Marine Litter and Plastic Waste (Macro- & Micro-plastics) in our Waterways and Shorelines

Background

 1          Plastics account for about 80% of litter found in the ocean [1]. Their persistence in the marine environment and potential harmful impact to marine ecosystems warrant a better understanding of the pathways of marine litter and microplastics in our waterways and shorelines.

2          Singapore views the issue of marine litter seriously and contributes to global and regional efforts to address marine litter. In June 2022, the Ministry of Sustainability and the Environment released Singapore’s National Action Strategy on Marine Litter (NASML), which outlined Singapore’s measures and actions to address this issue via six priority areas [2].

3          The NASML emphasises the importance of Research & Development, to ensure that Singapore’s response is supported by robust, science-based approaches. In 2016, a citizen science study was conducted by the National Parks Board (NParks) and the National University of Singapore (NUS) to establish baseline data on the amount and type of macro marine debris on Singapore’s shores. The NParks-NUS study, which was conducted between 2016 to 2019, found that over 90% of the marine litter found at six study sites along Singapore’s coastlines comprised plastic debris such as food packaging, plastic fragments and film. Given the high proportion of plastics in marine litter, the study emphasised the need to understand the extent of plastic pollution in Singapore’s environment and its impact on our coastlines. 

NEA’s Marine Litter and Microplastics Study

4          In 2021, NEA commissioned a Marine Litter and Microplastics Consultancy Study (or “Study”) to better understand the levels and pathways of macroplastics (plastic litter) and microplastics in Singapore’s inland waterways, coastal water, and recreational beaches [3]. The sampling programme was carried out at 16 rivers, 8 reservoirs, 9 marine water locations and 7 recreational beaches. The Study sought to build on the earlier NParks-NUS study in enhancing our understanding of the possible sources and pathways of the marine litter and microplastics found on Singapore’s shores.

5          The Study adopted a science-based sampling and testing methodology to identify the plastic polymer type, size and colour. The Study used the Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) [4]/ National Oceanic and Atmospheric Administration (NOAA) [5]-based definitions, classifying macroplastics as larger-sized plastic particles of diameter > 5mm, and microplastics as smaller fragments of diameter < 5mm [6]. Sampling was conducted monthly for a year to capture seasonal variations [7] at inland and coastal water bodies, as well as beaches, using standardised methods recommended by GESAMP and NOAA with a rigorous level of QA/QC. Microplastics collected under the Study were analysed using FTIR [8], a plastic polymer identification technology which has been used extensively in environmental microplastic research. The sampled plastics data, together with meteorological data, were used to inform a model, which simulated the plastic transport pathways and fate. More details on the study design, as well as the sampling and testing methodologies are provided in the Annex.

Key Findings

 6          This section outlines three key findings of the Study. First, the majority of macroplastics and microplastics found on Singapore’s recreational beaches originated from sea-based sources (e.g. ships, transboundary waste) rather than inland sources. Second, weather factors influenced the transport of plastic debris which eventually washed up on our shoreline. Third, the Study also identified the major plastic polymers found in microplastics found in Singapore.

Plastic Waste (Macro- and Micro-plastics) from Inland Waterways and on Shorelines

7          The Study found that only a small proportion of macroplastics (3%) and microplastics  [9] (0.25%) found at our recreational beaches originated from our major inland waterways (i.e. rivers, canals and reservoirs). This was based on modelling simulations of plastic behavior in the marine environment which incorporated meteorological data and environmental data collected from the 1-year sampling programme. This finding was further substantiated by the fact that over 90% of water samples collected at our river mouths recorded no macroplastics. This is attributable to the comprehensive waste collection system that Singapore has put in place and the litter traps installed in our waterways. Hence, it was found that a large proportion of the macroplastics and microplastics on Singapore’s recreational beaches originated from sea-based sources.

Weather Factors Influencing the Transport of Plastic Debris

8          Research has shown that bigger pieces of plastic debris tend to be dispersed much further from release sites as compared to smaller plastic fragments. Bigger pieces have larger exposed surface areas that allow surface winds to carry them over long distances. Conversely, smaller plastic fragments tend to be carried over shorter distances and settle more rapidly due to the smaller surface area which limits the impact of surface winds. However, these small plastic fragments (i.e. microplastics) could also be subjected to mechanical forces from wave and current action that could resuspend and carry them further out to sea.

9          Changing weather conditions (such as winds and marine currents during different monsoon and inter-monsoon seasons) also affect the amount of both macroplastics and microplastics, largely from sea-based sources, that wash ashore onto Singapore’s shorelines and recreational beaches.

10        The amounts of plastic debris collected from sampling surveys at recreational beaches at various times of the year (see Fig 2) indicate that during the Northeast (NE) monsoon (Dec - Mar) and inter-monsoon 2 (Oct – Nov) periods, the Northern recreational beaches show significantly higher levels of macroplastics and microplastics at more than 2.5 times the levels during the Southwest (SW) monsoon (Jun - Sep) and inter-monsoon 1 (Apr – May).

11        Similarly, at the Southern recreational beaches, macroplastic levels during the SW Monsoon and inter-monsoon 1 periods are 2 times those during the NE monsoon and inter-monsoon 2 periods. The data collected is consistent with fact that cleaning efforts along the beaches during SW and NE monsoons, as well as some portions of the prevailing inter-monsoon, have to be stepped up to cope with the larger amounts of debris. Currently, cleaning frequencies are increased from 4 times a week to twice a day during the SW and NE monsoons at the Southern and Northern beaches respectively. This study also found that macroplastics levels deposited at the Northern recreational beaches during Northeast monsoon were three times that of the Southern recreational beaches during Southwest monsoon, likely due to the larger and more open marine waters in the South of Singapore that enable better dispersal of plastic debris. Hence, monsoons have a significant impact on the macroplastic levels at the prevailing beaches during the respective monsoonal seasons, which can also be further influenced by geographical factors.

Dominant Plastic Polymers Associated with Microplastics

12        In terms of the microplastics polymer types, analysis revealed that they were predominantly those associated with post-consumer products. Polypropylene was the top plastic polymer identified, constituting 61 to 79% of microplastics across all sampled sites (see Fig. 3). Polypropylene is used in everyday consumer products such as food packaging (i.e. disposable bags, clear plastic food containers commonly used for takeaways, cups, bottle caps, soap and shampoo bottles), textiles/ropes, etc. The other polymers, namely polyethylene and acrylates, made up 4 to 14% and 8 to 11%, respectively. Plastic polymers such as polyamide, polyester and polyvinylchloride collectively comprised less than 8% of the microplastics sampled across inland and coastal waters, as well as beaches. This highlights that microplastics in our environment mainly originate from larger post-consumer plastic products.

Multi-Pronged Strategy to Manage Consumer Based Plastic Waste - Waste Management, Robust Cleaning Regime, Legislation and Education

13        The Study’s findings suggest that Singapore’s waste management, public cleaning and anti-littering efforts have contributed to minimising the amount of plastic debris and litter into our inland waterways and shorelines. This was evidenced by the low levels of macroplastics detected at our river outlets, underscoring the tangible impact of these initiatives.  

14        In addition, the substantial monsoonal influence of plastic debris along our beaches, as demonstrated in both NParks-NUS’s and NEA’s studies, affirms NEA’s existing approach of intensifying shoreline cleaning efforts during these seasons. 

15        The Study findings also suggest that the majority of the plastic litter that washes onto our shores was likely to be from sea-based sources such as ships and/or transboundary movement of plastic debris. Thus, this highlights the need for international and regional collaboration to comprehensively address this issue.

16        Noting the above, Singapore is doing its part to continue reducing land-based waste through legislation, enforcement and education. To encourage the upstream reduction and recycling of packaging waste, including plastics, we have put in place or will be implementing regulatory measures.  For example, businesses that place large amounts of packaging on the market are currently required to report packaging data as well as plans to reduce, reuse and recycle packaging. In addition, to reduce the use of disposable bags, the disposable carrier bag charge at supermarkets was implemented since 3 July 2023.  Singapore’s beverage container return scheme is also slated to be launched on 1 April 2026. The scheme will adopt an Extended Producer Responsibility approach to manage packaging waste and increase the recycling rate of beverage containers, including plastic drink bottles.  In addition, to raise awareness and promote actions by businesses and members of the public on reducing the use of disposables, NEA has also been running the nationwide Say YES to Waste Less (SYTWL) campaign annually since 2019.

Sustaining a Clean and Safe Environment - A Shared Responsibility

17        Our shared marine environment necessitates shared responsibility among countries to address the transboundary marine litter issue through practical and sustainable solutions. Singapore strongly supports regional and international efforts in this regard. At the ASEAN Working Group on Coastal and Marine Environment, we are working with ASEAN Member States on regional initiatives such as the ASEAN Regional Action Plan on Combatting Marine Debris in ASEAN Member States (2021-2025)  [11] and the Southeast Asia Regional Programme on Combating Marine Plastics (SEA-MaP).

18        Internationally, Singapore has also been contributing to initiatives undertaken by the United Nations Environment Programme (UNEP), G20 and International Maritime Organisation (IMO) to tackle the issue of marine debris and plastic pollution. These include sharing Singapore’s national strategies to address marine litter through the G20 Report on Actions against Marine Plastic Litter, and actively engaging in negotiations on the Intergovernmental Negotiating Committee to develop an International Legally Binding Instrument (ILBI) to end plastic pollution, including in the marine environment. Moreover, Singapore was among the first in Asia to ratify all six Annexes of the International Maritime Organization’s (IMO) International Convention for the Prevention of Pollution from Ships (MARPOL), the main international convention covering prevention of pollution of the marine environment by ships. MARPOL Annex V in particular prohibits the discharge of garbage, including all types of plastics, into the sea. In Singapore, MARPOL is implemented under the Prevention of Pollution of the Sea Act (PPSA) and its subsidiary legislation.

19        To achieve a meaningful and sustainable impact in preserving marine ecosystems, Singapore will continue actively contributing to coordinated efforts and partnerships in managing marine litter with partners, at regional and international levels.

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References:

[1] UNEP (2021) From Pollution to Solution: A global assessment of marine litter and plastic pollution.

Resource

Annex [PDF, 118.51 KB]