Analytical artifacts produced by a polycarbonate chamber compared to a Teflon chamber for measuring surface mercury fluxes.

We found significant differences in mercury fluxes measured with a dynamic surface mercury flux chamber made of Teflon versus one made of polycarbonate. While both materials responded reasonably well when virgin materials were used, the polycarbonate chamber was found to exhibit significant chamber blanks under light after it was exposed to surface mercury fluxes of >100 ng/m2/h. Most significantly, the polycarbonate chamber blocked all wavelengths of light below approximately 320 nm. Given that ultraviolet radiation plays an important role in soil mercury flux, the polycarbonate chamber was found to significantly underestimate observed fluxes from background soil in both high light conditions (by 1-4-fold) and under diffuse, low light conditions (by approximately 10-fold). These results suggest that Teflon produces fewer analytical artifacts in the surface emission of mercury measured with a flux chamber than polycarbonate.