Abstract
Heavy metals and radionuclides can enter the food chain via cereals and vegetables grown in contaminated soils. In the case of microelements such as zinc, studies have not focused only to assessing its environmental risk, but also to enhancing its uptake by plants as an important growth-limiting factor. In our study, digitalized autoradiograms of whole plants of celery (Apium graveolens L.), tobacco (Nicotiana tabacum L.) and sunflower (Helianthus annuus L.) grown in hydroponic nutrient media spiked with 137CsCl, 60CoCl2 and 65ZnCl2 were used for quantitative determination of uptake, long-distance transport and distribution of Cs+, Co2+ and Zn2+ ions in plant tissues. Results from autoradiography and gammaspectrometry of plants showed, that cesium was translocated to aboveground part of the plants with the shoot-to-root ratio 1.0 : 0.6. On the contrary, cobalt and zinc were more immobilized in roots, with the shoot-to-root ratio up to 1.0 : 3.8. The highest concentration of cesium, cobalt and zinc, expressed in specific radioactivity per unit of leaf surface (Bq/cm2) was found in top, rapidly growing leaves, the lowest concentration in the oldest leaves in low position. Detection limits 3, 2 and 14 Bq/cm2 by using X-ray film
 for 137Cs, 60Co and 65Zn, respectively were obtained. These data correspond to detection limits 10.5 pg Cs+/cm2, 7.2 pg Co2+/cm2 and 785 pg Zn2+/cm2 at specific radioactivity of commercially available 137CsCl, 60CoCl2 and 65ZnCl2. Resolutions 1-2 mm was sufficient for visualization of metal uptake and distribution in roots, stalks, leaves and leaf venation. Obtained data are part of quantitative study of uptake and translocation of both low level-radioactive contamination in plants and microelements applied as fertilizers.
Highlights
Heavy metals are present in soils and aqueous streams as both natural components or as a result of human activity i.e. metal-rich mine tailings, metal smelting, electroplanting, energy and fuel production, intensive agriculture, etc. (RASKIN et al, 1994)
Kinetics of cesium and cobalt bioaccumulation by celery (A. graveolens L.), tobacco (N. tabacum L.) and sunflower (H. annuus L.) hydroponically growing in nutrient media spiked with 137CsCl and 60CoCl2 were described in our previous papers (HORNIK et al, 2005; BARATOVA et al, 2006; VRTOCH et al, 2006; VRTOCH et al, 2007)
Resolution 1-2 mm was sufficient for visualization of distribution in roots, stalks, leaves and leaf venation
Summary
Heavy metals are present in soils and aqueous streams as both natural components or as a result of human activity i.e. metal-rich mine tailings, metal smelting, electroplanting, energy and fuel production, intensive agriculture, etc. (RASKIN et al, 1994). Heavy metals are present in soils and aqueous streams as both natural components or as a result of human activity i.e. metal-rich mine tailings, metal smelting, electroplanting, energy and fuel production, intensive agriculture, etc. (RASKIN et al, 1994). Radionuclides exist in the environment either naturally or artificially by aboveground nuclear testing, nuclear accidents and nuclear power generation (ZHU and SHAW, 2000). Cesium 137Cs (τ = 30.17 y) is produced during the fission of actinides or the neutron bombardment of 133Cs or 136Ba (WHITE and BROADLEY, 2000). Cobalt usually occurs in the environment in association with other metals such as copper, nickel, manganese and arsenic. Background soil cobalt levels range from 1.6
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