Heavy metals and metalloids

Jimenez B, Rodriguez-Estrella R, Merino R, Gomez G, Rivera L, Gonzalez MJ, Abad E, Rivera J (2005) Results and evaluation of the first study of organochlorine contaminants (PCDDs, PCDFs, PCBs and DDTs), heavy metals and metalloids in birds from Baja California, Mexico. Environ Pollut 133(1) 139-146. doi 10.1016/j.envpol.2004.05.014... 

Pollution of soils and waters by human activities is an important and widespread problem. This pollution by, organic and inorganic substances can affect individual organisms, human populations, and ecosystems, each in its own unique way. In particular former military installations, often used for weapons production and nuclear power plants represent a ongoing and substantial threat to environment and human health because of the specific pollutants that can be released Solvents, explosives, fuels, radionuclides, heavy metals, and metalloids all have been identified in the environment around these installations. Remediation technologies for these contaminated sites have been developed based on conventional systems utilising physical and chemical treatments, such as excavation and incineration, pump-and-treat methods, ultraviolet oxidation, soil washing, etc. 

In general terms, the binding of heavy metals and metalloid ions in the cement matrix is quite well understood. There appear to be three basic types of binding mechanism (e.g., Cocke Mollah 1993 Cougar et al. 1996 Glasser 1997). A metal ion may be ... 

Baur, I. 2002. The Immobilisation of Heavy Metals and Metalloids in Cement-Stabilized Wastes A Study Focussing on the Selenium Oxyanions SeOs and Se024. PhD thesis, Swiss Federal Institute of Science and Technology (ETHZ), Zurich, Switzerland. 

In the case of Lysimeter Teuftal, most dissolved heavy metal and metalloid concentrations are directly correlated to electrical conductivity. The plot in Fig. 7 shows the relative dilution of different components during a rain event in comparison to that of electrical conductivity. The trend is independent of the speciation of these components. It should be noted that there are three notable exceptions, namely Ni(H), Co(II), and Cu(II). The common property of these cationic species is that they are extremely insoluble under the highly basic conditions encountered in the leachates of cement-stabilized residues (pH 12.8). It is possible that precipitation is the cause of such behaviour. 

For the majority of heavy metal and metalloid species it is unclear which mechanism prevails. 

There are possibly a greater number of factors controlling heavy metal and metalloid species... 

Fig. 10l Illustration of possible mechanisms controlling the dissolved concentrations of heavy metals and metalloid species.

Adsorption to mineral surfaces such as Fe and Al (hydr)oxides has long been known to be an important process that limits the mobility of heavy metals and metalloid species in aqueous systems (e.g., Stumm 1992). The sorption of ionic species in MSWI bottom ash has been recently studied in detail by Meima Comans (1998, 1999). These authors used a sequence of selective chemical extractions to determine sorbent concentration, namely Fe and Al (hydr)oxides. Their model calculations suggested that Zn(II) and M0O4 sorbed to Fe (hydr)oxides, while Pb(II) and Cu(II) appeared to have a greater affinity for Fe (hydr)oxides. The sorption of Cd(Il) was found to be very weak. The interpretation of... 

Casas, J.M., Rosas, H., Sold, M. and Lao, C. (2003) Heavy metals and metalloids in sediments from the Llobregat basin, Spain. Environmental Geology, 44, 325-32. 

Biophysico-Chemical Processes of Heavy Metals and Metalloids in Soil Environments by Antonio Violante, Pan Ming Huang, and Geoffrey Michael Gadd... 

Goldberg, S., and L. J. Criscenti. 2008. Modeling adsorption of metals and metalloids by soil components. In Biophysico-chemical processes of heavy metals and metalloids in soil environments. Ed. A. Violante, P. M. Huang, and G. M. Gadd. 215-264. Hoboken, NJ Wiley-Interscience. 

Alkorta, L, Hernandez-Allica, J., Becerril, J.M., Amezaga, L, Albizu, L, and Garbisu, C. 2004. Recent findings on the phytoremediation of soils contaminated with environmentally toxic heavy metals and metalloids such as zinc, cadmium, lead, and arsenic. Reviews in Environmental Science and Bio/Technology, 3 71-90. 

Rosen, B.P. 2002. Transport and detoxification systems for transition metals, heavy metals and metalloids in eukaryotic and prokaryotic microbes. Comparative Biochemistry and Physiology—A Molecular and Integrative Physiology, 133 689-93. 

Treatment of Heavy Metals and Metalloids in Water by Heterogeneous Photocatalysis... 

Microorganisms can transfer methyl groups to various heavy metals and metalloids (e.g., Se, As), which results in mobilizing these heavy metals and promoting their potentiation as environmental toxicants. Such methylation is attributed to the enzymatic system involved in the anaerobic generation of methane, where the methyl donor is methylcobal-amin (methyl vitamin B12). This is exemplified by the case of mercury (see Figure 9.12). 

---