TY - JOUR

T1 - Phosphorus mobilization in sulfidic sediments in the Baltic Sea

AU - Zhou, C.

AU - Gao, Y.

AU - Zhang, H.

AU - Luo, M.

AU - Ma, T.

AU - Li, G.

AU - Vandeputte, D.

AU - Leermakers, M.

AU - Baeyens, W.

PY - 2024/1/10

Y1 - 2024/1/10

N2 - It is well-known that the geochemical behavior of phosphorus (P) in sediments is closely related to that of Fe and Mn, but their relations remain unclear in long-term sulfidic sediments such as those of the Gotland Basin in the Baltic Sea. Therefore, P mobilization in these sediments at both shallow and deep sites was investigated in relation to that of Fe, Mn, and S. To achieve that aim, classic sediment slicing and subsequent solid phase sequential extraction were combined with in situ DGT (Diffusive Gradients in Thin-films) sampling, DIFS (DGT induced flux in sediments) modelling, and Visual MINTEQ calculations. Correlations between total dissolved and labile dissolved concentrations of P, Mn, and Fe in porewater, and the associations between labile fractions of these elements in the solid phase suggested two kinds of sources for P: The dissolution of P-bearing Fe oxides and/or Mn carbonates was observed in the shallower sites, while P and Mn release from different solid sources was observed in the deepest sites. Although the formation of Fe sulfides leads to extremely low dissolved Fe level in porewater, the simultaneous release of P with Mn/Fe was confirmed by theoretical calculations with Visual MINTEQ. The DIFS model showed that the resupply ability of P from sediment solids is determined by labile pool size. The application of experimental and theoretical methods made it possible to clarify the relationships between P, Fe, Mn and S in sulfidic sediments which may contribute to a better understanding of the P cycle in other sulfidic regions.

AB - It is well-known that the geochemical behavior of phosphorus (P) in sediments is closely related to that of Fe and Mn, but their relations remain unclear in long-term sulfidic sediments such as those of the Gotland Basin in the Baltic Sea. Therefore, P mobilization in these sediments at both shallow and deep sites was investigated in relation to that of Fe, Mn, and S. To achieve that aim, classic sediment slicing and subsequent solid phase sequential extraction were combined with in situ DGT (Diffusive Gradients in Thin-films) sampling, DIFS (DGT induced flux in sediments) modelling, and Visual MINTEQ calculations. Correlations between total dissolved and labile dissolved concentrations of P, Mn, and Fe in porewater, and the associations between labile fractions of these elements in the solid phase suggested two kinds of sources for P: The dissolution of P-bearing Fe oxides and/or Mn carbonates was observed in the shallower sites, while P and Mn release from different solid sources was observed in the deepest sites. Although the formation of Fe sulfides leads to extremely low dissolved Fe level in porewater, the simultaneous release of P with Mn/Fe was confirmed by theoretical calculations with Visual MINTEQ. The DIFS model showed that the resupply ability of P from sediment solids is determined by labile pool size. The application of experimental and theoretical methods made it possible to clarify the relationships between P, Fe, Mn and S in sulfidic sediments which may contribute to a better understanding of the P cycle in other sulfidic regions.

KW - Authigenic P minerals

KW - DGT technique

KW - P-bearing solids

KW - Phosphorus mobilization

KW - Resupply kinetics

KW - Sulfidic sediments

KW - Dissolution

KW - Iron oxides

KW - Sulfur compounds

KW - Authigenic

KW - Authigenic P mineral

KW - Diffusive gradients in thin film techniques

KW - Mobilisation

KW - P-bearing solid

KW - Resupply

KW - Resupply kinetic

KW - Solid phasis

KW - Sediments

U2 - 10.1016/j.scitotenv.2023.168000

DO - 10.1016/j.scitotenv.2023.168000

M3 - Journal article

VL - 907

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

M1 - 168000

ER -