  The knowledge of isotopic and elemental abundances of the pristine solar
system material provides a fundamental test of galactic chemical evolution
models, while the composition of the solar photosphere is a reference pattern
to understand stellar abundances. However, spectroscopic or meteoritic
abundance determinations are only possible for an incomplete sample of the 83
elements detected in the solar system. Therefore, only relative abundances are
experimentally determined, with respect to H or to Si for spectroscopic or
meteoritic measurements, respectively. For this reason, the available
compilations of solar abundances are obtained by combining spectroscopic and
meteoritic determinations, a procedure requiring the knowledge of the chemical
modification occurred in the solar photosphere. We provide a method to derive
the mass fractions of all the 83 elements (and their most abundant isotopes) in
the early solar system material and in the present-day solar surface.
Calculations are repeated by adopting the most widely adopted compilations of
solar abundances. Since for a given [Fe/H], the total metallicity depends on
solar (Z/X), a 30% reduction of Z is found when passing from the classical
Anders&Grevesse to the most recent Lodders compilation. Some implications are
discussed, as, in particular, an increase of about 700 Myr of the estimated age
of Globular Clusters. Within the experimental errors, the complete set of
relative solar abundances, as obtained by combining meteoritic and photospheric
measurements, are consistent with the variations implied by the quoted physical
processes. Few deviations can be easily attributed to the decay of long-lived
radioactive isotopes. The huge lithium depletion is only partially explained by
introducing a rotational-induced mixing in the tachocline.
