2.2 Sampling and laboratory analysis
From
April 2015 to October 2017, the researchers conducted monthly
multi-water bodies sampling work in the Xiying River Basin (Fig.1;
Table1). The 655 precipitation, reservoir water and river water were
collected for this research (Fig.1; Table1).
For reservoir water sampling, the bottles were first flushed with runoff
water 3 times, then each bottle was placed under the water surface until
three quarters of the volume of the bottle was filled. The two sampling
bottles were continuously collected by means of the above method. Before
the experiment, all the collected samples were stored in the freezer
(-5℃). The researchers installed a precipitation collection device to
collect samples from the collection device at 20.00 (Beijing time). If
the precipitation was snow, it was filled into the vial after it had
naturally melted at room temperature indoors in the laboratory.
All
the samples were analyzed using a liquid water isotope analyzer DLT-100
(Los Gatos Research, Inc.) in the Stable Isotope Laboratory, College of
Geography and Environmental Science, Northwest Normal University. The
precision of measurement is ±0.6% for δ D and ±0.2% forδ 18O, respectively. The isotope ratio of the
samples was expressed as parts per mil (&) relative to the Vienna
Standard Mean Ocean Water (V-SMOW): δ (‰) =
(R S/R V-SMOW-1) ×1000.
Table 1 Date for sampling station