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Zinc incorporation in marine bivalve shells grown in mine-polluted seabed sediments: a case study in the Malfidano mining area (SW Sardinia, Italy)

DOI: 10.1007/s11356-018-3504-y DOI Help

Authors: Daniela Medas (University of Cagliari) , Ilaria Carlomagno (University of Roma Tre; Elettra-Sincrotrone Trieste) , Carlo Meneghini (University of Roma Tre,) , Giuliana Aquilanti (Elettra-Sincrotrone Trieste) , Tohru Araki (Diamond Light Source) , Diana Bedolla (Elettra-Sincrotrone Trieste) , Carla Buosi (University of Cagliari) , Maria Antonietta Casu (UOS of Cagliari) , Alessandra Gianoncelli (Elettra-Sincrotrone Trieste) , Andrei C. Kuncser (National Institute of Materials Physics) , V. Adrian Maraloiu (National Institute of Materials Physics) , Giovanni De Giudici (University of Cagliari)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Environmental Science And Pollution Research , VOL 209

State: Published (Approved)
Published: October 2018
Diamond Proposal Number(s): 16496

Abstract: Zinc incorporation into marine bivalve shells belonging to different genera (Donax, Glycymeris, Lentidium, and Chamelea) grown in mine-polluted seabed sediments (Zn up to 1% w/w) was investigated using x-ray diffraction (XRD), chemical analysis, soft x-ray microscopy combined with low-energy x-ray fluorescence (XRF) mapping, x-ray absorption spectroscopy (XAS), and transmission electron microscopy (TEM). These bivalves grew their shells, producing aragonite as the main biomineral and they were able to incorporate up to 2.0–80 mg/kg of Zn, 5.4–60 mg/kg of Fe and 0.5–4.5 mg/kg of Mn. X-ray absorption near edge structure (XANES) analysis revealed that for all the investigated genera, Zn occurred as independent Zn mineral phases, i.e., it was not incorporated or adsorbed into the aragonitic lattice. Overall, our results indicated that Zn coordination environment depends on the amount of incorporated Zn. Zn phosphate was the most abundant species in Donax and Lentidium genera, whereas, Chamelea shells, characterized by the highest Zn concentrations, showed the prevalence of Zn-cysteine species (up to 56% of total speciation). Other Zn coordination species found in the investigated samples were Zn hydrate carbonate (hydrozincite) and Zn phosphate. On the basis of the coordination environments, it was deduced that bivalves have developed different biogeochemical mechanisms to regulate Zn content and its chemical speciation and that cysteine plays an important role as an active part of detoxification mechanism. This work represents a step forward for understanding bivalve biomineralization and its significance for environmental monitoring and paleoreconstruction.

Journal Keywords: Bivalve; Biomineralization; Detoxification; Synchrotron x-ray techniques; Trace metals; Zinc

Subject Areas: Biology and Bio-materials, Environment

Instruments: I08-Scanning X-ray Microscopy beamline (SXM)