Model describing the rates of transfer processes of organic chemicals between atmosphere and water

• Published in: Environmental science & technology Vol. 20; no. 8; pp. 810 - 816
• Main Authors: Mackay, Donald, Paterson, Sally, Schroeder, William H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.08.1986
• Subjects: Applied sciences; Exact sciences and technology; Global environmental pollution; Pollution; Absorption; Atmospheric fallout; Volatilization; Transfer; Mathematical model; Deposition; Organic compounds
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es00150a009

A fugacity model was developed to describe simultaneously the dominant air/water exchange processes. The rates of processes of organic chemical volatilization, absorption at the water surface, dissolution in rainfall and wet and dry particle deposition are described. Correlations were derived for air-particle partitioning and for the washout ratio of organic chemicals as a function of a chemical's physical-chemical properties. Chemicals which had low vapour pressures but high Henry's law constants were subject to considerable cycling between air and water with intermittent periods of intense deposition followed by slower but prolonged volatilization. A steady state, nonequilibrium was achieved, in which the water was supersaturated with respect to the air. At low temperatures these effects were more pronounced. The model was illustrated for a hypothetical organic chemical similar in properties to a polychlorinated biphenyl and at concentrations typical of those encountered in the Great Lakes basin. Results were consistent with the observed behaviour of polychlorinated biphenyls in the basin.