Mobilisation of antimony from microplastics added to coastal sediment

• Published in: Environmental pollution (1987) Vol. 264; p. 114696
• Main Authors: James, Elanor, Turner, Andrew
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.09.2020
• Subjects: Antimony; Bioaccessibility; bioaccumulation; bioavailability; bioturbation; bovine serum albumin; coastal sediments; color; Contamination; Deposit-feeders; digestion; equations; estuaries; flame retardants; Kinetics; Microplastics; polyethylene; rubber; seawater; styrene; surfactants; taurocholic acid; toxicity; Deposit-feeders; Antimony; Bioaccessibility; Microplastics; Kinetics; Contamination
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2020.114696

Antimony (Sb) widely occurs in plastics as a pigment and reaction residue and through the use and recycling of electronic material enriched in Sb as a flame retardant synergist. In this study, clean estuarine sediment has been contaminated by different microplastics prepared from pre-characterised samples of different types of plastic (including a rubber) containing a range of Sb concentrations (256–47,600 μg g−1). Sediment-plastic mixtures in a mass ratio of 100:1 were subject to 6-h extractions in seawater and in seawater solutions of a protein (bovine serum albumin; BSA) and a surfactant (taurocholic acid; TA) that mimic the digestive conditions of coastal deposit-feeding invertebrates. Most time-courses for Sb mobilisation could be defined by a second-order diffusion equation, with rate constants ranging from 44.6 to 0.0216 (μg g−1)−1 min−1. Bioaccessibilities, defined as maximum extractable concentrations throughout each time course relative to total Sb content, ranged from <0.01% for a polycarbonate impregnated with Sb as a synergist exposed to all solutions, to >1% for acrylonitrile butadiene styrene containing a Sb-based colour pigment exposed to solutions of BSA and TA and recycled industrial polyethylene exposed to BSA solution. The potential for Sb to bioaccumulate or elicit a toxic effect is unknown but it is predicted that communities of deposit-feeders could mobilise significant quantities of Sb in sediment contaminated by microplastics through bioturbation and digestion. [Display omitted] •Plastics containing antimony were micronized and added to estuarine sediment.•The mobility of Sb was studied in seawater and solutions of a protein and a surfactant.•Mobilisation kinetics usually conformed to a second-order diffusion model.•Mobilisation ranged from <0.1% to >1% depending on the plastic and solution.•Sb could be mobilised via digestion and bioturbation of sediment by deposit-feeders. Antimony is mobilised from plastics added to sediment by seawater and solutions of a protein and a surfactant via a diffusion model.