Shallow circulation groundwater – the main type of water containing hazardous radon concentration

Abstract

Abstract. The main factors affecting the value of 222 Rn activity concentration in groundwater are the emanation coefficient of reservoir rocks (K em ), the content of parent 226 Ra in these rocks (q), changes in the volume and flow velocity as well as the mixing of various groundwater components in the circulation system. The highest values of 222 Rn activity concentration are recorded in groundwaters flowing towards an intake through strongly cracked reservoir rocks undergoing weathering processes. Because of these facts, waters with hazardous radon concentration levels, i.e. containing more than 100 Bq dm −3 222 Rn, could be characterised in the way that follows. They are classified as radon waters, high-radon waters and extreme-radon waters. They belong to shallow circulation systems (at less than a few dozen metres below ground level) and are contemporary infiltration waters, i.e. their underground flow time ranges from several fortnights to a few decades. Because of this, these are usually poorly mineralised waters (often below 0.2-0.5 g dm −3 ). Their resources are renewable, but also vulnerable to contamination.Waters of this type are usually drawn from private intakes, supplying water to one or at most a few households. Due to an increased risk of developing lung tumours, radon should be removed from such waters when still in the intake. To achieve this aim, appropriate legislation should be introduced in many countries.

222Rn and 226Ra activity concentrations in groundwaters of southern Poland: new data and selected genetic relations

“…These are usually waters with the highest level of 222 Rn activity concentration [36]. The authors took samples from springs, bog springs and seeps, as well as from shallow dug wells (with a few to a few dozen meters in depth), and occasionally also from mine adits and boreholes.…”

Radon in Groundwaters in the Baikal Region and Transbaikalia: Variations in Space and Time

“…Т.А. Прзялибский [Przylibski, 2011] изучил полный спектр вариаций параметра Q, который составил шесть порядков, что позволило разделить все водопроявления на шесть групп: 1 -<1 Бк/дм 3 ; 2 -1-9.9(9) Бк/дм 3 ; 3 -10-99.9(9) Бк/дм 3 ; 4 -100-999.9(9) Бк/дм 3 ; 5 -1000-9999.9(9) Бк/дм 3 ; 6 -≥10000 Бк/дм 3 .…”

“…Уровни содержания радона, определенные нами для Прибайкалья и Забайкалья (15 и 100 Бк/л), близки или совпадают с нижними границами, выделенными в [Przylibski, 2011] для группы 3 (10 Бк/дм 3 ) и группы 4 (100 Бк/дм 3 ). Это свиде-тельствует об объективности существования этих и, вероятно, других обсуждаемых здесь уровней со-держания радона в естественных водопроявлениях.…”

“…Прзялиб-ским [Przylibski, 2011], привлекает своей строгой формализацией (различие уровней на порядок) и в этом отношении может быть базовой для обоб-щенных условий миграции подземных вод в верх-ней части подземной гидросферы. Однако для практических исследований большей значимостью обладают уровни, непосредственно определенные для конкретного региона.…”

222Rn Concentration in Groundwaters Circulating in Granitoid Massifs of Poland

“…This is the reason for common occurrence of 222 Rn in groundwater environment [3,8,9]. The activity concentration of this gas in groundwater is mainly due to the parent 226 Ra content in the reservoir rock and the emanation coefficient of this rock [2,10,11] enabling the 222 Rn formed in it to be released from the structures of rock minerals and grains containing 226 Ra, and then dissolved in water. Therefore, the highest concentrations of radon could be expected in groundwaters flowing through granitoid reservoir rocks.…”