Radionuclides and silicate measured on water bottle samples during POLARSTERN cruise ANT-X/6

• Main Author: Friedrich, Jana
• Format: Dataset
• Language: English
• Published: PANGAEA 1997
• Subjects: Agulhas Basin; ANT-X/6; ANT-XI/4; Atlantic Ridge; AWI_Paleo; Conrad Rise; Continuous Flow Automated Analysis (Gordon et al.; 1993; WOCE Tech Rpt 93-1); Cosmonauts Sea; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH; water; DIVERSE; Elevation of event; Event label; Indian-Antarctic Ridge; Latitude of event; Lazarev Sea; Lead-210; standard deviation; Longitude of event; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; Polonium-210; PS22; PS22/857; PS22/868; PS22/872; PS22/876; PS22/877; PS22/879; PS22/886; PS22/891; PS22/895C1; PS22/899; PS22/903; PS22/907; PS22/931; PS22/941; PS22/945; PS22/949; PS22/953; PS22/960; PS22/969; Antarc*; Antarctic; Berichte zur Polarforschung; Cosmonauts sea; Polar Research; Polarforschung; Reports on polar research; Weddell Sea
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.52064; https://doi.org/10.1594/PANGAEA.52064

In this thesis the distribution of 210Po and 210Pb in the upper 600 m of the Antarctic Circumpolar Current and the Weddell Sea was investigated along north-south transects in austral spring and autumn. 210Po and 210Pb can serve as sensitive tracers for the special hydrographic conditions of the Antarctic Circumpolar Current and the Weddell Sea as well as for biological processes during phytoplankton blooms. The 210Po/210Pb disequilibrium was used as a tracer for particle export. This tracer integrates export on a timescale of 276 days because of the 138 day half-life of 210Po and complements the 234Th/238U disequilibrium as another tracer for plankton production arid export on a shorter timescale of several weeks. The distribution of 210Pb and its granddaughter 210Po is determined by the hydrographic conditions, through decay of 226Ra in the water column and low atmospheric 210Pb input, especially in the study area, and is modified by biological processes in the surface water. Low 226Ra activity north of the Polar Front causes low activities of its daughter nuclides 210Pb and 210Po. South of the Polar Front, upwelling Circumpolar Deep Water transports higher activities of the three nuclides into the surface water. The phenomenon of a minimum in total 2l0Po at the base of the euphotic Zone reaching from the Polar Front to the central Weddell Sea was observed in austral spring and fall. It may be a characteristic feature of Antarctic Surface Waters and the following explanations are favoured: - Upwelling of Circumpolar Deep Water with high 210Po activity at the southern boundary of the Antarctic Circumpolar Current and northward advection with the Antarctic Surface Water can cause higher 210Po activity in the southern surface water. A water layer of low motion with more intense scavenging of 210Po by particles may exist at the interface between the southwardly rising Circumpolar Deep Water and northwardly moving Antarctic Surface Water, because of the prolonged water residence time. It is hypothesized that this ...