Transformation of sedimentary and colloidal phosphorus across the land‒sea margin received effluents from agricultural and municipal activities

• Published in: Journal of cleaner production Vol. 379; p. 134686
• Main Authors: Hsu, Liang-Ching, Tzou, Yu-Min, Liao, Wen-Han, Teah, Heng Yi, Liu, Yu-Ting
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.12.2022
• Subjects: bioavailability; chemical speciation; Coastal sediment; Colloid; eutrophication; inventories; organic matter; Phosphorus; risk; saline water; Sludge; Speciation; species; X-ray absorption spectroscopy; Phosphorus; Sludge; Coastal sediment; Speciation; Colloid
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2022.134686

The transformation, transport, and release of phosphorus (P) are highly subject to anthropogenic activities and complex biochemical interactions. Its bioavailability and recalcitrance are generally regulated by P forms, arousing imposition for the accurate identification of chemical speciation. Here, P K-edge X-ray absorption near edge structure spectroscopy was exploited to determine the molecular P species on colloids, canal sludge, and coastal sediments collected in the area receiving mixed effluents from agricultural and municipal activities. Although Fe(III)-bonded P [Fe(III)–P] dominated the P inventory for colloids and sludge collected near the agricultural area, its proportion on colloids was approximately half of that on the sludge, suggesting the emerging contribution of other P species such as Al–P, Fe(II)–P, and organic-P (org-P) to carry colloidal P. Proportions of Fe(III)–P on colloids and sludge both declined seaward, yet the maximum P loss from colloids was derived from the org-P. The organic matter degradation plausibly drove the reduction of SO4 and Fe(III), leading to the prominent increase in FeS and the conversion of org-P to authigenic P. While Al–P accounted for a comparable proportion of colloidal P inventory to that of Fe(III)–P in adjacent coastal wetlands, the proportion of Fe(II)–P showed the greatest increase on colloids in the transition from fresh-to saltwater. Collective results attest to the significance of Fe(II) and Al in partitioning colloidal and sedimentary P, which should be taken into account to improve the assessment of the P dynamics and eutrophication risk. [Display omitted] •P retention is controlled by adsorption/coprecipitation with Fe(III) hydroxides.•The Fe(III) had a reduced role on colloidal and sedimentary P retention seaward.•Organic P contributed the greatest colloidal P loss in the seaward transition zone.•The Fe(II)- and Al–P became more significant in the seaward transition zone.•Fe(II) and Al are considered while assessing the P dynamics and eutrophication risk.