Occurrence of organic pollutants in plastics on beach: Stranded foams can be sources of pollutants in islands

Highlights

• High levels of PBDEs and OPEs were detected in stranded foams.

• TCEP and TPHP were the main chemicals in foams in most cases.

• OPEs can be additives and adsorbed chemicals on the surface of foams.

• Density of pollutants brought by stranded foams to the island was estimated.

Abstract

Increasing amount of plastic debris stranded on beach can introduce many foreign substances, including organic pollutants into island ecosystems. In the present study, stranded foams were collected from an island located in South China Sea, to investigate the levels and profiles of several flame retardants (FRs) and plasticizers, including polybrominated diphenyl ethers (PBDEs), organophosphate esters (OPEs), emerging brominated FRs, and dechlorane plus (DP). The concentrations of PBDEs and OPEs in plastic debris ranged from not detected (ND, <0.60 ng/g) to 0.46 mg/g and from ND (<0.70 ng/g) to 17.3 mg/g, respectively. The high levels of PBDEs and OPEs were expected as the fact that PBDEs and OPEs were incorporated additives in plastics. OPEs were the main chemicals in most of foams. Brominated FRs dominated in some samples. Core and surface parts in foams had similar composition profiles of pollutants. Significantly higher concentrations of tris(2-chloroethyl) phosphate (TCEP) and triphenyl phosphate (TPHP) were observed in surface samples than core samples (p < .05). TCEP and TPHP in foam surface seem to be from both incorporated additives and adsorbed chemicals from environmental matrices. The density of pollutants introduced by stranded foams in sampling area was estimated in comparison with air deposition of pollutants. The high loading of pollutants in stranded foams indicates that foams can be potential sources for organic pollutants, especially incorporated plastic additives, in islands.

Introduction

In recent years, with the development of the plastic industry, an increasing attention has been addressed to the environmental plastic pollution (Camacho et al., 2019). It was estimated that plastic wastes accounted for 10% of the world's municipal waste and 50–80% of the marine environment waste (Barnes et al., 2009; Zarfl and Matthies, 2010). Meanwhile, the amount of plastics moving from land to sea is thought to be still increasing (Jambeck et al., 2015). About 275 million tons of plastic wastes were generated in 192 coastal countries in 2010, and 4.8 to 12.7 million tons of plastics were entering the ocean (Jambeck et al., 2015) making the marine plastic pollution an important issue of concern.

Organic pollutants can be adsorbed on surface of plastics or be added to plastics as additives (Zarfl and Matthies, 2010). Plastic debris has a relatively large ratio of surface area to volume (Zhang et al., 2015). Therefore, they can be important carrier of pollutants, which were previously adsorbed from environmental matrices (Mato et al., 2001). Many studies have confirmed that plastics were traps for persistent organic pollutants (POPs) (Camacho et al., 2019; Endo et al., 2005; Heskett et al., 2012; Le et al., 2016; Rios et al., 2007; Turner and Holmes, 2011; van der Veen and de Boer, 2012). Some plastic additives, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and short-chain chlorinated paraffins (SCCPs), were POPs with properties of persistence, bioaccumulation, and toxicity (UNEP, 2009). Organophosphate esters (OPEs) are emerging flame retardants (FRs) and plasticizers (Wang et al., 2015). It was reported that elevated exposure to OPEs had adverse effects on humans (Saboori et al., 1991; Umezu et al., 1998). Meanwhile, halogenated flame retardants (HFRs) have been widely detected in recycled plastics, which caused non-negligible exposure risk to humans (Cao et al., 2019). It was estimated that non-fiber plastics contained an average of 7% additives by mass (Geyer et al., 2017). For instance, triphenyl phosphate (TPHP) was added in plastic materials used in computer video display units at 0.3 to 10% of mass (Carlsson et al., 1997). PBDEs were added in plastics used in television at 10.3 to 19.1% by weight (Allen et al., 2008). Up to 12.5% of tris(1,3-dichloropropyl) phosphate (TDCPP) by mass was added into baby plastic products (Stapleton et al., 2011). Plastic debris in environment may serve as important sources of additive-derived pollutants. However, little attention has been paid in tracing adsorbed and additive-derived pollutants in discarded plastic debris.

Islands play an important role in preserving biodiversity. Islands cover <5% of the global terrestrial area, but are home to >20% of the world's terrestrial plant and vertebrate species (Courchamp et al., 2014). However, biodiversity in island ecosystems is also threatened by organic pollutants. Human activities were important sources of pollutants in soil proximate to a research station in Antarctic (Cabrerizo et al., 2012). PBDEs were detected in soil and could be further accumulated by plants in Ny-Ålesund and London Island, Svalbard, the Arctic (Zhu et al., 2015). The Azotobacter population in soil had fallen by 51.8% in Andaman Islands, India, which was attributed to pesticide residues (Murugan et al., 2013). It was reported that plastics accumulated at a rapid rate of averaging 484 pieces/day on the beach (Cooper and Corcoran, 2010; Theodore and Merrell, 1980). Stranded plastics on beach can bring various foreign substances to islands. Plastics in ocean carry exotic species, for instance, bryozoans, barnacles and polychaete worms which may damage the island ecosystem (Barnes, 2002). In addition, plastic debris are also carriers of adsorbed or incorporated organic pollutants. In the present study, the levels and compositions of several FRs and plasticizers were studied in stranded plastics from an island in South China Sea. The loading of pollutants in plastics were estimated to give a preliminary view on the input of pollutants from plastics to islands.