Institut national de la recherche scientifique, Eau Terre Environnement Research Centre (ETE-INRS), 490 de la Couronne, G1K 9A9 Quebec, Canada.
J Environ Radioact. 2013 Oct;124:57-67. doi: 10.1016/j.jenvrad.2013.04.006. Epub 2013 May 6.
The aim of this paper is to present the first step of a new approach to make a map of radonprone areas showing different potential radon emission levels in the Quebec province. This map is a tool intended to assist the Quebec government in identifying populations with a higher risk of indoor radon gas exposure. This map of radon-prone areas used available radiogeochemical information for the province of Quebec: (1) Equivalent uranium (eU) concentration from airborne surface gamma-ray surveys; (2) uranium concentration measurements in sediments; and (3) bedrock and surficial geology. Positive proportion relationships (PPR) between each individual criterion and the 1417 available basement radon concentrations were demonstrated. It was also shown that those criteria were reliable indicators of radon-prone areas. The three criteria were discretized into 3, 2 and 2 statistically significant different classes respectively. For each class, statistical heterogeneity was validated by Kruskal-Wallis one way analyses of variance on ranks. Maps of radon-prone areas were traced down for each criterion. Based on this statistical study and on the maps of radon-prone areas in Quebec, 18% of the dwellings located in areas with an equivalent uranium (eU) concentration from airborne surface gamma-ray surveys under 0.75 ppm showed indoor radon concentrations above 150 Bq/m3. This percentage increases to 33% when eU concentrations are between 0.75 ppm and 1.25 ppm and exceeds 40% when eU concentrations are above 1.25 ppm. A uranium concentration in sediments above 20 ppm showed an indoor radon concentration geometric mean of 215 Bq/m3 with more than 69% of the dwellings exceeding 150 Bq/m3 or more than 50% of dwellings exceeding the Canadian radon guideline of 200 Bq/m3. It is also shown that the radon emission potential is higher where a uranium-rich bedrock unit is not covered by a low permeability (silt/clay) surficial deposit.
本文旨在介绍一种新方法的第一步，以制作魁北克省氡潜在排放水平不同的氡高发地区地图。该地图是一种工具，旨在帮助魁北克省政府识别室内氡气暴露风险较高的人群。该氡高发地区地图利用了魁北克省现有的放射性地球化学信息：（1）航空地表伽马射线调查中的等效铀（eU）浓度；（2）沉积物中的铀浓度测量；以及（3）基岩和地表地质。证明了每个单独标准与 1417 个可用地下室氡浓度之间存在正比例关系（PPR）。还表明，这些标准是氡高发地区的可靠指标。这三个标准分别离散化分为 3、2 和 2 个具有统计学意义的不同类别。对于每个类别，通过对等级的 Kruskal-Wallis 单向方差分析验证了统计异质性。为每个标准绘制了氡高发地区的地图。基于这项统计研究和魁北克的氡高发地区地图，在航空地表伽马射线调查中铀当量（eU）浓度在 0.75 ppm 以下的地区，有 18%的住宅室内氡浓度超过 150 Bq/m3。当 eU 浓度在 0.75 ppm 到 1.25 ppm 之间时，这一比例增加到 33%，当 eU 浓度超过 1.25 ppm 时，这一比例超过 40%。沉积物中的铀浓度超过 20 ppm 显示出室内氡浓度几何平均值为 215 Bq/m3，超过 69%的住宅超过 150 Bq/m3，或超过 50%的住宅超过加拿大 200 Bq/m3 的氡指导值。还表明，在富铀基岩单元未被低渗透性（淤泥/粘土）表土沉积物覆盖的地方，氡排放潜力更高。
