Contaminated soil pollution sources

Lead may also interact detrimentally with aquatic life. Once lead deposits in soil, it sticks to soil particles and is only displaced by rain water, ending up in water sources where it affects the aquatic life. Some plants accumulate Pb from both contaminated soils and water sources or more specifically water in the rhizosphere. Besides, contaminated soils are liable to remain polluted with lead this will affect soil fertility.3,4 The fact that large changes in the lead content of soil are required to produce changes in the aerial parts of the plants as compared to changes in aerial lead concentration is closely reflected in the leaf lead concentration. Accumulation of Pb in grasses remains a potential hazard to livestock.3... 

Table 1 indicates primary pollutant sources and waste modes, and Table 2 indicates the primary and secondary sources and associated pollutants. The primary sources of soil contamination include land disposal of solid waste sludge and waste-water industrial activities and leakages and spills, primarily of petroleum products. The solid waste disposal sites include dumps, landfills, sanitary landfills, and secured landfills. 

Cosson, R.P, C. Amiard-Triquet, and J.C. Amiard. 1988a. Utilisation des plumes dans le recherche des sources de contamination des oiseaux par les elements traces Cd, Cu, Hg, Pb, Se, et Zn chez les flamants de Camargue, France. Water Air Soil Pollut. 42 103-115. 

It is not always necessary or required to digest the entire sample in order to free the metals for analysis. In some cases it is not even desirable. In studies of contaminated soils, for instance, the analyte of interest may be present as a soluble salt from a pollution source, as well as also being present in the structure of the mineral crystals. The soluble form is of concern, as it is available to biota and may eventually contaminate groundwater. That in the insoluble particles is not of interest. In such cases, where the analyte is much more soluble than the matrix or where the metals included in the matrix are not of interest, an extraction process rather than complete solubilization is preferred. This is treated further in Section 5.10. 

The cost of cleanup is staggering. This can be seen by the fact that in 1994, the National Academy of Sciences estimated that over a trillion dollars, or approximately 4000 per person in the U.S., would be spent in the next 30 years on clean up of contaminated soil and groundwater [ 67 ]. In many cases, it is hard to find out which companies or parties are responsible for the contamination due to lack of tools to identify the pollution source. Chemical finger printing, state and federal agency records, and private parties history records of handling hazardous substances are seldom sufficient to allow a unique solution for the location of sources and the timing of source releases. Therefore, there... 

The phytoremediation process may be viewed as a symbiotic process between plants and soil microbes that involved in phytoremediation (Lasat, 2002). Plant and bacterial interaction can enhance the effectiveness of phytoremediation technology because plants provide carbon and energy sources or root exudates in the rhizosphere that will support microbial community in the degradation and transformation of soil pollutants (Siciliano and Germida, 1998). In addition, the presence of soil microbes can increase the water solubility or bioavailability of pollutants in soils, which facilitates the uptake of pollutants by plants (Lasat, 2002 Siciliano and Germida, 1998). However, the specificity of the plant-bacteria interactions besides being much intricate is dependent upon soil and the aqueous conditions, which can alter contaminant... 

Knox RC, Canter LW. 1996. Prioritization of ground water contaminants and sources. Water Air and Soil Pollution 88(3-4) 205-226. 

Lead is a well-known poison, but the effects of exposure to lower levels have been contentious. There is growing evidence of sub-clinical Pb poisoning, especially among young children who play in polluted parks, gardens and streets. Contaminated soil or dust particles may be transferred to children s hands and ingested accidentally. Humans are exposed to Pd from various sources and road dust and soils can contribute to the total lead exposure. Approximately one half of lead ingested in food is absorbed. 

Surfactants and microemulsion systems can be used for ex situ treatment of contaminated soil or in situ soil decontamination. In situ remediation is usually preferred if excavation of the contaminated soil is not possible or expensive, e.g. beneath buildings or for contaminations at great depth. Often bioremediation or natural attenuation is used for decontamination. In most cases, these techniques only permit the effective degradation of contaminants in the plume formed by dissolved pollutants which may be very large. However, for the remediation of a contaminated site, it is also necessary to remove the source where the pollutants maybe adsorbed in large quantities or may be present as solid or liquid phases. The latter are called NAPL (non-aqueous phase liquids) and a differentiation is made between LNAPL (light non-aqueous phase liquids) with a lower density than water and DNAPL (dense non-aqueous phase liquids) with a higher density than water (see Fig. 10.1). 

The distribution and the nature of past, existing and potential pollution sources have also to be thoroughly established and assessed in light of the pollution vulnerability of the aquifer system concerned. A general appreciation of the reactive processes which may take place during contaminant transport, in ah sub-surface compartments (soils, cappings layers, unsaturated and saturated zones in aquifers, river beds,. ..) is required too. 

The concept of containment as a method for dealing with contaminated ground is based on the use of low-permeability barriers to isolate the contaminated material, or any associated leachate or gaseous products, from the environment. The barriers can be constructed from natural or synthetic materials, or a combination of both, and can be placed over, under or around a contaminated area or pollution source. The technique can be used to isolate existing hazards such as a contamination source, to prevent the spread of contaminants from a disposal site such as landfill, or to isolate specially designed mono-disposal sites for contaminated soil. 

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