Concentration (fg/kg) of radioactive isotope Thorium-230 (230Th) in the Beaufort Sea at 3 stations in 2007 and at 4 stations in 2009

• Main Author: Roger Francois, University Of British Columbia
• Format: Dataset
• Language: English
• Published: Canadian Cryospheric Information Network 2011
• Subjects: Beaufort Sea; Carbon fluxes; Deep water; Natural radionuclides; Ocean circulation; Water column; International Polar Year-Multi-tracer investigation of the effect of climate change on nutrient and carbon cycles in the Arctic ocean; Arctic; Arctic Ocean; Climate change; International Polar Year; Sea ice
• Online Access: https://dx.doi.org/10.5443/11171; https://www.polardata.ca/pdcsearch/?doi_id=11171

The dataset consists of 230Th concentrations (fg/kg seawater) measured in the Beaufort Sea at three stations in 2007 (Sept 22-Oct 15) and four stations in 2009 (Aug 27 - Sep 12). 20L samples were collected and quickly filtered through an Acropak cartridge (0.45 um). The samples were then acidified to pH 2 with concentrated HCl and spiked with pre-weighed quantities of 229Th and FeCl3. Acidified samples were left to equilibrate for 12 to 24 hours and their pH adjusted to 8-9 to precipitate Fe hydroxide and scavenge 230Th and 229Th. The precipitates were let to settle tover 12 to 24 hours and recovered by suction with a peristaltic pump and centrifugation into a 50 ml centrifuge tube for transport to UBC where they were measured on a Element II ICP-MS. The 2007 station locations were: KC500 (71°05'N, 134°22'W, 6 samples at 6 depths), KC2000 (71°44'N, 135°30'W, 12 samples at 12 depths), and KC2700 (72°28'N, 136°56'W, 12 samples at 12 depths). The 2009 station locations were: L1 (71°06'N, 139°10'W, 12 samples at 12 depths), L2 (74°30'N, 137°00'W, 12 samples at 12 depths), L3 (75°17'N, 137°20'W, 12 samples at 12 depths), and L1.1 (72°31'N, 136°48'W, 12 samples at 12 depths). : Purpose: Variations in seawater 230Th concentration with depth provide information on the flux of particles sinking to the seafloor and deep water circulation. : Summary: Comparing measurements made in 2007 and 2009 to measurements made by others in 1995 will document recent changes in particle flux and carbon sequestration in the deep waters of the Beaufort Sea resulting from a reduction in summer sea ice cover, and changes in deep water circulation in the Arctic Ocean.