Projected plastic waste loss scenarios between 2000 and 2030 into the largest freshwater-lake system in Southeast Asia

Alexander Matthew David Finnegan,Christos Gouramanis

doi:10.1038/s41598-021-83064-9

Alexander Matthew David Finnegan, Christos Gouramanis

Open Access

https://doi.org/10.1038/s41598-021-83064-9

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Abstract

Freshwater plastic pollution is critically understudied in Southeast Asia (SEA). Recent modelling studies indicate that SEA rivers contribute vast quantities of plastic to the world’s oceans, however, these fail to capture the complexity of individual systems. We determine the volume of mismanaged plastic waste (MPW) entering Tonle Sap Basin (TSB)—the largest freshwater lake–river system in SEA, between 2000 and 2030. Using economic, population and waste data at provincial and national levels, coupled with high resolution population and flood datasets, we estimate that ca. 221,700 tons of plastic entered between 2000 and 2020, and 282,300 ± 8700 tons will enter between 2021 and 2030. We demonstrate that policy interventions can reduce MPW up to 76% between 2021 and 2030. The most-stringent scenario would prevent 99% of annual MPW losses by 2030, despite substantially higher waste volumes and population. If successfully implemented, Cambodia will prevent significant losses in natural capital, material value and degradation in TSB worth at least US$4.8 billion, with additional benefits for the Mekong River and South China Sea.

Highlights

Freshwater plastic pollution is critically understudied in Southeast Asia (SEA)
By 2030, under a Business As Usual (BAU) Scenario, we estimate that 34,392 tons year−1 will enter Tonle Sap Basin (TSB) equating to an additional ca. 282,300 ± 8700 tons between 2021 and 2030 (Fig. 2)
The annual mismanaged plastic waste (MPW) losses into TSB from 2000 to 2018 follows the trend in Cambodian economic growth and development as the nation emerged from civil war, inclusion into the World Trade Organization (WTO) and associated influx of foreign investment and goods to the present

Summary

Introduction

Freshwater plastic pollution is critically understudied in Southeast Asia (SEA). Recent modelling studies indicate that SEA rivers contribute vast quantities of plastic to the world’s oceans, these fail to capture the complexity of individual systems. Recent global modelling studies of riverine plastic pollution transported to the world’s oceans have demonstrated that SEA rivers contribute some of the highest quantities of plastic from continental interiors[18,19] Whilst these studies have been successful in producing large datasets, and identifying rivers or regions for further examination, the uniform approach used for global aquatic systems have failed to capture the complexities of individual systems. This would imply that a higher degree of accuracy in the global estimates of plastic losses could be achieved if key sites were examined in detail.

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