Under the Microscope: Readers often ask me where I get ideas for my articles. In fact anything can trigger an idea. For example, friends recently told me they had spent some time at the Dead Sea, writes William Reville
The buoyancy of the Dead Sea is such that floating is an involuntary matter. You can sit down and lean back in the water just as you would in an armchair and read the newspaper or a book as you float about. I decided to look further into this subject.
The Dead Sea is situated on the border between the West Bank, Israel, and Jordan on the Jordan Rift Valley, part of the Great Rift Valley. The surface of the Dead Sea is the lowest exposed point on the Earth's surface at 417.5 metres below sea level. The sea is 76 km long, up to 18 km wide and 400 metres deep at its deepest point.
The lake is closely associated with biblical history and is recently most famous for the discovery of the Dead Sea Scrolls.
The Great Rift Valley extends from Turkey to South Africa. This valley formed many million years ago in the Miocene epoch when the Arabian tectonic plate moved northward and then eastward away from Africa.
About three million years ago the valley of the Dead Sea was flooded by waters from the Mediterranean Sea. The water collected in a narrow bay connected to the sea.
About two million years ago the land between the Mediterranean and the Rift Valley rose so that the sea could no longer flood the area. The long bay eventually became a lake and this was the origin of the Dead Sea.
The Dead Sea is fed mainly by the River Jordan which enters the lake from the north. The lake has no outlet but the inflow of fresh water is rapidly removed by intense evaporation in the hot desert climate. When the water evaporates, salts remain behind making the Dead Sea the saltiest and most mineral-laden water in the world - nearly 10 times as salty as the ocean.
The salts include sodium chloride, magnesium chloride, potassium chloride, magnesium bromide and many other substances. Because of this high salt concentration, anyone can float easily in the Dead Sea due to the natural buoyancy. It is difficult to swim however because your arms and legs don't want to stay submerged in the buoyant water. The water has a greasy feel and it will sting cuts and cause irritation if it gets into your eyes. The area around the Dead Sea is of increasing interest to health researchers for various reasons.
The Dead Sea water contains 21 minerals and 12 of these are found in no other sea or ocean. It is claimed that some of these minerals cause relaxation, nourish the skin, stimulate the circulation and ease rheumatism and metabolic disorders.
Other therapeutic advantages offered by the Dead Sea region include the low content of pollens and other allergens in the atmosphere, the reduced harmful ultraviolet (UV) component of solar radiation, and the high atmospheric pressure at this great depth. Sunlight at the Dead Sea is lower in UV radiation because the particularly thick atmospheric layer above the Dead Sea has a strong filtering effect on UV. It is said that sunlight at the Dead Sea is particularly helpful for people who suffer from psoriasis. Also people who suffer reduced respiratory function, such as those with cystic fibrosis, seem to benefit from the increased atmospheric pressure.
The sea is called "dead" because it contains no life except for a small quantity of microbes. Fish carried into the Dead Sea by the River Jordan die as soon as the freshwater mixes with the strong salt waters.
However, the freshwater doesn't mix immediately with the saltwater and can float for a considerable time on the surface of the Dead Sea. Until the mixing takes place, the freshwater fish can continue to live in the floating freshwater layer.
The Dead Sea area is a very ancient area of civilisation. Jericho, just north of the Dead Sea is the oldest continually occupied town in the world. The biblical cities of Sodom and Gomorrah are believed to lie beneath the lake. Aristotle wrote about the unusual waters of the Dead Sea. During the Egyptian conquest, Queen Cleopatra got exclusive rights to build cosmetic-making facilities there.
Jesus Christ, John the Baptist and Herod the Great were closely linked with the Dead Sea area. Later, the Essenes settled in Qumram on the northern shore of the Dead Sea. They hollowed out storage caves in the soft rock for their library, which was found 2,000 years later and is commonly known as "The Dead Sea Scrolls".
Since the 1960s water inflow to the Dead Sea from the Jordan River has been reducing because of large-scale irrigation and low rainfall. The Dead Sea is rapidly sinking and unless measures are taken could become a thing of the past. It is unrealistic to stop using the River Jordan for human needs, so Israel has committed to bring water to the Dead Sea by building a canal from the Red Sea which, along the way, will service the needs of Jordan also. In May 2005, Jordan, Israel and the Palestinian authority agreed to begin feasibility studies on the project.
The scheme will produce 870 million cubic metres of fresh water (the desalination plant will be constructed in Jordan) and 550 megawatts of electricity a year.
William Reville is associate professor of biochemistry and public awareness of science officer at UCC