UN Enviroment Programme

Chapter 2. Main soil contaminants and their fate in the soil environment


The development of effective remediation techniques and regulatory safeguards to soil pollution depends on thorough knowledge of the nature of soil contaminants and the fate in the environment. This chapter illustrates that in many cases this fundamental scientific knowledge is still incomplete.

There is strong scientific consensus about the dangers of soil pollution by trace elements. Concerns about trace elements began in the mid twentieth century, and since that time extensive research has been undertaken on toxicity and environmental fate as well as on remediation techniques to ameliorate potential toxicity issues. These contaminants are not, however, of merely historical interest; in many developed countries, considerable legacy pollution persists and (as will be seen in Chapter 3) pollution caused by trace elements continues to grow in all societies that lack strong regulatory controls on soil protection.

Pollution due to radioactive contamination first featured strongly in societal consciousness with the 1945 atomic explosions in Hiroshima and Nagasaki and global contamination during the period of open-air weapons testing. Considerable legacy pollution from uranium mining to produce nuclear weapons also exists with concern for additional contamination by accidents in nuclear power facilities also widespread.

The risk from organic contaminants in soils have been with us for decades. While the dangers posed by many often legacy contaminants with known toxicity is regulated by global governance measures such as the Stockholm Convention, newer organic contaminants remain understudied. A growing number of organic contaminants are classified as emerging concerns in soil pollution research, and much less is understood about fate and behavior. The rapid expansion in products used, particularly pharmaceutical, personal care products and pesticides, has outstripped the ability of the scientific community to fully research the threats posed, both singly and in combination with other compounds, to allow comprehensive risk assessment and regulation.