Sediment profiles of 210Pb and 226Ra, radio-isotopes from the 234U decay series with half-lives of respectively 22.3 and 1600 year, were measured in multicores collected from the DISCOL Experimental Area in the Peru Basin during SO242-1, for determining biological mixing rates integrated over a ~100 year time-scale. Total 210Pb and 226Ra activity were determined directly by gamma-spectrometry, whilst total 210Pb was also measured indirectly by alpha-spectrometry via its granddaughter isotope 210Po. Activities of anthropogenic 137Cs proved to be generally below detection level. Radionuclide activities are reported in the data base as mBq g-1 dry sediment.
For alpha spectrometry measurement of 210Po, 0.5 g of freeze-dried and homogenised sediment contained in a plastic reaction tube was spiked with 1 ml of a standard solution of 209Po in 2M HCl, and then leached for 6 h in 10 ml of concentrated HCl heated to 85ºC. After diluting the fluid with 45 ml of demineralised water and adding 5 ml of an aqueous solution of ascorbic acid (40 g L-1), natural 210Po and added 209Po were collected from the fluid by spontaneous electrochemical deposition on silver plates, which were suspended in the fluid for at least 16 h while the fluid was heated to 70ºC. The Po isotopes collected on the silver plates were then measured by alpha-spectrometry using Canberra Passivated Implanted Planar Silicon detectors, with a count time of 1 day sufficient to reduce counting error to < 3%. 210Pb activity was calculated from 210Po, assuming secular equilibrium and correcting for the time elapsed since collection of the samples.
Median Latitude: -7.079800 * Median Longitude: -88.457035 * South-bound Latitude: -7.125400 * West-bound Longitude: -88.526350 * North-bound Latitude: -7.056217 * East-bound Longitude: -88.413767
Date/Time Start: 2015-08-02T21:27:28 * Date/Time End: 2015-08-22T04:21:40
Minimum DEPTH, sediment/rock: 0.0025 m * Maximum DEPTH, sediment/rock: 0.3500 m
SO242/1_108-1 (SO242/1_108-1_MUC 26) * Latitude: -7.074717 * Longitude: -88.448650 * Date/Time: 2015-08-18T00:08:10 * Elevation: -4169.1 m * Campaign: SO242/1 (JPI-OCEANS) * Basis: Sonne_2 * Method/Device: MultiCorer (MUC) * Comment: device position
SO242/1_119-1 (SO242/1_119-1_MUC 31) * Latitude: -7.100550 * Longitude: -88.413767 * Date/Time: 2015-08-20T08:37:35 * Elevation: -4204.1 m * Campaign: SO242/1 (JPI-OCEANS) * Basis: Sonne_2 * Method/Device: MultiCorer (MUC) * Comment: device position
|#||Name||Short Name||Unit||Principal Investigator||Method/Device||Comment|
|1||Event label||Event||de Stigter, Henko|
|2||Depth, top/min||Depth top||m||de Stigter, Henko|
|3||Depth, bottom/max||Depth bot||m||de Stigter, Henko|
|4||DEPTH, sediment/rock||Depth||m||de Stigter, Henko||Geocode|
|5||Lead 210||210Pb||Bq/kg||de Stigter, Henko||total|
|6||Lead 210, error||210Pb e||±||de Stigter, Henko||1s|
644 data points