TITLE HLY-04-02-DOC.txt & HLY-04-03-DOC.txt Dr D.A. Hansell University of Miami Rosenstiel School of Marine and Atmospheric Science Division of Marine and Atmospheric Chemistry 4600 Rickenbacker Causeway Miami, FL 33149 Tel: 1-305 361-4078 Fax 1-305 361-4689 http://www.rsmas.miami.edu/groups/organic-biogeochem/ N.R. Bates, Bermuda Biological Station for Res. Inc. 17 Biological Lane St George's GE01 Bermuda Tel: 1-441 297-1880 (x210) Fax: 1-441 297-8143 nick@bbsr.edu http://www.bbsr.edu/Labs/co2lab/co2main.html DATA CONTACT Dr D.A. Hansell University of Miami Rosenstiel School of Marine and Atmospheric Science Division of Marine and Atmospheric Chemistry 4600 Rickenbacker Causeway Miami, FL 33149 Tel: 1-305 361-4078 Fax 1-305 361-4689 http://www.rsmas.miami.edu/groups/organic-biogeochem/ FUNDING SOURCE AND GRANT NUMBER = NSF OPP-0124900 DATA SET OVERVIEW Dissolved Organic Carbon. -HLY-04-02 are the data for the SBI Spring cruise (15 May 2002 to 23 June 2002) -HLY-04-03 are the data for the SBI Summer cruise (16 July 2002 to 26 August 2002) Both cruises were in the Chukchi Sea and Beaufort Sea on board the USCGC Healy. Individual data point locations are identified with decimal latitude, longitude and depth (m). INSTRUMENT DESCRIPTION Shimadzu TOC/N-VCSH. References: http://www1.shimadzu.com/products/lab/toc.html DATA COLLECTION AND PROCESSING Samples were collected at most depths of the service hydrocasts. The DOC (dissolved organic carbon) samples were collected approximately 30-60 minutes after the CTD rosette reached the surface by gravity filtration through pre- combusted (450ŃC, 5 hours) 47 mm GF/F filters into acid washed 60 milliliter HDPE bottles. The water samples were stored frozen at -20ŃC until laboratory analysis. DOC samples were analyzed by high temperature oxidation (HTO) using a Shimadzu TOC-VCSH Total Organic Carbon Analyzer. Prior to analysis, the samples were acidified (10 «l of 85% H3PO4 per 10 ml of sample) and sparged with CO2 free ultra pure oxygen (1.5 minutes) to remove any inorganic carbon. One hundred µl of seawater was injected into a quartz combustion tube that was packed with platinum gauze, 10 cm of Shimadzu's regular sensitivity platinum catalyst (7% Pt on alumina balls), and platinum mesh. The combustion column was maintained at 680ŃC, and ultra pure oxygen (150 ml/min) was used as the carrier flow. The system was calibrated using potassium hydrogen phthalate (KHP) as the carbon source. Typical blank values were less than 8 µmol/l. On a daily basis, the blank and deep sea reference water (described below) were analyzed and the system was recalibrated using the KHP standard when the results of these references materials fell outside expected range. Typically, after the system was properly conditioned, recalibration was not necessary until the combustion tube was repacked. Deep Sargasso Sea water (>2000 meters) that had been acidified and sealed in 10 ml ampoules was used as a reference material for this analysis. This reference material has been analyzed by several laboratories and a consensus value (44-46 µmol/l) determined for the organic carbon of this reference. Analyzing this reference material several times per day along with the unknown samples provides a means for assessing instrument performance and the validity of the data. Precision on the analysis was determined to be ÷ 2%. DATA FORMAT Tab delimited ASCII files containing Dissolved Organic Carbon (DOC) and Total Dissolved Nitrogen (TDN) data from the two 2004 SBI Arctic cruises. HLY-04-02 was the spring cruise and HYL-04-03 was the summer cruise. DOC data reported in µmol/liter. DATA REMARKS Quality flag 2 are good data. Missing data are -9999.