Phosphorus cycling and burial in sediments of a seasonally hypoxic marine basin

Sulu-Gambari, Fatimah; Hagens, Mathilde; Behrends, Thilo; Seitaj, Dorina; Meysman, Filip J.R.; Middelburg, Jack; Slomp, Caroline P.

doi:10.1007/S12237-017-0324-0

Title

Phosphorus cycling and burial in sediments of a seasonally hypoxic marine basin

Author

Sulu-Gambari, Fatimah

Hagens, Mathilde

Behrends, Thilo

Seitaj, Dorina

Meysman, Filip J.R.

Middelburg, Jack

Slomp, Caroline P.

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 not recorded in sediment profiles of total P or organic C/total P.

Language

English

Source (journal)

Estuaries and coasts / Coastal and Estuarine Research Federation [Lawrence, Mass.] - Lawrence, Mass., 2006, currens

Publication

Lawrence, Mass. : Coastal and Estuarine Research Federation , 2018

ISSN

1559-2723 [print]

1559-2731 [online]

DOI

10.1007/S12237-017-0324-0

Volume/pages