“…Studies of xenobiotics in the presence of particulate materials, such as desert soils, sand, or silica gel 60-in varying degrees of hydration as a model substance-have shown bathochromic spectral shifts of sorbed anthracene, polychlorinated aromatic compounds, and pesticides (46), moving photochemically active strong bands into the sunlight spectral region. These compounds, and even Freons, showed significant photomineralization to H20 and C02 on surfaces under model conditions (54). Such processes may be significant sinks for fluoro compounds and other materials; they require further study.…”