Abstract:
A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is
an important requirement for the wider applicability of isotope mass balance methods in atmospheric and
water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique
and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method
based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture
using a class-A drying evaporation pan. We have carried out the study by collecting water samples from
a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap
method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared
the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation
pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare
well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining
time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The
conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may
be examined at other regions for its general applicability.
