Cadmium in the Atmosphere

Several hundred tonnes of solder containing cadmium are used in the UK every year and since this is a relatively volatile metal (B.Pt. 767 ), soldering operations inevitably lead to high local concentrations of cadmium in the atmosphere. There are also hazards associated with the use of cooking vessels glazed with cadmium-based enamels, for appreciable amounts of cadmium can be leached out during cooking. 

Apart from transistor-like devices, single-electron junctions can also be useful for sensor applications. The simplest one might be the monitoring of H2S. Since the formation of CdS nanogranules takes place when an initial cadmium arachidate layer is exposed to this gas, we can expect the appearance of single-electron conductivity only when it is present in the atmosphere. 

As a rule, simulations consider emissions of heavy metals from anthropogenic and natural sources, transport in the atmosphere and deposition to the underlying surface (Figure 6). It is assumed that lead and cadmium are transported in the atmosphere only as a part of aerosol particles. Besides, chemical transformations of these metals do not change removal properties of their particles-carriers. On the contrary, mercury enters the atmosphere in different physical and chemical forms and undergoes numerous transformations during its pathway in the atmosphere (Ilyn et al., 2002 2004 Ilyin and Travnikov, 2003). 

Ryaboshapko, A., Ilyin, I., Gusev, A., Afinogenova, O., Berg, T, Hjellbrekke, A-G. (1999). Monitoring and Modeling of Lead, Cadmium and Mercury transboundary Transport in the Atmosphere of Europe. EMEP Report 3/99, 124 pp. 

With respect to corrosion, the conventional classification of climates in marine, inland, industrial, etc. types is not sufficient. It should now be specified with respect to the actual chemical components in the atmosphere, as well as humidity and other factors. Recent research in this field has led to much more precise methods for estimating corrosion rates in polluted atmospheres (38). Economically, perhaps even more important problems are caused by the increased corrosion of water supply pipelines. Not only copper is dissolved, but also cadmium from soldered joints, and larger steel and cement pipelines may also be affected. 

The current emission level of cadmium from MSW incinerators represent less than 2.0% of total atmospheric emissions of cadmium in the EU countries. The enforcement of the new EU Directive on emissions of cadmium gives a maximum permissible concentration of 0.05 mg/Nm. In these conditions, emissions associated to the... 

Assuming a cadmium concentration of 10 ng/m in both indoor and outdoor air and a daily inhalation rate of 15 m for an adult, the average intake of cadmium from the atmosphere would be 0.15 xg, of which about 25% will be absorbed (OECD, 1994). 

National emission balance of heavy metals in the Czech Republic includes the emissions of cadmium, lead and mercury from all major pollution sources, for which the emission factors were available in the Atmospheric Emission Inventory Guidebook, published in other countries (Austria, Germany, Poland, Slovakia) or calculated from experimental measurements of projects of the Ministry of the Environment of the Czech Republic. The results of the cadmium emission balance in the Czech Republic in 1992 are presented in Table 2. The authors assume that the amount of emissions from the sources not included in this inventory do not exceed 5-10% of the total emissions (Fiala et al., 1998). 

In the city of Modena, the levels of lead, chromium, nickel, and cadmium in the air (as measured by automatic detectors) were compared with those contained in honey, larvae, and pollen samples taken monthly from beehives situated in the vicinity of the detectors themselves. The findings cannot be considered conclusive, as the average monthly data recorded by the automatic detectors referred to a single point in the atmosphere whereas the beehive data were referable to the area around the hive visited by bees in a given month. Nonetheless, they showed that the fresh honey recently imported into the honey chamber was the matrix that best reflected the trend in lead contamination of the atmosphere, as recorded by the detectors [89]. It was also observed, again with regard to lead in the honey matrix, that the values provided by the detectors were a reliable anticipation of the biological data. In the same study, the authors also tried to estimate the ratio of the mean concentration of the various contaminants in honey (in Jig/kg) and that in the air (in pg/m ), which may be estimated as approximately 1000-2000 for lead and nickel, 2000-4000 for chromium, and 3000-5000 for cadmium [90]. 

Qf the estimated 28 trillion metric tons of cadmium in the environment, almost all (99.9995%) is located in the subsurface hthosphere. The remaining 151.6 million metric tons reside in the hydrosphere (98.6%), surface hthosphere (0.9%), biosjhere (0.5%), and atmosphere (0.001%). 

Coal combustion releases fly ash into the atmosphere (Chapter 14) (Fisher and Natusch, 1979 Adriano et al., 1980). Fly ash contains toxic metals such as arsenic and cadmium. In the United States the Clean Air Act requires that fly ash be removed from coal emissions. As a result, antipollution devices such as air baghouses and electrostatic precipitators are used to trap these pollutants. 

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