Submarine groundwater discharge revealed by 224Ra and 223Ra in Coffs Harbour, Australia
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Submarine groundwater discharge (SGD) is an important link between the land and ocean. In this study, eddy diffusivity coefficients (Kh) and SGD rates were examined off the Jetty Beach in Coffs Harbour (Australia) in September 2017 and 2018. In order to estimate Kh, the apparent age and SGD, two short-lived radium isotopes 224Ra and 223Ra were measured along a shore-perpendicular transect and beach groundwater. Estimated SGD rates were 3.3 and 5.4 cm day−1 in 2017 and 12.7 and 9.3 cm day−1 in 2018, based on average 224Ra and 223Ra groundwater endmember activities. The SGD flow was higher in 2018 due to the combination of a spring tide and rainfall events that took place prior to sampling.
KeywordsSGD 224Ra 223Ra
This study is was conducted as the field work component of the course “Frontiers in Marine Science II—Physical and Chemical Oceanography” at Southern Cross University, National Marine Science Center in 2017 and 2018. CJS was supported by the Australian Research Council (DE160100443) and PGA was supported by the “la Caixa” Fellowship for Post-Graduate Studies, “La Caixa” Banking Foundation (LCF/BQ/AA17/11610004).
Compliance with ethical standards
Conflicts of interest
There were no conflicts of interest in this research (financial or non-financial).
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