5 NATURAL ABUNDANCE OF THE STABLE ISOTOPES ... - Falw.vu

Stable Isotopes of Hydrogen, Carbon and OxygenIn Volume 3 (Surface Water) certain circumstances will be discussed leading to deviationsfrom the common MWL. For instance, larger values of d are occasionally observed.Apart from this, deviations occur in evaporating surface waters, showing slopes of 4 to 5rather than 8. If 2 o and 18 o denote the original isotopic composition of an arbitrary surfacewater, the values after evaporation are related by:2 - 2 o 4.5 ( 18 - 18 o ) or 2 4.5 18 (7.35)(Fig.7.18). The release of relatively low- water vapour to the air results in a increase in ofthe remaining water, as illustrated by the model of Sect.4.4.5, here for 2 as well as 18 .123