Introduction and basic principles of isotope geochemistry; weathering; isotope geochemistry of river water; isotope geochemistry in the environment; isotopic composition of seawater past and present (Sr, Nd, Pb, Os, Ce); isotope geochemistry of detrital and authigenic clay minerals in marine sediments (Rb Sr, K Ar, O); the Sm N isotope system in detrital and authigenic argillaceous sediments.