(8)
where R1 is the D/H for one of the reservoirs,αR 1 = R 2 is the D/H for the other reservoir, and R D is the measured bulk ratio. We take α = 1.5, meaning two hydrogens have a D/H ratio fractionated by +500‰ relative to the two other hydrogens. Now the true stochastic ratio, given a priori knowledge of equal contributions from the two pools, is given by the corresponding mole fractions for the two pools, x D(1), x D(2)etc., so Equation (6) becomes: