Assessment of thorium in the environment (a review)

Thorium,the radioactive metal,present in natural sediments produced in the form of detritus minerals such as monazite,rutile,granitic complexes,syenitic complexes,thorite,thorianite and progenitor of u,th and ac series. it is used in variety of industrial purposes,medical applications and proposed as fissile material for nuclear energy via production of 233u from 232th. anthropogenic process including modern trends in agriculture causes environmental pollution and also affect the biochemical cycle. however,changes in ph or different redox conditions of rocks enable a fraction of thorium to be released in the environment eventually. this review focuses on the radiochemical techniques,such as alpha,gamma spectroscopy as well as inductively coupled plasma mass spectrometry (icp-ms) that are used for the measurement of thorium. a survey of current research activities intend to control the incorporation of thorium in order to minimize internal doses has been performed.