GNWT - Great Slave Lake Water Quality Monitoring Program

Water samples are collected 2-5 samples per year depending on the location of the sample site. Surface water grab samples are collected at ~10 cm – 50 cm beneath the surface into clean sample bottles. Discrete depth samples are collected at some sites, using a Kemmerer water sampler attached to a pre-measured line using a weighted messenger. Field measurements are also taken at site using YSI EXO 2 Sondes. A suite of water samples consists of ~3 L total of water collected into nine clean sample bottles separated by analysis type. All clean sample bottles are triple rinsed in the field with the sample water before filling. Most parameters are collected into PET bottles while trace mercury samples are collected into duplicate clean borosilicate vials using the “clean hands” and “dirty hands” protocol and additionally stored inside a double layer of PE bags. Total metals are preserved in the field to pH < 2 using HNO₃. QA/QC samples include field duplicates in addition to field and travel blanks. After collection in the field, all water samples are kept cool at ~4’C and dark in coolers for transport until delivered to the Taiga Environmental Laboratory in Yellowknife, NT for analyses. Samples are analyzed for a standard suite of > 80 analyses including physical parameters (Specific Conductance, pH, Turbidity, total dissolved solids, total suspended solids), chlorophyll-a, as well as total and dissolved nutrients, metals, major ions, and trace mercury.