| Summary: | The PARTNERS and Arctic-GRO projects sample the biogeochemistry of the six largest rivers draining to the Arctic Ocean. To the greatest extent possible, sample collection techniques are identical across rivers. Once collected, samples are returned to Woods Hole, MA, from where they are shipped to expert laboratories for analyses. Sample collection is as follows: PARTNERS Project (2002-2006): The PARTNERS sampling protocol was modeled on the USGS equal discharge increment sampling protocol. Five depth-integrated samples were collected across the river channel on each sampling date using a USGS D-96 depth-integrating sampler fitted with a Teflon nozzle and Teflon collecting bag. The samples were combined in a 14-L Teflon churn to form a composite sample to account for within-river vertical and horizontal heterogeneity. Under-ice samples were collected near the water surface, from a single, mid-channel hole in the ice. The Arctic Great Rivers Observatory (Arctic-GRO) Project (2009-2011): The Arctic-GRO sampling protocol followed the PARTNERS protocol. On each river, samples were collected five times per year: three during the freshet, one during late summer, and one under ice. In addition to this "comprehensive" collection of data five times per year, samples were also collected daily during the freshet and analysed for a subset of constituents. The daily freshet samples were collected from directly beneath the water surface using a polycarbonate collection bottle. The Arctic Great Rivers Observatory II (Arctic-GRO II) Project (2012-2016): The Arctic GRO II project collects targeted 'surface' and 'deep' samples. Samples are collected bi-monthly (every two months). During open water conditions, surface samples are collected from immediately below the water surface from three points across the river channel and composited. Under ice, surface samples are collected from a single, mid-channel hole in the ice. Deep sample collection began in summer, 2013. Deep samples are collected mid-channel, from a recorded depth.
|
|---|