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Determining groundwater Ra end‐member values for the estimation of the magnitude of submarine groundwater discharge using Ra isotope tracers
Author(s) -
Cho HyungMi,
Kim Guebuem
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl068805
Subject(s) - submarine groundwater discharge , groundwater , aquifer , seawater , geology , isotope , salinity , radium , hydrology (agriculture) , submarine , environmental science , groundwater discharge , oceanography , groundwater flow , chemistry , physics , geotechnical engineering , quantum mechanics , radiochemistry
Radium isotopes ( 228 Ra and 226 Ra) are excellent tracers of submarine groundwater discharge (SGD). To estimate SGD magnitudes, information on the end‐member values of Ra concentrations in groundwater is critical; however, the distribution characteristics of Ra in coastal aquifers are poorly understood. In this study, we show that Ra concentrations in coastal groundwater are primarily dependent on salinity based on the data ( n > 500) obtained from global coastal aquifers, although previous end‐member calculations averaged all Ra concentrations without considering salinity. If we assume that SGD is composed mainly of seawater infiltrating the aquifer, previous estimates of SGD for the Atlantic Ocean and the global ocean were overestimated twofold to threefold. This may be similar for other applications using different Ra isotopes. Our study highlights that the end‐members of Ra isotopes in groundwater should be carefully considered when estimating SGD using Ra isotope mass balances in the ocean.