title: Sulphur partitioning in sediments and biodeposits below mussel rafts in the Ria de Arousa (Galicia, NW Spain).
abstract: Forty four core samples were analyzed to determine sediment particle size, total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen and total sulphur. Sequential extraction of S was also carried out, differentiating AVS (acid volatile sulphide), elemental S, organic S and pyrite S. The results obtained show that the presence of mussel rafts causes intense changes in the physicochemical composition and properties of the sea floor in the Ria de Arousa. The percentage of silt and clay, TOC, TIC and total N were significantly higher in the biodeposit than in the sediment. In contrast, there were no differences between the biodeposit and the sediment in terms of pH (8.0-8.7) and redox potential. The sediment and biodeposit were always anoxic, with values of redox potentials below -100 mV. In accordance with these conditions, the dominant fraction of S was pyrite S (FeS(2)). The AVS fraction and elemental S were present at low concentrations, except in the uppermost part of each core. Pyrite was relatively stable when the biodeposit and sediment were maintained in suspension for 8 days in oxic sea water; unlike the AVS fraction, which disappeared within a few hours.
authors.affiliation: Departamento de Edafoloxía e Química Agrícola, Facultade de Bioloxía, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain. edajax@usc.es
authors.forename: Xosé L
authors.initials: XL
authors.lastname: Otero
authors.forename: R M
authors.initials: RM
authors.lastname: Calvo de Anta
authors.forename: Felipe
authors.initials: F
authors.lastname: Macías
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017756:Aquaculture; D049872:Bivalvia / Q000254:growth & development*; D002244:Carbon / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis / Q000302:isolation & purification; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000032:analysis; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010316:Particle Size; D012623:Seawater; D013440:Sulfides / Q000032:analysis / Q000302:isolation & purification; D013455:Sulfur / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D013440:Sulfides; C011342:pyrite; D013455:Sulfur; D002244:Carbon; D006861:Hydrogen Peroxide; D007501:Iron; D009584:Nitrogen