toxicity, and ozone depletion potential (Stefanini et al. 2020).
A major consequence of higher production of plastics will be the increase in the post‐consumer plastic waste stream, already ineffectively managed worldwide (Jambek et al. 2015; Lebreton and Andrady 2019). This burgeoning plastic waste not only impacts the municipal solid waste (MSW) stream that we poorly manage but also contributes to the unsightly urban litter. Unlike paperboard or wood, plastics do not biodegrade in any appreciable timeframe (see Chapter 11) and will persist as urban litter over an extended period of time. Cities with a high population density, such as Mumbai in India (76 800 persons/sq. mile), Karachi in Pakistan (49 000 persons /sq. mile), and Seoul in Korea (45 000 persons /sq. mile), will be particularly affected by the future plastic litter problem. A recent model based on population density (LandScan data), the GDP, and country‐level plastic consumption data, identified future global “hot spots” for plastic waste generation, assuming a “business as usual” scenario (Lebreton and Andrady 2017). Worst affected regions in the next decades were identified as South Asia, East Asia, and South East Asia on a regional basis and China, India, and the Philippines on a country basis.
Geyer et al. (2017) estimated 42% of the plastics entering the waste stream at present to be packaging‐related. The MSW in affluent countries is already rich in plastic packaging waste (Kaza et al. 2018). The fraction of all plastics in the MSW stream in the US has grown from negligible levels in 1970 to 16.3% by weight (357 MMT) by 2018, with PET, PE, and PP making up 32% of the total plastic waste. Plastic waste generation (PWG) per capita varies with the affluence of the country. Compared with the PWG of 88 ̶ 98 kg/year per capita for affluent countries such as Korea and the UK, less wealthy countries like India, China, and Pakistan generate only 13–19 kg/year per capita. The US has the highest PWG of 130 kg/year per capita (Law et al. 2020).
Proliferation of single‐use plastic packaging, including beverage bottles, single‐serve sachets, dessert cups, and disposable bags, has exacerbated the situation, especially in the more affluent countries (Geyer et al. 2017). How the generated plastic waste is managed also varies geographically, depending on the availability of adequate infrastructure. In affluent countries, a combination of landfilling and incineration is used, with the US relying heavily on landfilling.
1.2.1 Plastics in the Ocean Environment
In the 1970s, yet another dimension of plastic waste came to light with the discovery of plastic litter in the marine environment. The very first observations of plastics in the ocean dates back to 1972 (Carpenter and Smith 1972) and was followed by reports in the 1970s and 1980s on the high concentrations of plastics in the North Pacific (Day et al. 1990; Merrell 1980), North west Atlantic Ocean (Coltonet al. 1974), Mediterranean Sea (Morris 1980), and the Spanish Costa del Sol (Shiber 1982). A study of the ocean influx of plastics for the year 2010 (Jambeck et al. 2015) estimated that of the 270 MMT of plastics produced that year, about 32 MMT that ended up mismanaged waste was generated in coastal regions (constituting 50 km from the coastline). And assuming 3% of this waste to reach the ocean, the global marine influx was calculated to be between 4.8 and 12.7 MMT. The fraction of mismanaged waste plastics would not only be much higher today, compared to that in 2010 but the original estimate excluded plastics influx from marine activity such as fishing and riverine transport. Riverine transport of plastics from land into the ocean was identified as an important route in accumulating plastics waste (Leberton et al. 2017; Leberton and Andrady 2017; Schwarz et al. 2019), with the 20 top‐polluting rivers accounting for as much as 67% of the annual input of plastic debris (i.e., 1.15–2.41 MMT annually) into the ocean (Lebreton et al. 2017). Plastic debris from commercial fishing activity also contributes a significant amount of gear‐related debris (dolly ropes, net fragments, or floats) into the ocean, estimated at 0.6 MMT per year (Boucher and Friot 2017). Gear‐related plastics are mostly PE and PP that are positively buoyant, as well as nylons (PA) used, for instance, in gill netting, that sinks in seawater. Also included in this category are the crab pots deployed in large numbers each season. With a significant fraction of 12–20% of them lost each season, ending up as ghost‐fishing gear in the ocean. Ten thousand such pots are lost annually in Puget Sound alone.
Figure 1.5 Estimated plastic waste in the aquatic system versus projected population growth (2016–2030).
Source: Waste estimates from Borelle et al. (2020).
In 1997, Moore et al. (2001) reported an unusually high incidence of plastic micro‐debris in the North Pacific Gyre, a swirling vortex of water in the ocean, a couple of hundred miles North of Hawaii. In this 1.6 million sq. km. area (approximately 135°W to 155°W and 35°N to 42°N), the abundance of floating plastic fragments (some too small to be visible) was statistically higher than elsewhere at sea. A 2018 study estimated this garbage patch to carry 80 TMT of plastic, including ~1.8 trillion pieces of MPs (Lebreton et al. 2018). Misleadingly called the “Pacific Garbage Patch” in the media, the area is not a visible “patch” with obvious plastic floating debris, nor is it a floating island of dense plastic litter. The swirling water collects the micro‐plastic fragments at a statistically higher abundance and its center is calm and nonturbulent. Oceanographic modeling of particles subject to water currents predicts the formation of five such gyres, of which the North Pacific Gyre would be the largest (Eriksen et al. 2014; Van Sebille et al. 2015). How much plastic has accumulated in the deep water or the sediment at the gyre location, is not known. But, the floating stock of plastic debris is known to be a minuscule fraction (Eriksen et al. 2014) of what is estimated to reach the ocean each year, and a majority of ocean plastics are not visible at the surface. What is especially worrisome is that no mechanism in nature is able to remove the plastics from the ocean at a significant rate. With little or no degradation in the low‐temperature, anoxic sediment where the plastic debris ends up (Andrady 2011; Hurley et al. 2018), it is safe to assume that nearly all the plastic that ever entered the ocean still persists there in the sediment.
Plastics are now known to be present in all ocean basins (Andrady 2011; Cole et al. 2011; Derraik 2002; Peng et al. 2020; Law and Thompson, 2014), shorelines the world over (Li et al. 2016), in Antarctica (Ivar do Sul and Costa 2014; Waller et al. 2017), in the frozen polar ice masses (Peeken et al. 2018) (with the possibility of global warming releasing them gradually into the ocean) (Obbard et al. 2014), in remote alpine lakes (Gateuille et al. 2020), and even karst groundwater. Figure 1.5 shows the trend in plastics debris in aquatic environments.
Plastic waste in the ocean poses a variety of well‐known environmental problems and most of these are discussed throughout this volume. The main concerns might be summarized under the following eight categories.
1 Aesthetic damage to shorelines by beach plastic litter. Entanglement (Ryan 2018; Reinert et al. 2017) of marine life in plastic netting, rope, six‐pack rings, containers, and “ghost fishing” by lost and abandoned fishing gear (Richardson et al. 2019).
2 Sorption and adsorption of chemical species in seawater, river water, and wastewater by plastic debris. Some hydrophobic chemicals in seawater may concentrate in the plastic fragments and be transported elsewhere (see Chapter 9).
3 Ingestion of plastics (Reynolds and Ryan 2018; Santos et al. 2015), especially microplastics by a wide range of marine animals. Any chemicals the plastic carries may be bioavailable and lead to toxicity (Avio et al. 2015; Guo and Wang 2019; Rochman 2013; see Chapter 12).
4 Accumulation
