2.2. Sampling
Around NSL and the surrounding rivers, two samplings campaigns were
conducted during nondiversion and diversion water periods (Jul. 2018,
and Jan. 2019). According to the previous monitoring data for sulfates
in NSL (obtained from the Shandong South-to-North Water Diversion
Project Construction Administration), 17 samples were collected during
the diversion water period, including samples from 11 rivers entering
NSL, one from groundwater, one from a transfer channel and four from the
center of the lake; the samples were named Sample 1-17 (S1-S17).
Moreover, 11 samples were collected during the nondiversion water period
(Fig. 2 ). The water samples were filtered through a 0.45-μm
Millipore membrane of cellulose acetate and were hermetically stored in
high-density polyethylene (HDPE) bottles for chemical and isotope
analysis. In addition, a gypsum sample was collected from a large gypsum
mine near NSL.