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Sources of cadmium in the environment
ECOTOXICOLOGY
AND
ENVIRONMENTAL
SAFETY
7,9-24 ( 1983)
Sources of Cadmium
in the Environment’
M. HUTTON Monitoring ana’ Assessment Research Centre, Chelsea College, University of London, The Octagon Building, 459a Fulham Road, London SW10 OQX, United Kingdom Received August, 1981 This paper is concerned with quantifying the major sources of cadmium in the European Community and assessing the relative significance of such inputs to the environmental compartments, air, land, and water. The methodology involved identification of potential sources of cadmium, including natural processes, as well as those associated with human activities. This was followed by a review of any emission studies of these processes and subsequent estimation of an emission factor for each source. The emission factor was applied to the most recent production or consumption data for the process in question to obtain an estimate of the annual discharge. The steel industry and waste incineration, followed by volcanic action and zinc production, are estimated to account for the largest emissions of atmospheric cadmium in the region. Waste disposal results in the single largest input of cadmium to land; the quantity of cadmium associated with this source is greater than the total from the four other major sources-coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. The characterization of cadmium inputs to aquatic systemsis incomplete but of the sources considered, the manufacture of cadmium-containing articles accounts for the largest discharge, followed by phosphate fertilizer manufacture and zinc production.
I. INTRODUCTION In recent years, much attention has been paid to the environmental problems associated with heavy metals. Currently, there is considerable interest both in modeling the environmental 5ow of these metals and in the effectiveness of possible regulatory control strategies. An essential prerequisite of both activities is the identification of all potential sources of the metal in the environment and the accurate determination of the quantities released from these sources-source quanti5cation. In this paper, the sources of cadmium release to the environment are quantified at a regional level, the study area being the member states of the European Community (EC). The relative contribution of these sources has been determined in terms of the total quantity of cadmium released to three broad environmental compartments: air, land, and water. Previous estimates of cadmium release have been carried out for the European Community (Rauhut, 1980; Van Wambeke, 1980a) but these are incomplete and in some instances the values assigned to a particular process are considered to be inaccurate. The findings obtained in this study are considered in greater detail elsewhere (Hutton, 1982), with attention also being paid to forecasts of future trends in cadmium emissions. The general methodology adopted in this study involved the initial identification of potential emission sources in the EC associated with both natural processes and ’ Paper presented at the International Symposium, “Ecotoxicology of Cadmium,” May 6-8, 198 1, Neuherberg, Federal Republic of Germany. 9
0147-6513/83/010009-16$03.00/O Copyi& Q 1983 by Academic Res, Inc. All rights of reproduction in any form reserved.
10
M.
HUTTON
human activities. This was followed by a critical review of any emission studies which had been carried out on these sources. Requests for information were made to the industry or state body concerned when published data were lacking. The emission data obtained were used to determine a best judgement emission factor (grams of cadmium emitted per tonne of material produced/consumed). This emission factor was then applied to the most recent production data from the EC and an estimated discharge obtained. II. NATURAL
SOURCES
OF CADMIUM
The quantities of cadmium derived from natural sources are difficult to estimate, largely because there have been very few measurements of the emission or mobilization rates from such processes. Sea sprays, wind-blown dusts, and forest fires all release cadmium to the atmosphere but the amounts involved are thought to be relatively small (Nriagu, 1979). Volcanic action is considered to be the major natural source of cadmium in the atmosphere. This is related to the very large quantities of particulate matter emitted, together with high enrichment of cadmium in volcanic aerosols. An investigation into trace element emissions from Mount Etna in Sicily estimated that 2.8 X 10e2 t day-’ (t = tonnes) or about 10 t year-’ cadmium was discharged into the atmosphere (Buat-Menard and Arnold, 1978). This value is probably lower than the total discharge as the quantity of cadmium in the gaseous state was not measured. Indeed, more recent investigations by Bust-Menard (personal communication) indicate that the annual cadmium emission from Mount Etna lies within the range of 10 to 40 t. No published information exists on cadmium emissions from other active volcanoes in Europe but these are far less important than Mount Etna in terms of the quantity of particulate matter released. The weathering of crustal materials releases cadmium to soils and aquatic systems. This process plays a significant role in the global cadmium cycle but only rarely results in elevated concentrations in any environmental compartment. Black shales from the Carboniferous era are an exception as they contain up to 100 pg g-i cadmium and soils derived from these deposits also contain elevated levels (Holmes, 1975). III.
THE
MINING
OF NONFERROUS
METALS
Nonferrous metal mines, particularly those which exploit lead-zinc ore fields, are a significant source of environmental cadmium. At present, however, insufficient information is available to estimate the magnitude of cadmium discharges from mines in the EC. The cadmium content of the ore body, mining management practice, as well as the topography of mine site and proximity of adjacent watercourses, all influence the quantities of cadmium lost from individual sites. Wind-blown dispersal of spoil-heap material, as well as the activities involved in the processing of extracted ores, cause airborne contamination of cadmium on a local scale. Water-borne dispersal is considered to be the major route of cadmium loss from nonferrous metal mines and can result in the contamination of agricultural soils some distance downstream of the ore field. Flood and storm conditions will increase the mobilization of particulate matter into local watercources. It should be stressed that this problem is not confined to active mines; inadequate management
11
SOURCES OF CADMIUM
of disused lead-zinc mines has resulted in persistent contamination of adjacent waterbodies (Johnson and Eaton, 1980). Active lead-zinc mines are currently found in four member states, Italy, the F.R.G., France, and the Republic of Ireland. No published discharge data are available from these mines despite the probable importance of water-borne cadmium contamination. Van Wambeke (198Oa) assigned a value of 60 to 150 t Cd year-’ lost to waters from active and disused lead-zinc mines in the EC but the basis of this estimate was not stated. IV. PRODUCTION
OF NONFERROUS
METALS
A. Zinc and Cadmium There are two distinct processes employed in the primary production of zinc and cadmium-thermal smelting and electrolytic extraction. Thermal facilities emit much larger quantities of cadmium to the atmosphere, as a consequence of the elevated temperatures employed in the roasting, sintering, and smelting operations. Roth processes also discharge cadmium-rich dusts into the atmosphere during the delivery and handling of the zinc ores but these will remain airborne for only a short time and are deposited in close vicinity to the plant. Liquid wastes containing cadmium arise primarily from the use of wet gas purification devices. In electrolytic works, this water can be recycled to the production process. In contrast, waste waters from thermal plants are often discharged to adjacent water systems after undergoing a cleaning process. The major solid waste requiring disposal from thermal facilities, smelter slag, contains low cadmium concentrations. In contrast, the leach residues from electrolytic plants can contain elevated cadmium levels and care must be exercised in the dumping of such wastes. Of the 18 primary zinc plants operational within the EC, only 5 are essentially thermal facilities. Three of these plants, Duisburg, Noyelles Godault, and Avonmouth supplied estimates of an emission factor and the total quantity of cadmium emitted to the atmosphere in 1979; these are shown in Table 1. No emission information was available for the ISF smelter at Port0 Vesme. Sardinia, or the vertical retort at Harlingerode. The emission estimates for these two plants (Table 1) were made independently of the companies concerned and the assigned values must be viewed as provisional. In view of the relatively small quantities involved, no formal requests for atmospheric emission data were made to the owners of electrolytic refineries. Total atmospheric emissions of cadmium from the electrolytic plant at Datteln, F.R.G., were estimated to be 30 kg year-’ (Riipenack, 1978). Application of the corresponding emission factor (0.2 g Cd t-’ zinc) to the estimated quantity of zinc produced electrolytically in the EC in 1979 (928 X lo3 t) results in an atmospheric emission of less than 0.2 t year-‘. It is estimated that 50 tonnes of cadmium were released to waters in the EC from zinc production in 1979. Individual facilities vary greatly both in the quantity of cadmium released and also in the characteristics of the water body which receives the effluent. Thus, the ISF plant at Avonmouth is estimated to release 3 t year-’ to the Sevem Estuary (HMSO, 1980), the smelter at D&burg discharges about 1 t year-’ to the River Rhine, while the electrolytic plant at Datteln releases less than 40 kg Cd year-’ to the Rhine (Riipenack, 1978).
12
M. HUT-l-ON
TABLE 1 THERMAL ZINC PLANTS IN THE EC: PRODLJ~ION AND ESTIMATED AIRBORNE CADMIUM EMISSIONSDURING 1979 Zinc production Location of plant Duisburg (F.R.G) Noyelles Godault (France) Avonmouth (U.K.) Port0 Vesme (Italy) Harlingerode (F.R.G.)
((t yew’)
75 86 77.4 43” 81.2
x 103)
Cadmium emission factor (g Cd t-‘) 10-15
35-52 70 loo
Cadmium emission (t year-‘) 0.8 5 2.7
0 Estimated from annual zinc production capacity of the plant and total Italian zinc production in
1979.
The total quantity of cadmium entering landfills from zinc production in 1979 is estimated to be 200 tonnes. Most of this consists of leach residues which are disposed of in landhlls constructed with impermeable linings. B. Copper and Lead In 1979, 159.7 X lo3 t copper were produced from ores in the EC (Metallgesellschaft, 1980). Larger quantities of copper are produced in the EC by the refining of imported blister copper; it has been estimated that 487 X lo3 t copper originated from this source in the EC in 1979. The initial roasting of copper concentrates occurs at about 1200°C and this results in the vaporization of some of the cadmium present in the concentrates. An EPA study (Deane et al., 1976) gave an emission factor of 3 g Cd t-’ copper produced. No emission data are available for the refining of blister copper, but the use of a “cleaner” starting material and the elimination of a roasting stage suggests there will be a lower emission of cadmium and an atmospheric emission factor half that given for the production from ores has been assumed. Application of these emission factors to the 1979 production data, given above, results in an estimated atmospheric emission of about 1.5 t. Secondary production of copper is a rather general term and includes the smelter production of,copper from scrap and waste, the secondary production of refined copper, and the direct use of scrap. An experimental study of several scrap refineries in the U.K. (Mantle, personal communication) found that the stage where impurities in the scrap are oxidized is responsible for the largest emission of cadmium. This investigation also suggested that total atmospheric emissions of cadmium were unlikely to ,exceed 4 g Cd t-’ copper produced. However, the quantity of cadmium emitted from such facilities will be strongly influenced by the nature of the scrap charge and the emission factor for those refineries handling copper-cadmium alloy scrap is likely to be much greater than 4 g t -I. In 1976, the last year for which complete figures are available, secondary copper production totalled 1132 X lo3 t (CEC, 1979). Application of the emission factor of 4 g t-’ to total secondary copper production results in an estimated atmospheric cadmium emission of.4.5 t. Total atmospheric cadmium emissions from primary and secondary copper production have thus been estimated at 6 t year-‘.
SOURCES OF CADMIUM
13
The lack of published information makes any estimate of cadmium inputs to land and water rather tentative. In fact, the only estimate available for the EC was provided by Van Wambeke (1980a) who gave a figure of 15 t cadmium discharged to land&Is from “copper metallurgy” in 1975. In 1979, the total production of refined lead in the EC amounted to 1244 X lo3 t (CEC, 1979). About one-third of this quantity was actually produced from secondary materials, the most important being used lead-acid batteries. Indeed, many “primary” lead plants are fed with a mixed charge of roasted ores and scrap materials. It has thus been assumed that of the 1244 X lo3 t of refined lead produced, 829 X lo3 t were derived from primary sources and 4 15 X 1O3 t from secondary materials. The quantity of lead recovered from scrap in 1979 totalled 837 X lo3 t and this should be added to the secondary refined lead production value, to give the estimated overall secondary lead production figure (1252 X lo3 t). An American survey (Coleman et al., 1979) assigned an atmospheric emission factor of 2.5 g t-’ to primary lead production. However, in an experimental study (Dugdale and Hummel, 1978), a primary lead smelter in New Brunswick was estimated to emit more than 3 t Cd year-‘, which is equivalent to an emission factor of about 55 g t-l. It is not clear at present whether this value is representative of primary lead smelters in general. For the present, an emission factor of 5 g t-’ has been assumed from this source. Application of this factor to the estimated 1979 primary lead production value results in an atmospheric emission estimate of 4 t Cd year-‘. A large proportion of the material used for secondary lead production consists of relatively pure scrap lead and the emission factor of cadmium from this source has been assumed to be half that from primary production at 2.5 g Cd t-‘. It is thus estimated that secondary lead production in the EC resulted in an atmospheric cadmium emission of 3 t in 1979 making the total atmospheric cadmium emission from lead production to be 7 t. In view of the paucity of available information, any estimate of the inputs of cadmium to water and land from lead production must at present be tentative. The New Brunswick lead smelter, discussed above, was estimated to discharge 3 t Cd year-’ in liquid wastes, while the furnace slag contained 7 t Cd year-’ (Dugdale and Hummel, 1978). It is felt that these quantities, and the corresponding emission factors, may be atypical and not applicable to lead production in the EC. It has been provisionally estimated that lead production in 1979 resulted in cadmium inputs of 20 t to water bodies in the EC and 40 t to landfills. V. PRODUCTION AND DISPOSAL OF CADMIUM-CONTAINING MATERIALS At present, there is insufficient information available to allow an accurate estimation of cadmium discharges from the manufacture and disposal of cadmiumcontaining materiaIs in the EC. A previous analysis of the situation has been attempted (Rauhut, 1980) but the basis of the estimated values is not clear. Many of the assumptions employed in the present study are derived from a detailed investigation into the U.S. cadmium industry (Yost, 1979). It should be stressed that many cadmium-containing products have a long lifetime. For the sake of simplicity it has been assumed that product disposal occurs in the same year as manufacture. Additionally, the losses of cadmium which occur during product use have not been taken into account.
14
M. HUT-l-ON TABLE
2
FATE OF CADMIUM A.WXIATED WITH THE MANUFACI-URE AND DISPOSAL OF THE MAJOR USES OF CADMIUM IN THE EC
Compartmental Use Electroplating Pigments Stabilizers Ni-Cd batteries
Cadmium usea 0)
Landfill
Water pathway
1207 1315
713
60 26 7 13.7
722
9006
7 22
flow of cadmium (t) Waste disposal -
Steel cycle
Recycle
434
-
1289
-
-
708 646
-
218
’ Consumption data for 1975 from Hiscock (1978). * Predicted 1980 consumption, assuming an annual increase of 5% from 1975.
Table 2 shows the estimated fate of cadmium associated with the manufacture and disposal of the major uses of cadmium in the EC. The following assumptions were made in calculating the flow pattern depicted: Electroplating. Of the cadmium consumed in the production of plated items, 10% is lost to aqueous wastes and the remaining 90% is present on the product. Of the cadmium in aqueous wastes, 50% is recovered as residues and 50% is discharged to sewage treatment plants (“water”). The residues recovered are not reprocessed and are disposed to landfills. Of the cadmium present in the product, 40% enters the scrap steel cycle and 60% is landfilled. Pigments. No significant atmospheric emissions of cadmium occur in the manufacture of pigments. All solid residues produced during pigment manufacture are recovered and recycled. Of the cadmium used in pigment manufacture, 2% is ultimately discharged to sewage treatment plants (“water”). All the cadmium present in the product enters the municipal waste disposal pathway. Stabilizers. Of the cadmium consumed, 50% is used for liquid stabilizer production and 50% for solid stabilizers. Of the cadmium used in the manufacture of liquid stabilizers, 2% is present in filter residues and this is disposed of in landfills. Of the cadmium consumed in the production of solid stabilizers, 2% is not reclaimed from aqueous wastes and is lost to sewage treatment plants (“water”). All the product ultimately enters the municipal waste disposal pathway. Nickel-cadmium batteries. Of the total cadmium consumed, 50% is used for pocketplate cells and 50% for sintered-plate or sealed cells. Of the cadmium used to produce pocket-plate cells, 3% is lost as dusts; 10% of the cadmium in these dusts is discharged to sewage treatment plants (“water”) and 90% enters landfills. Of the cadmium present in pocket-plate cells, 50% is recycled and the remainder enters the waste disposal pathway. Of the cadmium consumed in the manufacture of sintered-plate and sealed cells, 5% is lost to aqueous wastes. Of the cadmium in aqueous wastes, 45% is recovered and landfilM, while the ,remainder is discharged to sewage treatment plants (“water”). The cadmium present in sintered-plate and sealed cells enters the waste disposal pathway. Alloys. Insufficient data exist to quantify the flow of cadmium from the manufacture and disposal of cadmium alloys. Nevertheless, losses of cadmium to landfills and water from product manufacture are unlikely to be significant. Additionally, it
15
SOURCES OF CADMIUM TABLE3
CADMIUMEMWIONFACTORSFORTHEEUROPEANIRONAND STEEL
INDUSTRY, DERIVED FROM THE U.K. STUDY Emission factor (g Cd t-l material produced) Process
Atmosphere
Sinter production Iron production Basic oxygen steelmaking Electric arc steelmaking
0.08 0 0.02 0.40
Solid wastes
Slags
0
0
0.67 0.36 3.65
ND I.11 0.29
Source:Praker(personalcommunication). Note. ND-not determined. is considered that atmospheric emissions from the production of copper-cadmium alloys in the EC will be less than 3 t Cd year-‘. Disposal of articles containing cadmium alloys will occur via the secondary copper industry and the municipal waste pathway. Inspection of Table 2 reveals that the quantity of cadmium discharged to water from electroplating units is greater than the combined total from all other major uses. The municipal waste disposal pathway is estimated to receive a total of 2643 t Cd year-’ from the disposal of pigments, stabilizers, and nickel-cadmium batteries. VI. IRON
AND
STEEL
PRODUCTION
Most of the cadmium released during the production of iron and steel is derived from the recycling of galvanized and cadmium-plated steel scrap, but the raw materials of the steel industry can also contain a significant amount of cadmium. A recent experimental investigation into the flow of cadmium through the U.K. iron and steel industries (Prater, personal communication) has provided much of the data base for estimation of the quantities of cadmium released by other member states. Table 3 lists the emission factors to air, solid wastes, and slags derived from this U.K. study. The term “solid wastes” refers to the flue dusts arrested by collection devices, while slag is the material which remains in the furnace. The higher atmospheric emission factor for electric arc steelmaking (EAS) compared with basic oxygen steelmaking (BOS) reflects the large quantities of steel scrap processed by electric arc furnaces. The amount of cadmium discharged in aqueous wastes from the steel industry has not been estimated, as it is considered that there is insufficient data to justify such a calculation. The experimental study, discussed above, did not consider open-hearth steelmaking so the atmospheric emission factor of 1 g t-i from the study of Rauhut (1980) has been adopted for this process. Data on the presence of cadmium in slags and solid wastes were not available for open-hearth steelmaking, so no estimates of the quantities discharged to these compartments could be made. Table 4 shows the estimated quantities of cadmium discharged by the EC iron and steel industries in 1979, both for individual countries and for processes. An additional “sink” for cadmium is the amount retained in the steel itself; applying the U.K.
16
M. HUTTON
TABLE 4 ESTIMATED DWHARGE (TONNES) OF CADMIUM FROM THE EC IRON AND STEEL INDUSTRY IN 1979 FOR INDIVIDUAL MEMBER STATES AND ACCORDING TO PR~CEW, Discharge medium Air
Country IMY Luxembourg The Netherlands United Kingdom Federal Republic of Germany Belgium France Denmark Total
7.7 0.7 0.9 5.9 10.7 1.4 6.3 0.5 34
Solid wastes
58.3: 4.4 5.2 40 59.5 14 46 1.5 229
Slags
15 5.5 6.1 16.4 40.9 14.5 21.7 0.1 120
hocess
Ironmaking Sinter production Pig iron Total
Steelmaking BOS EAS
OHS Total
10.6 0
0
0
65.8
ND
10.6
65.8
2.1 13.9
36 128
111 9
7.6
ND
ND
23.6
164
120
Note. ND-not determined; BOS-basic oxygen steelmaking; EAS-electCc steelmaking; and OHS-open-hearth steelmaking.
arc
findings to 1979 EC production (139 X lo6 t) indicates a total of about 70 t in crude steel. Atmospheric emissions from sinter and steel production for The Netherlands were not estimated from the emission factors given in Table 4. In this case, the values were obtained from a survey of cadmium in the EC iron and steelmaking industries (Steiner, personal communication). This study also noted that the arrested dusts from electric arc furnaces in France contained 600 pg g-’ cadmium compared with 300 pg g-’ for U.K. dusts. For this reason, the discharge factors applied to atmospheric emissions and solid wastes for EAS in France are double those given in Table 3. Examination of the values given in Table 4 reveals that the iron and steel industries in Luxembourg, The Netherlands, and Belgium display relatively low atmospheric emissions of cadmium. This finding is related to both the modest production rates of these countries and to the fact that almost ail the steel is produced by the basic oxygen process. In comparison, the higher atmospheric emission estimates for Italy and the U.K. are a consequence of the larger quantities of steel produced, together with the reliance placed upon electric arc steelmaking by these countries.
17
SOURCES OF CADMIUM TABLE 5
CADMIUM CONTENT (pg g-l) OFCam SAMPLED FROM THE FEDERAL REPUBLIC OF GERMANY AND THE UMTED KINGDOM Country of origin and coal type
Mean
Range
F.R.G. Lignite Bituminous coals
0.02 2.0
I-10
Sample size 1 27
Source Heinrichs ( 1977) Kautz et al., (1975)
U.K. Anthracite and bituminous coals from Wales ‘Power station’ coals
1.0
0.4-10
302
Chattejee and Pooley ( 1977)
0.4
0.3-0.8
NG
Gibson ( 1979)
Note. NG-not given.
The F.R.G. is the largest producer of iron and steel in the EC and was also estimated to emit more cadmium to the atmosphere than the other member states. Inspection of these emissions by process indicates that, in contrast to Italy and the U.K., the largest source of cadmium is open-hearth steelmaking followed by sinter production. The relatively smaIl contribution from electric arc steelmaking reflects its minor share in the steel market of F.R.G. The quantity of cadmium present in steel slags is estimated to be 120 t; this value is similar to the amount of cadmium entering landfills from zinc production in the EC. It should be made clear, however, that the cadmium present in steel slags is associated with much larger quantities of material. Furthermore, the cadmium in these slags is incorporated into a fused mass of material and is thus likely to display a low solubility. Slags from steel production are either disposed of in landfills or utilized commercially. The solid wastes derived from steelmaking are, in general, not recycled through the industry and have to be disposed of in landfills. Thus, it is estimated that over 200 t cadmium entered landfills from this source in the EC. The cadmium in solid wastes is present at higher concentrations than in slags and is associated with fine particulate matter suggesting that the cadmium will display a greater potential for biological uptake than the cadmium in steel slags. This point is particularly important for electric arc steelmaking, where the cadmium concentrations of the solid wastes are the highest of the three major steelmaking processes (Yost, 1979). VII. FUEL
COMBUSTION
A. Coal Combustion Table 5 summarizes the available data on cadmium the F.R.G. and the U.K., the two largest coal consumerS coals from Germany have the higher cadmium content, tries display a wide range of variation. The mean values taken into account when assigning an average cadmium
levels in coal samples from in the EC. Apparently, hard but values from both coungiven in Table 5 have been content of 1 pg g-’ to hard
18
M.
HUTTON
coals consumed in the EC. German lignites have also been assumed to contain 1 pg Cd g-‘, despite the very low level shown in Table 5. This value was based on only one sample and may not be representative of lignite in general. At present, the largest coal-consuming sectors of the EC are electrical power stations and coke ovens; these accounted for 56 and 30% of the total EC production in 1978. Other industries used about 6% while the domestic and commercial sector burnt 7% of the total consumed. The F.R.G. accounts for nearly all the lignite consumed in the EC and about 90% of this is burnt at power stations. Coal combustion in modem power plants occurs at about 15OO’C and results in vaporization of most of the cadmium present in coal. Experimental in-stack studies (Ondov et al., 1978; Coles et al., 1979) indicate that cadmium subsequently condenses in a preferential manner onto the smaller particles suspended in the flue gas. Although these particles are less efficiently retained than the coarser fly ash particles, an emission factor of only 0.02 g Cd t-’ has been assumed for this process. This figure is based upon a collection efficiency of 98% and is similar to estimates given by Coleman et al. (1979); Nriagu (1979); and Yost (1979). Little information exists on the emissions of cadmium from the other coal-consuming sectors and an emission factor of 0.02 Cd t-’ has also been assigned to these sectors. In the case of coke production, there is some experimental evidence to support this assumption, as coke ovens in the U.K. were estimated to emit 0.15 t cadmium from 10 X lo6 t coal, corresponding to an emission factor of just under 0.02 g t-’ (Prater, personal communication). Coal consumption in the EC for 1978 amounted to 287 X lo6 t (Eurostat, 1980). Atmospheric emissions from this process are therefore estimated to total just under 6 t, of which the U.K. accounts for about 2.5 t and the F.R.G. 1.5 t. The remaining cadmium, nearly 300 t, will be present in ashes, most of which will be disposed of in landfills and ash ponds. In 1978, power plants in the F.R.G. burnt 110 X lo6 t lignite (Eurostat, 1980). The quantity consumed is estimated to result in 2.2 t cadmium released to the atmosphere and 108 t incorporated in ashes.
B. Oil and Gas The cadmium content of crude oil is lower than coal (Hofstader et al., 1976) and an average value of 0.05 pg g-’ has been assigned to this material. Little information exists on the extent of cadmium release from the combustion of oils. It has been assumed that 2%, the same proportion estimated for coal combustion, will be released when oil is burnt. The majority of the cadmium in oil is thus expected to be retained in ashes. Fuel oil consumption in the EC totalled 301 X lo6 t in 1978, resulting in an estimated atmospheric emission of less than 1 t cadmium. The remainder of the cadmium, about 14.5 t, wiIl be present in ashes, most of which will be disposed of in landfills. Natural gas does not contain significant quantities of cadmium and is considered to be a negligible source of cadmium in the environment. VIII.
WASTE
DISPOSAL
The major sources of cadmium in municipal wastes are scrap metal and plastics containing pigments and stabilizers. The heterogeneous composition of municipal
19
SOURCES OF CADMIUM TABLE
6
FATE OF CADMIUM ENTERING MUNICIPAL WASTE DISPOSAL PATHWAY IN THE EC Cadmium in discharge medium country
Waste generated” (Xl06 t)
Waste landfille4P (Xl06 t)
IdY Luxembourg The Netherlands U.K. F.R.G. Belgium France Denmark Ireland
16 0.13 5.3 28’ 25 3.5 16 2.5 1.3
13.4 3.6 24.8 19.6 3 11.1 1.3
201 54 372 294 45 166 20
EC Total
91.1
16.8
1,152
a Source: Van Wan&eke ( 198Ob). b Source: U.K. Department of tbe Environment 9
Cadmium in landfills 0)
Waste incinerated” (Xl06 t) 2.6 0.1 1.7 3.2b 5.4 0.54 4.9 2.5 20.9
Atmosphere emissions 3.9 0.2 2.6 4.8 i.8 1.4 3.7 31.4
Ashes 35.1 1.4 23 43 72.9 7.3 66 33.8 282
(personal communication).
waste makes it difficult to estimate an average cadmium content for this material. Values of 12 pg g-’ for the U.K. and 30 Kg g-r for the F.R.G. have been reported (HMSO, 1980), and this study has assumed an average cadmium content of 15 fig g-* for the EC. Table 6 shows the quantities of municipal waste generated by each member state in 1977 and the estimated totals discharged directly to landhlls. The large quantities of waste disposed of in this manner result in more than 1000 t cadmium entering such sites (Table 6). The U.K. and the F.R.G. are the two largest contributors and together account for over half this total. At present, about 20% of the municipal waste generated in the EC is incinerated. The amounts combusted in 1978 by individual member states are shown in Table 6. Several studies have reported that fly ash from refuse incinerators contain elevated cadmium concentrations and that the cadmium in fly ash is predominantly associated with submicron particles, the particles least efhciently retained by control devices (Greenberg et al., 1978; Scott, 1979). Experimental measurements of trace element emissions from refuse incinerators reveal a relatively high emission rate of cadmium from this source, with values ranging from 0.7 to 4.4 g Cd t-’ (Greenberg et al., 1978; Scott, 1979). After examining the relevant data available, an emission factor of 1S g t-’ has been assigned to atmospheric cadmium release from refuse incineration. This value is considered to be representative of the larger facilities equipped with modem particulate control devices. Atmospheric emissions of cadmium from refuse incineration in the EC were estimated to total over 30 t in 1978 (Table 6). The largest contributors were, in decreasing order, the F.R.G., France, and the U.K. The cadmium retained in the incinerator is partitioned between colIected fly ash and the furnace clinker. However, as both wastes are generally landhlled, they have been considered as a single discharge medium in Table 6. The total of 282 t cadmium present in these ashes is considered to be of greater environmental significance than the 1152 t discharged by direct landfill. This is because the cadmium in fly ash is
20
M. HUTTON
expected to be more soluble than in untreated waste and will thus display a greater propensity for leaching from landfill sites. IX. SEWAGE
SLUDGE
The production of sewage sludge in the EC was considered by Van Wambeke (198Oa) to total 5 X lo6 t (dry weight) in 1975. More recent data have not been published; for the purposes of this study, it has been assumed that sludge generation in the EC has increased at an annual rate of 2%, indicating a generation of 5.5 X lo6 t sludge in 1980. The cadmium present in sewage sludge originates from both domestic and industrial sources, but the latter is thought to be responsible for the major portion of the total. In assigning an average cadmium content to sewage sludge in the EC, the mean value of about 30 pg g-’ obtained in an extensive U.K. survey (HMSO, 1980) has been adopted. Thus an estimated total of 165 t cadmium are assumed to be present in sewage sludge generated in the EC in 1980. The pattern of sewage sludge disposal varies between member states of the EC but detailed information is only available for The Netherlands, the F.R.G., and the U.K. (Scheltinga, 1979; Thormann, 1979; HMSO, 1980). On the basis of these figures, it has been assumed that 75% of the sludge generated in the EC is disposed of to land, 20% to water (sea), and 5% is incinerated. It has been additionally assumed that 25% of the cadmium present in sludge is released to the atmosphere upon incineration and the remainder is ultimately disposed of to land. This high atmospheric emission estimate is based upon the finding that some sewage sludge incinerators in the U.K. release one-third of the cadmium to air (HMSO, 1980). Application of this disposal pattern results in an estimated 2 t cadmium emitted to the atmosphere, 33 t to water, and 130 t to land. X. PHOSPHATE
FERTILIZERS
A. Fertilizer Manufacture The major source of cadmium discharges from phosphate fertilizer manufacture is associated with the wet process production of phosphoric acid which uses sulfuric acid to form phosphoric acid from rock phosphate. The cadmium originally present in the rock phosphate will become distributed between the phosphoric acid and gypsum waste. The major disposal route of the gypsum is by dumping in coastal waters but a proportion is landfilled and the remainder is utilized by the construction industries. Estimated annual discharges of cadmium to land and water from the manufacture of phosphoric acid by the wet process total 34 and 62 t, respectively. These values have been computed from a recent survey of the phosphate fertilizer industry in the EC (Feenstra, 1978). France is the largest phosphoric acid producing country in the EC and accounts for the major portion (27 t year-‘) of cadmium discharged to waters from this source. In the F.R.G., most of the gypsum is recovered and used as a construction material; as a consequence, cadmium discharges from phosphoric acid manufacture are relatively low.
B. Fertilizer Use The cadmium contents of phosphate fertilizers vary widely and depend upon the country of origin. Table 7 shows the estimated average cadmium levels in fertilizers
21
SOURCES OF CADMIUM
TABLE 7 ASSUMED CADMIUM CONTENT OF PHOSPHATE FERTILIZERS ACXXRDING TO COUNTRY OF ORIGIN
Country of origin
Cadmium content’ (g Cd t-’ PzOs)
Morocco U.S.A. Togo Senegal U.S.S.R. Tunisia/Algeriab Israel/Jordanb
60 35 160 255 0.8 60 35
(1Values modified from Feenstra ( 1978). * Values assigned by author of present study.
from the major exporters of rock phosphate to the member
states of the EC. The quantities of phosphate rock imported into the EC member states in 1979, broken down according to country of origin, have also been obtained (Anon, 1981). These data, in conjunction with the values given in Table 7, and the actual quantities of phosphate fertilizer consumed in the member states, have been used to estimate the amounts of cadmium discharged to agricultural land in the EC, as a consequence of fertilizer application. The estimated quantities for each member state are shown in Table 8. The total quantity of cadmium discharged to agricultural land from fertilizer use in the EC is thus estimated to be 3 12 t in 1979. XI. SUMMARY
AND
CONCLUSIONS
This paper has attempted to quantify the major sources of cadmium inputs into the environment of the EC. The values obtained are summarized in Table 9. In some cases, the assigned values should be considered as tentative until more precise estimates can be made. TABLE 8 ESTIMATED
DISCHARGES OF CADMIUM TO AGRICULTURAL FROM THE APPLICATION OF PHOSPHATE FERTILIzEM IN THE EC IN 1979
LAND
Country
Total cadmium discharged(t)
Italy The Netherlands United Kingdom Federal Republic of Germany Belgium/Luxembourg France Denmark Republic of Ireland
49 7 45 44 8
Total
144
7 8 312
22
M. HUTTON TABLE 9 SUMMARYOFCURRENTCADMIUMINPUTSTOTHE
EC ENWRONMENT(~~W-I) Compartment
Source Volcanic action Nonferrous metal production Zinc and cadmium Copper Lead Production of cadmium-containing Iron and steel production Fuel combustion Coal and lignite Oil and gas Waste disposal Sewage sludge disposal Phosphate fertilizers Totals Note.
ND-not
materials
Air
Land
Water
20
ND
ND
20 6 7 3 34
200 15 40
8 0.5
31 2 -
132
349: 390 14.5 1434 130 346 3009
50
ND 20 108 ND ND G 33 62 273
determined.
Cadmium release has been considered for three broad environmental compartments: air, land, and water. This approach conceals large differences in the mobility and environmental significance of the cadmium released which arise as a consequence of the precise disposal route employed. In the terrestrial compartment, for example, sewage sludge applied to agricultural land will be of greater significance from the perspective of human exposure and environmental mobility than sludge which is landfilled. Similarly, cadmium inputs to the aquatic environment from phosphate fertilizer manufacture and sewage sludge disposal generally occur in coastal waters and will generally be of little direct significance to human exposure. In contrast, a large proportion of aquatic cadmium discharges from electroplating will be incorporated in the sewage sludge and some of this will subsequently be applied to agricultural land. Another aspect of importance, not clear from Table 9, is that the environmental significance of cadmium in a particular waste stream is not necessarily directly related to the total quantity of cadmium present. Thus, the 200 t cadmium in solid wastes from zinc production are of greater potential significance than the 390 t cadmium present in ashes from coal combustion because they are associated with much smaller amounts of waste material. The iron and steel industries together with refuse incineration represent the two largest sources of atmospheric cadmium in the EC. The other major sources, zinc production and volcanic action, are next in ranking. All other sources account for less than one-quarter of the total atmospheric discharges. Municipal waste disposal results in the largest single input of cadmium to land in the EC. The quantity of cadmium associated with this pathway is greater than the combined total of the four other major sources. These processes are, in descending rank, coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. These five sources together contribute 90% of the total cadmium inputs to land in the EC.
SOURCES OF CADMIUM
23
The characterization of cadmium inputs to aquatic systems in the EC is incomplete. Of the sources considered in the present study, the manufacture of cadmium-containing articles accounts for the largest single input of cadmium. Phosphate fertilizer manufacture is next in ranking, followed by discharges from zinc production. ACKNOWLEDGMENT This research was supported by the Commission of the European Communities, Environment, Raw Materials and Material Technologies Research ProIrrammes, Directorate General for Science, Research and Development (Contract Number 333-ENV U.K.).
REFERENCES ANON. (1981). Phosphate rock exports January to December 1980. Phosphorus Potassium 111. BUAT-~NARD, P., AND ARNOLD, M. (1978). The heavy metal chemistry of atmospheric particulate matter emitted by Mount Etna volcano. Geophys. Res. Left. 5, 245-248. Commission of the European Communities (CFC) (1979). Raw Materials. Research and Development. I. Copper. II Lead and Zinc. CEC, DG XII, Brussels. CHATI-ERJEE, P. K., AND PGOLEY, F. D. (1977). An examination of some trace elements in South Wales coals. Proc. Australas. Inst. Min. Mettal. 263, 19-30. COLEMAN, R., LENT, J., SIEBERT, P., MILLER, C., AND COFFEY, E. (1979). Sources ofAtmospheric Cadmium. EPA450/5-79006, U.S. Environmental Protection Agency. C~LES, D. G., RAGAW, R. C., Ormov, J. M., FISHER, G. L., SILBERMAN, D., AND PRENTICE, B. A. ( 1979). Chemical studies of stack fly ash from a coal-tired power plant. Environ. Sci. Technol. 13,455-459. DEANE, G. L., LYNN, D. A., AND SURPENANT, N. F. (1976). Cadmium: Control Strategy Analysis. GCATR-75-36-G. U.S. Environmental Protection Agency. DUGDALE, P. J., AND HUMMEL, B. L. (1978). Cadmium in the lead smelter at Belledune: Its association with heavy metals in the environment. In Cadmium 77. Edited Proceedings, First International Cadmium Conference, San Francisco, 31 January-2 February 1977 pp. 53-75. Metal Bulletin Ltd., London. EUROSTAT. (1980). Energy Statistics Yearbook 1978. Statistical Office of the European Communities. Commission of the European Communities, Brussels. hENSTRA, J. F. (1978). Control of Water Pollution due to Cadmium Discharged in the Process of Producing and Using Phosphate Fertilizers. ENV/223/74-EN. Commission of the European Communities, Brussels. GIBSON, J. (1979). Con1 and the Environment. National Coal Board, London. GREENBERG, R. R., ZOLLER, W. H., AND GORDON, G. E. (1978). Composition and sire distribution of particles released in refuse incineration. Environ. Sci. Technol. 12, 566-573. HEINRICHS, H. (1977). Emissions of 22 elements from brown coal combustion. Nuturwiss. 64,479-48 1. HI-K, S. A. (1978). Production, Consumption and Uses of Cadmium in the European Community (1965-1976). ENV/223/74-E. Commission of the European Communities, Brussels. HMSO (1980). Cadmiun in the Environment and its Significance to Man. Pollution Paper No. 17. Department of the Environment. Central Directorate on Environmental Pollution, London. HOFSTADER, R. A., MILNER, 0. I., AND RUNNELS, J. H. (Eds) (1976). Cadmium. In Analysis of Petroleum for Trace Metals; Advances in Chemistry. Series: 156. pp. 81-94. Amer. Chem. Sot. HOLMES, R. (1975). The Regional Distribution of Cadmium in England and Wales. Ph.D. thesis, University of London. HVITON, M. (1982). Cadmium in the European Community: A Prospective Assessment of Sources, Human Exposure and Environmental Impact. MARC Report No 26, Monitoring and Assessment Research Centre, Chelsea College, University of London. JOHNSON, M. S., AND EATON, J. W. (1980). Environmental Contamination through residual trace metal dispersal from a derelict lead-zinc mine. J. Environ. Qual. 9, 175-179. KAUTZ, K., HIRSCH, H., AND SINGH DEO, R. (1975). Chemismus und morphologic von Kr&werksst&rben. VGB Krafwerkstechnik 55, 1EO- 187. METAUIGESELLSCHAFT (1980). Metal Statistics 1969-1979. Frankfurt am Main. NRIAGU, J. 0. (1979). Global inventory of natural and anthropogenic emissions of trace metals to the atmosphere. Nature (London) 279, 409-4 11. ONDOV, J. M., RAGAINI, R. C., AND BIERMANN, A. H. (1978). Elemental particle size emissions from coal-fired power plants: use of an inertial cascade impactor. Atmos. Environ. 12, 1175-l 185.
24
M. HUTTON
A. (1980). Industrial Emissions of Cadmium in the European Community: Sources, Levels and Control. ENV/223/74E. Commission of the European Communities, Brussels. R~PENACK, A. VON (1978). Emission control in cadmium metal production. In Cadmium 77. Edited Proceedings, First International Cadmium Conference, San Francisco, 31 January-2 February? 1977. pp. 49-53. Metal Bulletin Ltd., London. S~HELTINGA, H. M. J. (1979). Utilisation of sewage on land in Holland. In Utilisation of Sewage Sludge on Land, Oxford, 10-l 3 April 1978. pp. 309-3 16. Water Research Centre, Stevenage, Herts. SCOTT, D. W. (1979). The Fate of Cadmium in Municipal Refuse Incinerators. Warren Spring Laboratory Report CR 1710 (AP). Warren Spring, Stevenage, Herts. THORMANN, A. (1979). Utilisation of Sewage Sludge on Land. The situation, problems and development trends in Gesmany. In Utihsation of Sewage Sludge on Land, Oxford, IO-13 April 1978. pp. 290-308. Water Research Centre, Stevenage, Herts. VAN WAINBEKE, L. (1980a). Measures taken by the European Communities in respect of cadmium between 1977 and 1979 and inventory of emissions into the environment. In Cadmium 79. Edited Proceedings, Second International Cadmium Conference, Cannes, 6-8 February 1979. pp. 153-157. Metal Bulletin Ltd., London. VAN WAMBEKE, L. (1980b). Energy from Municipal Waste in the European Community. CEC Xl l/252/ 80-EN. Commission of the European Communities, Brussels. YOST, K. J. (1979). Some aspects of cadmium tlow in the U.S. Environ. Health. Perspect. 28, 5-16. RAUHUT,
AND
ENVIRONMENTAL
SAFETY
7,9-24 ( 1983)
Sources of Cadmium
in the Environment’
M. HUTTON Monitoring ana’ Assessment Research Centre, Chelsea College, University of London, The Octagon Building, 459a Fulham Road, London SW10 OQX, United Kingdom Received August, 1981 This paper is concerned with quantifying the major sources of cadmium in the European Community and assessing the relative significance of such inputs to the environmental compartments, air, land, and water. The methodology involved identification of potential sources of cadmium, including natural processes, as well as those associated with human activities. This was followed by a review of any emission studies of these processes and subsequent estimation of an emission factor for each source. The emission factor was applied to the most recent production or consumption data for the process in question to obtain an estimate of the annual discharge. The steel industry and waste incineration, followed by volcanic action and zinc production, are estimated to account for the largest emissions of atmospheric cadmium in the region. Waste disposal results in the single largest input of cadmium to land; the quantity of cadmium associated with this source is greater than the total from the four other major sources-coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. The characterization of cadmium inputs to aquatic systemsis incomplete but of the sources considered, the manufacture of cadmium-containing articles accounts for the largest discharge, followed by phosphate fertilizer manufacture and zinc production.
I. INTRODUCTION In recent years, much attention has been paid to the environmental problems associated with heavy metals. Currently, there is considerable interest both in modeling the environmental 5ow of these metals and in the effectiveness of possible regulatory control strategies. An essential prerequisite of both activities is the identification of all potential sources of the metal in the environment and the accurate determination of the quantities released from these sources-source quanti5cation. In this paper, the sources of cadmium release to the environment are quantified at a regional level, the study area being the member states of the European Community (EC). The relative contribution of these sources has been determined in terms of the total quantity of cadmium released to three broad environmental compartments: air, land, and water. Previous estimates of cadmium release have been carried out for the European Community (Rauhut, 1980; Van Wambeke, 1980a) but these are incomplete and in some instances the values assigned to a particular process are considered to be inaccurate. The findings obtained in this study are considered in greater detail elsewhere (Hutton, 1982), with attention also being paid to forecasts of future trends in cadmium emissions. The general methodology adopted in this study involved the initial identification of potential emission sources in the EC associated with both natural processes and ’ Paper presented at the International Symposium, “Ecotoxicology of Cadmium,” May 6-8, 198 1, Neuherberg, Federal Republic of Germany. 9
0147-6513/83/010009-16$03.00/O Copyi& Q 1983 by Academic Res, Inc. All rights of reproduction in any form reserved.
10
M.
HUTTON
human activities. This was followed by a critical review of any emission studies which had been carried out on these sources. Requests for information were made to the industry or state body concerned when published data were lacking. The emission data obtained were used to determine a best judgement emission factor (grams of cadmium emitted per tonne of material produced/consumed). This emission factor was then applied to the most recent production data from the EC and an estimated discharge obtained. II. NATURAL
SOURCES
OF CADMIUM
The quantities of cadmium derived from natural sources are difficult to estimate, largely because there have been very few measurements of the emission or mobilization rates from such processes. Sea sprays, wind-blown dusts, and forest fires all release cadmium to the atmosphere but the amounts involved are thought to be relatively small (Nriagu, 1979). Volcanic action is considered to be the major natural source of cadmium in the atmosphere. This is related to the very large quantities of particulate matter emitted, together with high enrichment of cadmium in volcanic aerosols. An investigation into trace element emissions from Mount Etna in Sicily estimated that 2.8 X 10e2 t day-’ (t = tonnes) or about 10 t year-’ cadmium was discharged into the atmosphere (Buat-Menard and Arnold, 1978). This value is probably lower than the total discharge as the quantity of cadmium in the gaseous state was not measured. Indeed, more recent investigations by Bust-Menard (personal communication) indicate that the annual cadmium emission from Mount Etna lies within the range of 10 to 40 t. No published information exists on cadmium emissions from other active volcanoes in Europe but these are far less important than Mount Etna in terms of the quantity of particulate matter released. The weathering of crustal materials releases cadmium to soils and aquatic systems. This process plays a significant role in the global cadmium cycle but only rarely results in elevated concentrations in any environmental compartment. Black shales from the Carboniferous era are an exception as they contain up to 100 pg g-i cadmium and soils derived from these deposits also contain elevated levels (Holmes, 1975). III.
THE
MINING
OF NONFERROUS
METALS
Nonferrous metal mines, particularly those which exploit lead-zinc ore fields, are a significant source of environmental cadmium. At present, however, insufficient information is available to estimate the magnitude of cadmium discharges from mines in the EC. The cadmium content of the ore body, mining management practice, as well as the topography of mine site and proximity of adjacent watercourses, all influence the quantities of cadmium lost from individual sites. Wind-blown dispersal of spoil-heap material, as well as the activities involved in the processing of extracted ores, cause airborne contamination of cadmium on a local scale. Water-borne dispersal is considered to be the major route of cadmium loss from nonferrous metal mines and can result in the contamination of agricultural soils some distance downstream of the ore field. Flood and storm conditions will increase the mobilization of particulate matter into local watercources. It should be stressed that this problem is not confined to active mines; inadequate management
11
SOURCES OF CADMIUM
of disused lead-zinc mines has resulted in persistent contamination of adjacent waterbodies (Johnson and Eaton, 1980). Active lead-zinc mines are currently found in four member states, Italy, the F.R.G., France, and the Republic of Ireland. No published discharge data are available from these mines despite the probable importance of water-borne cadmium contamination. Van Wambeke (198Oa) assigned a value of 60 to 150 t Cd year-’ lost to waters from active and disused lead-zinc mines in the EC but the basis of this estimate was not stated. IV. PRODUCTION
OF NONFERROUS
METALS
A. Zinc and Cadmium There are two distinct processes employed in the primary production of zinc and cadmium-thermal smelting and electrolytic extraction. Thermal facilities emit much larger quantities of cadmium to the atmosphere, as a consequence of the elevated temperatures employed in the roasting, sintering, and smelting operations. Roth processes also discharge cadmium-rich dusts into the atmosphere during the delivery and handling of the zinc ores but these will remain airborne for only a short time and are deposited in close vicinity to the plant. Liquid wastes containing cadmium arise primarily from the use of wet gas purification devices. In electrolytic works, this water can be recycled to the production process. In contrast, waste waters from thermal plants are often discharged to adjacent water systems after undergoing a cleaning process. The major solid waste requiring disposal from thermal facilities, smelter slag, contains low cadmium concentrations. In contrast, the leach residues from electrolytic plants can contain elevated cadmium levels and care must be exercised in the dumping of such wastes. Of the 18 primary zinc plants operational within the EC, only 5 are essentially thermal facilities. Three of these plants, Duisburg, Noyelles Godault, and Avonmouth supplied estimates of an emission factor and the total quantity of cadmium emitted to the atmosphere in 1979; these are shown in Table 1. No emission information was available for the ISF smelter at Port0 Vesme. Sardinia, or the vertical retort at Harlingerode. The emission estimates for these two plants (Table 1) were made independently of the companies concerned and the assigned values must be viewed as provisional. In view of the relatively small quantities involved, no formal requests for atmospheric emission data were made to the owners of electrolytic refineries. Total atmospheric emissions of cadmium from the electrolytic plant at Datteln, F.R.G., were estimated to be 30 kg year-’ (Riipenack, 1978). Application of the corresponding emission factor (0.2 g Cd t-’ zinc) to the estimated quantity of zinc produced electrolytically in the EC in 1979 (928 X lo3 t) results in an atmospheric emission of less than 0.2 t year-‘. It is estimated that 50 tonnes of cadmium were released to waters in the EC from zinc production in 1979. Individual facilities vary greatly both in the quantity of cadmium released and also in the characteristics of the water body which receives the effluent. Thus, the ISF plant at Avonmouth is estimated to release 3 t year-’ to the Sevem Estuary (HMSO, 1980), the smelter at D&burg discharges about 1 t year-’ to the River Rhine, while the electrolytic plant at Datteln releases less than 40 kg Cd year-’ to the Rhine (Riipenack, 1978).
12
M. HUT-l-ON
TABLE 1 THERMAL ZINC PLANTS IN THE EC: PRODLJ~ION AND ESTIMATED AIRBORNE CADMIUM EMISSIONSDURING 1979 Zinc production Location of plant Duisburg (F.R.G) Noyelles Godault (France) Avonmouth (U.K.) Port0 Vesme (Italy) Harlingerode (F.R.G.)
((t yew’)
75 86 77.4 43” 81.2
x 103)
Cadmium emission factor (g Cd t-‘) 10-15
35-52 70 loo
Cadmium emission (t year-‘) 0.8 5 2.7
0 Estimated from annual zinc production capacity of the plant and total Italian zinc production in
1979.
The total quantity of cadmium entering landfills from zinc production in 1979 is estimated to be 200 tonnes. Most of this consists of leach residues which are disposed of in landhlls constructed with impermeable linings. B. Copper and Lead In 1979, 159.7 X lo3 t copper were produced from ores in the EC (Metallgesellschaft, 1980). Larger quantities of copper are produced in the EC by the refining of imported blister copper; it has been estimated that 487 X lo3 t copper originated from this source in the EC in 1979. The initial roasting of copper concentrates occurs at about 1200°C and this results in the vaporization of some of the cadmium present in the concentrates. An EPA study (Deane et al., 1976) gave an emission factor of 3 g Cd t-’ copper produced. No emission data are available for the refining of blister copper, but the use of a “cleaner” starting material and the elimination of a roasting stage suggests there will be a lower emission of cadmium and an atmospheric emission factor half that given for the production from ores has been assumed. Application of these emission factors to the 1979 production data, given above, results in an estimated atmospheric emission of about 1.5 t. Secondary production of copper is a rather general term and includes the smelter production of,copper from scrap and waste, the secondary production of refined copper, and the direct use of scrap. An experimental study of several scrap refineries in the U.K. (Mantle, personal communication) found that the stage where impurities in the scrap are oxidized is responsible for the largest emission of cadmium. This investigation also suggested that total atmospheric emissions of cadmium were unlikely to ,exceed 4 g Cd t-’ copper produced. However, the quantity of cadmium emitted from such facilities will be strongly influenced by the nature of the scrap charge and the emission factor for those refineries handling copper-cadmium alloy scrap is likely to be much greater than 4 g t -I. In 1976, the last year for which complete figures are available, secondary copper production totalled 1132 X lo3 t (CEC, 1979). Application of the emission factor of 4 g t-’ to total secondary copper production results in an estimated atmospheric cadmium emission of.4.5 t. Total atmospheric cadmium emissions from primary and secondary copper production have thus been estimated at 6 t year-‘.
SOURCES OF CADMIUM
13
The lack of published information makes any estimate of cadmium inputs to land and water rather tentative. In fact, the only estimate available for the EC was provided by Van Wambeke (1980a) who gave a figure of 15 t cadmium discharged to land&Is from “copper metallurgy” in 1975. In 1979, the total production of refined lead in the EC amounted to 1244 X lo3 t (CEC, 1979). About one-third of this quantity was actually produced from secondary materials, the most important being used lead-acid batteries. Indeed, many “primary” lead plants are fed with a mixed charge of roasted ores and scrap materials. It has thus been assumed that of the 1244 X lo3 t of refined lead produced, 829 X lo3 t were derived from primary sources and 4 15 X 1O3 t from secondary materials. The quantity of lead recovered from scrap in 1979 totalled 837 X lo3 t and this should be added to the secondary refined lead production value, to give the estimated overall secondary lead production figure (1252 X lo3 t). An American survey (Coleman et al., 1979) assigned an atmospheric emission factor of 2.5 g t-’ to primary lead production. However, in an experimental study (Dugdale and Hummel, 1978), a primary lead smelter in New Brunswick was estimated to emit more than 3 t Cd year-‘, which is equivalent to an emission factor of about 55 g t-l. It is not clear at present whether this value is representative of primary lead smelters in general. For the present, an emission factor of 5 g t-’ has been assumed from this source. Application of this factor to the estimated 1979 primary lead production value results in an atmospheric emission estimate of 4 t Cd year-‘. A large proportion of the material used for secondary lead production consists of relatively pure scrap lead and the emission factor of cadmium from this source has been assumed to be half that from primary production at 2.5 g Cd t-‘. It is thus estimated that secondary lead production in the EC resulted in an atmospheric cadmium emission of 3 t in 1979 making the total atmospheric cadmium emission from lead production to be 7 t. In view of the paucity of available information, any estimate of the inputs of cadmium to water and land from lead production must at present be tentative. The New Brunswick lead smelter, discussed above, was estimated to discharge 3 t Cd year-’ in liquid wastes, while the furnace slag contained 7 t Cd year-’ (Dugdale and Hummel, 1978). It is felt that these quantities, and the corresponding emission factors, may be atypical and not applicable to lead production in the EC. It has been provisionally estimated that lead production in 1979 resulted in cadmium inputs of 20 t to water bodies in the EC and 40 t to landfills. V. PRODUCTION AND DISPOSAL OF CADMIUM-CONTAINING MATERIALS At present, there is insufficient information available to allow an accurate estimation of cadmium discharges from the manufacture and disposal of cadmiumcontaining materiaIs in the EC. A previous analysis of the situation has been attempted (Rauhut, 1980) but the basis of the estimated values is not clear. Many of the assumptions employed in the present study are derived from a detailed investigation into the U.S. cadmium industry (Yost, 1979). It should be stressed that many cadmium-containing products have a long lifetime. For the sake of simplicity it has been assumed that product disposal occurs in the same year as manufacture. Additionally, the losses of cadmium which occur during product use have not been taken into account.
14
M. HUT-l-ON TABLE
2
FATE OF CADMIUM A.WXIATED WITH THE MANUFACI-URE AND DISPOSAL OF THE MAJOR USES OF CADMIUM IN THE EC
Compartmental Use Electroplating Pigments Stabilizers Ni-Cd batteries
Cadmium usea 0)
Landfill
Water pathway
1207 1315
713
60 26 7 13.7
722
9006
7 22
flow of cadmium (t) Waste disposal -
Steel cycle
Recycle
434
-
1289
-
-
708 646
-
218
’ Consumption data for 1975 from Hiscock (1978). * Predicted 1980 consumption, assuming an annual increase of 5% from 1975.
Table 2 shows the estimated fate of cadmium associated with the manufacture and disposal of the major uses of cadmium in the EC. The following assumptions were made in calculating the flow pattern depicted: Electroplating. Of the cadmium consumed in the production of plated items, 10% is lost to aqueous wastes and the remaining 90% is present on the product. Of the cadmium in aqueous wastes, 50% is recovered as residues and 50% is discharged to sewage treatment plants (“water”). The residues recovered are not reprocessed and are disposed to landfills. Of the cadmium present in the product, 40% enters the scrap steel cycle and 60% is landfilled. Pigments. No significant atmospheric emissions of cadmium occur in the manufacture of pigments. All solid residues produced during pigment manufacture are recovered and recycled. Of the cadmium used in pigment manufacture, 2% is ultimately discharged to sewage treatment plants (“water”). All the cadmium present in the product enters the municipal waste disposal pathway. Stabilizers. Of the cadmium consumed, 50% is used for liquid stabilizer production and 50% for solid stabilizers. Of the cadmium used in the manufacture of liquid stabilizers, 2% is present in filter residues and this is disposed of in landfills. Of the cadmium consumed in the production of solid stabilizers, 2% is not reclaimed from aqueous wastes and is lost to sewage treatment plants (“water”). All the product ultimately enters the municipal waste disposal pathway. Nickel-cadmium batteries. Of the total cadmium consumed, 50% is used for pocketplate cells and 50% for sintered-plate or sealed cells. Of the cadmium used to produce pocket-plate cells, 3% is lost as dusts; 10% of the cadmium in these dusts is discharged to sewage treatment plants (“water”) and 90% enters landfills. Of the cadmium present in pocket-plate cells, 50% is recycled and the remainder enters the waste disposal pathway. Of the cadmium consumed in the manufacture of sintered-plate and sealed cells, 5% is lost to aqueous wastes. Of the cadmium in aqueous wastes, 45% is recovered and landfilM, while the ,remainder is discharged to sewage treatment plants (“water”). The cadmium present in sintered-plate and sealed cells enters the waste disposal pathway. Alloys. Insufficient data exist to quantify the flow of cadmium from the manufacture and disposal of cadmium alloys. Nevertheless, losses of cadmium to landfills and water from product manufacture are unlikely to be significant. Additionally, it
15
SOURCES OF CADMIUM TABLE3
CADMIUMEMWIONFACTORSFORTHEEUROPEANIRONAND STEEL
INDUSTRY, DERIVED FROM THE U.K. STUDY Emission factor (g Cd t-l material produced) Process
Atmosphere
Sinter production Iron production Basic oxygen steelmaking Electric arc steelmaking
0.08 0 0.02 0.40
Solid wastes
Slags
0
0
0.67 0.36 3.65
ND I.11 0.29
Source:Praker(personalcommunication). Note. ND-not determined. is considered that atmospheric emissions from the production of copper-cadmium alloys in the EC will be less than 3 t Cd year-‘. Disposal of articles containing cadmium alloys will occur via the secondary copper industry and the municipal waste pathway. Inspection of Table 2 reveals that the quantity of cadmium discharged to water from electroplating units is greater than the combined total from all other major uses. The municipal waste disposal pathway is estimated to receive a total of 2643 t Cd year-’ from the disposal of pigments, stabilizers, and nickel-cadmium batteries. VI. IRON
AND
STEEL
PRODUCTION
Most of the cadmium released during the production of iron and steel is derived from the recycling of galvanized and cadmium-plated steel scrap, but the raw materials of the steel industry can also contain a significant amount of cadmium. A recent experimental investigation into the flow of cadmium through the U.K. iron and steel industries (Prater, personal communication) has provided much of the data base for estimation of the quantities of cadmium released by other member states. Table 3 lists the emission factors to air, solid wastes, and slags derived from this U.K. study. The term “solid wastes” refers to the flue dusts arrested by collection devices, while slag is the material which remains in the furnace. The higher atmospheric emission factor for electric arc steelmaking (EAS) compared with basic oxygen steelmaking (BOS) reflects the large quantities of steel scrap processed by electric arc furnaces. The amount of cadmium discharged in aqueous wastes from the steel industry has not been estimated, as it is considered that there is insufficient data to justify such a calculation. The experimental study, discussed above, did not consider open-hearth steelmaking so the atmospheric emission factor of 1 g t-i from the study of Rauhut (1980) has been adopted for this process. Data on the presence of cadmium in slags and solid wastes were not available for open-hearth steelmaking, so no estimates of the quantities discharged to these compartments could be made. Table 4 shows the estimated quantities of cadmium discharged by the EC iron and steel industries in 1979, both for individual countries and for processes. An additional “sink” for cadmium is the amount retained in the steel itself; applying the U.K.
16
M. HUTTON
TABLE 4 ESTIMATED DWHARGE (TONNES) OF CADMIUM FROM THE EC IRON AND STEEL INDUSTRY IN 1979 FOR INDIVIDUAL MEMBER STATES AND ACCORDING TO PR~CEW, Discharge medium Air
Country IMY Luxembourg The Netherlands United Kingdom Federal Republic of Germany Belgium France Denmark Total
7.7 0.7 0.9 5.9 10.7 1.4 6.3 0.5 34
Solid wastes
58.3: 4.4 5.2 40 59.5 14 46 1.5 229
Slags
15 5.5 6.1 16.4 40.9 14.5 21.7 0.1 120
hocess
Ironmaking Sinter production Pig iron Total
Steelmaking BOS EAS
OHS Total
10.6 0
0
0
65.8
ND
10.6
65.8
2.1 13.9
36 128
111 9
7.6
ND
ND
23.6
164
120
Note. ND-not determined; BOS-basic oxygen steelmaking; EAS-electCc steelmaking; and OHS-open-hearth steelmaking.
arc
findings to 1979 EC production (139 X lo6 t) indicates a total of about 70 t in crude steel. Atmospheric emissions from sinter and steel production for The Netherlands were not estimated from the emission factors given in Table 4. In this case, the values were obtained from a survey of cadmium in the EC iron and steelmaking industries (Steiner, personal communication). This study also noted that the arrested dusts from electric arc furnaces in France contained 600 pg g-’ cadmium compared with 300 pg g-’ for U.K. dusts. For this reason, the discharge factors applied to atmospheric emissions and solid wastes for EAS in France are double those given in Table 3. Examination of the values given in Table 4 reveals that the iron and steel industries in Luxembourg, The Netherlands, and Belgium display relatively low atmospheric emissions of cadmium. This finding is related to both the modest production rates of these countries and to the fact that almost ail the steel is produced by the basic oxygen process. In comparison, the higher atmospheric emission estimates for Italy and the U.K. are a consequence of the larger quantities of steel produced, together with the reliance placed upon electric arc steelmaking by these countries.
17
SOURCES OF CADMIUM TABLE 5
CADMIUM CONTENT (pg g-l) OFCam SAMPLED FROM THE FEDERAL REPUBLIC OF GERMANY AND THE UMTED KINGDOM Country of origin and coal type
Mean
Range
F.R.G. Lignite Bituminous coals
0.02 2.0
I-10
Sample size 1 27
Source Heinrichs ( 1977) Kautz et al., (1975)
U.K. Anthracite and bituminous coals from Wales ‘Power station’ coals
1.0
0.4-10
302
Chattejee and Pooley ( 1977)
0.4
0.3-0.8
NG
Gibson ( 1979)
Note. NG-not given.
The F.R.G. is the largest producer of iron and steel in the EC and was also estimated to emit more cadmium to the atmosphere than the other member states. Inspection of these emissions by process indicates that, in contrast to Italy and the U.K., the largest source of cadmium is open-hearth steelmaking followed by sinter production. The relatively smaIl contribution from electric arc steelmaking reflects its minor share in the steel market of F.R.G. The quantity of cadmium present in steel slags is estimated to be 120 t; this value is similar to the amount of cadmium entering landfills from zinc production in the EC. It should be made clear, however, that the cadmium present in steel slags is associated with much larger quantities of material. Furthermore, the cadmium in these slags is incorporated into a fused mass of material and is thus likely to display a low solubility. Slags from steel production are either disposed of in landfills or utilized commercially. The solid wastes derived from steelmaking are, in general, not recycled through the industry and have to be disposed of in landfills. Thus, it is estimated that over 200 t cadmium entered landfills from this source in the EC. The cadmium in solid wastes is present at higher concentrations than in slags and is associated with fine particulate matter suggesting that the cadmium will display a greater potential for biological uptake than the cadmium in steel slags. This point is particularly important for electric arc steelmaking, where the cadmium concentrations of the solid wastes are the highest of the three major steelmaking processes (Yost, 1979). VII. FUEL
COMBUSTION
A. Coal Combustion Table 5 summarizes the available data on cadmium the F.R.G. and the U.K., the two largest coal consumerS coals from Germany have the higher cadmium content, tries display a wide range of variation. The mean values taken into account when assigning an average cadmium
levels in coal samples from in the EC. Apparently, hard but values from both coungiven in Table 5 have been content of 1 pg g-’ to hard
18
M.
HUTTON
coals consumed in the EC. German lignites have also been assumed to contain 1 pg Cd g-‘, despite the very low level shown in Table 5. This value was based on only one sample and may not be representative of lignite in general. At present, the largest coal-consuming sectors of the EC are electrical power stations and coke ovens; these accounted for 56 and 30% of the total EC production in 1978. Other industries used about 6% while the domestic and commercial sector burnt 7% of the total consumed. The F.R.G. accounts for nearly all the lignite consumed in the EC and about 90% of this is burnt at power stations. Coal combustion in modem power plants occurs at about 15OO’C and results in vaporization of most of the cadmium present in coal. Experimental in-stack studies (Ondov et al., 1978; Coles et al., 1979) indicate that cadmium subsequently condenses in a preferential manner onto the smaller particles suspended in the flue gas. Although these particles are less efficiently retained than the coarser fly ash particles, an emission factor of only 0.02 g Cd t-’ has been assumed for this process. This figure is based upon a collection efficiency of 98% and is similar to estimates given by Coleman et al. (1979); Nriagu (1979); and Yost (1979). Little information exists on the emissions of cadmium from the other coal-consuming sectors and an emission factor of 0.02 Cd t-’ has also been assigned to these sectors. In the case of coke production, there is some experimental evidence to support this assumption, as coke ovens in the U.K. were estimated to emit 0.15 t cadmium from 10 X lo6 t coal, corresponding to an emission factor of just under 0.02 g t-’ (Prater, personal communication). Coal consumption in the EC for 1978 amounted to 287 X lo6 t (Eurostat, 1980). Atmospheric emissions from this process are therefore estimated to total just under 6 t, of which the U.K. accounts for about 2.5 t and the F.R.G. 1.5 t. The remaining cadmium, nearly 300 t, will be present in ashes, most of which will be disposed of in landfills and ash ponds. In 1978, power plants in the F.R.G. burnt 110 X lo6 t lignite (Eurostat, 1980). The quantity consumed is estimated to result in 2.2 t cadmium released to the atmosphere and 108 t incorporated in ashes.
B. Oil and Gas The cadmium content of crude oil is lower than coal (Hofstader et al., 1976) and an average value of 0.05 pg g-’ has been assigned to this material. Little information exists on the extent of cadmium release from the combustion of oils. It has been assumed that 2%, the same proportion estimated for coal combustion, will be released when oil is burnt. The majority of the cadmium in oil is thus expected to be retained in ashes. Fuel oil consumption in the EC totalled 301 X lo6 t in 1978, resulting in an estimated atmospheric emission of less than 1 t cadmium. The remainder of the cadmium, about 14.5 t, wiIl be present in ashes, most of which will be disposed of in landfills. Natural gas does not contain significant quantities of cadmium and is considered to be a negligible source of cadmium in the environment. VIII.
WASTE
DISPOSAL
The major sources of cadmium in municipal wastes are scrap metal and plastics containing pigments and stabilizers. The heterogeneous composition of municipal
19
SOURCES OF CADMIUM TABLE
6
FATE OF CADMIUM ENTERING MUNICIPAL WASTE DISPOSAL PATHWAY IN THE EC Cadmium in discharge medium country
Waste generated” (Xl06 t)
Waste landfille4P (Xl06 t)
IdY Luxembourg The Netherlands U.K. F.R.G. Belgium France Denmark Ireland
16 0.13 5.3 28’ 25 3.5 16 2.5 1.3
13.4 3.6 24.8 19.6 3 11.1 1.3
201 54 372 294 45 166 20
EC Total
91.1
16.8
1,152
a Source: Van Wan&eke ( 198Ob). b Source: U.K. Department of tbe Environment 9
Cadmium in landfills 0)
Waste incinerated” (Xl06 t) 2.6 0.1 1.7 3.2b 5.4 0.54 4.9 2.5 20.9
Atmosphere emissions 3.9 0.2 2.6 4.8 i.8 1.4 3.7 31.4
Ashes 35.1 1.4 23 43 72.9 7.3 66 33.8 282
(personal communication).
waste makes it difficult to estimate an average cadmium content for this material. Values of 12 pg g-’ for the U.K. and 30 Kg g-r for the F.R.G. have been reported (HMSO, 1980), and this study has assumed an average cadmium content of 15 fig g-* for the EC. Table 6 shows the quantities of municipal waste generated by each member state in 1977 and the estimated totals discharged directly to landhlls. The large quantities of waste disposed of in this manner result in more than 1000 t cadmium entering such sites (Table 6). The U.K. and the F.R.G. are the two largest contributors and together account for over half this total. At present, about 20% of the municipal waste generated in the EC is incinerated. The amounts combusted in 1978 by individual member states are shown in Table 6. Several studies have reported that fly ash from refuse incinerators contain elevated cadmium concentrations and that the cadmium in fly ash is predominantly associated with submicron particles, the particles least efhciently retained by control devices (Greenberg et al., 1978; Scott, 1979). Experimental measurements of trace element emissions from refuse incinerators reveal a relatively high emission rate of cadmium from this source, with values ranging from 0.7 to 4.4 g Cd t-’ (Greenberg et al., 1978; Scott, 1979). After examining the relevant data available, an emission factor of 1S g t-’ has been assigned to atmospheric cadmium release from refuse incineration. This value is considered to be representative of the larger facilities equipped with modem particulate control devices. Atmospheric emissions of cadmium from refuse incineration in the EC were estimated to total over 30 t in 1978 (Table 6). The largest contributors were, in decreasing order, the F.R.G., France, and the U.K. The cadmium retained in the incinerator is partitioned between colIected fly ash and the furnace clinker. However, as both wastes are generally landhlled, they have been considered as a single discharge medium in Table 6. The total of 282 t cadmium present in these ashes is considered to be of greater environmental significance than the 1152 t discharged by direct landfill. This is because the cadmium in fly ash is
20
M. HUTTON
expected to be more soluble than in untreated waste and will thus display a greater propensity for leaching from landfill sites. IX. SEWAGE
SLUDGE
The production of sewage sludge in the EC was considered by Van Wambeke (198Oa) to total 5 X lo6 t (dry weight) in 1975. More recent data have not been published; for the purposes of this study, it has been assumed that sludge generation in the EC has increased at an annual rate of 2%, indicating a generation of 5.5 X lo6 t sludge in 1980. The cadmium present in sewage sludge originates from both domestic and industrial sources, but the latter is thought to be responsible for the major portion of the total. In assigning an average cadmium content to sewage sludge in the EC, the mean value of about 30 pg g-’ obtained in an extensive U.K. survey (HMSO, 1980) has been adopted. Thus an estimated total of 165 t cadmium are assumed to be present in sewage sludge generated in the EC in 1980. The pattern of sewage sludge disposal varies between member states of the EC but detailed information is only available for The Netherlands, the F.R.G., and the U.K. (Scheltinga, 1979; Thormann, 1979; HMSO, 1980). On the basis of these figures, it has been assumed that 75% of the sludge generated in the EC is disposed of to land, 20% to water (sea), and 5% is incinerated. It has been additionally assumed that 25% of the cadmium present in sludge is released to the atmosphere upon incineration and the remainder is ultimately disposed of to land. This high atmospheric emission estimate is based upon the finding that some sewage sludge incinerators in the U.K. release one-third of the cadmium to air (HMSO, 1980). Application of this disposal pattern results in an estimated 2 t cadmium emitted to the atmosphere, 33 t to water, and 130 t to land. X. PHOSPHATE
FERTILIZERS
A. Fertilizer Manufacture The major source of cadmium discharges from phosphate fertilizer manufacture is associated with the wet process production of phosphoric acid which uses sulfuric acid to form phosphoric acid from rock phosphate. The cadmium originally present in the rock phosphate will become distributed between the phosphoric acid and gypsum waste. The major disposal route of the gypsum is by dumping in coastal waters but a proportion is landfilled and the remainder is utilized by the construction industries. Estimated annual discharges of cadmium to land and water from the manufacture of phosphoric acid by the wet process total 34 and 62 t, respectively. These values have been computed from a recent survey of the phosphate fertilizer industry in the EC (Feenstra, 1978). France is the largest phosphoric acid producing country in the EC and accounts for the major portion (27 t year-‘) of cadmium discharged to waters from this source. In the F.R.G., most of the gypsum is recovered and used as a construction material; as a consequence, cadmium discharges from phosphoric acid manufacture are relatively low.
B. Fertilizer Use The cadmium contents of phosphate fertilizers vary widely and depend upon the country of origin. Table 7 shows the estimated average cadmium levels in fertilizers
21
SOURCES OF CADMIUM
TABLE 7 ASSUMED CADMIUM CONTENT OF PHOSPHATE FERTILIZERS ACXXRDING TO COUNTRY OF ORIGIN
Country of origin
Cadmium content’ (g Cd t-’ PzOs)
Morocco U.S.A. Togo Senegal U.S.S.R. Tunisia/Algeriab Israel/Jordanb
60 35 160 255 0.8 60 35
(1Values modified from Feenstra ( 1978). * Values assigned by author of present study.
from the major exporters of rock phosphate to the member
states of the EC. The quantities of phosphate rock imported into the EC member states in 1979, broken down according to country of origin, have also been obtained (Anon, 1981). These data, in conjunction with the values given in Table 7, and the actual quantities of phosphate fertilizer consumed in the member states, have been used to estimate the amounts of cadmium discharged to agricultural land in the EC, as a consequence of fertilizer application. The estimated quantities for each member state are shown in Table 8. The total quantity of cadmium discharged to agricultural land from fertilizer use in the EC is thus estimated to be 3 12 t in 1979. XI. SUMMARY
AND
CONCLUSIONS
This paper has attempted to quantify the major sources of cadmium inputs into the environment of the EC. The values obtained are summarized in Table 9. In some cases, the assigned values should be considered as tentative until more precise estimates can be made. TABLE 8 ESTIMATED
DISCHARGES OF CADMIUM TO AGRICULTURAL FROM THE APPLICATION OF PHOSPHATE FERTILIzEM IN THE EC IN 1979
LAND
Country
Total cadmium discharged(t)
Italy The Netherlands United Kingdom Federal Republic of Germany Belgium/Luxembourg France Denmark Republic of Ireland
49 7 45 44 8
Total
144
7 8 312
22
M. HUTTON TABLE 9 SUMMARYOFCURRENTCADMIUMINPUTSTOTHE
EC ENWRONMENT(~~W-I) Compartment
Source Volcanic action Nonferrous metal production Zinc and cadmium Copper Lead Production of cadmium-containing Iron and steel production Fuel combustion Coal and lignite Oil and gas Waste disposal Sewage sludge disposal Phosphate fertilizers Totals Note.
ND-not
materials
Air
Land
Water
20
ND
ND
20 6 7 3 34
200 15 40
8 0.5
31 2 -
132
349: 390 14.5 1434 130 346 3009
50
ND 20 108 ND ND G 33 62 273
determined.
Cadmium release has been considered for three broad environmental compartments: air, land, and water. This approach conceals large differences in the mobility and environmental significance of the cadmium released which arise as a consequence of the precise disposal route employed. In the terrestrial compartment, for example, sewage sludge applied to agricultural land will be of greater significance from the perspective of human exposure and environmental mobility than sludge which is landfilled. Similarly, cadmium inputs to the aquatic environment from phosphate fertilizer manufacture and sewage sludge disposal generally occur in coastal waters and will generally be of little direct significance to human exposure. In contrast, a large proportion of aquatic cadmium discharges from electroplating will be incorporated in the sewage sludge and some of this will subsequently be applied to agricultural land. Another aspect of importance, not clear from Table 9, is that the environmental significance of cadmium in a particular waste stream is not necessarily directly related to the total quantity of cadmium present. Thus, the 200 t cadmium in solid wastes from zinc production are of greater potential significance than the 390 t cadmium present in ashes from coal combustion because they are associated with much smaller amounts of waste material. The iron and steel industries together with refuse incineration represent the two largest sources of atmospheric cadmium in the EC. The other major sources, zinc production and volcanic action, are next in ranking. All other sources account for less than one-quarter of the total atmospheric discharges. Municipal waste disposal results in the largest single input of cadmium to land in the EC. The quantity of cadmium associated with this pathway is greater than the combined total of the four other major sources. These processes are, in descending rank, coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. These five sources together contribute 90% of the total cadmium inputs to land in the EC.
SOURCES OF CADMIUM
23
The characterization of cadmium inputs to aquatic systems in the EC is incomplete. Of the sources considered in the present study, the manufacture of cadmium-containing articles accounts for the largest single input of cadmium. Phosphate fertilizer manufacture is next in ranking, followed by discharges from zinc production. ACKNOWLEDGMENT This research was supported by the Commission of the European Communities, Environment, Raw Materials and Material Technologies Research ProIrrammes, Directorate General for Science, Research and Development (Contract Number 333-ENV U.K.).
REFERENCES ANON. (1981). Phosphate rock exports January to December 1980. Phosphorus Potassium 111. BUAT-~NARD, P., AND ARNOLD, M. (1978). The heavy metal chemistry of atmospheric particulate matter emitted by Mount Etna volcano. Geophys. Res. Left. 5, 245-248. Commission of the European Communities (CFC) (1979). Raw Materials. Research and Development. I. Copper. II Lead and Zinc. CEC, DG XII, Brussels. CHATI-ERJEE, P. K., AND PGOLEY, F. D. (1977). An examination of some trace elements in South Wales coals. Proc. Australas. Inst. Min. Mettal. 263, 19-30. COLEMAN, R., LENT, J., SIEBERT, P., MILLER, C., AND COFFEY, E. (1979). Sources ofAtmospheric Cadmium. EPA450/5-79006, U.S. Environmental Protection Agency. C~LES, D. G., RAGAW, R. C., Ormov, J. M., FISHER, G. L., SILBERMAN, D., AND PRENTICE, B. A. ( 1979). Chemical studies of stack fly ash from a coal-tired power plant. Environ. Sci. Technol. 13,455-459. DEANE, G. L., LYNN, D. A., AND SURPENANT, N. F. (1976). Cadmium: Control Strategy Analysis. GCATR-75-36-G. U.S. Environmental Protection Agency. DUGDALE, P. J., AND HUMMEL, B. L. (1978). Cadmium in the lead smelter at Belledune: Its association with heavy metals in the environment. In Cadmium 77. Edited Proceedings, First International Cadmium Conference, San Francisco, 31 January-2 February 1977 pp. 53-75. Metal Bulletin Ltd., London. EUROSTAT. (1980). Energy Statistics Yearbook 1978. Statistical Office of the European Communities. Commission of the European Communities, Brussels. hENSTRA, J. F. (1978). Control of Water Pollution due to Cadmium Discharged in the Process of Producing and Using Phosphate Fertilizers. ENV/223/74-EN. Commission of the European Communities, Brussels. GIBSON, J. (1979). Con1 and the Environment. National Coal Board, London. GREENBERG, R. R., ZOLLER, W. H., AND GORDON, G. E. (1978). Composition and sire distribution of particles released in refuse incineration. Environ. Sci. Technol. 12, 566-573. HEINRICHS, H. (1977). Emissions of 22 elements from brown coal combustion. Nuturwiss. 64,479-48 1. HI-K, S. A. (1978). Production, Consumption and Uses of Cadmium in the European Community (1965-1976). ENV/223/74-E. Commission of the European Communities, Brussels. HMSO (1980). Cadmiun in the Environment and its Significance to Man. Pollution Paper No. 17. Department of the Environment. Central Directorate on Environmental Pollution, London. HOFSTADER, R. A., MILNER, 0. I., AND RUNNELS, J. H. (Eds) (1976). Cadmium. In Analysis of Petroleum for Trace Metals; Advances in Chemistry. Series: 156. pp. 81-94. Amer. Chem. Sot. HOLMES, R. (1975). The Regional Distribution of Cadmium in England and Wales. Ph.D. thesis, University of London. HVITON, M. (1982). Cadmium in the European Community: A Prospective Assessment of Sources, Human Exposure and Environmental Impact. MARC Report No 26, Monitoring and Assessment Research Centre, Chelsea College, University of London. JOHNSON, M. S., AND EATON, J. W. (1980). Environmental Contamination through residual trace metal dispersal from a derelict lead-zinc mine. J. Environ. Qual. 9, 175-179. KAUTZ, K., HIRSCH, H., AND SINGH DEO, R. (1975). Chemismus und morphologic von Kr&werksst&rben. VGB Krafwerkstechnik 55, 1EO- 187. METAUIGESELLSCHAFT (1980). Metal Statistics 1969-1979. Frankfurt am Main. NRIAGU, J. 0. (1979). Global inventory of natural and anthropogenic emissions of trace metals to the atmosphere. Nature (London) 279, 409-4 11. ONDOV, J. M., RAGAINI, R. C., AND BIERMANN, A. H. (1978). Elemental particle size emissions from coal-fired power plants: use of an inertial cascade impactor. Atmos. Environ. 12, 1175-l 185.
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A. (1980). Industrial Emissions of Cadmium in the European Community: Sources, Levels and Control. ENV/223/74E. Commission of the European Communities, Brussels. R~PENACK, A. VON (1978). Emission control in cadmium metal production. In Cadmium 77. Edited Proceedings, First International Cadmium Conference, San Francisco, 31 January-2 February? 1977. pp. 49-53. Metal Bulletin Ltd., London. S~HELTINGA, H. M. J. (1979). Utilisation of sewage on land in Holland. In Utilisation of Sewage Sludge on Land, Oxford, 10-l 3 April 1978. pp. 309-3 16. Water Research Centre, Stevenage, Herts. SCOTT, D. W. (1979). The Fate of Cadmium in Municipal Refuse Incinerators. Warren Spring Laboratory Report CR 1710 (AP). Warren Spring, Stevenage, Herts. THORMANN, A. (1979). Utilisation of Sewage Sludge on Land. The situation, problems and development trends in Gesmany. In Utihsation of Sewage Sludge on Land, Oxford, IO-13 April 1978. pp. 290-308. Water Research Centre, Stevenage, Herts. VAN WAINBEKE, L. (1980a). Measures taken by the European Communities in respect of cadmium between 1977 and 1979 and inventory of emissions into the environment. In Cadmium 79. Edited Proceedings, Second International Cadmium Conference, Cannes, 6-8 February 1979. pp. 153-157. Metal Bulletin Ltd., London. VAN WAMBEKE, L. (1980b). Energy from Municipal Waste in the European Community. CEC Xl l/252/ 80-EN. Commission of the European Communities, Brussels. YOST, K. J. (1979). Some aspects of cadmium tlow in the U.S. Environ. Health. Perspect. 28, 5-16. RAUHUT,