www.nationalgeographic.co.uk 21st September 2010
Some of Brazil’s waterways have become choked with foam following one of the driest summers on record. Last August was the driest month in Brazil since 1943, according to the country’s National Institute of Meteorology. Untreated sewage pumped into rivers such as the Tiete River near Sao Paulo causes the foam which forms when water mixes with phosphates and phosphorus, found in products such as washing powder. The phenomena is a regular occurrence in Brazil throughout the months of June to August as the low water levels in the Summer months concentrate the chemicals. This year has been particularly bad as river levels are the lowest in 47 years. Heavy metals from industrial runoff make the foam toxic causing deformities in aquatic life and poisoning of those that eat it. Although a government clampdown on toxic pollution has reduced the number of heavy metals in Brazil’s waterways since the 1990s, the foam continues due to uncontrolled dumping of raw residential sewage. Scientists at the University of California, Los Angeles have described the Tiete as an “open-sewer”.
Various projects are under way to reduce the foam, such as spraying water on it, but little is being done to tackle the problem at its source.