Determination of Henry’s Law Constant of Formaldehyde as a Function of Temperature: Application to Air–Water Exchange in Tahtali Lake in Izmir, Turkey

Abstract

The Henry’s law constant (H) is an important parameter in predicting the transport, behavior and fate of organic compounds in environment. H is also required to model the air–water exchange of chemicals. Henry’s law constant of formaldehyde (HCHO) was determined at six temperatures (50, 40, 30, 20, 10, and 5°C) using a bubble-column technique. The apparent Henrys law constant (H*) values were strongly correlated to inverse of temperature (1/T, K) and the following relationship was obtained: $$\ln \;H^{{\text{*}}} = {\left( {{{\text{ - 1,641}}{\text{.3}}} \mathord{\left/ {\vphantom {{{\text{ - 1,641}}{\text{.3}}} T}} \right. \kern-\nulldelimiterspace} T} \right)} - 3.089$$ Seven concurrent ambient air and aqueous samples were also collected between October 11–17, 2005 at a sampling site located on the shoreline of Tahtali dam Lake in Izmir, Turkey to determine the magnitude and direction (deposition or gas-out) of HCHO flux. In all cases, the modeled gas-phase flux was positive (average ± SD, 3,181 ± 408 μg m⁻² day⁻¹) indicating that atmospheric HCHO deposited to the Tahtali Lake.