Accumulation of Radionuclides by Plants as a Monitor System

Abstract

The accumulation of radionuclides by plants acting as a monitoring system in the environment may occur by two modes; foliar absorption by the leaves and shoot ofthe plant, or by root uptake from the soil. Data on plant accumulation of radionuclides may be obtained from studies of fission product radionuclides deposited as worldwide fallout, and from tracer studies of plant physiology.The epidermal features of plant foliage may exert an effect upon particle retention by leaves, and subsequent uptake of radionuclHdes from the surface. The transport of radionuclides across the cuticle and epidermis of plant leaves is determined in part by the anatomy of the leaf, and by physiological factors.The foliar uptake of fallout radionuclides, "'Sr, 131I, and 137Cs, is described with examples from the scientific literature. The environmental half-life of 131I, for example, is considerably shorter than its physical half-life because of physical and biological factors which may produce a half-life as short as 0.23/day. 9'Sr and 137Cs are readily taken up by the leaf, but '37Cs undergoes more translocation into fruit and seeds than "°Sr which tends to remain in the plant part in which it was initially absorbed.Soil-root uptake is conditioned primarily by soil chemical and physical factors which may selectively retain a radionuclide, such as '37Cs. The presence of organic matter, inorganic colloids (clay), and competing elements will strongly affect the uptake of 9°Sr and 137Cs by plants from the soil.The role of plants as monitors of radionuclides is twofold: as monitors of recent atmospheric releases of radionuclides; and as indicators of the long-term behavior of aged deposits of radionuclides in the soil.

10.1007/s11183-008-1001-8

“…However, Sr, like Ca, seems unable to move along the phloem [38,151,152] or this ability is strongly reduced. These tissues participate in the long-distance transport of metal ions.…”

“…Both Sr and Ni were observed in the phloem elements (Figs. However, Sr and Ca are seemingly unable of phloem translocation [38,151,152] or this capacity is strongly reduced. The feasibility of Ni transport along the phloem was shown previously [150].…”

Uptake by plants of radionuclides from FUSRAP waste materials

“…Radionuclides could reach foliar surfaces by means of fugitive dust emissions from remedial action activities with subsequent deposition of contaminated particulate matter on adjacent vegetation. Radionuclides adsorbed on the surface of particles retained on plant foliar surfaces are likely to be available for foliar uptake and subsequent accumulation (Koranda and Robison 1978). However, techniques intended to minimize fugitive dust emissions (e.g., water sprays) are likely to be employed during remedial action activities.…”

“…On the basis of research with various trace metals, it can be concluded that the solubilization of radionuclides is determined largely by the form and concentration of the radionuclides involved as well as by the physicochemical characteristics of soil. Important soil characteristics include: soil solution composition; conductivity; pH; quantities of various clays and humic, fulvic, and other organic complexes present; type and density of charge on soil colloids; soil organic matter concentration and composition; and amount of reactive surface area (Cataldo and Wildung 1978;Koranda and Robison 1978). These phenomena are in turn dependent upon other properties of soil such as: particle size distribution; quantity and reactivity of hydrous oxides, carbonates, phosphates, sulfates, and other anions; mineralogy; degree of aeration; and microbial activity.…”

ACCUMULATION AND RETENTION OF LEAD BY CATTAIL (TYPHA DOMINGENSIS), HYDRILLA (HYDRILLA VERTICILLATA), AND DUCKWEED (LEMNA OBSCURA)

“…[6] Water hyacinths can also remove and retain heavy metals from aquatic systems. [11] In most cases, the removal of toxic metals does not have a fatal impact on the plants, and the metals are incorporated and sequestered from the immediate environment. [9,10] Even radionuclides can be taken up and accumulated by plants.…”