Environmental evaluation of radioactivity levels and associated radiation hazards in groundwater around the WIPP site

Characterizing 226Ra and its daughters in coastal zone groundwater of a typical human-activity affected bay: occurrence, safety, and source evaluation

Due to their extremely toxic properties, 226Ra and it daughters (222Rn, 210Pb, and 210Po) in drinking groundwater require monitoring. Recent studies have reported exceptionally high levels of natural 210Po (up to 10,000 Bq/m3), 226Ra, and 222Rn isotopes in groundwater. This study aims to provide background data on 226Ra and its daughter radionuclides in the typical agricultural-industrial Dongshan Bay (DSB) before the construction of Zhangzhou Nuclear Power Plant (Zhangzhou NPP). The measurement results indicate that no abnormally high activities of 210Po and 210Pb were detected in the investigated wells. Strong positive correlations between 210Pb and 210Po, as well as between 222Rn and 210Pb activities, suggest that the origins of 210Pb and 210Po in groundwater are strongly influenced by the decay of the parent radionuclides 222Rn and 210Pb, respectively. In the DSB coastal zone groundwater, significant deficiencies of 210Po relative to 210Pb and 210Pb relative to 222Rn were observed, providing further evidence that 210Po and 210Pb are also effectively scavenged due to their geochemical properties (specifically particle affinity) within the groundwater-aquifer system. A systematic comparison among all relevant water bodies in the DSB revealed that the activity concentrations of 210Pb and 210Po in groundwater were the highest, except for rainwater. Based on the evaluation of 210Pb sources, the results imply that submarine groundwater discharge (SGD) is an important pathway for transferring radionuclides (such as 210Pb) from land to the nearshore marine environment, even though the study area has a lower 210Pb background groundwater. By considering all the 210Pb's sources in the DSB, we found low 210Pb background groundwater discharge still needs to be taken into account for small-scale bays. This is because SGD was calculated to be one of the most important 210Pb sources in the bay during observation season. Regardless of whether the system is in a normal state or a nuclear accident emergency state, greater attention should be paid to the groundwater discharge of radionuclides into the ocean.

Environmental radiological baseline in unconventional oil and gas areas of Mexico

Environmental radioactivity study was performed in unconventional hydrocarbons areas for the first time in Mexico, where four unconventional hydrocarbon exploratory wells (UHEW) are planned. This study assesses natural radiological conditions in areas around UHEW. Equivalent dose rate distribution displayed in Geographic Information System (GIS) had a maximum of 1.83 mSv a-1 and minimum of 0.04 mSv a-1, GIS was also used for introducing land usage, water resources and population occupancy. Measurements of gross alpha and gross beta in water were below the national permissible limits for drinking water 0.5 and 1.0 Bq L-1 respectively, even though samples do not correspond to drinking water. Evaluation of 238U and 226Ra in groundwater were below minimum detectable concentration 1.3 and 1.0 Bq L-1, respectively. This study provides a radiological baseline for the impact of future industrial activities, especially if exploitation of unconventional hydrocarbons produces naturally occurring radioactive material.