This textbook presents the principles and methods for the measurement of radioactivity in the environment. In this regard, specific low-level radiation counting and spectrometry or mass spectrometry techniques are discussed, including sources, distribution, levels and dynamics of radioactivity in nature. The author gives an accurate description of the fundamental concepts and laws of radioactivity as well as the different types of detectors and mass spectrometers needed for detection. Special attention is paid to scintillators, semiconductor detectors, and gas ionization detectors. In order...