Environmental impact of some NORM industries in Mexico

Abstract

Industrial activities associated with metal mining, extraction and processing of oil and gas, power generation using fossil fuels, among others, may concentrate natural radionuclides in various products, by-products and wastes. Radiological implications of naturally occurring radioactive materials (NORM) generated by human activities need to be taken into account to control exposure to workers, public and the environment. Concerning these types of industries in Mexico, in this work we present the radiometric characterization of different materials with naturally occurring radioactive contents; wastes generated by silver mining in Xichú, environmental soils affected by and an industrial complex (oil refining, power generation and manufacture of agrochemicals) in Salamanca and produced waters from the oil and gas industry in Monclova. The activity concentrations of radionuclides from the natural series 238U and 232Th, besides 40K in the analysed samples have been determined by gamma-ray spectrometry and alpha-particle spectrometry. The levels of radioactivity found in Xichú and Salamanca are of the order of the values found in soils not affected by human activities, indicating that the NORM environmental radiological impact of these industries is very low. On the other hand, the activity concentrations of natural radionuclides, mainly 226Ra and 228Ra, in produced waters from Monclova showed values up to a thousand times higher than those found in natural waters, with a variable radiological impact in the region. A periodic radiometric monitoring is required to ensure a proper control of the produced waters and limit the potential radiological environment contamination.