AIR-WATER EQUILIBRIUM OF HEXACHLOROCYCLOHEXANES AND CHLOROMETHOXYBENZENES IN THE NORTH AND SOUTH-ATLANTIC

We have measured the meridional changes of the concentrations of four semivolatile organochlorinated compounds (SOCs) in the air and the surface water of the Atlantic Ocean between 50 degrees N and 50 degrees S. The surface water of the North Atlantic Ocean is undersaturated with alpha-hexachlorocyclohexane (alpha-HCH), gamma-hexachlorocyclohexane (gamma-HCH), tetrachloro-1,4-dimethoxybenzene, and pentachloromethoxybenzene (PCA), especially for limited inputs by continental air. The South Atlantic is close to a gas-water exchange equilibrium for these four compounds. This is indicated by the plots of the logarithm of the concentrations in air versus the inverse of the absolute temperature and by the comparison of the-measured contents in air and water. Particularly under conditions of a diminuishing input of SOCs from continental sources, the air-surface water equilibrium will render the oceanic system to a global nonpoint source of anthropogenic compounds in marine air.