Sources and Pathways of Marine Litter: A Global Assessment of Plastic Pollution in Coastal and Island Regions

Introduction

In just over a century, plastic has gone from being hailed as a “scientific wonder” to becoming an “environmental scourge” (Plummer, 2018). In fact, the social and economic benefits associated with plastic materials made them so popular that they have been documented in the most remote corners of the planet (Andrady & Neal, 2009; Thompson et al., 2009). Plastic pollution is defined as the totality of plastic accumulation in the environment, as well as the ecological impacts associated with its production, consumption, mismanagement, and emissions related to end-of-life practices (Nielsen et al., 2020). The scale of plastic pollution is striking, causing US$75 billion social and environmental costs every year (UNEP, 2014a). It has been estimated that over 8 million metric tons of plastics enter our oceans every year (Jambeck et al., 2015), and this flow is expected to nearly triple by 2040 (The Pew Charitable Trust & SYSTEMIQ, 2020), with tremendous consequences for the subsistence of marine life (Derraik, 2002).

A growing body of research has reported that plastic litter is one of the most serious threats to the underwater world, making the study of marine plastic pollution a key priority (Li et al., 2016). However, our knowledge of the magnitude and distribution of plastic pollution in the planet’s oceans is relatively new and there is still much uncertainty about the sources and pathways of marine pollution (Thompson et al., 2004; Cózar et al. 2014). This is due to the difficulties in assessing provenience (the geographic origin of the debris and the sector that is primary responsible for its release), means of release (the mechanisms by which the debris enters the marine environment), and entry points (where the release occurred) of plastic debris (Veiga et al., 2016). To bridge these gaps, existing assessment frameworks consider the annual amount of mismanaged plastic waste produced by coastal populations. In fact, it has been estimated that plastics consumed within a 50 km distance from the coast are at “high risk of entering the ocean” via direct littering, inland waterways, wastewaters, or transported by wind and tides (Jambeck et al., 2015).

This chapter explores the most common sources and pathways of plastic pollution in coastal and island regions, where mismanaged plastic waste is at the highest risk of becoming marine pollution, and it provides tangible implications and solutions to detect plastics in these areas. Coastal environments suffer particularly from plastic pollution, as they host hotspots for the production, accumulation, and release of plastic debris (Li et al., 2016). Second, coastal sites are exposed to the negative effects of plastic pollution, ranging from environmental degradation to jeopardy of marine ecosystems (Cózar et al., 2014; Lamb et al., 2018). A third element of concern is that marine pollution can impoverish local economies via reduced investments in coastal development (McIlgorm et al., 2011; Jang et al., 2014) and decline of coastal- and marine-dependent activities (e.g., fishing, mariculture, and tourism) (Mohammed, 2002; Staehr et al., 2018). In addition to the challenges experienced by coasts, islands face several barriers related to environmental management such as the limited physical space for storing and treating waste, a lack of resources to implement efficient waste infrastructure, higher waste management costs, and difficulty of implementing plastics circularity locally (Eckelman et al., 2014). Ultimately, understanding the distribution patterns of marine litter in coastal and island regions is crucial to unfold the impacts on the marine environment and root causes of marine pollution.