Data sets of isotopes of different water bodies at different altitudes in Qilian Mountains
From April 2016 to October 2018, four multi-water bodies sampling sites (A: Foothill, B: Arbor belt, C: Shrub belt, D: River source) were established in the XYR Basin. A total of 867 various types of samples were collected from the upstream mountainous regions.
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For precipitation, the researchers installed rainfall sampling devices at each sampling site. Precipitation samples were based on precipitation events. The sample collector bottles were placed two meters above ground level to avoid contamination during sample collection. The researchers poured the collected rainwater into the sampling bottle. If the precipitation event is snow, it was collected into a sampling bottle after the snow melted. For runoff, the container was placed under the water surface until the container was filled. A total of 82 runoff samples was collected at different altitudes (Table 1). For soil water, soil samples were collected from 10 cm to 100 cm, using soil spirals every 10 cm. All samples were placed in 100 mL polyethylene vials. A total of 450 soil samples were collected (Table 1). For plant water, during the sampling process, researchers selected typical vegetation from each sampling site each month and used scissors to cut the xylem or branches of the same vegetation into parts of equal length and then put them into a sampling bottle. A total of 90 plant samples were collected (Table 1). All samples were stored in a mobile freezer (-5°C), and transferred to a freezer laboratory (-15 °C) in a week from collection time. The samples were melted at room temperature (20~25°C) before further analyze. The plant and soil water were extracted using a cryogenic vacuum distillation apparatus (LI-2100, LICA United Technology Limited, China) for analysis. All 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 isotope ratio of samples was expressed as parts per mil (‰) relative to the Vienna Standard Mean Ocean Water (V-SMOW) using δ notation: δ(‰) = (RS/RV-SMOW-1)*1000, where δs is the isotope ratio of the samples relative to V-SMOW and Rs is the ratio of D/H or 18O/16O in the samples. The precision of measurement was ±0.6% for δ2H and ±0.2% for δ18O, respectively. Meteorological data were obtained from four weather stations in the corresponding observation point of the XYR basin. These weather stations record meteorological data such as temperature, precipitation, wind speed, evaporation, relative humidity, and soil moisture. Local meteorological elements are observed and recorded every 15 minutes.