title: Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis.
abstract: Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) >80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20±0.13 to (0.30±0.56)×10(3) mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (<25%) while degrees of sulfidization (DOS) were high (~50%) because of the contribution of acid volatile sulfide. DOP values correlated with DTMP values (p≤0.001), indicating that metals are gradually incorporated into pyrite as this mineral is formed. Significant correlations were also found between DTMP values and -log(Ksp(MeS)/Ksp(pyr)) for both harbors, indicating that incorporation of trace metals into the pyrite phase is a function of the solubility product of the corresponding metal sulfide. The order in which elements were pyritized in both harbors was Zn≈Mn<Fe<Cd≈Pb<Ni≈Co<<Cu. Lastly, a strong correlation (r(2)=0.87, p<0.01) was found between average reactive trace metal concentrations and metal concentrations measured in Armandia brevis (a deposit-feeding Opheliid polychaete), suggesting that these labile sedimentary metals are preferentially accumulated by the polychaete, making it a useful biomonitor of sedimentary metal exposure.
authors.affiliation: Department of Analytical Chemistry, Institute of Biomolecules (INBIO), Faculty of Sciences, CEI-MAR, University of Cadiz, Campus Rio S. Pedro, E-11510, Puerto Real, Cadiz, Spain.
authors.forename: Margarita
authors.initials: M
authors.lastname: Díaz-de-Alba
authors.affiliation: Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California, Mexico. Electronic address: huertam@uabc.edu.mx.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Huerta-Diaz
authors.affiliation: Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California, Mexico.
authors.forename: Francisco
authors.initials: F
authors.lastname: Delgadillo-Hinojosa
authors.affiliation: Centre Eau Terre Environnement, 490, rue de la Couronne, Québec, Québec G1K 9A9, Canada.
authors.forename: Landis
authors.initials: L
authors.lastname: Hare
authors.affiliation: Department of Analytical Chemistry, Institute of Biomolecules (INBIO), Faculty of Sciences, CEI-MAR, University of Cadiz, Campus Rio S. Pedro, E-11510, Puerto Real, Cadiz, Spain.
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Galindo-Riaño
authors.affiliation: Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Campus Ensenada, Km. 103 Carr. Tijuana-Ensenada, Ensenada 22800, Baja California, Mexico.
authors.forename: Arturo
authors.initials: A
authors.lastname: Siqueiros-Valencia
mesh_terms: D000818:Animals; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D019216:Metals, Heavy / Q000032:analysis*; D008800:Mexico; D008903:Minerals; D011077:Polychaeta / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D019216:Metals, Heavy; D008903:Minerals; D014874:Water Pollutants, Chemical
keywords: Armandia brevis; Pyrite; Sediment contamination; Speciation; Trace metal