Oceanic Pollution: Can The Ocean Cause Environmental Harm?

Oceans can cause pollution. Most ocean pollution begins on land, with nonpoint source pollution being the biggest contributor. Nonpoint source pollution occurs as a result of runoff, which includes small sources like septic tanks, cars, trucks, and boats, and larger sources like farms, ranches, and forest areas. Some water pollution starts as air pollution, which settles into waterways and oceans.

Additionally, plastic waste, which makes up 80% of marine litter, is a significant contributor to ocean pollution. Plastic waste can kill marine life, such as seabirds, fish, whales, and dolphins. It also breaks down into microplastics and nanoplastics, which can enter the tissues of marine organisms and, subsequently, humans.

Nonpoint source pollution

The effects of nonpoint source pollution are far-reaching. It can make river and ocean water unsafe for humans and wildlife, leading to beach closures after rainstorms. It can also impact the economies of coastal communities, as it diminishes the beauty and health of coastal lands and waters, making them less appealing to tourists.

Correcting the harmful effects of nonpoint source pollution is costly. Millions of dollars are spent annually to restore and protect areas damaged or endangered by nonpoint source pollutants.

Intentional discharge

One of the most challenging issues is plastic waste, with eight million metric tons of plastic entering our oceans annually. This waste is particularly harmful as it does not biodegrade, instead persisting in the environment for hundreds or even thousands of years. Plastic waste entangles marine life, is ingested by animals, and pollutes beaches and ocean floors.

Ships are another major contributor to ocean pollution, especially when crude oil spills occur. Oil spills are devastating for marine life, as the oil ensnares and suffocates animals, damages their ability to reproduce, and causes cancer and behavioural changes. Oil spills are also incredibly difficult to clean up, with oil persisting in the ocean for years. The largest oil spill in recent history was the 2010 Deepwater Horizon well blowout in the Gulf of Mexico, which spilled roughly 134 million gallons of oil into the ocean.

Deep-sea ocean mining also causes significant ocean pollution and ecosystem disruption. Drilling for substances such as cobalt, zinc, silver, gold, and copper creates harmful sulfide deposits deep in the ocean.

Intentional marine pollution is also perpetrated by ships preparing for repairs. An anonymous report from a junior officer on a crude oil tanker details how, after cleaning the tanks, a mixture of oil and water is pumped out through the oily water separator. While the water is discharged first, the automatic shut-off valve can be overridden, allowing the ship to pump thick black oil overboard.

Deep-sea ocean mining

Oceans are a significant source of pollution, with human activity on land being the cause of 80% of marine pollution. Nonpoint source pollution, which includes runoff from roads, farms, septic tanks, and vehicles, is a major contributor. Atmospheric pollution, caused by littering, and oil spills from boats, airplanes, and other vehicles, also play a significant role.

Mineral Sources and Extraction Methods

Deep-sea mining targets mineral-rich deposits at depths of 2,000 metres or more, with a particular focus on 'polymetallic nodules' found on the abyssal plain, which can provide access to multiple valuable commodities such as manganese, nickel, copper, and cobalt. Other sources include seafloor massive sulphides near hydrothermal vents and cobalt-rich ferromanganese crusts found on underwater mountain ranges. The relatively scattered nature of the polymetallic nodules makes them easier to collect with dredging machines driven along the ocean floor.

Environmental Impacts

The deep sea is the largest habitat for life on Earth, with unique species and ecosystems, but it is still poorly understood due to the challenges of accessing and studying this extreme environment. Deep-sea mining is expected to have major and long-lasting consequences for animal life and the highly biodiverse environment. Some of the key impacts include:

• Habitat removal: The removal of polymetallic nodules, which grow slowly over millions of years, will likely alter the sediment's geochemistry and destroy the habitat of many organisms, especially those that attach themselves to rocks.
• Sediment and plume disturbances: The dispersion of fine sediments by mining activities can create barriers to mobility and visualisation for organisms, likely reducing their reproduction rates.
• Water discharges and toxic compounds: Discharges from mining vessels, including dredging spoils, marine litter, and cooling or ballast waters, can increase seawater temperatures, reduce oxygen levels, and introduce heavy metals into the ecosystem, potentially contaminating seafood.
• Noise pollution: Noise from mining vehicles and equipment can interfere with communication between marine mammals, which rely on sound for vital activities such as finding food and mating.
• Light pollution: Many deep-sea organisms are adapted to darkness and have reduced visual capacity. Artificial light used during mining operations can disturb these light-sensitive organisms.
• Direct harm to marine life: Less mobile deep-sea organisms are likely to be killed through direct contact with heavy mining equipment, and sediment plumes may smother and suffocate marine animals.
• Long-term species and ecosystem disruption: Noise and light pollution in a naturally dark and silent environment can impair the feeding and reproduction of deep-sea species, especially those that are rare, long-lived, and slow to reproduce.
• Possible impacts on fishing and food security: Waste discharge from mining vessels can spread over large distances and threaten open ocean fish and invertebrates that are crucial to international fisheries and the economies of many small island nations.
• Economic and social risks: The development of shoreline facilities for processing and transshipment will likely lead to land acquisition and development, impacting coastal communities and driving habitat loss.
• Potential climate impacts: The loss of deep-sea biodiversity may impact the ocean's carbon cycle and reduce its ability to mitigate global temperature rise, as the ocean is the world's largest carbon sink.

Benefits and Alternatives

Proponents of deep-sea mining argue that it can help meet the growing demand for critical minerals needed for zero-carbon energy components and technologies. However, there are concerns about the potential environmental consequences, especially given the limited knowledge about the deep ocean. Recycling and technological innovations that reduce resource intensity are being explored as alternatives to deep-sea mining.

Atmospheric pollution

The National Oceanic and Atmospheric Administration (NOAA) states that 80% of ocean pollution comes from land-based sources. Nonpoint source pollution is the accumulation of pollution from small sources that can't be pinpointed, such as individual cars, boats, farms, and construction sites. This pollution becomes ocean pollution via runoff, when rain or snow moves pollutants from the ground into the ocean. Atmospheric pollution can also be caused by wind, which transfers dirt and other debris from nonpoint sources and deposits them on the ocean's surface.

Noise pollution

Ocean noise pollution is a form of environmental pollution caused by human activities such as commercial shipping, oil exploration, seismic surveys, offshore wind turbine installation, and military sonar. These activities generate unnatural and excessive sound underwater, which can have detrimental effects on marine life. Noise pollution can interfere with the key life functions of marine animals and, in some cases, even cause death.

Marine mammals, such as whales, dolphins, and porpoises, rely heavily on sound for communication, locating prey and mates, navigating, and defending their territories. However, the increasing noise pollution in the ocean is threatening their natural soundscape. Cargo ships, for example, can emit noise of up to 190 decibels, which is louder than a plane taking off. Noise travels faster in water than in air, so this increased noise level affects a wide range of animals and habitats.

The impacts of noise pollution on marine life include temporary or permanent hearing loss, behavioural and physiological changes, masking of natural sounds, injury, and death. Very loud noises can cause panic in marine mammals, leading to decompression sickness and tissue damage from rapid ascents. Naval sonar devices, which work similarly to echolocation used by whales and dolphins, have been linked to mass strandings of cetaceans. Noise pollution can also alter the behaviour of marine mammals, causing them to move away from their preferred habitats or adjust their feeding and breeding activities.

To address the issue of ocean noise pollution, there have been efforts to implement regulations and guidelines. The International Maritime Organization (IMO) has developed guidelines for the reduction of underwater radiated noise from shipping, but these have not been widely adopted. The European Union has set mandatory thresholds for underwater noise to protect species and habitats. Other suggested measures include building ships with quieter technology, ending seismic surveys for oil and gas exploration, and transitioning to renewable energy sources.

Overall, ocean noise pollution is a significant threat to marine life, and efforts to reduce and regulate this type of pollution are crucial for the protection of marine ecosystems.

Frequently asked questions