Distribution, residence time, and fluxes of tetrachloroethylene and 1,4-dichlorobenzene in Lake Zurich, Switzerland

A 1-year study of tetrachloroethylene and 1,4-dichlorobenzene in Lake Zurich, Switzerland, has been conducted. The seasonal distribution of the compounds reflects the circulation in the lake and is compatible with the assumption derived from laboratory studies that mass transfer to the atmosphere is the predominant elimination mechanism. A mass balance for 1,4-dichlorobenzene has been established for the central basin of the lake, and an average residence time of approximately 5 months has been found. By applying a simple steady-state model, an average annual mass transfer coefficient of 1 cm/h is obtained for the transport of 1,4-dichlorobenzene and tetrachloroethylene from the lake to the atmosphere.