TITLE: HLY-02-01 Moran JOSS Data Final

AUTHOR(S): S. B. MoranGraduate School of Oceanography,University of Rhode Island
Narragansett, RI, 02882Tel : (401) 874-6530Fax: (401) 874-6811
Email: moran@gso.uri.edu 

FUNDING SOURCE AND GRANT NUMBERNational Science Foundation OPP-0124917 

DATA SET OVERVIEW: The data in the accompanying file (HLY-02-03 Moran JOSS Data
 Final.txt) includes data corresponding to samples collected by the Moran
 Geochemistry Lab on the first leg of the SBI Phase II investigation in the
 Chukchi and Beaufort Seas from 09 May 2002 to 12 June 2002 aboard the USCGC
 HEALY (WAGB-20).  Data are organized by station and sample depth, with station
 position (latitude and longitude) also included.This dataset includes the
 following radio-isotopes: 234Th, 228Th, and 238U.  The thorium data includes
 dissolved, suspended particulate, and large particulate values in units of
 disintegrations per minute per liter (dpm/L).  The uranium data was derived
 from salinity (salinity ppt * 0.069 dpm/ppt = 238U dpm/L; Chen et al, 1986). 
 This data set also includes values for large particulate organic carbon (POC)
 and large particulate organic nitrogen (PON).

INSTRUMENT DESCRIPTION: Surface samples were collected using a well-head pump
 (5 m) and the HEALY's flow-through seawater intake system (7 m).  Sub-surface
 samples were collected using Challenger Oceanic Systems and Services (COSS)
 large- volume in-situ pumps.

DATA COLLECTION and PROCESSING: Thorium and large
 particulate organic carbon and large particulate organic nitrogen samples were
 collected by filtering seawater sequentially through a 53 ´m Nitex screen, a 1
 ´m nominal pore size Hytrex-II prefilter cartridge (length: 25 cm), and two 5
 ´m nominal pore size MnO2 adsorber cartridges (length: 8 cm).  Samples were
 collected over a period of 3.5 hours, and volumes ranged from ca. 200-1000 L. 
 Samples were always collected prior to benthic sampling to avoid sampling
 resuspended sediment.After pump retrieval, 53 ´m Nitex screen containing large
 particles was rinsed with Whatman GF/F (0.7 ´m nominal pore size) filtered
 seawater and sonicated for 10 min to dislodge trapped particles.  This
 suspension was then filtered onto a pre-combusted GF/F filter (25 mm diameter).
 In cases where particle loading was large, several GF/F filters were used. 
 Samples were stored frozen in the ships freezer after processing.  At the end
 of the cruise, samples were shipped to URI-GSO.  The filters were then
 sub-sampled for CHN analysis using a Carlo Erba EA 1108 CHN analyzer.  The
 remainder of the filter was analyzed for 234Th using a RIS¯ GM-25-5 beta
 counter.While the Nitex screens were being processed, the prefilter and MnO2
 adsorber cartridges were extracted from the pumps, allowed to drip-dry, then
 placed in tared beakers.  They were then dried at 60íC in a drying oven and
 then ashed at 500íC in a muffle furnace.  The ash weight was determined, then
 scraped from the beaker to a 125 ml Nalgene jar.  The ash was then analyzed 
 for 234Th by gamma detection at 63.3 keV using a Canberra planar detector. 
 For additional methods information, consult Charette and Moran (1999). In the
 shore based lab, 228Th was separated from 228Ra and plated according to methods
 described in Buesseler et al. (1992).  Briefly, MnO2cartridge ash was digested
 with HNO3 and spiked with 229Th yield monitor.  Thorium isotopes were isolated
 using ion-exchange columns (BioRad AG1-X8 resins).  Thorium was the
 electroplated onto 1 cm diameter stainless steel discs.  Activities of 228Th
 were determined by alpha spectroscopy.

DATA FORMAT:Data are presented as a tab-delimited text file named HLY-02-01
 Moran Joss Data Final , as it includes the thorium and large particulate carbon
 and nitrogen data from the spring cruise of the HEALY in 2002.Data are
 organized by collection date, station, and sample depth.  Each column header
 indicates what information is in each column.  Details are outlined in the
 pretext of the data file (Remarks).The following parameters (units in brackets)
 are reported in this dataset:  Date/Time of collection (UTC), Station ID,
 Station number, Latitude (Decimal Degrees), Longitude (Decimal Degrees), Sample
 Depth (m), Dissolved Th-234 (dpm/L), Particulate Th-234 (dpm/L), Large
 Particulate Th-234 (dpm/L), Total Th-234 (dpm/L), Dissolved Th-228 (dpm/ 100
 L), Particulate Th-228 (dpm/ 100 L), Large Particulate Th-228 (dpm/ 100 L),
 Total Th-228 (dpm/ 100 L), U-238 (dpm/L), Large Particulate Organic Carbon
 (´mol/L), and Large Particulate Organic Nitrogen (´mol/L).The following data
 flags were used in the dataset:-99.99=data unavailableThis is data version 2
 and was compiled on 16 March 2005, and is classified as FINAL.

DATA REMARKS:Though preliminary, these 234Th data are nearly finalized.  They
 may be modified slightly as we confirm our detector efficiencies.  The POC and
 PON data are final.   

REFERENCES:Buesseler et al. 1992.  Determination of thorium isotopes in seawater
 by non-destructive and radiochemical procedures.  Deep Sea Research I.  39
 (7/8): 1103-1114.Charette and Moran.  1999.  Rates of particle scavenging and
 particulate organic carbon export estimated using 234Th as a tracer in the
 subtropical and equatorial Atlantic Ocean.  Deep Sea Research II.  46:
 885-906.Chen et al.  1986.  238U, 234U, and 232Th in seawater.  Earth and 
 Planetary Science Letters.  80: 241-251.