Abstract
This paper shows for the first time a field-based estimation of the volume of dispersive density-driven long-term seawater circulation in coastal aquifers, which is crucial to the understanding of water-rock interaction and to the assessment of its potential impact on elemental mass balances in the sea. The Dead Sea is an ideal place for studying this type of circulation due to the absence of tides and the accessibility of the shallow fresh-saline transition zone. The unique antithetical behavior of 226Ra and 228Ra during seawater circulation in the Dead Sea aquifer, where 228Ra is added and 226Ra is removed, provides a robust new method for quantifying aquifer circulation. Here we estimate water circulation through the Dead Sea aquifer to be 400 million m3/yr (~2.5 million m3/yr per 1 km of shoreline), which is ~20% of the fresh water inflow prior to the 1960s. This large volume can affect trace element concentrations in the Dead Sea, e.g. it is a sink for 226Ra, Ba and U and a source for 228Ra and Fe. These results suggest that dispersive density-driven seawater circulation in aquifers may play an important role in mass balances in other lacustrine and oceanic settings.
Original language | English |
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Pages (from-to) | 146-158 |
Number of pages | 13 |
Journal | Earth and Planetary Science Letters |
Volume | 394 |
DOIs | |
State | Published - 15 May 2014 |
Bibliographical note
Funding Information:We thank the Hoffman Leadership & Responsibility Fellowship and the Rieger-JNF Fellowship for their support. We thank the Israel Ministry of National Infrastructure for funding this study. We thank William C. Burnett and Kirstin Eller (FSU) for the 228 Ra measurements by γ -spectrometry. We thank A. Katz, E. Morin, Y. Kolodny, I. Gavrieli, B. Lazar, M. Stein and Y. Rosenthal for fruitful discussions. We thank U. Ryb, M. Feldman, A. Abbo, H. Luzki, H. Hemmo, B. Rophe and U. Galilee for technical help. We thank O. Yoffe and D. Stiber for the trace element analysis. We thank N. Lensky for the the Dead Sea expeditions.
Keywords
- Dead Sea
- Radium
- Seawater circulation in aquifers