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.