LAUSR

Water resources usually need treatment prior to human consumption as it may contain particles, chemical substances or pathogens that can make it unsafe. Specific treatments are applied to improve water quality and different technologies are currently used in order to guarantee a good enough standard of the drinking water supply. The amount of natural radionuclides dissolved in raw water mainly depends on the specific activities of radionuclides in rocks and soils as well as subsequent interactions between water and rocks. However, radionuclides can also be present attached to particulates or in the form of colloids (Chabaux et al., 2008). Naturally occurring radionuclides consist of primordial nuclides (mainly 238U, 235U, 232 Th decay chains and 40K), as well as cosmogenic nuclides such as 7Be, 3H and 14C. Anthropogenic radionuclides such as 60Co, 90Sr, 137Cs or 239/240Pumay also be present due to nuclear weapons tests carried out in the atmosphere or accidents at nuclear power plants, while radionuclides such as 99mTc or 131I are used in medical applications and can be found in surface waters or sediments (Fischer et al., 2015, 2009; Rose et al., 2013). Thus, depending on water flow characteristics and water