Elemental distribution contamination problems

Incineration can be applied to all contaminants that have high heat content. It eliminates odor and leachate problems, which are usually associated with landfills, but metals can react with other elements in the feed stream, such as chlorine or sulfur, and form more volatile and toxic compounds. The process has high maintenance and operation costs. Straitz et al. (1995) reported that incineration is a reliable, cost-effective approach to treat VOCs and a wide range of objectionable gas. Chaouki et al. (1995) conducted experiments that examined the effect of fluidized bed combustion on the properties and characteristics of a soil contaminated with PCBs. Particle size distribution and PCB contents were determined before and after a 30-minute incineration. The incineration promoted agglomeration soil, increases in soil pH, and decreases in the PCB content to undetectable levels. 

Imaging of elemental and isotopic distributions on surfaces has proved useful for diffusion measurements, corrosion and reactivity studies, contamination identification, and many other applications. SIMS imaging is particularly useful because of its high sensitivity. An example was the application to a problem in which a U-... 

The recent surge of research into the behavior of arsenic in the environment has followed the discovery of human health problems linked to high concentrations of the element in some groundwaters, soils, and contaminated land. Rather fewer studies have been undertaken of selenium, although serious health problems related to selenium toxicity or deficiency have been reported. There have also been many studies of the distribution of both arsenic, and more recently selenium, in metalliferous exploration, especially for gold. 

Trace metals in sea water are present at very low concentrations (normally lower than 10 A/) thus, the study of metal distribution and speciation poses problems that have been overcome only in the last few decades. A prerequisite for determination of trace metals is the collection and processing of uncontaminated samples for the element of interest. Improvements in analytical procedures have led to a decrease by some orders of magnitude in the reported concentration of some elements, especially so for ubiquitous and contamination-prone elements, such as Fe or Pb. These changes lead to the concept of oceanographic consistency as a criterion for accepting trace chemical measurements (83). 

For numerous questions related to the speciation of metal(loid) contaminants in natural and waste matrices, the combination of X-ray fluorescence, diffraction and absorption presented in this chapter offers a unique access to the problem. X-ray microscopy cannot compete with the atomic resolution offered by electron microscopy, but it offers a number of unique features. The chemical and structural information obtained by pSXRF and pSXRD can be used to identify the host solid phase by mapping the distributions of elements and solid species, respectively. Then the molecular-scale binding mechanism of trace elements by the host phase can be unraveled by pEXAFS spectroscopy. All these techniques can be applied with minimum preparation, minimizing any possible alteration of the sample. However, caution should be taken to not modify the initial form of the metal species by photon-assisted oxidation or reduction. This problem can be circumvented by decreasing the exposure time, photon density, or temperature. The polarization of the synchrotron radiation can be used to analyze anisotropic materials, which is important since many environmental minerals have a layered structure. 

Many weUs have been dug in recent years under the auspices of UNICEF for the people of Bangladesh who needed freshwater sources. It turned out that many of such wells are contaminated with arsenic. Arsenic is a natural element, and fairly widely distributed among rocks. Arsenic is often associated with important industrial metal ores containing lead and copper. Arsenic has thus also caused environmental pollution problems, in association with ore mining and smelting. 

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