(2)
According
to the definition of deuterium excess (d) , its calculation can be
seen in the following formula (Dansgaard, 1964).
d =δ D-8×δ 18O (3)
For
δ18Opv
and δDpv, the hydrogen and oxygen isotopes in
precipitating water vapor is difficult to measure directly because of
the dynamic nature of the local atmosphere and strong seasonality
impact. In this study, this was calculated by means of formula 4 (Xu et
al., 2011; Gibson et al., 2008), the vapor–precipitation balance
method, which has been successfully employed in many research studies
for many districts (Gat et al., 1994; Zuber, 1983; Gonfiantini, 1986;
Gibson and Edwards, 2002).