Chemical kinetic mechanism for atmospheric chromium.

A chemical kinetic mechanism for the atmospheric chemistry of chromium has been developed. The chemistry of chromium is of particular interest because its oxidation state is believed to affect its toxicity. Chromium can be reduced from the hexavalent form to the trivalent form by several chemicals including trivalent arsenic, divalent iron, vanadium, and sulfur dioxide. Trivalent chromium can be oxidized to hexavalent chromium by reactions with manganese. Computer simulations were conducted for several scenarios using typical atmospheric concentrations. The simulation results suggestthattypical conditions favor the reduction of Cr(VI) to Cr(III). Under some extreme conditions, Cr(III) could be oxidized slowly to Cr(VI)