Oil's Impact: Water Pollution And The Devastating Effects

Oil pollution in water is a pressing issue that threatens human life, wildlife, and vegetation. Even a small amount of oil can contaminate a large volume of water—just one litre of oil can pollute one million litres of water. Oil spills can have devastating consequences for the environment, and the recovery process can range from weeks to decades. With oil's ability to quickly spread, it is crucial to act fast to contain spills and minimise their impact. This is particularly important as oil pollution can enter water sources through various pathways, from storage facilities and pipelines to shipping accidents and natural seeps from the ocean floor.

Oil density and water type

The density of an oil-water mixture can be calculated using a retort to get the oil/water ratio. The formula for calculating the density of the mixture is:

V1 x D1) + (V2 x D2) = (V1 + V2)DF

Where:

• V1 = percentage of oil
• V2 = percentage of water
• D1 = density of oil
• DF = density of the mixture

The density of oil and water will vary depending on a number of factors, including temperature and pressure. The density of oil is typically given in terms of its specific gravity, which is the ratio of the density of oil to the density of water at a specific temperature (usually 60°F or 15.5°C). The specific gravity of oil can range from about 0.8 to 0.95, with some oils having higher or lower specific gravities.

The density of water also varies with temperature and pressure. At 20°C, the density of pure water is 998.2 kg/m3, but this can increase as the temperature decreases. For example, at 0°C, the density of water increases to 999.8 kg/m3. The salinity of water can also affect its density, with salt water being denser than fresh water.

When oil and water are mixed, the density of the mixture will depend on the relative proportions of oil and water, as well as their individual densities. In general, oil is less dense than water, which is why oil floats on top of water when the two are immiscible. However, when oil is emulsified in water or when the oil has a higher density than the water, the oil droplets can become suspended in the water, resulting in a stable mixture.

Natural oil seepage

The world's largest natural oil seepage is located at Coal Oil Point in the Santa Barbara Channel, California. This area, along with other natural seeps in California, has been leaking for thousands of years and contributes about five million gallons of oil to the ocean annually. The seeps in California often result in large slicks of black, brown, and tan oil that can be easily observed from the air and may travel over 100 miles along the coast.

Natural oil seeps are the largest source of oil entering the world's oceans, accounting for nearly half of the annual oil release. In the Gulf of Mexico, there are more than 600 natural oil seeps that leak between one and five million barrels of oil per year. These seeps occur due to various geological processes, such as aquathermal pressuring, clay dehydration reactions, and mineral transformation.

While natural oil seeps have been exploited for their resources, they also have environmental impacts. The oil can be toxic to marine life, including fish, sea stars, shrimp, and seabirds. However, natural seeps release oil slowly over time, allowing ecosystems to adapt, whereas oil spills from human activities can quickly release overwhelming quantities of oil. Organizations like NOAA's Office of Response and Restoration (OR&R) work to track and study natural seeps, enhance techniques to determine the origin of oil, and train observers to understand how natural factors influence oil movement.

Oil spill containment

To effectively contain an oil spill, several methods and technologies are employed. One of the most commonly used methods is the deployment of oil spill containment booms, also known as curtain booms. These booms act as barriers and are designed to contain the oil in a specific area, preventing it from spreading further into the water body. They are made with flexible internal foam flotation and a fabric skirt, which provides stability and durability. The booms come in various sizes and strengths to accommodate different water conditions, from calm waters of ponds and lakes to the rough open waters of the ocean.

There are different types of containment booms available to suit specific environments and conditions. For instance, the lightweight EconoMax boom is designed for calm waters, making it ideal for deployment in ponds, lakes, and canals. On the other hand, the OptiMax boom is a versatile option that can be used in rivers, streams, and near-shore ocean environments. It is strong and buoyant, making it a popular choice for contractors working in fast-moving waters. For rough open waters, a rugged boom with high tensile strength is required, such as the ABASCO rough-water containment boom, which offers excellent wave conformance.

In addition to the standard booms, there are also inflatable booms, such as the AirMax and RubberMax, which are made from high-quality Urethane fabric and offer compact storage and quick deployment. These booms are highly visible, aiding mariners and vessel operators in navigating potential hazards. Another innovative solution is the FlexiBelt boom, designed for use by ships during refueling. It automatically adjusts to the changing distances between the ship's hull and the seawall, ensuring effective containment.

The successful containment of an oil spill relies on the swift deployment of these booms and barriers, as well as the availability of custom solutions to meet specific needs. By utilizing these technologies and strategies, the impact of oil spills on our precious water resources can be mitigated, protecting both the environment and the communities that depend on these ecosystems.

Clean-up methods

Clean-up and removal of oil spills are essential to protect the marine ecosystem from the harmful effects of oil pollution. Various methods, tools, and techniques are employed to address oil spills in water bodies, ranging from manual labour to advanced technologies. Here are some of the commonly used clean-up methods:

In-Situ Burning

Also known as "in situ burning," this method involves setting fire to freshly spilled oil, typically when it is floating on the water surface. In-situ burning is considered highly effective, capable of removing up to 98% of the spilled oil. However, it is not suitable for thinner layers of oil or when unfavourable weather conditions are present. This technique was employed during the Deepwater Horizon drilling site explosion in the Gulf of Mexico in 2010.

Oil Booms

Oil booms are large floating barriers designed to contain and collect spilled oil. They have three main components: a freeboard that traps the oil above the water surface, a "skirt" that acts as a barrier wall below the water surface, and a chain or cable that connects and stabilizes the boom. While oil booms are simple and popular, they are only effective when the oil is concentrated in one area.

Skimming

Skimmers are machines specifically designed to separate and suck up oil from the water surface, similar to a vacuum cleaner. They are highly effective in recovering most of the spilled oil and can facilitate the processing of the collected oil for reuse. However, skimmers can be prone to clogging due to the presence of debris.

Sorbents

Sorbents are materials that can absorb or adsorb oil, making it easier to remove from the water. Natural sorbents, such as straw, corncob, peat moss, or vermiculite, can absorb 3 to 15 times their weight in oil. On the other hand, synthetic sorbents are more efficient, with a capacity to absorb up to 70 times their weight. Additionally, researchers have developed a polyurethane foam "sponge" that can absorb up to 90 times its weight and be reused.

Hot Water Flushing

This method involves spraying hot water at 170°C through high-pressure nozzles onto areas with trapped oil. The pressure flushes the oil to the water surface, where it can be collected using booms or skimmers. Hot water flushing is particularly useful in areas where larger machinery cannot access, such as beaches. However, it may not be suitable for the open sea due to the risk of dispersing oil and endangering marine life.

Manual and Mechanical Removal

In some cases, manual labour with hand-held tools like shovels, rakes, or even hands may be employed to clean up oil from shorelines. This method is labour-intensive and time-consuming but can be necessary when heavy machinery cannot access the affected areas. When accessible, mechanical removal with heavy machinery, such as backhoes or front-end loaders, may be utilized.

Human health risks

Oil spills and leaks are a major cause of water pollution, with oil having the potential to contaminate millions of litres of freshwater. Oil pollution can occur through industrial or domestic operations, such as spills in fuel depots or oil leaks in vehicles, as well as through transportation and transfers of oil. Oil pollution has severe consequences for human health, causing approximately 1.8 million deaths in 2015, according to a study published in The Lancet.

One of the most significant human health risks associated with oil pollution is the ingestion of contaminated water. Unsafe water can cause various illnesses, and it is estimated that it sickens about 1 billion people annually. Waterborne pathogens, including disease-causing bacteria and viruses from human and animal waste, pose a significant threat when present in drinking water sources. Low-income communities are particularly vulnerable to the health risks of oil pollution, as their homes are often located closest to the most polluting industries.

Oil spills can also have detrimental effects on the environment, causing damage to vegetation, birds, and marine animals. The clean-up process can be challenging, and recovery times can range from weeks to decades, depending on the type and amount of oil spilled, as well as local weather conditions. Coral reefs, mangroves, and marshes are especially sensitive to oil pollution and may take years or even decades to recover.

In addition to the immediate health risks associated with ingesting contaminated water, long-term exposure to oil and gas from spills can have irreparable health consequences for humans. Several short-term studies have been conducted, reporting alarming health impacts on individuals exposed to oil and gas from some of the most notorious spills, including Exxon Valdez, Hebei Spirit, Tasman Spirit, Prestige, and Deepwater Horizon. These health effects include respiratory damage, liver damage, decreased immunity, increased cancer risk, reproductive damage, and higher levels of toxic substances such as hydrocarbons and heavy metals.

Indigenous communities, such as those in the Amazon, are particularly vulnerable to the health risks associated with oil spills. A study by Webb et al. (2016) found that men involved in cleaning up an oil spill in the Peruvian Amazon had twice as much mercury in their urine compared to those not involved. Mercury is a highly toxic substance that can cause brain and liver damage. Another study by San Sebastian and Hurtig (2004) concluded that oil exploitation in the Amazon basin of Ecuador constituted a public health emergency.

Frequently asked questions