Activation analysis of the elements of very small amounts in Tone-river water system

Several methods of pretreatment for the activation analysis of environmental water samples were investigated, and the results of applying such pretreatment to the water in the riverhead regions of Tone-river and Tamagawa-river are reported. The water samples were concentrated to about one tenth of the original volume with a rotary evaporator, and pretreated as follows. The concentrated river water corresponding to one litre of original volume was dried with an infrared lamp. The elements that cannot be determined with the residue were pretreated by Fe(CH)3 and PbS coprecipitation methods. The samples were irradiated with the F-ring (thermal neutron flux of 2x1012n.cm-2.sec-1 of the TRIGA-II reactor in Rikkyo University. The activated samples were measured with the 4096 or 1024 channel pulse height analyzer connected to a Ge(Li) detector. As the result of gamma-ray spectroscopy, there was no interference effect of Fe and Pb coprecipitation agents utilized in ferric hydroxide coprecipitation and lead sulfide coprecipitation. It was possible to determine the elements that were difficult to determine from the evaporation residual samples. Other elements were determined from the evaporated residual samples. As the results of analysis of Tone-river and Watarase-river water, the determination of twenty four elements were possible. At the region of inflow of mining drain, the concentrations of Zn, Mn, Cu and Co as well as Sb were higher than the upstream regions. (Iwakiri, K.)