Abstract: 7120 A. Introduction

1. Occurrence

Water may contain gamma-emitting radionuclides from a variety of sources. Naturally occurring radionuclides from terrestrial and cosmogenic sources may enter groundwater and surface water via precipitation, erosion, geochemical processes, or industrial activities (e.g., those related to mining and refining geologic material). Anthropogenic (human-made) radionuclides may be introduced as a byproduct of nuclear power generation, nuclear weapons testing and development, nuclear medicine applications, or other industrial processes. For more information about the occurrence of natural and anthropogenic radioactivity, see Section 7110 A.1.