Bioaccumulation of Trace Elements in Animals and Trophic Transfer

Increasingly, animals are used as sentinels of human exposure and as bioindicators of environmental contamination 51,52 . Different groups of animals differ with respect to the magnitude and type of exposure to trace elements. Several workers have advocated the use of free ranging animals such as mammals and birds for various reasons 53-55 . Small mammals depend exclusively on the quality of food, water, and air in a particular habitat and locality they are physiologically similar enough to...

In Situ Immobilization

Reducing trace element solubility, mobility, and bioaccumulation in contaminated soils is an effective, low-cost means of remediation that does not require drastic disturbance of the site. Naturally occurring or artificial soil amendments such as liming material, phosphate, zeolite, bentonite, clay, Fe metal, Fe and Mn oxides, and organic matter, may be used to mitigate the toxic effects of trace elements 38 . These amendments reduce trace element mobility by promoting the formation of...

Cadmium

Cd is a non-essential heavy metal occurring naturally in Zn and Pb ores 9 . Industrial uses of the metal and agricultural activities have led to widespread dispersion of this element in the environment and human food items. Studies have shown that the average concentration of trace elements in the general agricultural environment has increased over the years. Kjellstrom et al. 155 reported that the Cd content of Swedish wheat increased about threefold between 1900 and 1980. On similar lines,...

Short Rotation Forestry Using Sewage Sludge and Biosolids Implications

Short-rotation forestry (SRF) is advocated as a means of phytoremediation and for disposing of sewage sludge 157 . Fast growing trees such as Salix (willow), Populus (poplar), Alnus (alder), and Eucalyptus (eucalypts) are ideal trees for SRF and have gained importance in mitigating CO2, industrial effluents, and other air pollutants. Large quantities of fertilizer and water are required to sustain the intensive management of SRF. This demand prompted the application of sewage sludge, with the...

References

Zakrzewski, S., Principles of Environmental Toxicology, American Chemical Society Washington, D.C., 1991. 2. Yassoglou, N. et al., Heavy metal contamination of roadside soils in the Greater Athens area, Environ. Pollut, 47, 293, 1987. 3. Ho, Y.B. and Tai, K.M., Elevated levels of lead and other metals in roadside soil and grass and their use to monitor aerial metal depositions in Hong Kong, Environ. Pollut., 49, 37, 1988. 4. Body, P.E., Dolan, P.R., and Mulcahy, D.E., Environmental lead a...

Complex Formation With Organic Acids

Organic acids are the other group of biomolecules that can function as chelators of heavy metals inside the cell, converting the metals to almost inactive and nontoxic forms. With regard to Al, at least two organic acids are known to function as chelators. One is citric acid 138 nearly two-thirds of Al in hydrangea leaves remain present in the cell sap in soluble form as Al-citrate complex at a 1 1 molar ratio of Al to citrate, a nontoxic form of Al. Another acid that has been reported to form...

Metal Tolerant Plants And Chelators Might Promote Phytoremediation Technology

Use of soil amendments such as synthetics (ammonium thiocyanate) and natural zeolites has yielded promising results 62-66 . EDTA, NTA, citrate, oxalate, malate, succinate, tartrate, phthalate, salicylate, acetate, etc. have been used as chelators for rapid mobility and uptake of metals from contaminated soils by plants. Use of synthetic chelators significantly increased Pb and Cd uptake and translocation from roots to shoots, facilitating phytoextraction of the metals from low-grade ores....

Materials And Methods Used

The influence of fly ash on soil properties and wheat characteristics was investigated in a greenhouse pot experiment in which an acidic soil classified as Typic Haploxeralf was used, and in a field experiment in an acid soil from Central Greece, classified also as Typic Haploxeralf. Some chemical properties of the soils used are presented in Table 4.1. Fly ash was collected from the electrostatic precipitator of a lignite-fired electric power plant in Northern Greece and aged for 3 months by...

Heavy Metal Detoxification Mechanisms In Plants

By virtue of their stationary status, plants, unlike animals, cannot migrate to avoid unfavorable fluctuation or changes in their environment thus, they must change their metabolic activities suitably to allow them to cope with the changing environment or otherwise perish. The resulting changes in their metabolism are called stress response, which may enable the plant to survive under the condition of stress. This may occur for a short time only, known as acclimation, or the changes induced may...

Chelation at Cytoplasm and Vacuole Level

Chelation in the cytoplasm is an intracellular buffer system to control PTE toxicity through reduction of the concentration of cytotoxic-free PTE ions. In this system, metallothioneins (MT), metal-binding polypeptides, and or MT-like proteins may be involved. In contrast to ectomycorrhizal fungi, the participation of these compounds in metal detoxification has not been confirmed in AMF 69,70 . However, evidence suggesting the presence of Cd-binding thiols in AMF as well as high concentrations...

Strategies For Enhanced Uptake Of Trace Elements To Facilitate Phytoextraction

27.6.1 Chelate-Assisted or Chemically Induced Phytoextraction This strategy of phytoextraction is based on the fact that the application of metal chelates to the soil significantly enhances metal accumulation by plants. The literature to date reports a number of chelates that have been used for chelate-induced hyperaccumulation. These include EDTA, CDTA (irans-1,2-diaminocyclohexane-N,N,N ',N'-tetraacetic acid), DTPA (diethylene triaminepentaacetic acid), EGTA ethyleneglycol-bis(P-aminoethyl...

Phytoremediation and the beginning of interest in mycorrhiza

At first, the necessity to include soil microorganisms in phytoremediation was neglected. People used compounds that increase the availability of toxic compounds, therefore stimulating the accumulation of metals in plants 16-18 , as well as fertilizers to boost plant biomass production 19 . The most efficient varieties were selected techniques involving genetic engineering were also used 20-23 . The plants' ability to produce organic compounds influencing the rhizosphere and increasing the...

Hmw Pc And Metal Tolerance

Although the accumulation of PCs could be a major component of the heavy metal detoxification process, the increased tolerance to metals may involve other aspects of PC function. The first argument in favor of this came from Delhaize et al. 87 , who observed that, although Cd-sensitive and Cd-tolerant cells of Datura innoxia synthesized the same amount of PCs during the initial 24-h exposure to 250 M Cd, the concentration was toxic to the Cd-sensitive cells only, as revealed by a cell viability...

Experimental Studies On The Effects Of Different Fertilizers On Metal Removal From Contaminated Soils Using Wheat

To optimize and manipulate the process of metal phytoextraction successfully, the author studied the effects of three fertilizers (urea, horse manure, and ispolin fertilizer on the basis of mixture of organic fertilizers, humic acids, and industrial population of worms) on yields and physiological characteristics of wheat (Triticum aestivum) and removal of metals from two Podzol soils with loam (site 1) and sandy loam (site 2) textures. Soil in site 2 was contaminated with several metals (Cd,...

Zinctransporting Genes In Plants

Zinc is a constituent of several enzymes carbonic anhydrase dehydrogenases aldolases Cu Zn superoxide dismutase isomerases transphosphory-lases and RNA and DNA polymerases. Therefore, Zn deficiency results in malfunction or no function of these enzymes. Zn-metalloproteins (Zn-finger motif) are regulators of gene expression (DNA-binding transcription factors). In the absence of these, RNA polymerase cannot complete its function of transcribing genetic information from DNA into RNA. Zinc is a...

Info

Despite the difficulty in predicting the effects of microbial genes in a complex multicellular organism like a plant, the successful introduction of a modified bacterial mercuric ion-reductase gene into yellow poplar (Liriodendron tulipifera) and Nicotiana tabacum demonstrates that bacterial genes may be extremely valuable in phytoremediation. Two Arabidopsis mutants resistant to high levels of aluminum have been characterized 34 . The genes have yet to be cloned, but one of the mutants, on...

PH Changes in the Rhizosphere and Bioavailability of Trace Elements

Without doubt, most plants growing under natural conditions cause pH to rise in the rhizosphere. As pointed out by Cunningham 16 , 62 plant species contain an average of 250 meq of absorbed cations per 100 g of oven-dry shoots and 360 meq anions per 100 g of oven-dry shoots. In general, roots release HCO3 or OH to maintain electrical neutrality in the rhizosphere an excess of 1100 meq of HCO3 per 100 g dry matter, rather than H+ ion, and the soil near roots become more alkaline instead of more...

Fertilizer Value of Sewage Sludge

Sewage sludge is increasingly used as a fertilizer because land application is considered a more environmentally friendly disposal method and because of its great fertilizer value Table 3.3 . Nowadays, sewage sludge can be produced for agricultural use as dry granular, palletized, or fortified organic-based materials, which have more specialized uses in agriculture and horticulture compared with the conventional forms 23 . The technology for applying sludge is advanced and includes surface...