The influence of particle size and mineralogy on both phosphorus retention and release by streambed sediments

Simon D. Clarendon, David M. Weaver, Peter M. Davies, Neil A. Coles

Research output: Contribution to journalArticle

Abstract

Purpose In many streams worldwide including those on the south coast of Western Australia (WA), sediments of the >2-mm fraction often contribute up to 50% of the streambed. However, most analysis and interpretation of sediment chemistry, including phosphorus (P), is conducted on the 2-mm fraction to P retention and release in sandy-gravely streams.

Material and methods Sediment samples were collected from streams in agricultural catchments, and P retention and release by the 2-mm (typically lateritic; iron rich) sediment fractions were examined using fluvarium and batch experiments. Phosphorus sorbed by sediment was estimated on a mass (mg P kg(-1)) and area basis (mg P m(-2)).

Results and discussion Phosphorus sorption measurements suggested that mineralogy as well as particle size were important factors influencing P retention by stream sediments. Stream sediments retained approximately 30% of added P. In a desorption phase, approximately 8% of the retained P was released into stream water.

Conclusions Stream sediments in south western WA appear to be net immobilisers of P, retaining more P than they release, dependent on the stream P concentration. Exclusion of the >2-mm fraction when determining stream sediment P dynamics may therefore underestimate whole stream sediment P retention and release.

Original languageEnglish
Pages (from-to)2624-2633
Number of pages10
JournalJournal of Soils and Sediments
Volume19
Issue number5
DOIs
Publication statusPublished - May 2019

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