Global perspectives on quartet radium isotopes in lakes

Area of Science:

• Geochemistry
• Environmental Science
• Hydrogeology

Background:

• Lake-groundwater systems are vital for ecosystems and human activities.
• Global radium (Ra) distribution, radiation risks, and salinization tracing remain understudied.
• Understanding Ra dynamics is crucial for managing water resources and assessing environmental risks.

Purpose of the Study:

• To characterize ionic composition and Ra dynamics in global lake-groundwater systems.
• To assess radiation risks associated with elevated Ra activities.
• To utilize Ra isotopes for tracing salinization timescales and understanding aquifer-lake interactions.

Main Methods:

• Integrated data retrieval and geochemical analysis of ~50 global lake-groundwater systems.
• Development of Ra transport models for saline and freshwater lakes.
• Application of a modified ²²⁶Ra-Ba-Cl mass balance model to quantify salinization timescales.

Main Results:

• Saline lakes (SO₄·Cl-Na-type) dominate arid basins, while freshwater lakes (Ca·Mg-HCO₃-type) are in humid catchments.
• Elevated Ra activities exceeding US drinking standards were found in ~29% of samples, posing radiation risks.
• Salinization timescales were quantified for Lake Urmia and Daqaidam Lake (15.4-17.3 ky) using Ra-based models.

Conclusions:

• Radium isotopes serve as effective tracers for global radiation risk mapping and aquifer-lake dynamics.
• Lacustrine groundwater discharge and saline lake water intrusion are significant hydrological processes.
• The study provides a framework for managing brine resources and assessing hydrological resilience.