Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary
Phosphorus (P) is often a limiting nutrient within freshwater and estuarine systems, thus excess inputs of P from anthropogenic activities (dominantly agriculture) can induce eutrophication in receiving water bodies. The sequestration of P within estuarine sediments is controlled by sorption and pre...
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Journal Article |
| Published: |
Elsevier Science BV
2015
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.11937/11860 |
| _version_ | 1848747918228455424 |
|---|---|
| author | Kraal, P. Burton, E. Rose, A. Kocar, B. Lockhart, Robert Grice, Kliti Bush, R. Tan, E. Webb, S. |
| author_facet | Kraal, P. Burton, E. Rose, A. Kocar, B. Lockhart, Robert Grice, Kliti Bush, R. Tan, E. Webb, S. |
| author_sort | Kraal, P. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Phosphorus (P) is often a limiting nutrient within freshwater and estuarine systems, thus excess inputs of P from anthropogenic activities (dominantly agriculture) can induce eutrophication in receiving water bodies. The sequestration of P within estuarine sediments is controlled by sorption and precipitation processes, which are impacted by local redox conditions and burial environment. Despite the global spread of oxygen depletion in coastal marine systems, P burial under reducing conditions remains poorly understood. We investigated P cycling in relation to iron (Fe) redox chemistry in sediments from the eutrophic Peel-Harvey Estuary in Western Australia, using a combination of porewater analysis, sequential chemical P extractions, synchrotron-based micro-scale X-ray fluorescence mapping and Fe K-edge X-ray absorption spectroscopy, and PO¾- sorption experiments. The sediments represented redox regimes varying from strongly reducing, organic-rich sediments with little or no reactive Fe(III) (oxyhydr)oxides to oxygenated sediments that were enriched in reactive Fe(III) phases. Organic P and Fe-associated P were the main P burial phases, and the latter was quantitatively important even in sediments with an overall strongly reducing character.We attribute this to adsorption of P onto micro-scale Fe(III) oxyhydroxide enrichments and/or Fe-bearing clay minerals. The organic-rich sediments showed a strong decline in P contents with depth; P was released from organic matter and Fe phases but apatite precipitation was apparently inhibited in these sediments. Despite greater and stronger PO¾- sorption capacity, the oxic sediments contained relatively little P due to a lack of the primary P source in marine sediments: organic matter. Our results provide detailed insight into P burial in dynamic estuarine sediments and show that micro-scale spectroscopic analyses greatly advance our understanding of P sequestration processes. |
| first_indexed | 2025-11-14T06:56:47Z |
| format | Journal Article |
| id | curtin-20.500.11937-11860 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:56:47Z |
| publishDate | 2015 |
| publisher | Elsevier Science BV |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-118602017-09-13T14:53:53Z Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary Kraal, P. Burton, E. Rose, A. Kocar, B. Lockhart, Robert Grice, Kliti Bush, R. Tan, E. Webb, S. organic-rich sediments Organic P and Fe-associated P Phosphorus (P) is often a limiting nutrient within freshwater and estuarine systems, thus excess inputs of P from anthropogenic activities (dominantly agriculture) can induce eutrophication in receiving water bodies. The sequestration of P within estuarine sediments is controlled by sorption and precipitation processes, which are impacted by local redox conditions and burial environment. Despite the global spread of oxygen depletion in coastal marine systems, P burial under reducing conditions remains poorly understood. We investigated P cycling in relation to iron (Fe) redox chemistry in sediments from the eutrophic Peel-Harvey Estuary in Western Australia, using a combination of porewater analysis, sequential chemical P extractions, synchrotron-based micro-scale X-ray fluorescence mapping and Fe K-edge X-ray absorption spectroscopy, and PO¾- sorption experiments. The sediments represented redox regimes varying from strongly reducing, organic-rich sediments with little or no reactive Fe(III) (oxyhydr)oxides to oxygenated sediments that were enriched in reactive Fe(III) phases. Organic P and Fe-associated P were the main P burial phases, and the latter was quantitatively important even in sediments with an overall strongly reducing character.We attribute this to adsorption of P onto micro-scale Fe(III) oxyhydroxide enrichments and/or Fe-bearing clay minerals. The organic-rich sediments showed a strong decline in P contents with depth; P was released from organic matter and Fe phases but apatite precipitation was apparently inhibited in these sediments. Despite greater and stronger PO¾- sorption capacity, the oxic sediments contained relatively little P due to a lack of the primary P source in marine sediments: organic matter. Our results provide detailed insight into P burial in dynamic estuarine sediments and show that micro-scale spectroscopic analyses greatly advance our understanding of P sequestration processes. 2015 Journal Article http://hdl.handle.net/20.500.11937/11860 10.1016/j.chemgeo.2014.11.006 Elsevier Science BV restricted |
| spellingShingle | organic-rich sediments Organic P and Fe-associated P Kraal, P. Burton, E. Rose, A. Kocar, B. Lockhart, Robert Grice, Kliti Bush, R. Tan, E. Webb, S. Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| title | Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| title_full | Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| title_fullStr | Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| title_full_unstemmed | Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| title_short | Sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| title_sort | sedimentary iron–phosphorus cycling under contrasting redox conditions in a eutrophic estuary |
| topic | organic-rich sediments Organic P and Fe-associated P |
| url | http://hdl.handle.net/20.500.11937/11860 |