Absorption and translocation of technetium in pea plant

Soil availability, plant uptake and soil to plant transfer of 99Tc—A review

“…This concurs with other reports that activity is considerably less in storage organs and reproductive parts than in vegetative parts (Bell et al, 1988;Dehut et al, 1989;Murphy and Johnson, 1993;Thiessen et al, 1999). Many studies have reported that Tc is readily translocated to above ground plant parts in annuals (Mousny et al, 1979;Cataldo et al, 1989;Dehut et al, 1989;Degenkolb et al, 1994;Woodard-Blankenship et al, 1995). Values of 85-93% of total 99 Tc taken up being transported to shoot tissues have been reported (Mousny et al, 1979;Sheppard et al, 1983;Lembrechts and Desmet, 1984).…”

“…Many studies have reported that Tc is readily translocated to above ground plant parts in annuals (Mousny et al, 1979;Cataldo et al, 1989;Dehut et al, 1989;Degenkolb et al, 1994;Woodard-Blankenship et al, 1995). Values of 85-93% of total 99 Tc taken up being transported to shoot tissues have been reported (Mousny et al, 1979;Sheppard et al, 1983;Lembrechts and Desmet, 1984). The rapid translocation of 99 Tc to plant leaves might be explained by the fact that xylem walls are negatively charged and so do not adsorb anions (Mousny et al, 1979;Woodard-Blankenship et al, 1995).…”

“…Depending on plant species, and source of nitrogen supply, the critical deficiency levels of molybdenum vary between 0.1 and 1.0 µg g Ϫ1 (0.1 and 1.0 ppm) leaf dry weight (Gupta and Lipsett, 1981). A number of Tc studies have shown that roots tend to accumulate a greater proportion of TcO Ϫ 4 than shoots at lower external concentrations than at high ones (Mousny et al, 1979;Cataldo et al, 1989;Dehut et al, 1989;Echevarria et al, 1997). This is also found with Mo concentrations in plants (Marschner, 1995).…”

“…There are active Cl Ϫ transporters that move Cl Ϫ through the root plasmamembrane (White and Broadley, 2001 (Mousny et al, 1979). Manganese is transported into plants in the cationic form (Mn 2+ ) and is relatively immobile within plants (Marschner, 1995).…”

“…Discharges of 99 Tc to the marine environment have received much attention in recent years (Brown et al, 1999) providing added incentive to dispose of 99 Tc in permanent terrestrial repositories. In addition, as part of decontamination and decommissioning assessments, there is current interest in the potential of plants to extract toxic elemental pollutants, including radionuclides such as 99 Tc, from contaminated effluents and soils (Meagher, 2000;Willey et al, 2002 (Pourbaix, 1966;Mousny et al, 1979;Rosetti, 1998 2 ) but with a shift in favour of higher oxidation states. Tc can exist in all valence states from +7 to Ϫ1 but the +7, +4 and 0 states are the most stable (Curtis et al, 1999;Rosetti, 1998).…”