Cadmium emission

Figure 6 Three-dimensional plot of cadmium emissions to the US atmosphere for the period 1970-1990. (sources Davis and Associates, 1970 USEPA, 1975a,h, 1976, 1978 Wilher et al, 1992).

Tire wear is an ablation product of vehicle operation not found in exhaust which can be considered significant. Tire wear emissions have been estimated at 7 million ton/year in the United States (54). Both zinc and cadmium are components of tire rubber, and tire debris is a significant source of atmospheric emissions of these metals. Zinc comprises approximately 1.5% of tire dust by weight. In Los Angeles, tire dust is one of two major sources of atmospheric zinc, the other being metallurgical emissions (55). Cadmium emissions from tire debris was estimated at... 

In addition, two sets of data from the Battery Association of Japan (BAJ), formerly known as the Japan Storage Battery Association (JSBA), equally clearly demonstrate that the levels of cadmium emissions to air and water in Japan have decreased steadily over the period from 1980 through 1992 in spite of the greatly accelerated production of NiCd batteries in Japan during that same time period (Mukunoki and Fujimoto 1996). Japan is the world s largest producer of NiCd batteries, and currently accounts for over 70% of the world s NiCd battery production. If there is any country where potential enviromnental contamination by cadmium from NiCd battery manufacture should be... 

Table VI. Cadmium Emissions from Production and Recycling NiCd Batteries ...

Elgersma et al. 1992, Emission Factors for Aqueous Industrial Cadmium Emissions in the Rhine River Basin A Historical Reconstruction for the Period 1970-1988, Edited Proceedings Seventh International Cadmium Conference - New Orleans, Cadmium Association (London), Cadmium Council (Reston VA) and International Lead Zinc Research Organization (Research Triangle ParkNC). 

Represents 0.8 % of total Cadmium Emissions to Surface Water in EU. 

Figure 22. The Contribution of Ni-Cd Batteries to Total Cadmium Emissions...

Official reports from France and Switzerland (Chambaz D. and al. (1998), French Society of Public Health (1999)) confirm that municipal waste incinerators do not present any risk for the population as regards cadmium emissions. 

Several sites may have higher concentration of cadmium emissions. These are industrial waste landfills and the origin of their cadmium emissions is not proven to be from spent batteries. 

Cadmium releases from landfills have been evaluated by the Draft Risk Assessment Report on Cadmium (DRAR 2000). They can be evaluated at less than 0.3 tonnes/y, this representing less than 0.8% of total emissions of cadmium in water in the EU countries. The major contributors to total cadmium emissions into surface waters are zinc and lead producers, fuel combustion for electricity generation, fuel combustion for road transportation, phosphate industries and non-ferrous metallurgy (DRAR 2000). 

Based on the measurement prescribed in the Surveillance program, the yearly cadmium emissions of the recycling plant are estimated to approx. 0.2 kg to the atmosphere and approx. 0.5 kg to water (1999). 

Cadmium is widely distributed in the earth s crust at an average concentration of about 0.1-0.2 mg/kg and is commonly found in association with zinc. Volcanic activity is major natural source of cadmium release to the atmosphere. The annual global flux from this source has been estimated to be 820 tons. Deep sea volcanism is also a source of environmental cadmium release, but the role of this process in the global cadmium cycle remains to be quantified (OECD, 1994). About 10-15% of total airborne cadmium emissions arise from natural processes (WHO, 1992a). 

The results of the cadmium emission inventory in Slovakia carried out by the Slovak Hydrometerological Institute in 1992 and 1994 are shown in Table 1. Shutting down environmentally and economically ineffective productions have significantly reduced emissions of cadmium (Magulova et ah, 1996). 

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). 

The results of earlier cadmium emission estimates within the German Federal Environmental Protection Agency, the available data from Paris Commission program (PARCOM), the European Soil and Sea Quality and Atmospheric Deposition of Selected Substances (ESQAD) data and emissions estimated by national experts in some countries are presented in Table 5 (Anon, 1994). 

Table 4. Trend of annual cadmium emission in Hungary (t)...

TABLE 1. Estimates of Atmospheric Cadmium Emissions (Tonnes/Year) from Human Activities... 

Another source of cadmium is fertilizers containing phosphate. Moroccan phosphate rock contains more than 50 g/tonne of cadmium and is no longer used as a fertilizer within the European Union. Industries for the production of zinc are a third source. Even here the situation is improved, as is exemplified by the following figures. In 1970 the total cadmium emissions to the atmosphere in Sweden were estimated to be 25 tonne/year. A large metal producer, Boliden, accounted for half this... 

Spent NiCd batteries are, when incinerated or disposed of in landfills, a source of heavy cadmium emissions. An EU Directive, 2000/60/EC, recommended that the use of 32 chemicals should be phased out within 20 years. According to the recommendation, NiCd batteries should be banned from 2008. The recommendation of 2000 was, however, moderated in 2001. Instead of banning NiCd batteries, new take-back systems and deposit schemes should be developed in order to reduce the risk to human health and the environment. 

Clean air from the filter bag housing is typically passed to a scavenger unit to ensure that discharged gases are within permitted limits for cadmium emissions. 

Direct cadmium emissions to water arise from the chemical and metal industries, the transport sector, waste streams, and agriculmre [6]. Of course, also the destiny of emissions to air is land and/or fresh and marine waters, where cadmium is washed from impervious surfaces, collected and directly or indirectly (via waste-water treatment plants) discharged to a receiving water [6]. 

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