Contaminants1Contaminants are biological, chemical, physical or radiological substances that, in sufficient quantity, will cause adverse effects on living organisms through exposure via air, water, soil, and/or food.1 A naturally occurring element or compound may be deemed a contaminant once it reaches toxic concentrations naturally or through actions by humans. For example, carbon dioxide or hydrogen sulfide of volcanic origins can be toxic to life where they are released. Alternatively, an intact natural ore body may contain trace metals such as copper, cadmium, lead, selenium, zinc, etc., at very low concentrations. However, disturbing the ore body for mining purposes may enhance the release of trace metals at concentrations far beyond what would have been released if it were left undisturbed.2 Salts that are often considered innocuous can become toxic to surrounding landscapes and waters at the elevated concentrations that exist in oil and gas produced waters. Polycyclic aromatic hydrocarbons and volatile organic compounds are by products of petroleum production and without proper containment can be released into air, land, or water.3,4,5

Anthropogenic contaminants are substances not generally found in nature, and have been produced by humans for agricultural or industrial applications. Examples are pesticides applied intentionally to protect agricultural products or polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs), produced as insulating and fireproofing materials, respectively. Once released in the environment, some contaminants degrade quickly while others are persistent and move up through food chains or are picked up by air and water and circulate over wide distances. Toxicological effects in the environment often occur at very low concentrations of these chemicals. Contaminants of emerging concern, such as pharmaceuticals, personal care products and perfluorinated products give rise to concerns about risks to human health and the environment because of their increased presence in surface waters and limited knowledge of their effects at low concentrations in complex mixtures. 6


1993 Photo of the Bunker HIll Superfund Site in the Coeur d’Alene Basin, USA. The majority of the
settlement funds will be dedicated to restoration and remediation at Bunker Hill. Photo credit:
USFWS/Dan Audet

Restoration efforts that target contaminated lands and waters are unique because not only must a remediation effort first focus on contaminant clean-up, but monitoring for the contaminant(s) is often necessary during the restoration phase. These activities may blur the lines between remediation and restoration of contaminated lands and waters and often require multiple regulatory bodies work together to fully address contaminant effects on a site. The restoration of contaminated lands provides additional challenges because the disturbed areas are often large, activities that released the contaminant may be ongoing and difficult to define, and/or the political environment may hamper restoration efforts.



2 Luoma et al Luoma, S.N., J.N. Moore, A.M. Farag, T. Hillman, D. Cain, M. Hornberger, and
abcdefgE. Axtmann. 2008.  Mining Impacts on Fish in the Clark Fork River, Montana: A Field
abcdefgEcotoxicology Case Study, In: The Toxicology of Fishes, edited by Richard T.
abcdefgDiGuilio and David E. Hinton. pages 779-804.





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