This is somewhat outside my field, but a quick search found that the current literature estimates are between 0.4-1.7 x 10^11 g/year accumulation. That's around a hundred billion grams. Two references are: Ceplecha, Zdenek, Astronomy and Astrophysics 311(1):329-332 (July 1996) and Wasson & Kyte, 1987 Geophysical Research Letters, 14:779, 1987
As to atmospheric mass loss, one recent reference is: Ski, K, Elphic, RC, Hirahara, M, Terasawa, T, and Mukai, T, "On Atmospheric Loss of oxygen ions from earth through magnetospheric processes", Science, 2001, Mar 9:291(5510):1939-41. They estimate that over three billion years the net loss of oxygen (the only ion they address) amounts to about 2% of the current atmospheric oxygen content -- about an order of magnitude lower than earlier estimates because of channeling of these ions back into the atmosphere by the magnetosphere.
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