Hernández-Almeida, Iván; Sierro, Francisco Javier; Filippelli, Gabriel M; Voelker, Antje H L; Diz, Paula: Sedimentary phosphorus components from IODP Site 306-U1314 [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.980480 (dataset in review)

Reactive (organic, P-Fe bound and authigenic) and detrital P phases from IODP Site 306-U1314 between 60-84.12 mcd, which correspond to ca. 779-1069 ka. The age model was previously published in Hernández-Almeida et al. (2012, doi:10.1029/2011PA002209) and it is made by aligning the benthic foraminifera δ18O record (mainly Cibicidoides wuellerstorfi and Melonis pompilioides) to the LR04 benthic stack (Lisiecki and Raymo, 2005; doi:10.1029/2004PA001071). Samples used in this study were recovered during International Ocean Drilling Program Expedition 306. Site U1314 was cored in the Gardar Drift on the eastern flank of the Reykjanes Ridge, in the subpolar North Atlantic. Sequential extractions to determine sedimentary P components were performed on a subset of 64 samples at 32-42 cm intervals using the procedure outlined by Filippelli and Delaney (1996, doi:10.1016/0016-7037(96)00042-7) after Ruttenberg (1992, doi:10.4319/lo.1992.37.7.1460), with the modification that adsorbed and iron-bound P were combined into one step, dithionite-extractable or oxide-associated P. The sequential extraction technique yields chemical information about the reactivity of phosphorus within sediments; the geochemical fractionation leads to the apportionment of phosphorus in several operationally-defined pools (Ruttenberg, 1992; Anderson and Delaney, 2000; doi:10.4319/lo.2000.45.2.0509). Reactive phosphorus pools, so-called because the phosphorus has the geochemical potential for release to the environment, include organic phosphorus, adsorbed and oxide-bound phosphorus, and authigenic-biogenic phosphorus. Approximately 1 g of dried and ground sample was weighed into new 15 mL polyethylene centrifuge tubes. Samples with reagents were shaken on an orbital shaker for the recommended amount of time depending on the protocol for each extraction step and then centrifuged for 10 min. All supernatants were decanted into acid cleaned polyethylene bottles, pooled, and saved for analysis. A Spectrophotometer, Shimadzu, UV-Vis-NIR Spectrophotometer at Indiana University was used for the determination of P concentrations for authigenic P, organic P, and detrital P (steps II-IV) from the sequential P extraction using the molybdate blue technique for color development (Strickland and Parson, 1975, hdl:10013/epic.46454.d001). Dithionite-extractable P (step I) concentrations were determined by ICP-AES. Each sample were measured at least twice for each of the P phases, being the reproducibility of all phases on average ±13 µg/g (1 SD).