Contaminated soils Worldwide. Similar to Europe, industrial activities, agricultural chemicals or improper disposal of waste contaminate soils in other world regions. For example, about 435.000 underground storage tanks in the United States with many of them containing petroleum hydrocarbons of some type have leaked and contaminated soils(Kansas State University, 2005). Nearly 15 million underground storage tanks have been closed since 1984 but the number of sites that need remediation is difficult to estimate. Worldwide, the magnitude of the problem is even much larger but the extent less well known(Kansas State University 2005). Specifically, a comprehensive inventory on the global extent of soil contamination is lacking Agricultural activities contribute to soil degradation and diffuse soil pollution by introducing pollutants or toxic substances like cadmium by application of mineral phosphate fertilizers).