The Ocean's Trash: Where Does It Come From?

Marine debris, or rubbish in the ocean, is a pressing issue that threatens marine life, ecosystems, and even humans. Marine debris comes from many sources, including littering, inadequate waste management, and industrial activities. Rivers, streams, and maritime transport are significant conduits for plastic waste to reach the ocean, while rubbish left on beaches and plastic waste from boats also contribute to the problem. Once in the ocean, plastic waste breaks down slowly, forming microplastics that release harmful chemicals and endanger marine life through ingestion and entanglement. The impact of plastic pollution extends throughout the marine food web, affecting fish populations and ultimately human activities and health. Addressing the issue of plastic in the ocean requires a multifaceted approach, including improved waste management, reduced use of single-use plastics, and corporate responsibility.

Rivers, streams and waterways

Rivers, streams, and waterways are a major source of plastic waste in the oceans. Rivers carry trash over long distances, connecting land surfaces with the oceans. This makes them a crucial battleground in the fight against marine pollution. According to hydrogeologist Christian Schmidt, rivers collectively discharge between 0.47 million and 2.75 million metric tons of plastic into the seas annually.

Litter from streets and landfills can be blown or washed into rivers and streams, eventually flowing into the ocean. This includes lightweight plastics, which can escape into the environment by being blown away during transportation. Once in the ocean, plastic breaks down slowly, persisting as microplastics that harm marine life.

A significant proportion of river-borne plastic originates from just a handful of rivers. Notably, around 90% of river-borne plastic comes from just 10 rivers, eight of which are in Asia: the Yangtze, Indus, Yellow, Hai, Ganges, Pearl, Amur, and Mekong. The remaining two are the Nile and Niger rivers in Africa. These rivers carry massive amounts of plastic waste, with the Yangtze alone dumping up to 1.5 million metric tons of plastic into the Yellow Sea.

The impact of these rivers highlights the importance of effective waste management and public awareness in reducing plastic pollution. China, for instance, has taken steps to curb waste by banning the import of foreign recyclable waste and implementing waste sorting in several cities. Similarly, India has launched the Namami Gange project to clean the Ganges and introduced bans on disposable plastics in certain states.

In conclusion, rivers, streams, and waterways play a significant role in transporting trash to the oceans. The plastic waste they carry contributes to the growing problem of marine pollution, threatening marine ecosystems and the natural environment. Addressing this issue requires better waste management practices, increased public awareness, and a reduction in the use of single-use plastics.

Human behaviour on beaches

One of the main issues with human behaviour on beaches is littering. Intentional littering and dumping are significant causes of marine debris, with beachgoers leaving trash on the sand or throwing it into the water. This can include plastic waste, such as water bottles and food packaging, but also items such as broken glass, which can pose a danger to both humans and animals.

Another issue is the improper disposal of waste. Many people do not have access to proper waste disposal or recycling services, and even when trash is put into bins, it can be blown away by the wind during transportation or collection. This is a particular problem with lightweight plastics, which are easily carried by the wind.

The presence of rubbish on beaches and in the ocean can pose serious health risks to humans and wildlife. Polluted beaches can make people sick through contact with dirty water or sand, and bacteria, fertilisers, animal and human waste, and trash can cause a range of illnesses. Marine animals can ingest plastic or become entangled in it, leading to choking, internal injuries, or starvation. Plastic can also release chemicals such as bisphenol A (BPA), which can interfere with the reproductive systems of fish and build up in the bodies of top predators such as sharks and dolphins through a process called bioaccumulation.

To reduce the impact of human behaviour on beaches, several interventions have been proposed, including educational and policy changes. Educational interventions have been shown to improve children's awareness and concern for marine issues, while policy changes such as increasing the number and convenience of trash receptacles on beaches can also reduce littering. Modifying the behaviour of beachgoers can lead to a significant reduction in marine pollution.

Fishing practices and gear

The durability of modern fishing gear materials, such as plastic nylon and polypropylene, further exacerbates the problem. Unlike natural materials used in the past, these synthetic materials can persist in the ocean for up to 600 years. They only break down when exposed to sunlight at the surface, eventually decaying into smaller plastic bits that are ingested by marine life or join the floating garbage patches.

The North Pacific Garbage Patch, also known as the Great Pacific Garbage Patch, is a vast area in the North Pacific Ocean holding tens of thousands of tonnes of plastic. It is estimated that 75% to 86% of the plastic waste in this patch originates from offshore fishing activities, with major contributions from industrialised fishing nations such as the United States, China, Japan, and Korea.

Fishing gear from just a few regions is responsible for a significant portion of the floating plastic debris in the North Pacific Garbage Patch. A study found that 86% of the plastic waste in this patch was comprised of fishing nets. Another expedition to the south Pacific's Henderson Island found an estimated 18 tonnes of plastic debris on a 2.5-km stretch of beach, with fishing gear being a significant contributor.

The issue of ghost gear is not limited to targeted marine species but has impacted at least 136 different species of marine animals, including unintended targets such as seabirds. The entanglement in ghost gear can lead to injuries, suffocation, or starvation for these animals.

Maritime transport and trade

Marine debris is a global issue that affects the health of the world's oceans, coastlines, and waterways. It is caused by human activities, both on land and at sea, and can be a result of littering, improper waste management, or natural disasters. While marine debris includes a variety of materials such as plastics, metals, rubber, paper, and textiles, plastic waste is the most common form of litter in the ocean, accounting for 80% of all marine debris.

In addition to plastic leakage and waste from ships, the maritime industry also contributes to ocean pollution through point source and non-point source pollution. Point source pollution refers to pollution that comes from a single source, such as an oil or chemical spill from a ship or an offshore platform. While less frequent, these incidents can have significant impacts on marine environments. Non-point source pollution, on the other hand, occurs as a result of runoff from various sources, including ships and ports. This can include septic tanks, vehicles, and other sources unique to the maritime industry.

The impact of plastic pollution from maritime transport and trade is far-reaching. Plastics can be transported by ocean currents to even the most remote areas of the ocean, affecting marine life and ecosystems worldwide. Marine animals, such as fish, seabirds, sea turtles, and marine mammals, are at risk of entanglement or ingestion of plastic waste, leading to suffocation, internal injuries, starvation, and drowning. Additionally, microplastics have now become part of the food chain, being ingested by marine life and even making their way into the seafood we consume.

The maritime industry plays a crucial role in addressing plastic pollution. Beyond proper waste management practices, the industry can support projects aimed at preventing marine debris from entering the ocean. This includes funding research, outreach, and education initiatives to raise awareness and promote behavioural changes related to plastic use and disposal. By working collaboratively with governments and non-governmental organizations, the maritime industry can contribute to global efforts to reduce plastic pollution and protect the health of our oceans.

Inadequate waste management

In developing countries, waste management infrastructure is often inadequate or lacking altogether. This results in waste being dumped or discarded improperly, increasing ocean pollution. For example, in some regions, there is limited access to solid waste collection services, which can lead to littering and improper waste disposal. Additionally, insufficient funding for waste management programs can be a challenge, as it requires significant investment in facilities, staff, and equipment.

The impact of inadequate waste management is exacerbated by the fact that plastic waste does not biodegrade quickly. Plastic can persist in the ocean for decades, breaking down into microplastics that pose significant harm to marine life and ecosystems. These microplastics can interfere with the digestion and reproduction of marine animals, leading to malnutrition and reduced reproductive success.

Furthermore, improper waste management can lead to the release of chemical pollutants into the ocean. For instance, bisphenol A (BPA), a chemical found in plastics, can build up in the bodies of marine organisms through bioaccumulation. This can impact the reproductive systems of fish and other marine life, leading to a decrease in healthy offspring.

To address the issue of inadequate waste management, it is crucial to implement successful waste management programs and improve waste management infrastructure. This includes encouraging recycling, reducing single-use plastics, and ensuring proper disposal of hazardous waste. Additionally, increasing public awareness and education about proper waste management can help individuals understand the impact of their waste on the environment and the importance of proper disposal and recycling.

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