Environmental Impacts of Cargo Shipping
Atmospheric Pollution:
Exhaust gases from ships are considered to be a significant source of air pollution, both for conventional pollutants and greenhouse gases.
There has been a realisation that cargo transport by ship is low in air pollutants, because for equal weight and distance it is the most efficient transport method, according to shipping researcher Amy Bows-Larkin. This is also true in comparison to air freight (air cargo). However, because sea shipment accounts for far more annual tonnage and the often large distances, shipping's emissions are globally substantial. The difficulty is that the year-on-year increasing amount of shipping overwhelms gains in efficiency. There are now over 100,000 cargo ships at sea and of which are about 6,000 are large container ships.
There has been a realisation that cargo transport by ship is low in air pollutants, because for equal weight and distance it is the most efficient transport method, according to shipping researcher Amy Bows-Larkin. This is also true in comparison to air freight (air cargo). However, because sea shipment accounts for far more annual tonnage and the often large distances, shipping's emissions are globally substantial. The difficulty is that the year-on-year increasing amount of shipping overwhelms gains in efficiency. There are now over 100,000 cargo ships at sea and of which are about 6,000 are large container ships.
Oil Spills:
Most commonly related with ship pollution are oil spills. Whilst they are less frequent than the pollution that occurs from daily operations, oil spills have devastating effects. Being toxic to marine life, the components in petroleum are very difficult to clean up, and last for years in the sediment and marine environment of our oceans. Marine species that are constantly exposed to these components can show development problems, vulnerability to disease, and unusual reproductive cycles. One of the well known oil spills was the 'Exxon Valdez' incident in Alaska. The ship got stuck and dumped a massive amount of oil into the ocean in March 1989. Despite efforts of scientists, managers and volunteers, over 400,000 seabirds, about 1,000 sea otters, and enormous numbers of fish were killed.
'Ship-Breaking':
Ship breaking, also known as ship demolition, ship dismantling, ship recycling, ship disposal, ship de-commissioning etc is a type of ship disposal process involving the breaking up of ships for scrap recycling. In 2012, approximately 1,250 cargo ships reached the end of their service life and were broken down to recover steel. Yet only a fraction was handled in a safe, sustainable way. More than 70% of all end-of-life ships were simply run ashore on tide affected beaches in developing countries such as Pakistan, India and Bangladesh, where 'untrustworthy' ship-breaking companies make use of minimal enforcement of environmental and safety rules to maximise profits. But the remaining 30% also remain an issue – ship recycling facilities in Turkey and China still face massive difficulties in agreeing with all standards of environmentally appropriate management of hazardous waste.
Invasive Species:
Aquatic plants, aquatic animal species and aquatic pathogens that are non-indigenous may flourish in a new marine environment when introduced by various factors, one of which is cargo shipping. The presence of aquatic invasive species may cause ecosystem and infrastructure damage, economic losses and may pose risks to human health. The primary cargo shipping related pathway for the transfer of aquatic invasive species is ballast water (explained further down the page). One common aquatic invasive animal species is the Asian Gypsy Moths that are a highly destructive environmental pest, whose eggs can be transported aboard cargo ships and on intermodal containers.
Wildlife Collisions:
Marine mammals, such a whales and dolphins risk being struck by cargo ships, causing injury and/or death. For example, if a cargo ship is traveling at a speed of only 28 km/h there is a 79% chance of a collision being lethal to a whale. One important example of the impact of cargo ship collisions is the endangered North Atlantic right whale, of which 400 or less remain. These incidents are its greatest danger. Between 1970 and 1999, 35.5% of recorded deaths were attributed to collisions. During 1999 to 2003, events of serious injury were attributed to cargo ship strikes averaged once a year. In 2004 to 2006, that number increased to 2.6 on average. Deaths from collisions has become an extinction threat.
Sound Pollution:
Sound pollution caused by cargo shipping and other human operations has increased in recent history. The noise produced by cargo ships can travel long distances and marine species who may rely on sound for their communication, feeding and orientation can be harmed by this noise/sound pollution. The Convention on the Conservation of Migratory Species has identified ocean noise as a 'potential threat to marine life'.
Bilge Water:
On a cargo ship, oil rarely leaks from engines and machinery spaces or from engine maintenance activities and mixes with water in the bilge, the lowest part of the hull of the ship, but there is a filter to clean bilge water before being removed. Oil, gasoline, and by-products from the biological breakdown of petroleum products can harm fish and wildlife and pose threats to human health if ingested. Oil can kill fish or have various horrific long-term effects. Bilge water also may contain solid wastes and pollutants containing high levels of food waste/plant and animal tissue, oil and other chemicals.
A typically large cargo ship will generate an average of 8 tonnes of bilge water for each 24 hours of operation. To maintain ship stability and eliminate potentially hazardous conditions from oil vapours in these areas, the bilge spaces need to be flushed and periodically pumped dry (as shown in the pictures below). However, before a bilge can be cleared out and the water removed, the oil that has been accumulated needs to be extracted from the bilge water, after which the extracted oil can be reused, incinerated, and/or offloaded in a port. If a separator, which is normally used to extract the oil, is faulty or is deliberately bypassed, untreated oily bilge water could be discharged directly into the ocean, where it can damage marine life. A number of cargo ships, as well as cruise liners have been charged with environmental violations related to this issue in recent years.
A typically large cargo ship will generate an average of 8 tonnes of bilge water for each 24 hours of operation. To maintain ship stability and eliminate potentially hazardous conditions from oil vapours in these areas, the bilge spaces need to be flushed and periodically pumped dry (as shown in the pictures below). However, before a bilge can be cleared out and the water removed, the oil that has been accumulated needs to be extracted from the bilge water, after which the extracted oil can be reused, incinerated, and/or offloaded in a port. If a separator, which is normally used to extract the oil, is faulty or is deliberately bypassed, untreated oily bilge water could be discharged directly into the ocean, where it can damage marine life. A number of cargo ships, as well as cruise liners have been charged with environmental violations related to this issue in recent years.
Ballast Water:
Ballast water removal by cargo ships can have a negative impact on the marine environment. Cargo ships/carriers, cruise ships and large tankers use a huge amount of ballast water, which is often taken on in the coastal waters in one region/geographic location after ships discharge wastewater or unload cargo, and then removed at the next port, wherever more cargo is loaded. Ballast water removal typically contains a variety of biological materials, including plants, animals, viruses, and bacteria. These materials often include non-native, unnecessary invasive, exotic species that can cause extensive ecological and economic damage to aquatic ecosystems along with serious human health problems. Although ballast water looks very similar to bilge water, each are disposed of through different filters within the actual ship and through different exits. As you can see from the images below and above, bilge water comes out near the very bottom of the sides of the cargo ship, whereas ballast water comes out higher up in the sides of the cargo ship.
International Regulation:
Some of the major international efforts in the form of agreements are the Marine Pollution Treaty, Honolulu, which deals with regulating marine pollution from cargo ships, and the UN Convention on Law of the Sea, which deals with marine species and pollution. While plenty of local and international regulations have been introduced throughout maritime history, many of the current regulations are considered insufficient. "In general, the treaties tend to emphasise the technical features of safety and pollution control measures without going to the root causes of sub-standard shipping, the absence of incentives for compliance and the lack of enforceability of measures."In the Caribbean, many ports lack proper waste disposal facilities, and so many ships dump their waste at sea.
Cleaning:
Grey-water is wastewater from the sinks, showers, galleys, laundry, and cleaning activities aboard a cargo ship. It can contain a variety of pollutant substances, including detergents, oil and grease, metals, organic compounds, petroleum components, nutrients, food waste, and medical and dental waste. Sampling done by the EPA (Environmental Protection Agency) and the state of Alaska found that untreated grey-water from cargo ships, as well as cruise liners can contain pollutants at variable strengths and can contain levels of bacteria several times greater than is typically found in untreated domestic wastewater. Grey-water has potential to cause adverse environmental effects because of concentrations of nutrients and other food wastes, in particular.