Research Paper (postgraduate), 2010
11 Pages, Grade: A
2 The Great Pacific Garbage Patch
3 Threats of plastic debris to marine biota and human health
3.1 Ingestion of plastic
3.2 Plastic ingestion and persistent organic pollutants
3.3 Entanglement of plastic debris
3.4 Plastic scrubbers (small plastic particles)
3.5 Invasive species
4 Other socio-economic considerations
5 Possible solution options
5.1 Policy measures
5.2 Market based instruments
Rapid population growth and enormous urban and coastal developments have increased the anthropogenic pollution into the oceans. Human activities may responsible for the decline in biodiversity and productivity of marine ecosystems, resulting in the depletion of human marine food resources (Jenssen, 2003).
In addition, the marine environment is an important resource for human welfare and health and fortunately in recent years awareness of its intrinsic value has increased (Derraik, 2002). One particular type of threat to marine ecosystems is the pollution from plastics. These particles are a serious treat to the marine biota and human life and entail significant economic and social costs. Further, they reduce the aesthetic and perhaps intrinsic value of the marine environment (Jenssen, 2003).
The aim of this paper is to examine the threats from plastic pollution and introduce an interesting case study from the North Pacific Ocean. The paper will describe the current policies and propose market based instruments which can provide solution to the issue.
The Great Pacific Garbage Patch is a floating plastic accumulation in the middle of the Pacific Ocean, between Hawaii and California (Figure 1). It includes all kinds of plastic debris from everyday life. For example bottles, plastic bags and toys. After the plastic components reach the ocean they are dispersed in various ways. Onshore winds force some debris back to shore, while offshore winds will push the debris into the currents. High pressure circulation systems, known as gyres, accumulate the trash into patches. The biggest gyre is located in the Central North Pacific. It may take 1 to 5 years for trash to reach the center of the gyre. Most of the trash is though to originate from the west coast of North America and the east coast of Asia. During their journey, plastics photodegrade and disintegrate into small particles and eventually into their molecular monomers, but always remain in the polymer form in the upper layer of the ocean. In this region researchers found six kilograms of plastic fragments for every kilogram of zooplankton smaller than 0.333 mm in size (Moore, 2008).
The Great Pacific Garbage Patch is estimated to be twice the area of Texas (Bradshaw, 2009). It was discovered in 1988, but it received greater public attention only after it was documented by the researcher Captain Charles Moore in 1997. According to him, the plastic content of the patch has tripled since its initial discovery (Moore, 2002). It is a very complicated transboundary issue over non-point source pollution which involves international law, politics, economic, biological, social and safety issues.
The content of the debris is mainly plastic and the source is estimated to be 80% land- based and with the remaining 20% from ships. For example a typical cruise ship with 3,000 passengers produces more than 8 tons of solid waste per week (Clemmitt, 2009).
The pollution in this case may affect many countries including the USA (Hawaii), Japan and China, as well as their trading partners, potential tourists and other individuals indirectly.
This marine trash has several physical and chemical effects on marine biota. Additionally, the accumulation of plastic or toxic plastic particles in fish and marine mammals may have serious consequences to humans as it enters the food chain.
One of the threats to marine life is the ingestion of plastic debris. Small plastic particles are often eaten by sea animals that mistake them for food or plankton. Accumulation of plastic in the digestive tracts of animals reduces meal size by decreasing the storage volume of the stomach, which may lead to starvation, sickness, drowning and death. (EPA, 2009). In the case of seabirds, reduced food uptake adversely affects fitness and especially impacts migratory species. Further, adult seabirds may regurgitate food for their chicks increasing infant mortality. In the Hawaiian Islands, for example, 90% of Laysan Albatross (Diomedea immutabilis) chicks are affected (Fry et al., 1987).
Worldwide, at least 267 species are affected by marine debris ingestion, including 86% of all sea turtle species, 44% of all seabird species, and 43% of all marine mammal species (Laist, 1997). The issue may be underestimated as many of the victims are undetected as they are eaten by predators or sink in the ocean. A study, carried out in the North Pacific showed that 8 out of 11 species had plastic particles in their digestive tracts (Blight et al., 1997).
Over the last 20 years, persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and furans have increasingly polluted the food web. These “second generation” toxins can bioaccumulate and by entering the food chain may cause irreversible harm to the environment and human health. Recent studies have shown that these toxins have several reproductive, cognitive, and neurologic impacts on marine biota (Dewailly et al. 1999; Jenssen, 2003). They also affect hormone levels, fertility and brain capacity (Jenssen, 2003). Hormone receptors cannot distinguish between natural hormones and endocrine disruptors, therefore the human body reacts as it would to natural hormones. Hormone disruption has been implicated in lower sperm counts and higher ratios of females to males in both humans and animals (Moore, 2002).
Further, marine animals are significantly dependent on their well developed cognitive abilities to survive (e.g. antipredator, reproductive, parental behaviour and feeding success) (Wibe, 2003). Any neural, behavioural or cognitive dysfunction can become a serious threat to ecosystem functions. Additionally, effects are not always detectable, as even low levels of these toxins can have significant effects (Jenssen, 2003). The issue of hormone disruption in humans is a major environmental issue. As the harmful effects were realised, an international ban was introduced for the 12 most toxic PCBs in 2000. Even though as a result the production of these particular PCBs decreased, several thousand new synthetic chemicals are introduced into the market every year for which the detrimental effects and the capacity to bioaccumulate or biomagnify are not fully understood (Jenssen, 2003).
Entanglement of plastic debris, especially lost or abandoned fishing gear may cause serious harm to marine animals. Entangled animals may drown, lose fitness and their ability to defend themselves from predators or become unable to feed. It mainly affects sea mammals (e.g. seals, whales), turtles and birds. It is a particular problem for endangered species resulting in the further decline of already reduced populations. For example the decline in the population of the endangered Hawaiian Monk Seal (Monachus schauinslandi) has been observed to be aggravated by the entanglement of pups (Henderson, 2001). Due to the vast extent of the Great Pacific Garbage patch it is likely that the accumulated plastic has serious consequences for the Pacific Ocean’s species.
Recent studies draw attention to small plastic particles (<0.5 mm) originating mostly from hand cleaners, face cosmetic preparation, airblast cleaning media and degradation of bigger plastic pieces. For example, in airblasting technologies the polyethylene particles are used to strip paint from metal surfaces, such as engines. These are recycled but after final discharge they are often heavily polluted with toxic heavy metals. Waste water treatment plants are not prepared for 100 % removal of these particles, therefore after partial treatment they are discharged into the water system and enter the oceans (Gregory, 1996). The possible impacts of these scrubbers are not fully understood yet, but they are likely to pose a significant risk to the environment and human health.
 Endocrine disruptors are exogenous substances that act like hormones in the endocrine system and disrupt the physiologic function of endogenous hormones. They are sometimes also referred to as hormonally active agents (Moore, 2002).
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