Cl2 deposition on soil matrices

Deposition of chlorine gas, Cl-2, on synthetic soil sample matrices was examined in a small chamber to ascertain its potential significance as a chemical sink during large-scale releases. The effects of organic matter, clay and sand mass fractions of the soil matrix, soil packing, and exposure to ultraviolet (UV) light on the observed Cl-2 deposition were examined. Organic matter content was found to be the dominant soil variable investigated that affected Cl-2 deposition; all other variables exhibited no measurable effect. Analytical results from the top 8.5 mm of soil columns exposed to Cl-2 were fit to a simple kinetic model with six adjustable parameters. The kinetic model included two reactive bins to account for fast- and slow-reacting material in the soil matrices. The resulting empirical equation agreed with the data to within a factor of two and accurately predicted results from soil mixes not used to optimize the adjustable parameters. Total Cl-2 deposition, assuming a penetration depth of 8.5 mm, was calculated to be as high as 160 metric tons per square kilometer for soil with an organic content of 10%, and inferred deposition velocities were as high as 0.5 cm/s for organically rich soil. Published by Elsevier B.V.