Phosphorus sorption characteristics and interactions with leaf litter‑derived dissolved organic matter leachate in iron‑rich sediments of a sub‑tropical ephemeral stream

Iles, Jordan A., Pettit, Neil E., Donn, Michael J., and Grierson, Pauline F. (2022) Phosphorus sorption characteristics and interactions with leaf litter‑derived dissolved organic matter leachate in iron‑rich sediments of a sub‑tropical ephemeral stream. Aquatic Sciences, 84 (4). 56.

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This study investigated the infuence of dissolved organic matter (DOM) additions on phosphate sorption kinetics of iron-rich sediments (39–50% hematite and goethite) from an ephemeral stream in the arid Pilbara region of sub-tropical northwest Australia. While phosphate sorption in stream sediments is known to be strongly infuenced by sediment mineralogy as well as interactions with DOM, the mechanisms and signifcance of DOM on P-release from sediments with high sorption capacities, are largely undescribed. We assessed phosphorus (P) sorption behaviours by adding a range of solutions of known inorganic P concentrations that were amended with variable loadings of DOM derived from leachates of leaf litter to sediments from stream pools during the non-fowing phase. We compared the sorption capacity of the sediments and concurrent changes in DOM composition measured using fuorescence spectroscopy. We show that the low-dose DOM addition (~ 4 mg L−1 DOC) had the efect of reducing sediment P adsorption capacity, while for the high-dose DOM addition (~ 45 mg L−1 DOC), it was increased. The high-dose DOM was similar to pore water DOC and likely saturated sediment surface adsorption sites and produced P–OM–Fe complexes. This resulted in increased removal of P from solution. Sediment P sorption characteristics were well ftted to both Freundlich and Langmuir isotherm models regardless of DOC concentration. Langmuir P sorption maxima ranged from 0.106 to 0.152 mg g−1. General P sorption characteristics of these iron-rich sediments did not difer among pools of contrasting hydrological connectivity. Our results show how humic-rich DOM can modulate the sediment P availability in dryland streams. Unravelling the complexities of P availability is of particular significance to further our understanding of biogeochemical processes in aquatic ecosystems where P often acts as a limiting nutrient.

Item ID: 76677
Item Type: Article (Research - C1)
ISSN: 1420-9055
Keywords: Ephemeral stream, Fluorescence spectroscopy, Groundwater, High molecular weight organic carbon, Hematite, Sorption kinetics
Copyright Information: © The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit
Funders: Australian Research Council (ARC)
Projects and Grants: ARC LP120200002
Date Deposited: 01 Nov 2022 02:06
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410201 Bioavailability and ecotoxicology @ 60%
41 ENVIRONMENTAL SCIENCES > 4105 Pollution and contamination > 410501 Environmental biogeochemistry @ 40%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1803 Fresh, ground and surface water systems and management > 180306 Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water) @ 100%
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