AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 A Peer Reviewed International Journal of Asian Academic Research Associates AARJMD ASIAN ACADEMIC RESEARCH JOURNAL OF MULTIDISCIPLINARY URANIUM UPTAKE AND TRANSLOCATION IN PLANT M.F. ABDEL-SABOUR* *Nuclear Research Center, Atomic Energy Authority, Abstract Uranium and related radionuclides exist in the environment naturally and, in recent times, have been added by nuclear power and weapons. The carcinogenic nature and long half-lives of many radionuclides make them a potential threat to human health. Plant uptake of radionuclides into the human food chain is one of several vectors used for calculating exposure rates and perregion forming risk assessment Results reveled that U uptake by plants seems to be pH-dependent in most studies. Soil acidity and the saturation condition at the tailings impoundment edge tend to enhance U availability for plant uptake. Uranium transportation in soil is dependent on the direction of the surface or soil water flow when it is soluble and mobile (consequently being bioavailable). This was supported with the finding that migration of U from the contaminant band was substantial only in the sandy soil. Moreover, investigations indicated that adsorption of contaminated water was the main source of the Uaccumulation in the different plant organs. Key words: Food chain, Accumulation, U-translocation, Concentration ratio. Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 262 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 Introduction In addition, phytoremediation has been used to extract radionuclides and other pollutants from contaminated sites. The accuracy and success of these applications depend on an understanding of the processes involved in plant uptake of radionuclides. One important impediment to such understanding is that plant tissue concentrations of radionuclides have rarely shown a linear relationship to radionuclide concentrations in the substrate (soil). One of the pathways neglected in radionuclides risk assessments, which has subsequently been shown to be important in many cases (e.g. Nair et al., 1982; kelly et al., 1983) is the food chain pathway. After Chernobyl accident, all pathways are being investigated, the ingestion pathway to men must be included therefore, the chemical characteristics of the radioactive material become important. Initially, following an atmospheric release to the environment, various radionuclides will be deposited onto plants by wet or dry deposition depending on meteorological conditions, and the point of deposition will depend on a number of factors, including wind speed and radioactive half life. At the point of deposition the chemical form of a particular radionuclide could be very different from that at the time of release, but the processes involved in uptake of the radionuclide into the crop and hence the subsequent ingestion by man will involve folior absorption, root uptake, resuspension and translocation, all dependent on the chemical properties of the particular radionuclide. Plant uptake of radionuclides is one of many vectors for introduction of contaminants into the human food chain. Thus, it is critical to understand soil-plant relationships that control nuclide bioavailability. The contamination of land by naturally occurring radionuclides in the wastes from “nonnuclear” industries is an area of increasing concern. This has led to the introduction of new safety standards to control such wastes. Industries affected by this will include uranium mining and milling, metal or coal mining, radium and thorium factories and the processing of materials containing technologically enhanced levels of natural radioactivity. However, wastes produced previously by these industries are often stored in conditions, which do not meet the more stringent safety standards. Netten and Morley (1983) investigated uranium, molybdenum, copper, and selenium uptake by the radish plant grown on uranium-rich soils. Radishes were grown in the naturally occurring uranium-containing soils found in the Okanagan Valley of British Columbia, Canada. They indicated that bioaccumulation was not observed for U, Cu and, with some exceptions, Se. Mo bio-accumulates readily in the radish. Their data reveled that U and Mo uptake seems to be pH-dependent in this plant. As expected radish roots can be a significant source of U and Mo. Ingestion of radishes from these soils could easily surpass the maximum daily intakes of U set by the Canadian government. The activity concentrations of natural uranium isotopes ( 238U and 234U), thorium isotopes (232Th, 230Th and 228Th) and 226Ra were studied in soil and vegetation samples (Fabaceae, Poaceae and Asteraceae) from a disused uranium mine located in the Extremadura region in the south-west of Spain (Vera-Tome et al., 2002) . Their results characterized radio-logically the area close to the installation and one affected zone was clearly manifested as being dependent on the direction of the surface water flow from the mine. The activity concentration mean values (Bq/kg) in this zone were: 10924, 10900, 10075 and 5289 for 238U, 234U, 230Th and 226Ra, respectively, in soil samples and 1050, 1060, 768 and 1141 for the same radionuclides in plant samples. In an unaffected zone, the activity concentration mean values (Bq/kg) were: 184, 190, 234 and 7251 for 238U, 234U, 230Th and 226Ra, respectively, in soil samples and 28, 29, 31 and 80 in plant samples. The activity concentrations obtained for 232Th and 228Th showed that the influence of the mine was only important for the uranium series radionuclides. The relative radionuclide mobilities were determined from the activity ratios. Correlations between radionuclide activity concentrations and stable element concentrations in the soil samples are a good tool to understand the possible distribution paths for natural radionuclides. Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 263 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 Activity concentrations and plant/soil concentration ratios (CRs) of 239,240Pu, 241Am, 244Cm, Th and 238U were determined for 3 vegetable crops grown on an exposed, contaminated lake bed of a former reactor cooling reservoir in South Carolina, USA(Whicker et al., 1999) . The crops were turnip greens and tubers (cv. White Globe), bush beans (Phaseolus vulgaris) and husks and kernels of sweetcorn cv. Silver Queen. Although all plots were fertilized, some received K2SO4, while others received no K2SO4. The K2SO4 fertilizer treatment generally lowered activity concentrations for 241Am, 244Cm, 232Th and 238U, but differences were statistically significant for 241Am and 244Cm only. Highly significant differences occurred in activity concentrations among actinides and among crops. In general, turnip greens exhibited the highest uptake for each of the actinides measured, while corn kernels had the least. For turnip greens, geometric mean CRs ranged from 2.3 X 10 -3 for 239,240 Pu to 5.3 X 10-2 for 241Am (no K2SO4 fertilizer). For corn kernels, geometric mean CRs ranged from 2.1 X 10-5 for 239,240Pu and 232Th to 1.5 X 10-3 for 244Cm (no K fertilizer). In general, CRs across all crops for the actinides were in the order: 244Cm > 241Am > 238U > 232Th > 239,240Pu. Lifetime health risks from consuming crops contaminated with anthropogenic actinides were similar to the risks from naturally occurring actinides in the same crops (total 2 X 10 -6); however, these risks were only 0.3% of that from consuming the same crops contaminated with 137Cs. 232 Plant uptake of uranium and radionuclides: Morton et al., (2002) investigated the extent of U and Th uptake and cycling by blueberry (Vaccinium pallidum) in native habitat. Also, they identified the soil properties and processes that contribute most to U and Th bioavailability in this natural system. Composite samples of plant leaves and stems, and samples from surface (AE) horizons and from the upper part of the Bs horizon (fragmental, mixed, frigid, Typic Haplorthod) at two sites in New Hampshire, USA were collected. They calculated the concentration ratios (CRs) for U and Th for all plant tissues, using both the AE and Bs horizons as the base. Soil concentrations of U ranged from 16 to 25 µg g-1, with a mean of 21.1 µg g-1. Soil concentrations of Th ranged from 14 to 97 µg g-1, with a mean of 41.8 µg g-1. Mean U concentrations were 8.65 x 10-3 µg g-1 in leaf tissue, and 7.95 x 10-3 µg g-1 in stem tissue. Mean Th concentrations were 1.59 x 10-1 µg g-1 in leaf tissue, and 9.10 x 10-2 µg g1 in stem tissue. They stated that Blueberry plants are cycling both U and Th in this system, with Th cycling occurring to a greater extent than U. In addition, Th was translocated preferentially to plant leaves while U concentrations showed little preferential translocation. Uranium uptake, however, seemed more sensitive than Th uptake to soil properties. Mortvedt (1994) discussed the soil-plant relationships of U, Th and Po. He stated that plant concentrations have been related to total contents of these radionuclides in the soil as a plant/soil concentration ratio (CR), even though the fraction of these radionuclides which may be available to plants and their soil/plant relationships are not well known. CR values have been used to predict transport of radionuclides and other elements through the food chain and for biogeochemical exploration for U. Little information is available on the uptake and transport mechanisms of radionuclides in plants, though recent advances have been made regarding the effects of soil pH, soil texture, and organic matter contents on radionuclide uptake, as well as their mobility in soil. He suggested a mechanisms relating to Ca uptake and translocation in plants and may be similar to those of some radionuclides, especially 226Ra. Lakshmann and Venkateswarlu (1988) investigated U-uptake by potatoes, Raphanus sativus, Lagenaria leucantha [L. siceraria], Solanum melongena and Abelmoschus [Hibiscus] esculentus in pots (spiking the soil and irrigation water with U). Increase in U-uptake was observed with increased U level in water but not in soil. However, the concentration factor for uptake of U by vegetables decreased with increasing U levels in the water. Rice was similarly grown and the Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 264 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 distribution of U within plant parts was measured. They indicated that concentration in the grain was significantly less than in the husk, which was significantly less than in straw. Uptake of 226Ra, 210Pb, and 210Po in mature big sagebrush (Artemisia tridentata) was studied by Simon and Fraley (1986) in the environs of a U mine in Shirley Basin, WY. Radionuclide solutions were injected into the soil to elevate the soil activity while minimizing root disturbance and preventing soil surface contamination. The objectives of this study were to measure the concentration in leaves resulting from root uptake as a function of time and to determine the equilibrium concentration ratio (CR) for each radionuclide. The vegetation was sampled approximately every 90 d for a 2-yr period. The maximum internal plant concentration of 226Ra, 210 Pb, and 210Po was detected at the first sampling (81 d after soil injection for 226Ra, 28 d for 210Pb and 210Po). The concentration in leaves decreased over time following the first sampling to an apparent steady-state value. The steady-state CR values for 226Ra, 210Pb, and 210Po, as determined in mature sagebrush, were approximately 0.04, 0.009, and 0.08, respectively, and were determined as the geometric mean of the CR data pooled over the 2nd-yr period. The CR data were fit by nonlinear least squares to a exponential function that decreased with time to a constant value. In field lysimeters Sheppard et al., (1984) studied plant growth, plant uptake, and the redistribution in soil of U and Cr. The objective of the experiment was to characterize the plant uptake and migration in the soil of U and Cr when placed at different depths in the unsaturated soil zone within the influence of a water table. Total uptake of Cr by the plants was directly proportional to Cr concentration in the soil, over eight orders of magnitude. Thus, independent of the amount of Cr applied, the plant took up a similar fraction, about 0.007. Chromium placement depth in the soil did not influence Cr uptake by the plants although the Cr was relatively immobile in both soils. Plant uptake of U was independent of plant species and U placement depth for loam soil, but highly dependent on placement depth in sandy soil. In the latter, much more U was taken up by the plants when it was placed near the soil surface, implying that uptake was dependent upon root activity. Migration of U from the contaminant band was substantial only in the sandy soil. Dreesen and Cokal (1984) evaluated a technique for assessing the potential uptake of contaminants growing on chemical waste burial sites using several plant species; i.e. Atriplex canescens, Kochia scoparia, barley, lucerne and Melilotus officinalis; growing on uranium mill tailings materials. They noticed that plant availability of Mo, Se, Cl and other trace metals in the waste was greater than in the surface soil from a uranium mining area. They observed a significant differences between spp. in the content of nutrients and contaminants in their aerial parts. Barley contained higher levels of U and much higher levels of Si than the other spp., while lucerne had higher levels of Al, Ba, Co and V and M. officinalis had higher levels of Ba and V than barley. The water table interface is the transition between unsaturated, usually aerated, soil and water-saturated, often anaerobic soil. Plant roots may approach this transition zone and absorb elements soluble in and below the transition zone. Sheppard and Evenden (1985) examined this possibility; elements that differ in solubility were studied as a function of oxidation-reduction potential. Barley (Hordeum vulgare cv. Conquest) was grown in field lysimeters, and treatments included various elements (iron, technetium and uranium plus phosphorus), element placement depths, and water table regimes. Measurements included plant uptake of each element, plant root distribution, and soil profiles of total and extractable amounts of each study element and related elements. They stated that transition from aerobic to anaerobic conditions occurred 10 cm above the water table interface. The mobility of the elements decreased in the order Tc > U > P > Fe. They noticed that the redox gradient markedly modified the mobility of Tc and U. while Fe was more soluble in the reducing environment than in the oxidizing environment, but no migration of Fe was detected. The plant roots were almost entirely confined to the oxidized layers of soil. The plants absorbed no treatment Fe, very little treatment P and U (from the shallow placement only), but substantial amounts of Tc. A fluctuating water table further restricted plant uptake. The water table Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 265 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 interface markedly changed the mobility of some of the studied elements but the effect on rooting depth was more profound. Thus, the water table interface did not present a unique condition for plant roots to absorb elements as the elements diffused upward from the reducing environment. Sheppard nd Evenden (1988) evaluated the major assumption in the use of concentration ratios to describe the transfer of elements in the environment. The ratios examined in detail were the 'concentration ratio' (CR) of leaf to soil and the 'partition coefficient' (Kd) of solid- to liquid-phase concentrations in soil. The 'translocation ratio' of berry to leaf was also computed when possible. Soil was experimentally contaminated to evaluate this linearity over more than a 1000-fold range in concentration. A secondary objective was to determine CR and Kd values in a long-term (2 y) outdoor study using a peat soil and a slow-growing native plant species, blueberries (Vaccinium angustifolium). The elements I, Se, Cs, Pb and U were chosen as environmentally important elements expected to provide a broad range in CR and Kd values. Their results indicated that relationships of leaf and leachate concentrations were not consistently linearly related to the total soil concentrations for each of the elements. A field study was conducted in an area of enhanced natural radioactivity to assess concentration ratios (CR = concentration in dry plant /concentration in dry soil) of 232Th, 230Th, 226 Ra, 228Ra, and the light rare earth elements (REE's) La, Ce and Nd (Linsalata et al,. 1989). Twenty-nine soil and 42 plant samples consisting of relatively equal numbers of seven crop varieties were obtained from 11 farms on the Pocos de Caldas Plateau, Minas Gerais, Brazil. This region is the site of a major natural analogue study to assess the mobilization and retardation processes affecting Th and the REE's at the Morro do Ferro ore body and U series radionuclides at a nearby open pit U mine. Thorium (IV) serves as a chemical analogue for quadrivalent Pu and the light REE's (III) as chemical analogues for trivalent Am and Cm. The geometric mean CR's (X10-4) decreased as follows: 228Ra (148) > 226Ra (76) > La (5.4) > Nd (3.0) = Ce (2.6) > 232Th (0.6). They indicted that these differences may reflect the relative availability of these metals for plant uptake. Significant differences were found in the CR's (for any given analyte) among many of the plants sampled. The CR's for the different analytes were also highly correlated. The reasons for the correlations in CR's among elements with such diverse chemistries as Ra-REE or Ra-Th are not clear but are apparently related to the essential mineral requirements or mineral status of the different plants sampled. This conclusion is based on the significant correlations obtained between the Ca content of the dried plants and the CR's for all of the elements studied. Samples of upper and lower foliage of Quercus ilex (and associated soil) were taken in summer and winter from 41 areas evenly distributed over the urban territory of Rome, and from 5 non-urban (control) areas; in addition, one tree was sampled over the course of one year (Capannesi et al., 1988). Elemental concentrations were determined by gamma-spectrometric measurements on neutron flux-irradiated samples. Results indicated a direct relation between concentration of pollutant elements (e.g. Pb) and the presence of pollution sources, i.e. vehicular traffic. Urban structure exerted a major role in that, to a certain extent independent of traffic level, dense building formed a barrier hindering dispersion of particulates and favouring resuspension of pollutant elements from the soil (and also leading to relatively high concentration of elements not characteristic of pollution sources such as Ta, Th, U and rare earths). Some elements, particularly Mn, showed an inverse relation with pollution levels. No significant seasonal trends were observed. It is concluded that the results confirmed the validity of use of Q. ilex as a biological monitor of pollution by stable elements. Steubing et al., (1993) investigated the potential of using higher plants as indicators of uranium distribution in soil at a site in Germany where uranium concentrations ranged from 5-1500 mug/g soil and reached a maximum of 1860 mug/kg in soil water. Results indicated that Sambucus nigra was the best indicator of uranium contamination. Chemical analysis of its leaves provided more detailed information regarding uranium distribution than soil analyses. The plants not only indicate Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 266 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 the location of mineralization but also the migration pathway of U-containing soil-water. They indicated that adsorption of contaminated water was the main source of the U-accumulation in the different plant organs. Ibrahim and Whicker (1992) determined radionuclide concentrations in soil and tailings and in mixed grasses of Agropyron, Koeleria, Hordeum and Oryzopsis spp., mixed forbs of Melilotus, Kochia and Salsola spp., and Artemisia spp., at an uranium mill in Wyoming and were found to be elevated. Plant:soil concentration ratios were in the order 238U > 230Th > 210Po > 226Ra > 210Pb. It was concluded that for sulfuric acid leached tailings, Ra and Pb are sequestered as sulfates which were highly insoluble relative to U and Th sulfates, resulting in reduced availability for plant uptake. Soil acidity and the saturation condition at the tailings impoundment edge tend to enhance radionuclide availability for plant uptake. Pinto beans (Phaseolus vulgaris), sweetcorn, and zucchini squash (Cucurbita pepo) were grown in a pot study using alluvial soils contaminated with various radionuclides (Fresquez et al., 1998). Soils as well as washed edible (fruit) and non-edible (stems and leaves) crop tissues were analysed for tritium (3H), 137Cs, 90Sr, 238Pu, 239,240Pu, 241Am, and total uranium (totU). Most radionuclides, with the exception of 3H and totU, in soil and crop tissues were detected in significantly higher concentrations (P<0.05) than in soil or crop tissues collected from regional background locations. Significant differences in radionuclide concentrations among crop species (squash were generally higher than beans or sweetcorn) and plant parts (non edible tissue were generally higher than edible tissue) were observed. Most soil:plant concentration ratios for radionuclides in edible and nonedible crop tissues grown in the studied soils were within default values in the literature commonly used in dose and risk assessment models. Overall, the maximum net positive committed effective dose equivalent of beans, sweetcorn, and squash in equal proportions was 74 mrem/year (740 µS/year). This upper bound dose was below the International Commission on Radiological Protection permissible dose limit of 100 mrem/year (1000 µS/year) from all pathways and corresponds to a risk of an excess cancer fatality of 3.7 X10 -5 (37 in a million), below the US Environmental Protection Agency's guideline of 10-4. Two sampling campaigns were performed in 1993 at the marsh area (Odiel marsh) located in the city of Huelva, SW Spain. Spartina densiflora and substrate soil (5 cm deep) samples were collected in several locations across the area (Martinez et al., 1997). Activity concentrations of 210 Po, U and Th isotopes were determined in the plant and substrate samples. The production of phosphoric acid from phosphate mineral in the vicinity enhanced the concentrations of these radionuclides in certain areas of the marsh. Moreover, concentrations in plants were affected by the concentration of the same element in its substrate. Indeed, high concentration levels in plants were coincident with high concentration in soils. However, concentration ratios (CR), defined as the ratio between the concentration of an element in the plant and of that in its substrate, were higher when substrate concentrations were low, whereas low CR values were found in areas where substrate concentrations were high. Moreover, both variables (CR and soil concentration) were non-linearly related, at least in the case of radio nuclides from the 238U decay chain. Levels of 210Pb were measured in 13 edible vegetables and their associated soils from a vegetable garden and a farm close to the uranium mining and milling facilities of Pocos de Caldas, Brazil, (Santos et al., 1993) an area with a high radiation background. The 210Pb concentration were compared with those found at a control vegetable garden distant from the mining and milling operations. Edible vegetables collected at the farm and vegetable garden in the mining area had higher levels of 210Pb levels than those from the control site. Soil contamination in the mine vicinity, occurring by mineral dust deposition or by natural fallout, diminished with increasing distance from the mineral processing facility. The 210Pb levels in the soils studied were 8-220 Bq/kg. The surface/mass ratio and hairiness affected the plants' ability to take up 210Pb and 210Po. For lichens and bryophytes the 210Pb levels were higher than those in the control region. Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 267 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 Effect of fertilizers on uptake of Uranium by plants: The use of P fertilizers is necessary for a sustainable agriculture, but it involves radioactive contamination of soils. Phosphorus fertilizers contain different amounts of trace elements. The problem of cadmium (Cd) loads and other heavy metals is well known. However, only a limited number of investigations examined the contamination of phosphates with the two heaviest metals, uranium (U) and thorium (Th), which are radioactive. Also potassium (K) is lightly radioactive. Measurements were made on the radioactivity content of phosphates, P fertilizers and soils. The radiation doses to workers and public as well as possible contamination of soils from phosphate rock or fertilizer caused by these elements or their daughter products is of interest with regard to radiation protection. Variable amounts of the radionuclides U, Th and Ra can remain in P fertilizers, originating in the phosphate rock. Experimental work has shown that plant uptake of radionuclides in P fertilizers or phosphogypsum is minimal (Mortvedt 1992). In some phosphates uranium and thorium are enriched compared to the average content in the earth’s crust or soil. The question arises if the appertaining radioactivity in fertilizers applied over many years becomes harmful compared to the natural background. Heavy metals contents in raw materials used in phosphate fertilizer industry as well as phosphate products were determined (Abdel-Sabour and Rizk, 2002). The samples were collected from Abu-Zabal phosphate factory in El-Qalubia governorate Egypt. The samples include: Rock phosphate, gypsum, limestone, sulfur (as raw materials), sulfuric and phosphoric acids, mono phosphate (soft and granulate), triple phosphate (as final products). The aim of the study was to determine the elemental pattern in phosphate ingredient materials as well as the fertilizers produced. The results revealed that the main source of heavy metals including U and rare earths in the produced phosphate fertilizers is mainly due to the impurities in rock phosphate. Rock phosphate exhibited the highs 238U and 232Th activities compared to limestone and sulfur. While the highest 40K activities was noticed in case of limestone followed by sulfur raw material. They concluded that a potential metal accumulation in soil is expected on the long run due to the high application rate of phosphate fertilizers. Phosphogypsum (PG) is a residue of the phosphate fertilizer industry that has relatively high concentrations of 226Ra and other radionuclides. Thus, it is interesting to study the effect of PG applied as a Ca amendment on the levels and behavior of radionuclides in agricultural soils. A study involving treatments with 13 and 26 Mg ha-1 of PG and 30 Mg ha-1 of manure was performed, measuring 226Ra and U isotopes in drainage water, soil, and plant samples (El-Mrabet et al., 2003). The PG used in the treatment had 510 ± 40 Bq kg-1 of 226Ra. The 226Ra concentrations in drainage waters from PG-amended plots were similar (between 2.6 and 7.2 mBq L-1) to that reported for noncontaminated waters. Although no significant effect due to PG was observed, the U concentrations in drainage waters (200 mBq L-1 for 238U) were one order of magnitude higher than those described in noncontaminated waters. This high content in U can be ascribed to desorption processes mainly related to the natural adsorbed pool in soil (25 Bq kg -1 of 238U). This is supported by the 234U to 238U isotopic ratio of 1.16 in drainage waters versus secular equilibrium in PG and P fertilizers. The progressive enrichment in 226Ra concentration in soils due to PG treatment cannot be concluded from their data. They concluded that PG treatment did not determine any significant difference in 226Ra concentration in drainage waters or in plant material [cotton (Gossipium hirsutum L.) leaves] except 40K were found in the vegetal tissues. The effects of large applications of fertilizers on the uptake of uranium and thorium by cotton and wheat from soils containing small amounts of natural radionuclides were studied by Butnik and Ishchenko (1990). The uranium content of cotton plant parts decreased by a factor of 2.9 and that of thorium by a factor of 3.8; the uptake of uranium in wheat grain was less than the control by a factor of 1.4 and that of thorium by a factor of 2.6. They noticed that complete mineral fertilizer treatment had a greater effect on radionuclide uptake than individual applications of mineral Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 268 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 nutrients. The smallest uptake of uranium and thorium by cotton resulted from combined use of complete mineral fertilizer and manure treatment. Their results showed that fertilizer application altered the relative amounts of water-soluble, exchangeable, acid-soluble and fixed forms of the radionuclides in the soil. Phosphorus fertilizers decreased the exchangeable thorium fraction by 20%, and, in combination with manure, by 40%. A greenhouse experiment was conducted to evaluate differences in growth and uptake (U), influx (IN) and transport (TR) of nutrients by 40 exotic genotypes (Baligar et al., 1993). Genotypes were selected from the world collection (27 entries originated in Africa (Ethiopia, Sudan, Nigeria, Uganda and Tanzania), 8 were from India and 5 were from the USA or of unknown origin) and were tested in a dark red latosol at 2, 41 or 64% Al saturation. Growth of shoots and roots and nutrient uptake parameters were affected by soil Al saturation, genotype and their interactions. Growth and uptake parameters were used to separate the genotypes into most efficient and least efficient categories at various levels of Al saturation. Shoot nutrient U, IN and TR were positively correlated with shoot and root dry weight, and inversely related to soil Al saturation and shoot Al concentration. The method appeared to be reliable for separating genotypes into Al-tolerant and sensitive types. Genotypes used in the study showed intra-specific genetic diversity in growth and U, IN and TR of essential elements. Their results suggested that selection for acid-tolerant genotypes and further breeding for Al tolerance is feasible; SC283 (IS7173C) from Tanzania appears to be of most use in breeding programmes. Laboratory and greenhouse studies were conducted to quantify apatite and phillipsite (zeolite) sequestration of selected metal contaminants (Knox et al., 2003). The laboratory batch study measured the sorption of aqueous Co 2+, Ba2+, Pb2+, Eu3+, and UO22+. They indicated that apatite sorbed more Co2+, Pb2+, Eu3+, and UO22+ from the spike solution than phillipsite, resulting in distribution coefficients (Kd values) of > 200 000 L kg-1. However, phillipsite was more effective than apatite at sorbing aqueous Ba2+. Results from the laboratory study were used to design the greenhouse study that used a soil affected by a Zn-Pb smelter from Pribram, Czech Republic. Two application rates (25 and 50 g kg-1) of phillipsite and apatite and two plant species, maize (Zea mays L.) and oat (Avena sativa L.), were evaluated in this study. Apatite and, to a slightly lesser extent, phillipsite additions significantly enhanced plant growth and reduced Cd, Pb, and Zn concentrations in all analysed tissues (grain, leaves, and roots). The sequestering agents also affected some essential elements (Ca, Fe, and Mg). Phillipsite reduced Fe and apatite reduced P and Fe concentrations in oat tissues; however, the level of these elements in oat leaves and grains remained sufficient. Sequential extractions of the soil indicated that the Cd, Pb, and Zn were much more strongly sorbed onto the amended soil, making the contaminants less phytoavailable. The contents of rare earth elements (REEs; La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and other trace elements (Be, As, Ag, Cd, Sb, Cs, Bi, and U) in waste water treatment sludges were determined (Kawasaki et al., 1998). In night-soil sludges and sludges of waste water treatment plants in the food industry, the distribution patterns of REEs normalized vs. average REEs were almost flat. It was considered that the REE patterns of uncontaminated sludges reflected the pattern of the continental crust. The crust-normalized REE patterns of sludges of waste water treatment plants in the chemical industry and municipal sewage sludges did not always show flat plots. The sludges that did not show a flat REE pattern were considered to be contaminated with some of the REEs. The coefficient of variation of each element determined among the 10 samples of night-soil sludges and the 14 samples of sewage sludges ranged from 34 to 77% and from 26 to 84%, respectively. Among the 10 samples of food industry sludges and the 10 samples of chemical industry sludges, the coefficient ranged from 60 to 143% and from 67 to 172%, respectively. The variations of the content of each element among the food industry sludges or the chemical industry sludges were larger than those among the night-soil sludges or the sewage sludges. The contents of Be, As, Cs, REEs, and U in all the sludges were lower than or the same as those in a field soil. Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 269 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 Some of the food and chemical industry sludges contained larger amounts of Ag, Cd, and Sb than the soil. All the night-soil sludges and sewage sludges contained much larger amounts of Ag and Bi than the soil. The effects of iron oxides and organic matter on the partitioning and chemical lability of U and Ni were examined for contaminated riparian sediments from the U.S. Department of Energy's Savannah River Site (Andrew et al., 2003) . In sequential extractions of four sediments that ranged from 12.7 to 82.2 g kg-1 in organic carbon, U was found almost exclusively in moderately labile fractions (93% in acid-soluble + organically bound). Nickel was distributed across all operationally defined fractions, including substantial amounts in the very labile fractions (4–15% in water-soluble + exchangeable), noncrystalline and crystalline iron oxides (38–49%), and in the nonlabile residual fraction (25–34%). Aqueous U concentrations in 1:1 sediment–water extracts were highly correlated to dissolved organic carbon (DOC) (R2 = 0.96; p < 0.0001) and ranged from 29 to 410 µg L-1. Aqueous concentrations of Ni exceeded U by two to three orders of magnitude (124–2227 µg L-1) but were not correlated with DOC (R2 = 0.04; p = 0.53). Partitioning and solubility trends suggest that Ni availability is controlled primarily by iron-oxide phases, whereas U availability is dominated by naturally occurring organic carbon. Discrete mineral phases were also identified as nonlabile reservoirs of anthropogenic metals. In spite of comparably high sediment concentrations, Ni appears to be significantly more available than U in riparian sediments and therefore warrants greater consideration in terms of environmental consequences (i.e., transport, biological uptake, and toxicity). Abdel-Haleem et al., (1997) studied the U and Th Enrichment in Corn and Sesame Seeds due to Organic Waste Application to Sandy Soil. Uptake by plant depends upon several factors including plant species and above, all the availability of U in soil. Uranium content in most biological and plant materials are often very low and methods with low detection limits are needed to obtain results of reasonable accuracy. Neutron activation analysis methods are very often applied for the determination of U and Th because of the low detection limits for these elements. An attempt is made to evaluate the uranium and thorium quantities transferred to corn and sesame seeds due to organic waste disposal to sandy soil. The tested organic wastes were biosolids (Bs) and municipal solid waste (MSW) applied at increasing rates. Sludge samples showed higher values of both Np and Pa (derivatives of U and Th) concentration compared to MSW samples. They indicated that increasing organic waste rate of application, significantly increases Np-239 and Pa-232 contents in seeds of tested crops. However, MSW treatment resulted always a higher accumulation of Np-239 and Pa-232 in sesame seeds than Bs treatments. A significant linear regression equation was obtained between the rate of application for any tested organic source and Np-239 or Pa-232 content in sesame seeds or corn grains. This linear relation indicates that these metals are readily available to the plant. They stated that always, transfer values for corn in general were higher than those for sesame by one order of magnitude. The data can also be used for evaluation of the U and Th accumulation parameter due to the organic waste disposal to agriculture land. Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 270 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 Conclusion Results reveled that U uptake by plants seems to be pH-dependent in most studies. Soil acidity and the saturation condition at the tailings impoundment edge tend to enhance U availability for plant uptake. Uranium transportation in soil is dependent on the direction of the surface or soil water flow when it is soluble and mobile (consequently being bioavailable). This was supported with the finding that migration of U from the contaminant band was substantial only in the sandy soil. Moreover, investigations indicated that adsorption of contaminated water was the main source of the U-accumulation in the different plant organs. Correlations between radionuclide activity concentrations and stable element concentrations in the soil samples are a good tool to understand the possible distribution paths for natural radionuclides. Concentration ratio (CR) values have been used to predict transport of radionuclides and other elements through the food chain and for biogeochemical exploration for U. Frequently, The CR data were fitted by nonlinear least squares to a exponential function that decreased with time to a constant value. Which was confirmed later with the results indicating that relationships of leaf and leachate concentrations were not consistently linearly related to the total soil concentrations for U. Uranium uptake, however, seemed more sensitive than Th uptake to soil properties. However several translocation studies in general indicated that U-concentration in the grain was significantly less than in the husk, which was significantly less than in straw. Repeatedly, reports shown the tendency of U like other heavy metals to be accumulated in plant roots. Thus it is expected that radish and like roots can be a significant source of U. A significant correlations obtained between the Ca content of the dried plants and the U-CR which may suggested the close relation between Ca and U uptake. Fertilizer application (chemical and organic) can alter the relative amounts of water-soluble, exchangeable, acid-soluble and fixed forms of the U in the soil. Variable amounts of the radionuclides U, Th and Ra can remain in P fertilizers, originating in the phosphate rock. This lead to a conclusion that a potential U accumulation in soil is expected on the long run due to the high application rate of phosphate fertilizers. Increasing organic waste (biosolids (Bs) or municipal solid waste (MSW) compost) rate of application, significantly increases U and Th contents in seeds of tested crops (sesame and corn). It was noticed that always, transfer values for corn in general were higher than those for sesame by one order of magnitude. However, MSW treatment resulted always a higher accumulation of U and Th in sesame seeds than Bs treatments. This indicates that these metals are readily available to the plant due to the organic compounds in the soil. Asian Academic Research Journal of Multidisciplinary www.asianacademicresearch.org 271 AARJMD VOLUME 1 ISSUE 20 (APRIL 2014) ISSN : 2319 - 2801 References Abdel-Haleem, A.S., M.F. 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