River (Fig. 6). There are two possible explanations: (1) these waters
are modern recharge waters but are closer to the annual weighted
average of precipitation for northern Primorye (Kharitonova et al.,
2012). Na–HCO3 water was fed by meteoric waters via weakened
fault zones in the northwestern part of the area, where Mesozoic
rocks are exposed as remnants or insignificantly overlapped by
Quaternary deposits or (2) these waters may represent older
groundwater that were recharged under a different (colder) climatic
regime. The fact that a groundwater from 140 m depth and
high TDS in the Razdolnoe Spa is isotopically identical to modern
recharge waters at the Razdolnaya River would support the second
scenario. At the same time, the intricate hydrogeological conditions
of the deposit, presence of confining layers and low water
discharge attest to the complex feeding of the aquifer and, hence,
wide drainage area.
Tritium content in surface waters of the region varies from 4.7
TU to 29.3 TU, average 13 TU and correlates well with 3H concentrations
in atmospheric precipitations (Kharitonova et al., 2012).
Studied Na–HCO3 water sampled from depth of 10 m, contains
12.8 TU, very close to concentrations of tritium in surface waters
of that area, is being formed in conditions of fast water recharge.
At the same time water from the depth of 140 m shows 5.1 TU.
Concentrations of tritium in mineral waters are definitely influenced
by time and intensity of borehole exploitation: when large
amounts of water are being taken, activation of outer areas of
deposit occurs (cone of depression), i.e. a closed system becomes
an opened one, into where waters with different concentrations
of 3H start flowing. This hypothesis is clearly illustrated by data
from being exploiting deposits of mineral groundwater spa of
Primorye (Kharitonova et al., 2012).
High-resolution tritium analyses show very low, but measurable
levels of tritium in all of the confined aquifers located on
the south-west coast of Primorye (Dubinsky, 2014). Because the
age of the water in these aquifers is very old when compared to
the half-life of tritium (12.35 years), there should be no tritium
present within the confined aquifers. The tritium in these deep
aquifers is either due to leakage from other aquifers or to contamination
as a result of the exploitation (casing column problem).
There is an insufficient evidence to distinguish between these
alternatives.