Environmental Engineering Reference
In-Depth Information
the highest concentrations were measured at the beginning of rainy periods and at
the end of winter (precisely when snow starts to melt). These findings suggest that
the main emission source of Pt in municipal sewage is runoff from roads and urban
areas (Kümmerer et al. 1999).
4.3
Other Environmental Emission Sources of PGEs
Analysis of PGEs in environmental samples do not support the thesis that emissions
from VECs and hospitals constitute the total input of these metals into wastewater
(Kümmerer et al. 1999). Therefore, it is necessary to consider other sources. The
more important alternative sources are the electronics industry, glass production,
jewelry production, dentistry use, the production of Pt-based pharmaceuticals, and
industrial-scale catalytic processes.
The amount of emitted Pt found is influenced by sampling location, and residue
levels largely depend on the nature of local emission sources (Lottermoser 1994).
More information on PGEs emission sources and forms in which PGMs are emitted
is needed to better understand the flow of PGEs in the environment (Moldovan
2007).
5
Bioavailability of and Occupational Exposure to PGEs
Only a limited number of studies have been published that deal with the bioavail-
ability, mode of penetration into live organisms, and the environmental fate of
PGEs. However, many scientists are increasingly concerned about the medium to
high mobility of PGEs that are emitted to the environment from car catalytic
converters. Moreover, Pt emitted in metallic or oxidized form (probably not
strongly allergenic) may undergo transformation (when deposited as road dust) to
a soluble form, and subsequently contaminate water, sediment, and soil, ulti-
mately reaching the food chain and, thereby, animals and humans (Ducoulombier-
Crepineau et al. 2007).
5.1
Effects on Plants
Certain PGE species can be remobilized as a consequence of being bound to soil
particles that are taken up by plants, and thus may enter the food chain (Zereini et al.
1997; Hees et al. 1998; Lustig and Schramel 2000; Fritsche and Meisel 2004).
Evidence indicates that PGEs, particularly Pd, are transported to biological materi-
als by binding to sulfur-rich low molecular weight species in plant roots (Ek et al.
2004). Additionally, the solubility of PGEs may increase in the presence of natural
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