Dataset: Trace metal concentrations of lake water, river water, and groundwater at Lake Tahoe from 2013 to 2016

Water depth profile samples from Lake Tahoe were collected seven times at different seasons between the Spring of 2013 and Summer 2016. Van Dorn bottles (Wildco Beta Plus acrylic 2.2 L, with no metal parts that touch the sample) were used for water collection at depths of 50, 100, 150, 200, 250, 300, 350, 400, and 450m and a one-liter HDPE bottle attached to a 2.5-meter long plastic rod was used to collect surface water samples. Samples were collected at the Mid-lake Tahoe Profile (MLTP) station (39.09231° N; 120.00275° W). From each depth, one liter of water was dispensed into an acid-washed sample rinsed LDPE bottle for trace metals and Pb isotope analyses as described in Chien et al. (2017). Groundwater samples were obtained from two wells at the Lake Tahoe fire station and three wells at the Hatchery, and river water samples were collected from Third Creek, Trout Creek, Upper Truckee River, Ward Creek, Incline Creek, Blackwood Creek, and General Creek. All water samples were filtered with acid washed 0.45 μm filters (SupaPore) before nutrient, trace metal, and Pb isotope analyses. Samples for trace metal and Pb isotopes analyses were acidified to pH < 2 with concentrated double distilled nitric acid. MilliQ water blanks were also collected and analyzed similarly.

Due to low trace metal concentrations in the lake water, about 200 mL of each water sample was first dried down on a hotplate and then reconstituted with 10 mL 2% HNO3 for concentration analyses (20-fold concentration increase). TSP total and soluble trace metal concentrations, and lake, river, and groundwater trace metal concentrations of Al, V, Cr, Mn, Fe, Co, Ni, Cu, Cd, and Pb were analyzed by a High Resolution Inductively Coupled Plasma Mass Spectrometry (Element XR) with triple detector mode. Instrument calibration was done using gravimetrically prepared multi-element standards in the range of concentrations represented by our samples.