943bd-4807-4291-a111-ae9c55602bfc
Umnuay, Gullaya
(1980)
The behaviour of dissolved phosphate during mixing in the Beaulieu Estuary and its relation to that of iron and other elements.
University of Southampton, Masters Thesis, 159pp.
Record type:
Thesis
(Masters)
Abstract
Ultrafiltration of River Beaulieu water indicated that 50to 85% of the reactive dissolved phosphate occurred, in association with, onaverage, more than 93% of the dissolved iron, in the colloidal fraction ofmolecular weight > 105. Dissolved organic carbon mostly occurred(~65%) in the molecular weight range < 103, with > 5%associated with iron colloids in the high molecular weight range (> 105).Dissolved silicon was almost wholly in true solution.
During mixing in the Beaulieu Estuary, extensive removalof dissolved iron was observed with 90–95% removal in the salinity range 0–15°/ooand almost complete removal as the salinity approached about 20°/oo. The extentof removal of iron appeared to be influenced by the amount of DOC in the riverwater. In contrast, the DOC behaved essentially conservatively except for onesurvey in which there was an apparent removal of 20% relative to the riverwater concentration.
Dissolved silicon showed conservative behaviour in owsurvey but on other occasions there was evidence of removal, generally in therange 10–25% but up to an apparent 70% in another survey. It is suggested thatthis large-scale apparent removal may reflect uncertainties in interpretation.
The behaviour of phosphate in the Beaulieu Estuary wascomplex. An initial increase in concentration with increasing salinity, whichcommonly occurred, may be due to desorption from river-borne suspended solids.After this stage, some removal was usually observed, probably associated withthe process of iron removal. The pattern of behaviour of phosphate wasirregular, however, and it is possible that mobilization from bottom sediments ledto changes not directly related to the mixing of the river and sea waterend-members.
Laboratory experimental studies were carried out on theinteraction of dissolved phosphate with estuarine sedimentary material. Maximumadsorption of phosphate in river water occurred between pH 3–6; adsorption wasdecreased in more saline water, supporting the view that desorption may occurin the early stages of estuarine mixing. There was a marked reduction in thecapacity of suspended solids to adsorb phosphate when iron coatings wereremoved from the particles. Removal of organic matter also tended to decrease theadsorption capacity of the sediment.
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Umnuay 1980 Thesis
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Published date: 1980
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Local EPrints ID: 459251
URI: http://eprints.soton.ac.uk/id/eprint/459251
PURE UUID: 96241959-96b8-47f1-9971-ac741368f5d2
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Date deposited: 04 Jul 2022 17:07
Last modified: 16 Mar 2024 18:29
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Author:
Gullaya Umnuay
Thesis advisor:
J.P. Burton
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