Asked by: Tina Hayes, Brighton
The Mediterranean Sea is completely enclosed, apart from the 14km-wide Strait of Gibraltar and the 200m-wide Suez Canal, so water cycles very slowly and pollutants tend to accumulate. One third of the world’s shipping passes through the Mediterranean and between them, ships discharge between 100,000 and 150,000 tonnes of crude oil each year. Coastal discharges from industry and cities also result in high concentrations of mercury, cadmium, zinc, lead and untreated sewage. In 2007, a litre of Mediterranean seawater contained 10g of petrochemicals. Recently the Mediterranean has been cleaned up slightly and it is now ‘only’ the third most polluted, behind the Gulf of Mexico and the Baltic Sea.