Determination of ~(99)Tc in Natural Water: Bio-sensoring Versus Direct Analysis

摘要

The artificial element ~(99)Tc β~― -emitter, E_(β~―, max) = 292 keV, t_(1/2) 2.13 x 10~5 y) is released in the aquatic environment by discharges from nuclear industry, and the 1960s bomb testing programs. Information on the actual ~(99)Tc concentrations in natural waters is difficult to obtain, mainly due to the low ~(99)Tc abundance and the large water samples needed in analytical procedures. Information on the ~(99)Tc presence may also be derived from ~(99)Tc accumulation in water plant species such as Fucus serratus L, which concentrate ~(99)Tc up to a factor of 10~4. Although in a strictly analytical sense direct analysis of ~(99)Tc in water is preferable, the associated practical problems mean that bio-sensor plants may deserve a relevant position in routine ~(99)Tc analysis. This paper discusses the applicability of bio-monitor plants, set in the context of the analytical survey. It is shown that plant physiological models concerning Tc accumulation are necessary to make firm decisions of the biomonitor properties and the plant-environment relationships of potential biomonitor plant species.