Abstract
This is a study on the ratios of 236U/238U in a coral core sampled at Europa Island in the southern Mozambique channel, spanning the period from 1940 through 2012. The primary aim of the work was to obtain a record of variations and trends of these ratios in the local sea water and link them to known nuclear bomb tests (mainly in the Pacific Ocean), fallout from which might have reached this region via the prevailing ocean currents, and assess any significant delays which could characterize ocean currents. Values close to 10-9 for the ratio were obtained on the oldest samples from the core, representing the pre-nuclear test era. This is ca. 2 orders of magnitude higher than published values obtained on Caribbean pre-nuclear coral core, and analyses of a prenuclear standard (Vienna KkU) during this work. This indicates some contamination in the chemical sample preparation. Probably due to this high background, no anomalies were observed prior to 1960 although US nuclear tests were carried out in the 1950’s in the Pacific Proving Grounds of the Marshall Islands, and British tests is south Australia. A single very high value (5.94 ×10-7) obtained for 1988 is believed to result from contamination by a hot particle. Disregarding this, the results obtained show two anomalies that are considered real as they rise and fall over several years. ..
M.Sc. (Geology)