Radium is a naturally occurring radioactive element commonly found at low levels in natural systems such as lacustrine or marine sediments. Anthropogenic activities including former uranium mining activities can lead to the dissemination of radium isotopes having high radiological toxicities, which potentially threaten the safety of nearby environments. Although radium mobility in oxidized environments is known to be largely governed by sorption/desorption onto Fe and Mn oxyhydroxides and coprecipitation with sulfate minerals (e.g. barite), little is known regarding its behavior under reducing conditions, which are the conditions typically encountered in organic-rich systems such as wetlands and lake sediments.

The present study aims at understanding the behavior of long-lived radium isotopes (²²⁶Ra and ²²⁸Ra), during early diagenesis of lake sediments contaminated by former uranium mining activities. Solid and pore water concentrations of ²²⁶Ra and ²²⁸Ra were determined using ultra low background gamma spectrometry, which allowed improvement of detection limits and measurement accuracy.

This study shows that the downcore distribution of radium isotopes is closely related to the reductive dissolution of iron and manganese oxyhydroxides below the sediment-water interface. The resulting diffusive fluxes of ²²⁶Ra and ²²⁸Ra (4.1 10⁻²⁵ and 4.7 10⁻²⁸ mol cm⁻².s⁻¹) are however significantly lower than other radium-impacted environments, such as uranium mill tailings pond and phosphate industry-impacted sediments, and are similar to those reported for natural marine environments. Hence, in the reduced lake sediments of Saint-Clement, the major fraction of radium is trapped by the solid phase, while early diagenesis only induces a slight mobility of this radioelement.

镭是天然存在的放射性元素，通常在诸如湖泊或海洋沉积物的自然系统中含量低。人为活动，包括以前的铀矿开采活动，可能导致具有高放射毒性的镭同位素的传播，这有可能威胁附近环境的安全。尽管众所周知，在氧化环境中镭的迁移率主要受羟基和氢氧化铁和锰的吸附/解吸以及与硫酸盐矿物质（例如重晶石）的共沉淀的控制，但人们对还原条件下的行为知之甚少，而还原条件是有机硅中通常遇到的条件。丰富的系统，例如湿地和​​湖泊沉积物。

本研究旨在了解在被前铀矿开采活动污染的湖泊沉积物早期成岩过程中长寿命镭同位素（²²⁶ Ra和²²⁸ Ra）的行为。使用超低本底伽马能谱仪测定了²²⁶ Ra和²²⁸ Ra的固体和孔隙水浓度，这可以提高检测限和测量精度。

这项研究表明，镭同位素的下层分布与沉积物-水界面以下的铁和氢氧化锰铁的还原溶解密切相关。但是，所产生的²²⁶ Ra和²²⁸ Ra的扩散通量（4.1 10 ^-25和4.7 10 ^-28  mol cm ^-2 .s ^-1）显着低于其他受镭影响的环境，例如铀厂尾矿池和磷酸盐工业-受影响的沉积物，与报告的自然海洋环境相似。因此，在圣克莱门特减少的湖泊沉积物中，大部分镭被固相捕获，而早期成岩作用仅引起该放射性元素的轻微迁移。