Polymer-Specific Modeling of the Environmental Emissions of Seven Commodity Plastics As Macro- and Microplastics

Abstract

Plastic has been identified as an emerging contaminant in aquatic and terrestrial ecosystems. Uncertainties remain concerning the amounts present in the environment and the main responsible sources. In this study, the emissions of macro- and microplastics have been mapped for seven polymers in Switzerland. The modeling is based on a complete analysis of the flows from production and use to end-of-life using probabilistic material flow analysis. We estimate that 94 ± 34 g/capita/year of low-density polyethylene, 98 ± 50 g/cap/a of high-density polyethylene, 126 ± 43 g/cap/a of polypropylene, 24 ± 13 g/cap/a of polystyrene, 16 ± 12 g/cap/a of expanded polystyrene, 65 ± 36 g/cap/a of polyvinyl chloride, and 200 ± 120 g/cap/a of polyethylene terephthalate enter the Swiss environment. All polymers combined, 540 ± 140 and 73 ± 14 g/cap/a are emitted into soil as macroplastics and microplastics, respectively, and 13.3 ± 4.9 and 1.8 ± 1.1 g/cap/a are emitted into freshwater as macroplastics and microplastics, respectively. The leading emission pathway is littering for both terrestrial and aquatic environments. Construction, agriculture, and pre- and postconsumer processes cause important emissions of microplastics into soils, and postconsumer processes, textiles, and personal care products release most of the microplastics into waters. Because mass flows into soils are predicted to be 40 times larger than those into waters, more attention should be placed on this compartment. Our work also highlights the importance of referring to specific polymers instead of just “plastics”.

The Way of Macroplastic through the Environment

“…The exact amount of litter that is released into the environment each year is difficult to determine. Estimations are around 1.3-3.5 kg per capita for Germany [62] or 540 g ± 140 g per capita for soil and 13.3 g ± 4.9 g per capita for freshwater in Switzerland [28]. Using the conservative value estimated for Switzerland, an extrapolation to the world population of 7.59 billion people results in an annual plastic input via littering of 4.2 Mt.…”

“…As a comparison, Ryberg et al (2019) [52] calculated the amount of annual littering entering the environment at 0.8 Mt. A large share of the littered plastic are PET bottles [28] and cigarette butts. Cigarette butts, mostly consisting of the polymer cellulose acetate (CA), are declared as the most common waste item, and it is assumed that 4.5 trillion cigarette butts are released into the environment each year worldwide.…”

“…In Germany, this waste stream is estimated at 3000 t annually [62]. For MaP, discharge from WWTP into the environment is possible via storm water overflow tanks in the combined system [28] or via stormwater tanks, which have an overflow, in the separation system [70]. As no data are available on the input of MaP into wastewater or the quantity of stormwater discharged, a quantification of MaP entering the environment via sewage is not yet possible.…”

“…Definition Macroplastic. While the size of microplastic is defined as particles with a diameter < 5 mm [26], MaP is commonly defined in distinction to microplastics as items with a diameter ≥ 5 mm [6,[27][28][29]. However, both size classifications are not internationally standardised.…”

Microplastics in Soils and Sediment: Sources, Methodologies, and Interactions with Microorganisms

“…Certain terrestrial environments are highly contaminated by microplastic pollution, those highly subject to plastic garbage or in close proximity to other plastic waste conduits (Blasing and Amelung 2018;Su et al 2020). Major sources of microplastics on land include plastic mulching film (Liu et al 2014), urban waste (Kole et al 2017), wastewater treatment sludge (Gatidou et al 2019), road and tire debris (Siegfried et al 2017;Nizzetto et al 2016), construction sites (Kawecki and Nowack 2019), artificial turf deterioration (Li 2019), and single use plastic products (Efimova et al 2018), among others. The microplastic pollution that comes from wastewater generated by residential and business communities contains heavy loads of synthetic microfibers, the most abundant type of microplastic in wastewaters (Okoffo et al 2019).…”