Isotopic peculiarities of meteoric water in polar regions

It is demonstrated that the slope m and the intersect q of the regression line δD = m δ18O + q describing the correlation between δD and δ18O in precipitation water of typical global climatic zones are in the normal range of m = 7 to 9 and q = 8 to 12 with one pronounced exception. Meteoric water in nothern polar and arctic zone is distinguished by normal m value (7.68) and an extremely low a value (4.50). This anomaly is probably due to the fact that the arctic ice cover prevents the formation of that particular surface layer the evaporation of which produces the common source of meteoric water with δD = -22 permill and δ18O = -4 permill. (author)