High Naturally Occurring Radioactivity in Fossil Groundwater from the Middle East

Abstract

High levels of naturally occurring and carcinogenic radium isotopes have been measured in low-saline and oxic groundwater from the Rum Group of the Disi sandstone aquifer in Jordan. The combined 228Ra and 226Ra activities are up to 2000% higher than international drinking water standards. Analyses of the host sandstone aquifer rocks show 228Ra and 226Ra activities and ratios that are consistent with previous reports of sandstone rocks from different parts of the world. A compilation of previous data in groundwater from worldwide sandstone aquifers shows large variations in Ra activities regardless of the groundwater salinity. On the basis of the distribution of the four Ra isotopes and the ratios of the short- to long-lived Ra isotopes, we postulate that Ra activity in groundwater is controlled by the balance of radioactive decay of parent Th isotopes on aquifer solids, decay of the dissolved radium isotopes, and adsorption of dissolved Ra on solid surfaces. The availability of surface adsorption sites, which depends on the clay content in the aquifer rocks, is therefore an important constraint for Ra activity in sandstone aquifers. These findings raise concerns about the safety of this and similar nonrenewable groundwater reservoirs, exacerbating the already severe water crisis in the Middle East.

Radioactivity in drinking water: regulations, monitoring results and radiation protection issues

“…In any case, in such dry areas there are few alternative resources. In southern Jordan, nearby the cited area, the possibility of exploitation of this fossil, non-renewable aquifer has been studied [76].…”

Climate change, water resources, and the politics of adaptation in the Middle East and North Africa

“…This aquifer, known also as Saq aquifer, has been utilized extensively in Saudi Arabia (Lloyd and Pim 1990). The recent discovery of high radioactivity in this aquifer (Vengosh et al 2009) would require, however, further investment for remediation given the health risks associated with long-term consumption of high radium water (ibid). Egypt and Libya are jointly drawing on the Nubian Sandstone Aquifer for irrigation and human consumption.…”

Distinguishing seawater from geologic brine in saline coastal groundwater using radium-226; an example from the Sabkha of the UAE

“…However, clear direct evidence that the model functioned as described, and is currently active, was lacking. Here we use the presence of Ra-226 to provide such primary evidence based on 1) its elevated activity of several hundred to thousands of Bq/m 3 (Becquerels per cubic meter) in subsurface brines (Kraemer and Reid, 1984;Vengosh et al, 2009), 2) near absence in open ocean and coastal seawater (b16 Bq/m 3 , Okubo et al, 1979;Moore et al, 1985;Liu et al, 2010;Su et al, 2010;Ohta et al, 2011;Charette et al, 2013), and 3) lack of supply in significant amounts (as compared to formation brines) by sedimentary grains (b~6 Bq/m 3 ). The presence of radium in significant amounts (greater than a few hundred Bq/m 3 ) in the sabkha brine would therefore be strong evidence for the ultimate source of solutes being from geologic brines, whose accumulation in the sabkha brine, additionally, would have to be recent owing to the geologically short half-life of Ra-226 (t 1/2 = 1601 y).…”