Contamination of large areas of soil by harmful products from agriculture, industry, cities and mining has occurred over the last few decades. The European Environment Agency has estimated that the total costs for the clean-up of contaminated sites in Europe would amount to €109 billion. Traditional remediation methods such as digging and isolation are being supplemented by methods using microbial activity or phyto-management that promise to be cheaper and have less unintended side effects.

An example for a contaminated soil and/or area is the Spanish study site Guadiamar. In April 1998, by the breaking of a dam around a waste basin, about 4 hm3 of acid waters and 2 hm3 of mud, rich in heavy metals, were released into the Agrio and Guadiamar rivers affecting more than 4,600 ha of agricultural and pasture land. A time-lapse animation see from satellite can be viewed below.