Plastiglomerates from uncontrolled burning of plastic waste on Indonesian beaches contain high contents of organic pollutants

Abstract

This study reports on plastiglomerate and other new forms of plastic pollution in the tropical marine continent of Indonesia. Twenty-five samples were collected from an island beach in the Java Sea where plastiglomerate, plasticrusts, and pyroplastic were formed by the uncontrolled burning of plastic waste. The most common plastic types were polyethylene and polypropylene (PE/PP), as shown by ATR-FTIR spectroscopy. However, acrylates/polyurethane/varnish (PU) and a copolymer of styrene and acrylonitrile were found as well. This suggests that plastiglomerates can form from a wider variety of plastic polymers than previously reported. FTIR analysis also indicates thermo-oxidative weathering, making the charred plastic more brittle and susceptible to microplastic formation. A subset of the samples was analyzed for associated chemical contaminants. One plastiglomerate with a PU matrix showed high concentrations of phthalates. All samples had high concentrations of polycyclic aromatic hydrocarbons (PAHs), likely due to the burning of the plastic in open fires. The burning leads to a change in the physical and chemical properties of the plastics contained in the plastiglomerates. Plastiglomerate and plastic waste of similar origin are therefore often more weathered and contaminated with organic pollutants than their parent polymers. The highest PAH concentration was found in a plastitar sample. Plastitar is defined as an agglomerate of tar and plastics that adheres to coastal rocks. In contrast, our study documents a more mobile, clastic plastitar type. This clastic plastitar could pose an additional ecological risk because of its mobility. These new types of plastic pollution could be an important vector for chemical contamination of nearby coastal habitats such as coral reefs, seagrass meadows, and mangroves.

Plastitar records in marine coastal environments worldwide from 1973 to 2023

“…This observation supports the notion that plastitar derives from tanker-released oil (Domıńguez-Hernańdez et al, 2022) and suggests that plastitar may, to some extent, contain ship-released plastic (Vauk and Schrey, 1987;Unger and Harisson, 2016). Oil is also transported across the Adriatic Sea (Liubartseva et al, 2023) and extracted in the Java Sea (Setiawan et al, 2017) suggesting that the nearby plastitar records in Croatia (Fajkovićet al, 2020) and Indonesia (Utami et al, 2023) could derive from these oil sources. To further examine potential links between plastitar and tanker-released oil, it would be interesting to compare beached plasto-tarball samples and benthic plasto-tar crust samples with pelagic tanker-released oil and tarball samples.…”

“…To further examine potential links between plastitar and tanker-released oil, it would be interesting to compare beached plasto-tarball samples and benthic plasto-tar crust samples with pelagic tanker-released oil and tarball samples. Furthermore, our map shows that almost all plastitar records (except Utami et al, 2023) were made in the northern hemisphere (Figure 3). Yet, pelagic tarballs have repeatedly been reported off the South African coast (Eagle et al, 1979;Shannon and Chapman, 1983a;Shannon and Chapman, 1983b;Shannon et al, 1983) along which oil is transported (Figure 3).…”

“…In 2020, beached plasto-tarballs (aggregations of plastic debris, pellets and fragments with tarballs) were collected on Z ̌irje island, Croatian Adriatic Sea coast (Fajkovićet al, 2020). Very recently, a single non-floating tar matrix containing a plastic cap, sand, leaves, coral and shell fragments was reported as plastitar on Panjang island, Indonesian Java Sea coast (Utami et al, 2023) and plastitar encrusting coastal rocks was detected in Italy (Adriatic and Ligurian Sea), Cabrera island, Menorca island and Sardinia island (western Mediterranean Sea; Saliu et al, 2023; Table S1).…”

“…Interestingly, plotting all plastitar records (Table S1) in a global map showed that most plastitar records (except Fajkovićet al, 2020 andUtami et al, 2023) were made along the major oil transportation routes (Figure 3). This observation supports the notion that plastitar derives from tanker-released oil (Domıńguez-Hernańdez et al, 2022) and suggests that plastitar may, to some extent, contain ship-released plastic (Vauk and Schrey, 1987;Unger and Harisson, 2016).…”