Natural Alpha Emitters in Rivers From Andalucia, at the South of Spain

Identification and effects of anthropogenic emissions of U and Th on the composition of sediments in a river/estuarine system in Southern Spain

“…A detailed account of the analytical techniques used for the separation of each fraction from 2 or 3 g (dry weight) of sediment sample is given in l vanovich and Harmon (1992) and Martínez-Aguirre (1991 ).…”

“…Once the fractions were separated, they were spiked with well known activities of 236 U and 229 Tb and the extraction of U-and Th-isotopes was carried out according to the method given in lvanovich and Harmon (1992) and Martínez-Aguirre (1991 ). Finally, U and Th activities are measured by surface barrier or ion implanted Si detector (X-spectrometry.…”

U/Th dating of impure carbonates: 230Th/232Th activity ratios in detrital material

“…This is repeated twice to extract all Th from the organic phase. The Th fraction requires further purification and 15 ml of distilled water is finally used as the inorganic phase to back-extract U from the same organic phase, TBP + Xylene [8], shaking for 5 min followed by a 5-min rest. The process is repeated twice to extract as much U as possible.…”

“…The resin in cleaned with another 20 ml of 7 M HNO 3 . Finally, Th is extracted from the resin with 20 ml of 2 M HCl [8]. This solution is ready for electrodeposition onto a stainless-steel disk.…”

“…The system is connected to a power supply. Electrodeposition [8,9] of U or Th is carried out for 1 h at 1.2 amperes. One min before the hour, 1 ml of ammonia solution 25% is added to the solution.…”