Survey Metadata

Helicopter-supported sample collection was carried out during July of 1996 in the North Gataga survey area, northern Kechika Trough, British Columbia.  A sediment sample and a water sample were collected at each site using a float-equipped Bell 206 helicopter.  A total of 471 lake sediment and water samples were collected from 445 sites at an average sample site density of 1 site per 11.2 km².

Sediments were sampled using a Hornbrook-type torpedo sampler and samples placed in large Kraft paper bags.  Some departures from standard national Geochemical Reconnaissance (NGR) sampling strategies were incorporated particularly pertaining to overall site density and the number of sites sampled in each lake.  First, every lake in the survey area was sampled rather than sampling only a selection of lakes at a fixed density.  Secondly, centre-lake sediment samples were collected following standard NGR procedure, but sediment from the centres of all major known or inferred sub-basins was also collected.

The data are published in BC Open File 1997-15/GSC Open File 3499.

An additional 250 mL lake water sample was also collected for more extensive multi-element ICP-MS analysis.  These samples were collected at every second sediment site for a total of 235 sites at an average density of approximately one site per 21.3 km².  These supplementary water data are published in BC Open File 1999-6/GSC Open File 3704.

This survey was carried out using National Geochemical Reconnaissance (NGR) protocols.

Lake water samples were collected in 250 mL Nalgene bottles using a custom-designed sampling apparatus.  Waters were sampled from approximately 15 cm below the lake surface and precautions were taken to minimize suspended solids.