Harbors, Environmental Issues of

Water Pollution

Water pollution can take many forms. It can be caused by ships deballasting (discharging ballast) before being loaded for a voyage. Ships use ballast to maintain stability during a voyage from one port to the next. They take water on board from one region and travel to another, where they discharge it before taking on cargo. However, a major concern with ballast water is that it can contains aquatic organisms, examples of which include jellyfish, zebra mussel, small crustaceans, and phytoplankton that are not native to an area and for which there are no natural predators. This has become an increasing problem with larger ships traveling greater distances more rapidly. With faster journeys, organisms are more likely to stay alive long enough to infest another region.

Ballast water can also contain toxic substances, such as heavy metals, chemicals, and oily substances that are suspended in the water being taken on board. Ballast has also, in the past, included the use of large stones taken on board in one country and thrown over the side when the ship arrives at its destination. While not necessarily as great a problem as the organisms and toxic substances in ballast water, those stones can still cause problems in ports, particularly if they are deposited in sufficient numbers to alter currents, tidal flows, or cause a physical blockage.

Another cause of pollution in ports is the deliberate discharge of waste from ships, despite international action to prevent it. In many ports, particularly in developing countries or countries where environmental protection is not high on the agenda or in very poor areas, it remains the practice for waste to be dumped into the water. This may be in a river where the waste washes down to the sea, or it may be in a port or harbor where dumping is quick and easy or there are no [Page 673]facilities into which the waste can be discharged. Oily water is produced in the engine rooms of ships and small boats, and it has been common for this to be thrown into a harbor; many small fishing harbors may have a dark ring around them at the high-water mark, which is the result of floating oily waste being left behind as the water level drops. Other things dumped into the water include garbage, plastics, packaging, old fishing nets and floats, together with sewage and the remains from fish processing done at the quayside.

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