An Introduction to Aquatic Toxicology - Chapter 2: What Causes Aquatic Contamination?

Elsevier, An Introduction to Aquatic Toxicology, 2014.
Nikinmaa, M.

The chapter details the most common aquatic contaminants. In addition to listing contaminants, the reader is first reminded that contaminants affect both climate change and ocean acidification by affecting the efficiency of photosynthesis of oceanic microalgae, which carry out almost half of global photosynthesis. Thereafter, it is pointed out that the toxicity of a compound is related not only to its amount in the environment but also to its water and lipid solubility affecting the uptake route, the fugacity of the compound (i.e. its tendency to dissociate from the matter it is currently associated with and associate with other constituents of the environment), its transformation—occasionally the transformed products are more toxic than the parent compound, and finally the complex formation, which often reduces the toxicity of a compound. A listing of toxicants is then made according to toxicant type, with an emphasis on which is the main source or use of the toxicant class. Thus, pesticides, pharmaceuticals, and paper- and pulp-mill effluents, for example, are treated each as one entity, although each group has several types of compounds having different modes of action. Further, contamination is understood broadly encompassing both radiation and genetically modified organisms. The problems associated with defining the toxicity of nanomaterials are highlighted. Chemical contaminants are broadly divided into inorganic and organic categories, with metals being the major inorganic contaminants. The chapter then considers the major uses of the toxicants and their routes to the environment. The reasons why the contaminants may affect organisms are also briefly introduced.