Radium Isotopes Reveal Seasonal Groundwater Inputs to Cockburn Sound, Western Australia

The mass balance and activity ratios of naturally occuring radium (Ra) isotopes (223Ra, 224Ra, 226Ra, 228Ra) were investigated in Cockburn Sound, W.A. to further understand submarine groundwater discharge (SGD) into this coastal water.

Water samples from 11 marine stations and 20 groundwater sites (encompassing three aquifer layers) were analysed for Ra at four times, at the end of winter (September 2003), early summer (December 2003), late summer (March 2004) and mid-winter (July 2004).