Uptake of heavy metals

Recent reviews have focused on the role of mycorrhizal fungi in the uptake of heavy metals from polluted soils and their transfer to the plant (123). Several experimental data provide clear evidence that both ectomycorrhizal and ericoid fungi protect their host against these metals (123-125). The position with regard to the AM fungi is less clear (123). 

Tandy, S., Schulin, R., and Nowack, B., The influence of EDDS on the uptake of heavy metals in hydro-ponically grown sunflowers, Chemosphere, 62, 1454-1463, 2006. 

The uptake of heavy metals from soils is also determined by their contents in soil and by plant species. If these crops are used for anaerobic digestion one has to consider that there is a remarkable risk of an accumulation of heavy metals in soil. In the case of combustion, most heavy metals can be removed by filtering the ash and it can be used safely as fertiliser. Thus cultivation and combustion of short rotation coppice is a smart scheme of removing heavy metals from contaminated soils. 

Net uptake of heavy metals is due to the removal of heavy metals in crops or trees in the catchment and/or in aquatic plants and fish in a lake. Weathering relates to the... 

The receptors of interest are soils of agricultural (arable lands, grasslands) and non-agricultural (forests, steppes, heath lands, savanna, etc.) ecosystems. In non-agricultural ecosystems, the atmospheric deposition is the only input of heavy metals. Regarding the Forest ecosystems, a distinction should at least be made between Coniferous and Deciduous Forest ecosystems. When detailed information on the areal distribution of various tree species (e.g., pine, fir, spruce, oak, beech and birch) is available, this should be used since tree species influence the deposition and uptake of heavy metals and the precipitation excess. On a world scale, soil types can be best distinguished on the basis of the FAO-UNESCO Soil Map of the World, climate and ecosystem data from NASA database (1989). 

Figure 3. Coefficients of bio geochemical uptake of heavy metals by typical plant species of Meadow Steppe Ecosystems of East European Plain. Aerial parts 1—legumes 2—grasses 3—forage crops roots 4—legumes, 5—grasses, 6—forage crops (Dobrovolsky, 1994).

Lee, J., Bae, H., Jeong, J., Lee, J.-Y., Yang, Y.-Y., Hwang, L, Martinoia, E., and Lee, Y., 2003a, Functional expression of a bacterial heavy metal transporter in Arabidopsis enhances resistance to and decreases uptake of heavy metals. Plant Physiol. 133 589-596. 

Studies on the content of heavy metals in food are conducted in the majority of countries worldwide. Toxic heavy metals attract particular attention. Studies carried out on a range of foods and on daily food intakes have revealed that the amounts of heavy metals found in foods are within acceptable limits and do not exceed values observed in other European countries. The present daily uptake of heavy metals has decreased when compared with the values reported in the 1980s. 

Ryan, J.A. Factors affecting plant uptake of heavy metals from land application of residuals. In Proceedings of the National Conference on Disposal of Residues on Land, St. Louis, Missouri, September 13-15, 1976. 

Otte, M. L. (1991). Contamination of coastal wetlands with heavy metals factors affecting uptake of heavy metals by salt marsh plants. In Ecological Responses to Environmental Stresses, ed. J. Rozema J. A. C. Verkleij, pp. 126-33. London Kluwer Academic. Peters, R. W. Shem, L. (1992). Use of chelating agents for remediation of heavy metal contaminated soil. In Environmental Remediation, ed. American Chemical Society, pp. 70-84. Washington, D.C. American Chemical Society. 

Hozhina, E.I., Khramov, A.A., Gerasimov, P.A. and Kumarkov, A.A. (2001) Uptake of heavy metals, arsenic, and antimony by aquatic plants in the vicinity of ore mining and processing industries. Journal of Geochemical Exploration, 74, 153-62. 

Smith EH. Uptake of heavy metals in batch systems by a recycled iron-bearing material. Water Res 1996 30 2424-2434. 

Uptake of elements by plants is important in understanding essential nutrients for plants, potential health concerns for humans and animals that eat the plants, and use of plants as a remediation agent to remove toxic elements from soils. The uptake of heavy metals by wheat from fertilizers and sewage sludge applied to agricultural lands was investigated by using ICP-MS [263]. 

Clemente, R., Walker, D. J., and Bernal, M. P. (2005). Uptake of heavy metals and As by Brassica juncea grown in a contaminated soil in Aznacollar (Spain) The effect of soil amendments. Environ. Pollut. 138, 46-58. 

T. E. Jensen, M. Baxter, J. M. Rachlin and V. Jani (1982). Uptake of heavy metals by Plectonema boryanum (Cyanophyceae) into cellular components, especially polyphosphate bodies an X-ray energy dispersive study. Envinron. Poll., A27, 119-127. 

Heavy metal mobilization is often followed by microorganism and plant uptake, and intracellular accumulation. Filamentous fungi transport heavy metals and radionuclides along their hyphae. This may be a mechanism of mobilization from mycor-rhizal fungi to higher plants. An alternative pathway involves direct root uptake of heavy metals mobilized by microbial acid production or chelation. 

More recently, Brennsteiner et al. [ 175] noted that the electrochemical removal efficiency for nickel is dependent on the pH of the contaminant solution. Maximum efficiency was achieved at pH = 7.0, but only when the carbon electrode was preplated with a layer of copper the role of surface chemistry was not investigated. Seco et al. [172] did characterize the surface chemistry of a commercial activated carbon (pHp r = 6.1) and studied its uptake of heavy metals (Ni, Cu, Cd, Zn), as well as of some binary systems. They interpreted the monotonic uptake increase with pH to be consistent with the surface complexation model a decrease in competition between proton and metal species for the surface sites and a decrease in positive surface charge, which results in a lower cou-lombic repulsion of the sorbing metal. In the binary uptake studies, they concluded that Ni (as well as Cd and Zn) is not as strongly attracted to the. sorbent as Cu. 

Klassen RB, Crenshaw K, KozyrakI R,Verroust PJ,Tlo L, Atrlan S, Allen PL, and Hammond TG. Megalln mediates renal uptake of heavy metal metallothlonein complexes. Am J Physiol Renal Physiol 287 F393-403,2004. 

TABLE 11.7. Plant Uptake of Heavy Metals from Sewage Sludge... 

Net uptake of heavy metals is due to the removal of heavy metals in crops or trees in the catchment and/or in aquatic plants and fish in lake. Weathering relates to the release of HM from primary minerals in the catchment. Sedimentation is the result of the setting of suspended particles in the lake. As a result of this process, the pollutant absorbed to the suspended particles is transported from the water compartment to the sediment compartment. Resuspension of sediment particles is the result of the turbulence at water-sediment interface. As a result of this process, the pollutant absorbed to the sediment particles is transported from the sediment compartment to the water compartment. The exchange processes at the sediment water interface include advection or infiltration, molecular diffusion, and bioturbation and bioirrigation (the latter are the transport of HM resulting from the ventilation of tubes and burrows in the sediments by benthic organisms). To scale these processes to the catchment, the sedimentation and resuspension rates are multiplied by the ratio of the lake area and the catchment (de Vries et al, 1998). 

Direct studies of the effect of pressure on surface charging are rare. The conductance of an anatase dispersion in HCI increased with pressure [179], This suggests a release of pre-adsorbed HCI from the surface at elevated pressure. On the other hand, the pressure effect was negligible in anatase dispersions in water or in NaCl. The experimental setup was designed to study desorption kinetics, and only the sign of the pressure effect could be determined. A similar method was used to study the pressure effect on proton adsorption on alumina dispersions in water [2928,3059], and in NaCl [2928], HNO,. and NaNO, [927] solutions, and the effect was negligible for a pressure of about 10 Pa. On the other hand, the same pressure had a substantial effect on uptake of heavy-metal cations [927] and of anions [2928,3059] on alumina. 

Folsom, B.L. jr., Lee, C.R. Bates, D.J. (1981) Influence of Disposal Environment on Availability and Plant Uptake of Heavy Metals in Dredged Material. Techn. Rept. EL-81-12. Vicksburg/MS. O.S. Army Corps of Engineers Waterways Experiment Station... 

Muramoto S and Oki Y (1984) Influence of anionic surface-active agents on the uptake of heavy metals by water hyacinth (Eichomia crassipes). Bull Environ Contam Toxicol 33 444-450. 

In order to avoid critical uptakes of heavy metals to human nutrition via foods of... 

Hart B.T., Day G., Beckett R. (1988), Influence of dissolved organic matter on the uptake of heavy metals and toxic organics by suspended particulate matter in natural waters, Proc. Science, Technology ... 

Some experiments have been made to evaluate if the application of electric fields could enhance phytoremediation, or plant uptake of heavy metals, of the contaminated sites (O Connor et al, 2003 Zhou et al, 2007). Cu uptake was significantly higher with ryegrass root when stimulated by an electric field. On the other hand, the Cd uptake seemed to be unaffected by the electric field. Anyway, it was concluded that the combination of the two techniques represented a very promising approach to the decontamination of metal-polluted soils, which would require validation in field conditions. It was also possible to incorporate sulfur-oxidizing bacteria and EK to enhance copper removal from contaminated sulfur-containing soil (Maini et al., 2000). 

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