• As in the case of PCBs noted above, however, air-water exchange has been shown to dominate contaminant deposition and loss processes in many aquatic systems for a wide range of persistent organic pollutants, including PCBs, PAHs, chlorinated hydrocarbons (HCHs), toxaphene, and PCDDs/Fs.

• The presence of polycyclic aromatic hydrocarbons (PAHs), phenols, chlorinated hydrocarbons, dyes, and heavy metal ions in industrial wastewater adversely affects the quality of fresh water and poses a serious threat to human beings and water-dwelling species.

• Chlorinated water is sometimes used for filter backwashing.