Vengosh Avner, Hirschfeld Daniella, Vinson David, Dwyer Gary, Raanan Hadas, Rimawi Omar, Al-Zoubi Abdallah, Akkawi Emad, Marie Amer, Haquin Gustavo, Zaarur Shikma, Ganor Jiwchar
Division of Earth and Ocean Sciences, Nicholas School of the Environment, 205 Old Chemistry Building, Box 90227, Duke University, Durham, North Carolina 27708, USA.
Environ Sci Technol. 2009 Mar 15;43(6):1769-75. doi: 10.1021/es802969r.
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.
在约旦迪西砂岩含水层鲁姆组的低盐度和有氧地下水中，检测到了高含量的天然存在且具有致癌性的镭同位素。镭 - 228和镭 - 226的总活度比国际饮用水标准高出2000%。对砂岩含水层岩石的分析表明，镭 - 228和镭 - 226的活度及比率与世界不同地区砂岩岩石的先前报道一致。对全球砂岩含水层地下水中先前数据的汇编显示，无论地下水盐度如何，镭的活度都有很大差异。基于四种镭同位素的分布以及短寿命与长寿命镭同位素的比率，我们推测地下水中镭的活度受含水层固体中母钍同位素的放射性衰变、溶解镭同位素的衰变以及溶解镭在固体表面的吸附之间平衡的控制。因此，取决于含水层岩石中粘土含量的表面吸附位点的可用性是砂岩含水层中镭活度的一个重要限制因素。这些发现引发了对这种及类似不可再生地下水库安全性的担忧，加剧了中东地区本就严峻的水危机。
