Physical speciation of Pu-239 + 240 and Cs-137 in oligotrophic and organic rich ground water of tropical environment

Laboratory experiments were carried out in oligotrophic and organic rich ground water to study the fractionation of Pu-239 + 240 and Cs-137 in suspended particulate matter and in various dissolved fraction. The experimental solutions were spiked with Pu-239 + 240 and Cs-137 solution. The total concentration of Cs-137 and Pu-239 + 240 in unfiltered water were partitioned into suspended particulates by using conventional filtration assembly. The colloidal components were concentrated with ultra-filtration stirred cell ranging from <0.45 μm to 1.1 nm in six different stages. Fractionation of Cs-137 and Pu-239 + 240 associated with the particulate matter in the size range of 2.7 μm - 0.22 μm in oligotrophic and organic rich ground water are <30% and <20%, respectively. For the dissolved state in the oligotrophic environment, the maximum concentrations of Cs-137 and Pu-239 + 240 were observed in fraction concentrated with ≤1.1 nm. In organic rich ground water, Cs-137 and Pu-239 + 240 were distributed in all the dissolved fractions with a marginally higher concentration associated with 1.6 nm (10,000 NMWL). The possibility of formation of pseudo colloid of Cs-137 and Pu-239 + 240 by complexation with naturally occurring organic and inorganic colloids was investigated in detail