Biota can uptake and bioconcentrate compounds through vapor phase absorption. For example, leaves exposed to elemental mercury vapors will absorb the mercury into the aqueous phase and the lipid phases of the leaves. Kow for mercury = 4.17. It readily absorbs into lipids and proteins, as well as dissolves into water. Therefore, the LFER describing the equilibrium distribution of elemental mercury between leaves and the vapor phase (Kla = C(leaf)/C(air)) includes terms specifically for the percentage of lipids and water in a leaf. Also, leaves contain air cavities which will include the mercury laden vapor. Kla = a + bKwa + cKoa a= the percentage of leaf that in an air vacuole (0.2), b = the percentage of water in a leaf (0.7), and c = the percentage of lipids in a leaf (0.02). Kwa is the water-air distribution coefficient (i.e. Kh = 9.3 x 10^-2 M/atm at 25 C for elemental Hg) and Koa is the octonal-air distribution coefficient for Hg. If wet leaf density is 890 kg/m^3 and the background mercury vapor concentration is 3 ng/m^3, what is the equilibrium concentration of elemental mercury in the leaf?