Microplastics as a Vector for HOC Bioaccumulation in Earthworm Eisenia fetida in Soil: Importance of Chemical Diffusion and Particle Size

Abstract

The role of microplastics as a carrier in the bioaccumulation of hydrophobic organic contaminants (HOCs) in soil organisms is poorly understood. Two environmentally relevant scenarios, including earthworm Eisenia fetida exposed to contaminated soil amended with clean microplastics (S1) and clean soil introduced with precontaminated microplastics (S2), were simulated to estimate the importance of microplastics in bioaccumulation. Three polychlorinated biphenyls and polyethylene particles with different sizes were employed. The microplastics under the S1 scenario significantly decreased the polychlorinated biphenyl congener (PCB) bioaccumulation, whereas for the S2 scenario, the PCBs on the microplastics can be assimilated by earthworms. Compared to plastic-free treatments, the freely dissolved concentrations (C free ) of PCBs were consistently lower in the soils amended with microplastics. Biodynamic model analysis suggested that the contribution of microplastic ingestion to bioaccumulation under the S2 scenario (mean 26.1%) was higher than that under S1 (8.7%), likely because of the slow chemical transfer between plastics and ambient media. These results indicated whether microplastics act as a source or a sink of HOCs depended strongly on the diffusion gradients between microplastics and soils. As ingestion of smallest particles (50−150 μm) showed the greatest contribution to bioaccumulation under S1 and S2 scenarios, the gradual breakdown of microplastics may increase their relative importance in contaminant transfer.

Effect of acetylated cellulose nanocrystals on solid‐state foaming behaviors of chain‐extended poly(butylene adipate‐co‐terephthalate)

“…PBAT, type Ecoflex F Blend C1200 (obtained from BASF) with a density of 1.25-1.27 g/cm 3 , melt flow index (MFI) of 2.5-4.5 (at 190 C, 2.16 kg), the weight-average molecular weight of 68 800 Da, and the melting range of 110-120 C, was used in this study. The multifunctional epoxy-based CE (ADR-4370s) was provided by BASF (Germany).…”

“…where ρ p and ρ f were the densities of CPBAT specimens before and after foaming in g/cm 3 , respectively.…”

“…Due to numerous benefits of plastic products including durability, light-weight, and cost-effective, their usage has increased by leaps and bounds. [1][2][3] Unfortunately, millions of tons of waste plastics leak into the marine environment through surface runoffs, rivers, and other ways annually. In recent years, microplastics (MPs) contamination has become a main cause of concern among scientists and the public.…”

Weight of Evidence for the Microplastic Vector Effect in the Context of Chemical Risk Assessment

“…Alternatively, the bias caused by testing chemical uptake from contaminated MP by clean organisms can be balanced by also testing the opposite treatment, i.e. by using (relatively) clean MP ingested by contaminated test organisms (Koelmans et al 2013b;Rummel et al 2016;Scopetani et al 2018;Wang et al 2020b). Studies that make an effort to use pre-equilibrated exposure media and organisms (e.g.…”

Microplastics’ journey into the gut : human exposure to microplastics and associated chemicals

“…A reduction in chemical bioavailability due to the chemical uptake by microplastics is still considered counterintuitive by many, yet, is in fact what thermodynamics predicts and has been shown now by several studies that chemical bioavailability can decrease depending on the conditions. 136,170,171 Although the sorptive capacity of LDPE was lower than micelles, LDPE was still a significant sink for the released PCBs from the digested olive oil triglycerides since the mass concentration of LDPE was two times higher than micelles in the scenario studied.…”