Determine the potential for Zn and Cd accumulation by shrub willow from natural peat soils extremely high in both metals, and investigate the toxicity thresholds in the plant tissue that could limit growth and therefore the utility of willow as a phytoremediator of soils.
It is projected that the anthropogenic emission into the atmosphere, for several heavy metals, is one-to-three orders of magnitude higher than natural fluxes [ 17 ]. Heavy metals in the soil from anthropogenic sources tend to be more mobile, hence bioavailable than pedogenic, or lithogenic ones [ 1819 ].
Metal-bearing solids at contaminated sites can originate from a wide variety of anthropogenic sources in the form of metal mine tailings, disposal of high metal wastes in improperly protected landfills, leaded gasoline and lead-based paints, land application of fertilizer, animal manures, biosolids sewage sludgecompost, pesticides, coal combustion residues, petrochemicals, and atmospheric deposition [ 1220 ] are discussed hereunder.
Fertilizers Historically, agriculture was the first major human influence on the soil [ 21 ]. To grow and complete the lifecycle, plants must acquire not only macronutrients N, P, K, S, Ca, and Mgbut also essential micronutrients.
Some soils are deficient in the heavy metals such as Co, Cu, Fe, Mn, Mo, Ni, and Zn that are essential for healthy plant growth [ 22 ], and crops may be supplied with these as an addition to the soil or as a foliar spray.
Cereal crops grown on Cu-deficient soils are occasionally treated with Cu as an addition to the soil, and Mn may similarly be supplied to cereal and root crops. Large quantities of fertilizers are regularly added to soils in intensive farming systems to provide adequate N, P, and K for crop growth.
The compounds used to supply these elements contain trace amounts of heavy metals e. Metals, such as Cd and Pb, have no known physiological activity. Application of certain phosphatic fertilizers inadvertently adds Cd and other potentially toxic elements to the soil, including F, Hg, and Pb [ 24 ].
Pesticides Several common pesticides used fairly extensively in agriculture and horticulture in the past contained substantial concentrations of metals.
Examples of such pesticides are copper-containing fungicidal sprays such as Bordeaux mixture copper sulphate and copper oxychloride [ 23 ]. Lead arsenate was used in fruit orchards for many years to control some parasitic insects.
Arsenic-containing compounds were also used extensively to control cattle ticks and to control pests in banana in New Zealand and Australia, timbers have been preserved with formulations of Cu, Cr, and As CCAand there are now many derelict sites where soil concentrations of these elements greatly exceed background concentrations.
Such contamination has the potential to cause problems, particularly if sites are redeveloped for other agricultural or nonagricultural purposes. Compared with fertilizers, the use of such materials has been more localized, being restricted to particular sites or crops [ 8 ]. Biosolids and Manures The application of numerous biosolids e.
Certain animal wastes such as poultry, cattle, and pig manures produced in agriculture are commonly applied to crops and pastures either as solids or slurries [ 25 ]. Although most manures are seen as valuable fertilizers, in the pig and poultry industry, the Cu and Zn added to diets as growth promoters and As contained in poultry health products may also have the potential to cause metal contamination of the soil [ 2526 ].
The manures produced from animals on such diets contain high concentrations of As, Cu, and Zn and, if repeatedly applied to restricted areas of land, can cause considerable buildup of these metals in the soil in the long run. Biosolids sewage sludge are primarily organic solid products, produced by wastewater treatment processes that can be beneficially recycled [ 27 ].
Land application of biosolids materials is a common practice in many countries that allow the reuse of biosolids produced by urban populations [ 28 ]. The term sewage sludge is used in many references because of its wide recognition and its regulatory definition.
However, the term biosolids is becoming more common as a replacement for sewage sludge because it is thought to reflect more accurately the beneficial characteristics inherent to sewage sludge [ 29 ]. It is estimated that in the United States, more than half of approximately 5.
In Australia over tonnes of dry biosolids are produced each year by the major metropolitan authorities, and currently most biosolids applied to agricultural land are used in arable cropping situations where they can be incorporated into the soil [ 8 ].
There is also considerable interest in the potential for composting biosolids with other organic materials such as sawdust, straw, or garden waste.The potential of Arundo donax L.
for phytoextraction of cadmium (Cd) from contaminated soil and water was probed. The plants were grown under greenhouse conditions in pots containing a nutrient solution or soil with increasing doses of Cd (0, 50, , , , , and μg L−1) for 21 days.
The glossary that follows assumes a definition of ecology--the study of interactions between organisms and their environment--much wider than what fits under the field's habitual statistical caninariojana.cominism and ecopsychology are mentioned, for example, as are terms from organic gardening and permaculture.
A pot experiment and a field trial were conducted to study the remediation of an aged field soil contaminated with cadmium, copper and polychlorinated biphenyls (PCBs) ( ± mg kg −1 Cd, International Journal of Phytoremediation.
Published online: 19 May Article. Agreen house study was conducted to investigate the potential of four plant species for phytoextration of Cs-contaminated soil. Approximately 4 to 6 folds more Cs was removed from the contaminated soil in shoots of canola tBrassica napous), than in those of clover (Trifolium bratense).
Cadmium-contaminated soil collection The cadmium-contaminated soil was collected from a highly cadmium-contaminated agricultural field in the Mae Sot district, Tak province (Northern Thailand) (N. Heavy metals pose a significant threat to arable land around the world.
We describe the dangers of heavy metal contamination in agricultural settings and discuss methods of assessing the risk of.