Release of nitric oxide and iodine to the atmosphere from the freezing of sea-salt aerosol components.

The known room-temperature, solution-phase reaction between nitrite ions and iodide ions, which occurs in acidic conditions (pH < 5.5), is shown to be accelerated when neutral aqueous solutions are frozen. The reaction is proposed to occur in liquid "micropockets" within the ice structure at temperatures between the freezing point and the eutectic temperature.

Spectroscopic and optimization modeling study of nitrous acid in aqueous solution.

Nitrous acid (HONO) and the nitrite ion represent a particularly important conjugate pair of trace species with regard to heterogeneous behavior within the bulk, and on the surface, of aqueous atmospheric dispersions: this role results from their chemical reactivity, photolysis pathways, solubility, and ambient concentration levels. The actual ratio of NO(2)(-): HONO in solution is determined by the pH and the nitrous acid dissociation constant (pK(a)) which is generally quoted in the literature as 3.27 at 298 K.

Freezing halide ion solutions and the release of interhalogens to the atmosphere.

The effect of freezing on a variety of acidified and neutral, nitrite ion and halide-containing mixtures has been investigated using UV/vis spectroscopy. Several trihalide ions were formed and monitored, including I(2)Cl(-), I(2)Br(-), ICl(2)(-) and IBr(2)(-). A mechanism to explain the observations is given in terms of steps involving INO and the nitroacidium ion, [H(2)ONO](+).