Phosphorus cycling and burial in sediments of a seasonally hypoxic marine basin
Sulu-Gambari, F; Hagens, M.; Behrends, T; Seitaj, D.; Meysman, F.J.R.; Middelburg, J.; Slomp, C.P. (2018). Phosphorus cycling and burial in sediments of a seasonally hypoxic marine basin. Est. Coast. 41(4): 921–939. https://dx.doi.org/10.1007/s12237-017-0324-0
In: Estuaries and Coasts. Estuarine Research Federation: Port Republic, Md.. ISSN 1559-2723; e-ISSN 1559-2731, more
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| Keyword |
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| Author keywords |
Phosphorus; Recycling; Burial efficiency; Benthic flux; Cable bacteria |
| Authors | | Top |
- Sulu-Gambari, F
- Hagens, M.
- Behrends, T
- Seitaj, D., more
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- Meysman, F.J.R., more
- Middelburg, J., more
- Slomp, C.P.
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| Abstract |
Recycling of phosphorus (P) from sediments contributes to the development of bottom-water hypoxia in many coastal systems. Here, we present results of a year-long assessment of P dynamics in sediments of a seasonally hypoxic coastal marine basin (Lake Grevelingen, the Netherlands) in 2012. Sequential phosphorus extractions (SEDEX) and X-ray absorption spectroscopy (XAS) indicate that P was adsorbed to Fe-(III)-(oxyhydr)oxides when cable bacteria were active in the surface sediments in spring. With the onset of summer hypoxia, sulphide-induced dissolution of the Fe-(III)-(oxyhydr)oxides led to P release to the pore water and overlying water. The similarity in authigenic Ca-P concentrations in the sediment and suspended matter suggest that Ca-P is not formed in situ. The P burial efficiency was ≤ 32%. Hypoxia-driven sedimentary P recycling had a major impact on the water-column chemistry in the basin in 2012. Water-column monitoring data indicate up to ninefold higher surface water concentrations of phosphate in the basin in the late 1970s and a stronger hypoxia-driven seasonal P release from the sediment. The amplified release of P from the sediment in the past is attributed to the presence of a larger pool of Fe-bound P in the basin prior to the first onset of hypoxia. Given that P is not limiting, primary production in the basin has not been affected by the decadal changes in P availability and recycling over the past 40 years. The changes in P dynamics on decadal time scales were |
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