Oil Spill Disaster: Water Pollution Explained

Oil spills are a major source of water pollution, with thousands occurring in US waters each year. They can be caused by human error, natural disasters, technical failures, or deliberate releases, and have a range of negative impacts on the environment, economy, and society. Oil spills can harm wildlife, ruin beaches, and make water unsafe to drink or for seafood production. They can also have economic repercussions, impacting tourism, fishing, and port activity. Oil spills are difficult and expensive to clean up, and even with the best methods available, it is impossible to remove 100% of the spilled oil.

Oil spills from tankers, offshore platforms, rigs, and wells

The number of oil spills and the quantity of oil spilled from tankers have decreased significantly in recent decades. However, not all oil spills come from tankers. They can also occur from other sites, such as offshore oil rigs and damaged pipelines. The Deepwater Horizon spill in the Gulf of Mexico in 2010, caused by an explosion in a drilling rig, is an example of a significant offshore platform spill. While technologies for drilling in deep water have improved, oil companies are moving to more challenging drilling locations, resulting in no clear trend in the frequency of these types of spills.

Accidental spills from oil platforms today account for about 3% of oil spills in the oceans. Notable examples include the Deepwater Horizon and Ixtoc I spills, which went on for months until relief wells were drilled, resulting in enormous amounts of leaked oil. While there has been an overall substantial increase in pipeline oil spills over the past four decades, they are estimated to contribute only 1% of oil pollution to the oceans due to underreporting and the fact that many leaks occur on land.

The impact of oil spills on marine life can be catastrophic. Oil cannot dissolve in water and forms a thick sludge that suffocates fish, impairs the flight of marine birds, and blocks light from photosynthetic aquatic plants. Oil penetrates the structure of the plumage of birds and the fur of mammals, reducing its insulating ability and making them more vulnerable to temperature changes and less buoyant in the water. Oil spills can also contaminate drinking water supplies, as seen in incidents in Malaysia, Ecuador, and the United States.

The cleanup and recovery process after an oil spill is challenging and depends on factors such as the type of oil, water temperature, and shoreline characteristics. Physical cleanups are very expensive, and chemical remediation is now the norm, using compounds to herd and thicken oil for recovery, disperse it in the water, or facilitate burning it off. Bioremediation, using microorganisms or biological agents to break down or remove oil, is an emerging technology in this field.

Oil toxicity and its impact on marine life

Oil spills are a major source of water pollution and can have a devastating impact on marine life. Oil spills can occur in many ways, from accidental spills during mining to malfunctions and attacks on tankers. Oil spills can have both acute and chronic effects on marine life, including fish, birds, sea otters, dolphins, whales, and corals.

One of the main ways oil harms marine life is by destroying the insulating ability of fur-bearing mammals, such as sea otters, and the water repellency of birds' feathers. This loss of insulation and water repellency exposes these creatures to the elements, and they can die from hypothermia. Oil can also smother fish and block the light from photosynthetic aquatic plants, leading to localized ecological disasters.

In addition, oil spills can cause reproductive and developmental issues in marine life. For example, juvenile sea turtles can mistake oil for food, and dolphins and whales can inhale oil, affecting their lungs, immune function, and reproduction. Oil can also impact the growth and development of fish, with adult fish experiencing reduced growth, enlarged livers, changes in heart and respiration rates, fin erosion, and impaired reproduction. Even when lethal impacts are not observed, oil can make fish and shellfish unsafe for human consumption.

Oil spills can also have long-term effects on marine ecosystems. They can alter the structure and function of marine communities and ecosystems, reduce the fitness of marine organisms, and increase their susceptibility to diseases. Oil spills can also have economic impacts, affecting coastal fishing and fisheries and decreasing property values in affected areas.

Furthermore, oil spills can lead to oxygen depletion in water due to the formation of oil slicks on the surface. This can have severe consequences for marine life, particularly in shallower waters. The accumulation of oil pollutants in the tissue and bodies of marine life can also induce health and reproductive problems and even mass mortality events.

Overall, oil toxicity poses a significant threat to marine life and can have both immediate and long-term impacts on the delicate balance of marine ecosystems.

Oil spills and drinking water contamination

Oil spills are a major threat to drinking water sources. Oil spills can occur in many ways, including accidental spills while mining oil, malfunctions of oil rigs, or attacks on tankers. These spills can contaminate oceans, rivers, lakes, and other bodies of water connected to the ocean, impacting both the environment and human communities.

The immediate effects of an oil spill are hazardous, with toxic chemicals released into the surrounding water and land. Oil spills can cause serious short- and long-term health issues for those exposed, including oil rig workers, first responders, and nearby residents. The health effects of oil spills include dizziness, irritability, coughing, lung problems, and potential mental health issues such as depression and anxiety.

Oil spills also have severe ecological consequences. Oil can coat the feathers and fur of birds and marine animals, impairing their movement, insulation, and ability to fly. When animals attempt to clean themselves, they ingest the oil, causing internal organ damage and problems with digestion, breathing, and reproduction. Oil spills can also block sunlight from reaching photosynthetic plants in the water, killing them.

Additionally, oil spills impact marine life, such as fish stocks, that humans rely on for food and economic activities like fishing and hunting. This can have a significant impact on rural communities and poverty-stricken countries that depend on these resources for survival. The contamination of water sources can also lead to increased poverty in countries that lack access to alternative sources of clean water, such as bottled water or rainwater collection systems.

Furthermore, oil spills are challenging and costly to clean up, often requiring manual labour, specialised equipment, and chemical dispersants. While natural processes like biodegradation can help break down oil, immediate containment and cleanup efforts are crucial to minimising the environmental and health impacts.

To address the issue of oil spills and drinking water contamination, regulations such as the Oil Pollution Act in the US have been implemented to prevent and mitigate the effects of oil spills. These regulations require oil storage facilities and vessel operators to prepare "Facility Response Plans" and have cleanup plans in place to prevent spills and minimise damage.

Oil spills and air quality

Oil spills are a significant environmental concern, impacting not only the water and land but also the air we breathe. When oil is released into the environment, it can have detrimental effects on air quality, posing risks to both human health and ecosystems. Here's an overview of the relationship between oil spills and air quality:

Release of Volatile Organic Compounds (VOCs)

Oil spills often result in the release of VOCs, such as benzene, toluene, ethylbenzene, and xylene. These toxic chemicals escape from the unrefined mixture of crude oil and pose a threat to human health. As VOCs evaporate, they react in the atmosphere, contributing to the formation of smog, which can have negative consequences for respiratory health and the climate.

Particulate Matter Formation

Oil spills also lead to the formation of particulate matter, which consists of tiny particles that can be inhaled. This includes not only dust but also heavy metals and polycyclic aromatic hydrocarbons. When inhaled, these particles can have long-lasting effects on respiratory health. Particulate matter combines and reacts with the vapours released from oil spills, exacerbating the impact on air quality.

Combustion of Spilt Oil

In some cases, oil spills may be deliberately burned or accidentally catch fire. This combustion releases air pollutants, including nitrogen oxides (NOx), which contribute to the formation of ground-level ozone or smog. Exposure to smog can trigger asthma attacks and respiratory issues. Burning spilt oil also releases particulate matter, which can penetrate deep into the lungs and even enter the bloodstream, carrying carcinogenic substances that increase the risk of cancer.

Impact on Ecosystems and Climate

The airborne compounds released during oil spills have far-reaching consequences for ecosystems. They can smother plants, disrupt animal habitats, and contaminate food sources. VOCs can alter atmospheric chemistry, indirectly increasing greenhouse gas concentrations and fuelling climate change. Oil spills can also affect weather patterns and air quality in the surrounding areas, impacting local communities and vulnerable individuals.

Prevention and Monitoring Strategies

To mitigate the impact of oil spills on air quality, prevention and monitoring strategies are crucial. This includes deploying barriers and absorbent materials to contain the spill, as well as using skimmers to remove oil from water surfaces. Agencies and organisations, such as the Washington State Department of Ecology, work to prevent oil spills and respond quickly to minimise their impact on both water and air quality. Effective monitoring methods, such as those developed by the Environment Agency, are essential for tracking chemicals released during oil spills and assessing their impact on air quality.

Oil spill clean-up methods

Oil spills are a major source of water pollution, contaminating water sources and destroying marine life. Oil spills can occur in many ways, from accidental spills while mining to malfunctions and attacks on tankers.

Oil Booms and Skimmers

The use of oil booms is a straightforward and popular method of controlling oil spills. These are physical floating barriers that act like a fence to prevent the oil from spreading or floating away. Booms float on the water surface and have three parts: a 'freeboard' that rises above the water to prevent oil from splashing over; a 'skirt' placed below the surface to stop oil from escaping under the booms; and a cable or chain that connects and stabilises the boom. Once the oil is contained, skimmers—machines that suck up the oil from the water like a vacuum cleaner—are deployed to remove the oil.

Sorbents

Sorbents are materials that soak up liquids through absorption (pulling in through pores) or adsorption (forming a layer on the surface). Materials used as oil sorbents include hay, peat moss, straw, and vermiculite. After absorption, the sorbent materials, now heavier, must be retrieved to prevent them from sinking and posing a risk to aquatic life.

In-Situ Burning

This method involves igniting the oil floating on the surface to burn it off. In-situ burning can remove up to 98% of an oil spill and is more effective than most other methods. However, it releases toxic fumes that can harm the environment and marine life.

Dispersants

When oil cannot be contained by booms, dispersal agents like Corexit 9500 are used to accelerate the disintegration of oil. These chemicals are sprayed onto the spill from aircraft and boats, aiding the natural breakdown of oil components. Dispersants increase the surface area of each oil molecule, allowing it to chemically bond with water. While effective for large spills, they can create tarballs as oil mixes with sand and debris in the water, and their toxicity can harm marine organisms like corals and seagrass.

Hot Water and High-Pressure Washing

This method is used when oil is inaccessible to mechanical removal methods like booms and skimmers. Water is heated to around 170°C and then sprayed with high-pressure wands or nozzles to dislodge the oil, which is then flushed to the water surface and collected.

Manual Labour

This method uses handheld tools like rakes and shovels, along with manual labour, to clean up oil and oily debris from shorelines. Mechanised equipment may also be used to reach inaccessible areas. While cost-effective, this process is labour-intensive and time-consuming.

Bioremediation

Bioremediation involves using specific microorganisms, such as bacteria, fungi, archaea, and algae, to remove toxic substances. These microbes metabolise and break down petroleum products into simpler, non-toxic molecules. This process is time-consuming and is typically used when oil approaches the shoreline rather than in deep seas.

Chemical Stabilisation by Elastomizers

Compounds like 'Elastol', or poly iso-butylene (PIB) in powdered form, are used to solidify oil on the water surface, preventing its spread. This method is quick, with reaction times of 15-40 minutes, and the solidified oil is easy to retrieve. While PIB is non-toxic, it may entangle or suffocate aquatic animals.

Natural Recovery

Natural recovery relies on the sun, wind, weather, tides, and naturally occurring microbes to clean up oil spills. This method is cost-effective but highly time-consuming and unreliable, requiring constant monitoring. It is typically used when shorelines are remote or inaccessible, or when the environmental impact of other clean-up methods would be too great.

Frequently asked questions