HR: 0830h
AN: OS11A-05    [Abstracts]
TI: Particulate and Dissolved 210Po and 210Pb in Water Columns from the East and West of the Luzon Strait
AU: * Su, Y
EM: ycchung@mail.nsysu.edu.tw
AF: Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung, 80424 Taiwan
AU: Chung, Y
EM: ycchung@mail.nsysu.edu.tw
AF: Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung, 80424 Taiwan
AB: The Luzon Strait between Taiwan and the Luzon Island is where the Kuroshio intrudes into the South China Sea (SCS). Its deep sill depth (about 2200m) also allows transport and exchanges of the deep water and its properties between the SCS and the West Philippine Sea (WPS). During a recent cruise (October, 2004) conducted for biogeochemical studies in the Luzon Strait area, water samples were collected and filtered on board for measurements of 210Po and 210Pb in both the particulate and dissolved phases in attempt to decipher the transport and exchange processes via the distribution of these and other radionuclides, including 226Ra and 228Ra. This paper is to focus on the 210Po and 210Pb distributions at a location east of the Strait (St. 5) along the Kuroshio path and a location west of the Strait (St. F) in the northeast SCS. 210Po was determined by alpha counting of the auto-plated Po isotopes, including a known 209Po spike and the 210Po from the sample. 210Pb was then determined on the same sample by re-purifying for either alpha counting of the re-grown 210Po or beta counting of 210Bi, the energetic beta emitter of 210Pb daughter. Preliminary results show that the dissolved 210Po is higher at St. F than at St. 5 within the upper 1000m layer with a maximum at both stations around a few hundred meters depth, suggesting a contribution from dissolution on decomposition of sinking organic particulates. Below 1000m depth the dissolved 210Po is lower at St. F than at St. 5, but its values are fairly constant with depth at each station. The particulate 210Po at St. F is fairly uniform at about 8 dpm/100kg which is much higher than any open ocean deep water values and is also higher than our previous results (about 5 dpm/100kg). As the particulate concentrations vary between about 0.1 and 0.3 mg/kg, the specific 210Po activity of these particulates may range from 270 to over 1000 dpm/g. Results on 210Pb in both phases of these samples will be presented together with the corrected 210Po data for the discussion of their status of radioactive disequilibrium at the Joint Assembly Meeting.
DE: 1050 Marine geochemistry (4835, 4850)
DE: 4835 Inorganic marine chemistry
DE: 4850 Organic marine chemistry
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly