Basics of Environmental Sampling and Analysis - Fundamentals of Environmental Sampling and Analysis - page 14

2.1.2 Common Organic Pollutants
and Their Properties
There are an estimated total of 7 million chemicals with approximately 100,000
present in the environment. The number of chemicals commonly considered as
important environmental pollutants, however, is likely a few hundred. Among them,
few are routinely measured in environmental laboratories. A smaller list of
''priority'' chemicals has been established by various organizations based on
selected factors such as quantity, persistence, bioaccumulation, potential for
transport to distant locations, toxicity, and other adverse effects (Mackay, 2001).
Such chemicals receive intense scrutiny and analytical protocols are always
available.
The Stockholm Convention, signed by more than 90 countries in Sweden in
May 2001, listed 12 key persistent organic pollutants (POPs). Commonly known as
''the dirty dozen'', the POPs are aldrin, chlordane, DDT, dieldrin, endrin, heptachlor,
hexachlorobenzene, mirex, toxaphene, PCBs, dioxins, and furans. Most of the 12
key POPs are no longer produced in the United States, and their uses in developing
countries have also declined. Of the 12 chemicals, 10 were intentionally produced by
industries and 9 were produced as insecticides or fungicides. Only two of the 12
chemicals, dioxins and furans, are unintentionally produced in combustion
processes (Girard, 2005).
The U.S. EPA published 129 priority pollutants (114 organic and 15 inorganic)
in water. Many other countries have similar priority pollutant lists reflecting their
pollution sources and monitoring priorities, such as the black and grey list by the
European Union in 1975 and the black list by China (58 organic and 10 inorganic).
The lists should be regarded as dynamic. For instance, the number of drinking water
contaminants regulated by the U.S. EPA has increased from about five in 1940 to
more than 150 in 1999 (Weiner, 2000). Appendix B is a list of 114 organic pollutants
on the U.S. EPA priority list. Their chemical structures, molecular weights, and
aqueous solubilities are also provided in this appendix.
Important chemical pollutants can be divided into nine categories based
primarily on their chemical characteristics. Figure 2.1 lists the structure of several
important organic compounds by their functional groups.
1. Element: Metals (Cu, Zn, Pb, Cd, Ni, Hg, Cr) and metalloids (As, Se)
2. Inorganic compounds: Cyanide, CO, NOx, asbestos
3. Organo-metallic and metalloid compounds: Tetraethyl lead and tributyl tin
4. Hydrocarbons: Saturated and unsaturated aliphatic and aromatic hydrocar-
bons including BTEX compounds (benzene, toluene, ethylbenzene, and
xylene) and polycyclic aromatic hydrocarbons (PAHs)
5. Oxygenated compounds: Alcohol, aldehyde, ether, organic acid, ester,
ketone, and phenol
6. Nitrogen compounds: Amine, amide, nitroaromatic hydrocarbons, and
nitrosamines