Basten Gokkon, Jakarta – Uncontrolled burning of plastic waste on Indonesian beaches has given rise to plastic-rock hybrids that deposit in and may pollute coastal ecosystems and fisheries, a new study has found.
Molten plastic mixed with natural and artificial debris, known as plastiglomerate, and other new forms of plastic pollution were found on an island beach in Indonesia's Java Sea, a group of Indonesian and German researchers reported in their recently published paper in the journal Scientific Reports. Lead author Dwi Amanda Utami, a geologist at Indonesia's National Research and Innovation Agency, said these new types of plastic pollution could contribute to the chemical contamination of nearby coastal habitats such as coral reefs, seagrass meadows, and mangroves.
"We know that Indonesia is famous for being the second-largest plastic waste contributor in the world, especially for plastic debris that leaks into the ocean from land-based sources," Dwi told Mongabay in a phone interview.
Meanwhile, burning garbage on the beach is a common practice in the country, done for reasons ranging from keeping warm to serving as a quick solution to eradicating fishing and tourism waste where incineration facilities are unavailable, Dwi said. After the plastic debris melts, it reconsolidates with natural components on the beach, such as coral fragments, sand or dry leaves, to create "Frankenrock" hybrids: plastiglomerates, which are a meld of plastic, beach sand, pebbles, corals and shells; pyroplastics, which are plastic clumps that have been weathered down by the elements to resemble beach pebbles; and plasticrusts, a layer of plastic blanketing rocky coastal surfaces.
Dwi said coastal plastic debris typically disintegrates over time into smaller fragments and even microplastics due to exposure to sunlight, rain and waves, but burning has expedited that process and likely released new pollutants that could be carcinogenic.
"It's concerning when a marine biota eats these microplastics and it is later consumed by humans. The concern is that it might cause health problems to humans," she said.
Study co-author Lorenz Schwark, a geochemist at Kiel University in Germany, said in a statement that, "To better assess environmental damage, we are currently researching the exact composition of the organic pollutants associated with the plastic, such as organophosphorus compounds."
Dwi, Schwark and their colleagues collected 25 of these plastic-rock samples from beaches on Panjang Island on the western side of Java Island and analyzed them in a laboratory. Dwi said this was the most robust sampling for research on plastiglomerates done to date. Previous studies have been carried out in places like Aves Island in India's Andaman archipelago, but more samples from other islands are needed important to better understand the full extent of this microplastic pollution in the ocean, Dwi said.
"None of the previous research from all over the world had sampled that much just from one site, and my research site was only on the northern part of Panjang Island, not the whole island, so this is just a small part," she said. "I'm sure other places must have burned plastics that have formed into artificial rocks, but since this is still a new research topic, there's still much that can be developed and found."
Plastic waste in the ocean negatively affects the marine ecosystem as sea creatures like whales, turtles and fish mistake floating plastic waste for food, swallowing material they can't digest. The plastic accumulates in their bodies over their lifetime, killing them or working their way up the food chain and eventually circling back to humans.
Proper management of plastic waste is lacking in coastal communities across Indonesia, an archipelago of some 17,000 islands, according to a 2020 study. It also noted that the use of plastic was increasingly outpacing mitigation efforts. Waste in most coastal communities doesn't end up in a landfill or anywhere near a recycling facility, the study found. In fact, an average 2 metric tons of plastic waste per week might end up in the ocean from just a single village. Residents burn their waste or dump it, either directly into the sea or in piles that can be washed away in heavy rains, the study found.
Indonesia produces about 6.8 million metric tons of plastic waste annually, according to a 2017 survey by the Indonesia National Plastic Action Partnership. Only 10% of that waste was recycled in the 1,300 recycling centers operating across the country, while nearly the same amount, about 620,000 metric tons, wound up in the ocean.
"Compared to normal plastic waste, the unique properties of Plastiglomerates require a specific form of coastal management," Dwi said in the statement from the authors. "If trash from urban areas on tropical beaches were better disposed of and managed, a serious problem could be prevented."
Indonesia plans to reduce that figure by 70% by 2025. Beach cleanups are among the popular measures being carried out in the country. Local governments are also implementing efforts to reduce the consumption of single-use plastics, including outright bans, while the private sector is investing in sustainable alternatives. The national government also plans to make producers take greater responsibility for the waste generated by their products.
"I think this plastic waste problem is very massive and encompasses from upstream to downstream," Dwi said. "There will be more new findings about plastic waste both macro and micro. Nowadays, the good thing is both the government and society are aware of the danger from plastics and are trying to reduce single-use plastics."
Utami, D. A., Reuning, L., Schwark, L., Friedrichs, G., Dittmer, L., Nurhidayati, A. U., ... Cahyarini, S. Y. (2023). Plastiglomerates from uncontrolled burning of plastic waste on Indonesian beaches contain high contents of organic pollutants. Scientific Reports, 13(1). doi:10.1038/s41598-023-37594-z
Corcoran, P. L., Moore, C. J., & Jazvac, K. (2014). An anthropogenic marker horizon in the future rock record. GSA Today, 24(6), 4-8. doi:10.1130/gsat-g198a.1
Turner, A., Wallerstein, C., Arnold, R., & Webb, D. (2019). Marine pollution from pyroplastics. Science of The Total Environment, 694, 133610. doi:10.1016/j.scitotenv.2019.133610
Gestoso, I., Cacabelos, E., Ramalhosa, P., & Canning-Clode, J. (2019). Plasticrusts: A new potential threat in the Anthropocene's rocky shores. Science of The Total Environment, 687, 413-415. doi:10.1016/j.scitotenv.2019.06.123
Phelan, A., Ross, H., Setianto, N. A., Fielding, K., & Pradipta, L. (2020). Ocean plastic crisis – Mental models of plastic pollution from remote Indonesian coastal communities. PLOS ONE, 15(7), e0236149. doi:10.1371/journal.pone.0236149