- Email: [email protected]
Regional differences in worldwide emissions of mercury to the atmosphere
Pergamon
Atmospheric Environment Vol. 30, No. 17, pp. 2981 2987, 1996 Copyright © 1996 Published by Elsevier Science Ltd Printed in Great Britain. All rights reserved 1352-2310/96 $15.00 + 0.00
1352-2310(95) 00498-X
REGIONAL DIFFERENCES IN WORLDWIDE EMISSIONS OF MERCURY TO THE ATMOSPHERE N I C O L A P I R R O N E , G E R A L D J. K E E L E R a n d J E R O M E O. N R I A G U Department of Environmental & Industrial Health, School of Public Health, The University of Michigan, Ann Arbor, MI 48109-2029, U.S.A. (First received 18 December 1994 and in final form 30 November 1995)
Abstract--Annual emissions of anthropogenic Hg to the atmosphere in different regions of the world during the last decade show an interesting dichotomy: the emissions in the developed countries increased at the rate of about 4.5-5.5°/'0 yr-1 up to 1989 and have since remained nearly constant, while in developing countries the emissions continue to rise steadily at the rate of 2.7-4.5% yr- 1. On a global basis, however, thetotalanthropogenicemissionsofHgincreasedbyabout4% yr -1 duringthe 1980s, peakedin 1989 at about 2290 t and are currently decreasing at the rate of about 1.3% yr-1. Solid waste disposal through incineration processes is the dominant source of atmospheric mercury in North America ( ~ 40%), Central and South America ( ~ 34%), western Europe ( ~ 28 %) and Africa ( ~ 30%), whereas coal combustion remains the dominant source in Asia (~42%) and eastern Europe and the former USSR (~40%). Mining and smelting of Zn and Pb represent the major industrial source of Hg in Oceania (~35%). Copyright © t996 Published by Elsevier Science Ltd Key word index: Mercury, emission source, atmosphere, trend, incinerator, emission factor, urban area, global scale, regional scale, Detroit.
INTRODUCTION Mercury is a highly toxic element that has been present at varying concentrations in air, water and soil ecosystems as well as in biota (Lindqvist, 1985; Nriagu, 1989). Studies in various parts of the world show that dangerous imbalances have occurred in the global mercury cycle because human activities redistribute this element in a manner that results in elevated concentrations in the food chain (Lindqvist, 1985; Nriagu and Pacyna, 1988; Nriagu, 1989; U.S.EPA, 1994). The rate at which the concentration of mercury is increasing in the atmosphere is of considerable environmental interest and is receiving intensive scrutiny. From measurements on seven Atlantic oceanographic cruises during 1977-1990, Slemr and Langer (1992) estimated the annual increase in atmospheric Hg levels to be 1.5% in the Northern Hemisphere and 1.2% in the Southern Hemisphere. Swain et al. (1992) reported a 2% yr-X increase in Hg deposition rates in remote lakes in Wisconsin and Minnesota. Increases of 1-2% have been observed in lake and peat sediments of Alaska (Engstrom et al., 1994), Arctic Canada (Lockhart, 1994), northern Ontario (Johnson, 1987), and Scandinavia (Lindqvist et al., 1991). Mason et al. (1994) inferred a 0.6% yr -1 increase in atmospheric Hg levels from geochemical model calculations. Increases much higher than 2% y r - ~ have been reported in sediments of Florida
wetlands (Delfino and Crisman, 1993) and the Great Lakes (Kemp et al., 1978; Mudroch, 1993). By contrast, the deposition rate of atmospheric Hg observed by Iverfeldt et al. (1995) in southwestern Sweden dropped (nearly 60%) from an average of 27/.tgm -2 y r - 1 during the 1985-1989 to 10 #g m -2 y r - 1 during the 1990-1992. The gaseous Hg levels in air dropped from 3.2 ng m - 3 during the 1985-1989 to 2.7 ng m - 3 during the 1990-1992, showing a decrease (nearly 18%) much lower than that observed in deposition rate of total Hg. Whether the atmospheric Hg concentrations have increased continuously or declined in recent years remains equivocal. This paper presents annual inventories of anthropogenic Hg emissions to the atmosphere during the last decade in North America, South and Central America, western Europe, eastern Europe and the former USSR, Africa, Asia, and Oceania. Mercury emissions from coal, oil and wood combustion, incineration of medical and solid waste, pyrometallurgical processes for Pb and Zn production, and a miscellaneous category which includes chlor-alkali plants, degassing of latex paint, crematoria, fluorescent lamp breakage, dental laboratory, cement manufacturing, primary and secondary mercury production, and other coal uses are included in the calculations. Differences between the trends in industrial emissions of mercury from local (Detroit, Michigan) and global sources have also been discussed.
2981
2982
N. PIRRONE et al. METHODS
Estimates of Hg emissions from power plants are based on average Hg concentrations and annual combustion of hard coal, lignite and brown coal in electric power plants as well as for industrial, commercial and residential purposes (Sabbioni et al., 1983; Smith, 1986; Swaine, 1990; Meij, 1991; EIA, 1991, 1992; Pacyna et al., 1993; U.S.-EPA, 1993). The average Hg concentrations in coals used in the calculations (and the reported ranges) were 0.18 (0.01-3.3) #g g- ~ for North America, 0.29 (0.1-2.0)#gg-1 for western Europe, 0.3 (0.15-1.8) #gg- 1 for eastern Europe and the former U.S.S.R, 0.18 (0.08-7.0) #g g- 1 for Africa, and 0.2 (0.02-1.3) #g g- 1 for Oceania (Sabbioni et al., 1983; Smith, 1986; Swaine, 1990; Meij, 1991; Pacyna et al., 1993; U.S.-EPA, 1993; Bloom and Prestbo, 1993; Chu and Porcella, 1995). Based on these regional average Hg concentrations, the uncontrolled emission factors were estimated to be 12, 11.2, 7, 7, and 7.7 #gMJ -~ for eastern Europe and former U.S.S.R., western Europe, North America, Africa, and Oceania, respectively. In the absence of reliable data for the local coals, the uncontrolled emission factor for Central and South America was estimated to be 7.0 pg M J - t using the average Hg concentration in North American coals. The uncontrolled emission factor for Asia (12#gMJ -1) was based on the Hg contents of coals of eastern Europe and former U.S.S.R. The Hg emission estimates assume a 40% control efficiency for Hg release from coal-fired power plants in the developed countries (U.S.-EPA, 1993), mostly due to the installation of control equipments which remove sulfur and nitrogen compounds from exhaust gases and to coal cleaning (U.S.-EPA, 1994; Pacyna and Keeler, 1994). No control was assumed for the developing countries (Nriagu, 1984; Nriagu and Pacyna, 1988). Because many old coal combustion plants in eastern Europe and the former U.S.S.R. have been shut down due to the decline in economic growth at the beginning of the 1990s, a 30% control efficiency was applied in estimating the Hg emissions to the atmosphere during the period of 1990-1992, but no controls were assumed before then. Mercury emissions from the incineration of municipal (MSW) and medical (MDW) solid wastes were derived assuming a waste generation rate (U.S.-Department of Commerce, 1993; U.S.-EPA, 1994) of 1-1.8 and 0.02kg d - 1person- 1, respectively, for developed countries, whereas for developing countries a waste generation rate of 0.6 kg d-Xperson-lfor MSW and 0.005kgd-~person -~ for MDW was assumed (Cointreau, 1986). The Hg content in MSW ranges from 0.3 to 9 gt -1 in Europe (Pacyna, 1986; NREL, 1993) and from 0.36 to 5.8 gt -~ in North America (NREL, 1993; U.S.-EPA, 1993). The Hg concentrations in MDW may be 10 to 50 fold higher than that found in MSW (U.S.-EPA, 1993, 1994). An emission factor of 1.2 gt -1, assuming a 60% emission control efficiency, was adopted for MSW incinerators in developed countries (U.S.-EPA, 1993), while an emission factor of 1.0 gt-1 without emission control was assumed for garbage burning in the developing countries. Estimates of Hg emissions from MDW incinerators assume emission factors of 30 g t- ~ in developed countries (U.S.-EPA, 1994) and 10-20 gt-1 in developing countries. The uncontrolled emission factors for oil-burning power plants vary from 3.1 ngBtu-~for distilled oils to 3.3ng Btu-1 for residual oils (U.S.-EPA, 1993). An average emission factor of 2.2 ng Btu- 1 for both distilled and residual oil assuming a 25% emission control efficiency was adopted for the developed countries (U.S.-EPA, 1993), and for the developing countries which generally have limited emission controis, an average factor of 3.0 ng Btu- ~ was used. Fuel wood consumption data for various countries were obtained from the United Nations (1992) and EIA (1994) compilations. An emission factor of 0.03gt-lof wood burned (U.S.-EPA, 1993) was used for all the countries assuming no emission control.
Many zinc and lead smelters (especially in the developing countries) rely almost exclusively on electrostatic precipitators for air pollution control. This device removes very limited amounts of gas phase mercury. We have adopted the emission factors 3 gHgt-1of Pb produced and 25 g H g t of Zn produced reported in Nriagu and Pacyna (1988). The amounts of Pb and Zn produced in various countries were obtained from the U.S. Bureau of Mines (1987, 1993) compilations. The miscellaneous category includes emissions from the chlor-alkali plants (still used in the developing countries), degassing of latex paint, crematoria, fluorescent lamp breakages, dental laboratory, cement manufacturing, primary and secondary mercury production and other coal uses e.g. byproduct coke production, carbon black production. The emission factors for these sources are derived from Cole et al. (1992) and U.S.-EPA (1993, 1994).
RESULTS AND DISCUSSION Table 1 shows the annual emissions of Hg in different regions of the world during the last decade. The table provides the first published inventories for anthropogenic Hg emissions in Africa, South America and Asia. Our data are in reasonable agreement with the recent inventories for Europe during the 1980s (Pacyna, 1989; Lindqvist et al., 1991; Pacyna and Munch, 1991) which generally fall in the range of 390-1100 t y r - L Industrial emissions of Hg in the United States alone during the 1980s have been reported to be 448 t y r - 1 (Voldner and Smith, 1989), 540 t y r - 1 (Cole et al. 1992) and 600 t y r - 1 (Johnson, 1987). These values are higher than our estimate for all of N o r t h America. The total (worldwide) industrial emissions fall in the range of 910-6,200tyr -1 reported by Nriagu and Pacyna (1988) for 1983/1984, and are lower than the previously reported average values of 4 5 0 0 t y r -1 by Lindqvist et al. (1991) and Johnson (1987) for the 1980s and the 11,000 t y r -1 by Lantzy and MacKenzie (1979) for the mid-1970s. The incineration of solid wastes and garbage (MSW + M D W ) is the dominant anthropogenic source of atmospheric mercury in N o r t h America ( ~ 40%), Central and South America ( ~ 34%), Africa ( ~ 30%) and western Europe ( ~ 28%). The coal combustion in electric power plants and industrial utilities is the dominant source in the developing countries of Asia ( ~ 4 2 % ) and eastern Europe and the former U.S.S.R. (58% during 1983-1989, and 40% during 1990-1992). Mining and smelting of Zn and Pb represent the dominant industrial source of Hg in Oceania, while the burning of fuel wood is an important source of atmospheric mercury in the developing countries of Africa ( ~ 16%) and Central and South America ( ~ 11%). Oil combustion accounts for a significant fraction (4-16%) of Hg emitted in each region. Asia is implicated as the leading source of anthropogenic mercury in the atmosphere and accounts for about 46% of the global total. The strong Asian source strength is rarely given due consideration in the discussion of global mercury pollution. Eastern
W o r l d w i d e e m i s s i o n s of m e r c u r y
2983
Table 1. Worldwide mercury emissions to the atmosphere by region and by source category (t yr-1) Region
Source category
North America
Western Europe
Eastern Europe and former U.S.S.R.
Africa
1984
1985
1986
1987
1988
1989
1990
1991
1992
68.4 91.1 24.6
73.7 92.7 25.5
75.0 94.4 25.6
73.7 96.2 26.3
76.5 105.0 27.0
80.6 117.1 28.2
81.4 122.1 28.3
81.4 127.2 27.9
80.6 128.6 27.5
81.3 129.4 28.2
27.5 4.4 4.4 33.1
29.3 4.4 4.6 34.5
30.0 4.8 4.9 35.2
29.2 4.4 5.1 35.2
28.3 4.6 5.3 37.0
38.5 5.9 5.6 41.4
41.1 5.9 5.6 42.7
42.0 6.3 4.4 43.4
40.9 5.9 4.4 43.2
39.6 6.2 4.4 43.4
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes ~n production - - P b production Wood combustion Miscellaneous Total
Central and South America
1983
254
62
65
66
69
95.1 76.6 33.8
88.4 77.0 33.9
101.2 75.6 33.8
101.4 78.2 34.9
96.0 83.7 35.1
95.5 91.4 35.8
44.4 3.6 1.4 38.3
46.4 3.9 1.5 37.7
48.3 3.8 1.5 39.6
48.3 3.8 1.6 40.2
49.7 3.8 1.6 40.5
62.2 4.9 1.7 43.7
7.9 0.56 9.5 8.3 64
7.9 0.60 9.4 8.5
5.3 23.0 11.6
327
4.8 23.4 11.7
7.8 0.59 9.3 8.6
333
6.0 23.8 11.8
9.9 0.68 9.1 9.0
331
332
5.6 24.2 11.8
6.2 24.7 12.0
6.2 24.8 12.1
11.1 0.74 8.7 9.3
11.0 0.80 8.2 9.4
11.0 0.79 8.2 9.5
71
71
72
73
94.5 94.2 36.0
95.4 97.1 36.2
95.6 97.6 37.3
94.6 99.0 37.6
65.0 5.1 1.6 44.5
67.7 5.0 1.6 45.5
67.7 5.0 1.6 45.7
68.5 5.0 1.6 46.0
9.9 0.78 9.4 9.2
Total
293
289
304
308
310
335
341
348
351
352
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes - - Z n production - - P b production Wood combustion Miscellaneous
247.2 37.9 41.1
246.7 38.4 40.9
251.0 39.0 41.1
259.6 39.3 41.1
264.0 39.5 41.2
267.0 39.7 40.7
262.8 40.0 40.0
166.6 40.4 38.2
130.4 40.7 37.0
114.4 41.0 29.9
34.5 3.5 3.9 55.2
35.5 3.6 4.0 55.4
35.5 3.7 4.0 56.1
35.7 3.7 4.1 57.5
36.6 3.6 4.1 58.4
48.3 4.7 4.2 60.7
49.7 4.8 3.9 60.2
49.6 4.9 3.6 45.5
49.9 4.9 3.6 40.0
51.3 4.8 3.6 36.8
Total
423
424
430
441
447
465
461
349
307
282
22.0 25.8 6.1
23.1 27.0 6.3
23.9 28.2 6.5
24.3 29.4 6.5
25.2 30.3 6.6
25.9 31.2 6.8
25.2 32.2 7.1
24.6 34.2 7.5
29.7 34.0 7.7
28.7 35.0 8.0
5.4 0.4 13.9 11.0
5.5 0.4 14.6 11.5
5.4 0.4 15.4 12.0
5.1 0.5 16.1 12.3
5.4 0.5 16.9 12.7
7.6 0.6 17.6 13.4
7.6 0.5 18.0 13.6
7.6 0.6 18.5 14.0
7.1 0.6 18.5 14.6
7.6 0.6 18.5 14.8
85
88
92
94
98
103
104
107
112
113
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes - - Z n production - - P b production Wood combustion Miscellaneous
282.0 239.8 46.6
301.0 246.6 48.0
331.4 253.2 48.6
348.4 260.5 50.3
369.6 264.5 52.0
379.2 275.5 55.3
410.4 282.3 59.0
412.0 288.9 61.5
417.6 296.8 63.8
420.0 300.5 68.4
29.4 2.0 26.8 94.0
28.7 2.2 27.6 98.1
36.7 2.4 28.4 105.1
37.5 2.6 29.3 109.3
39.8 2.6 30.1 113.8
41.2 2.7 30.9 117.7
40.2 3.0 31.5 124.0
51.3 3.1 31.8 127.3
52.4 3.5 32.0 129.9
55.7 3.5 32.0 132.0
Total
721
806
838
872
903
950
976
996
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes Zn production - - P b production Wood combustion Miscellaneous
and the former 20-22%
7.1 0.59 9.6 8.1
5.2 22.5 11.2
317
61
Total
Europe
5.0 22.1 10.5
284
Coal combustion Solid waste incineration Oil combustion Pyrometallurgieal processes ~n production - - P b production Wood combustion Miscellaneous
World total
about
4.7 21.7 10.6
270
Total
7.1 0.51 9.7 8.0
Total
Oceania
270
4.2 21.3 10.5
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes - - Z n production - - P b production Wood combustion Miscellaneous
Asia
265
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes Zn production - - P b production Wood combustion Miscellaneous
release from this region
Hg
emissions
has declined
5.3 5.2 1.2
6.1 5.3 1.2
6.9 5.8 1.2
7.4 6.5 1.3
8.1 6.7 1.3
8.1 7.0 1.4
7.0 7.2 1.4
8.6 7.3 1.4
7.4 1.2 0.30 3.2
7.6 1.2 0.31 3.1
7.2 1.2 0.32 3.1
7.7 1.1 0.33 3.3
7.8 1.2 0.34 3.5
10.4 1.6 0.35 4.1
10.6 1.6 0.35 4.3
10.1 1.6 0.35 4.3
10.7 1.4 0.35 4.2
10.9 1.7 0.35 4.5
25
24
24
25
27
32
33
33
32
35
1905
1989
2042
2104
2224
2288
2217
2201
2199
but
to about
1012
5.1 5.2 1.2
1861
U.S.S.R. used to account
of the global
752
6.3 5.1 1.1
for
North
the
16%
13%.
America and
mercury
15%, to
the
and western Europe respectively, global
contribute
of the
atmosphere.
about
anthropogenic Anthropogenic
2984
N. PIRRONE et al.
sources in Africa ( ~ 5%), Central and South America ( ~ 3 % ) , and Oceania ( ,-~ 1.5%) together account for < 10% of the annual global emission of atmospheric mercury. There are a number of interesting temporal differences in the regional emission patterns. The emissions in Asia, Oceania, Africa and Central and South America continue to rise steadily at annual rates of about 4.5%, 4.4%, 3.7% and 2.7%, respectively (with 1983 as the base year). By contrast, the emissions in Western Europe and North America increased at the rate of 5.5°,/o yr -~ and 4.8% yr -1 up to 1989 and have since remained nearly constant (Table 1). The sharp (nearly 40%) drop in industrial emissions from Eastern Europe and the former U.S.S.R. between 1990 and 1992 can be attributed to the social and economic upheaval in the region. It is significant that a sharp drop in Hg deposition rates (nearly 60%) and gaseous Hg (nearly 18%) levels were observed in the southwestern Sweden over the period 1990-1992 compared to the levels of the 1985 1989 (Iverfeldt et al., 1995). It is likely that the combined effects of the reduction in atmospheric Hg emissions in eastern Europe and former U.S.S.R. and the occurrence of the long-range transport of mercury from this region to Scandinavia, may explain the reduced Hg deposition rates. Worldwide, the steady increase in emissions which began before 1983 peaked in 1989 at 2290 t and subsequently declined to about 2200 t in 1992. The rate of increase up to 1989 was about 4% y r - 1, a figure that is higher than the 1-2% y r - 1 reported in many parts of Europe and North America (see above). Global emissions are currently decreasing at a rate of 1.3% yr -1, It is interesting to note that the levels of carbon monoxide, another man-made trace gas released from many sources similar to those of Hg, also increased worldwide at a rate of about 1.2% y r during the 1980s (Khalil and Rasmussen, 1994) and
declined by about 2 to 6% yr-1 between 1988 and 1993 (Khalil and Rasmussen, 1994; Novelli et al., 1994). Recent measurements of atmospheric Hg distribution in many parts of the world provide a check on the veracity of the current inventory. Assuming that most of the anthropogenic Hg is in elemental form in the atmosphere, distributed uniformly throughout the troposphere (of volume 3.1 x 1018 m3), and that the lifetime of elemental mercury in the global atmosphere is one year (Lindqvist et al., 1991), the average ambient Hg concentration is estimated to be 0.71 ng m-3. Average Hg emission from natural sources has been estimated to be 2500 t y r - 1 (Nriagu, 1989) which is equivalent to 0.81 ng m - 3 in ambient air; the range in reported natural flux is 2200-3200tyr -~ or 0.7-1.0 ng m - 3. The calculated average (natural + anthropogenic) concentration of Hg in the atmosphere thus is about 1.5 ng m-3, in excellent agreement with the 1-2 ngm 3 found in many parts of the world (Fitzgerald, 1986; Gill and Fitzgerald, 1987; Lindqvist et al., 1991; Fitzgerald et al., 1991; Keeler et al., 1994; Mason et al., 1994; Schroeder and Markes, 1994; Pirrone et al., 1995a; Rea et al., 1995). The Hg concentration in the preindustrial atmosphere has been estimated to be 0.3ngm -3 (Mason et al., 1994). The difference (nearly 0.5 n g m -3) between the calculated total Hg concentration (1.5 ng m - 3) and the contributions from industrial sources (0.71 ng m-3) and baseline natural sources (0.3 n g m -3) can be attributed to recycled anthropogenic mercury. In view of the inherent errors in these calculations, one can conclude that natural sources, industrial sources and the recycling of anthropogenic mercury each contribute about one-third of the current Hg ° burden in the global atmosphere. The emission data presented here, though lower than those reported by previous authors, should in no
,-- 4 0 .
-
"7
30
400
300
m
i,
I
-r
20
200
10
100
I1)
[~::~Coal Consumption I T C I P D
0 1986
l
1987
'-I
1988
-~r[Hg]p
"1
l
l
1989
1990
1991
]
0
1992
Fig. 1. Trends of: ([~) coal consumption in the state of Michigan (10 6 tyr- i); (11) total target capacity of incineration plants (TCIP) operating in Detroit, Michigan (104 kg h- ~);(A) arithmetic mean of the airborne particulate Hg concentration ([Hg]p) in Detroit, Michigan (pg m-3).
~
Worldwide emissions of mercury
2985
elO
- ' ~ s , , . . 2 zl ea e4 DETROIT eS~
eS4 el v~-~
e3
.jr 2
eSl
"
b
LAKE
r
St, CLAIR
$30 4~S29"e
°S o12 ~$32
-~S12 WINDSOR DEARBORN
15kin !
!
Fig. 2. Locationofsamplingsites(~)andtop 12 major incinerators (O) in Detroit. The name ofeach plant, target capacity, date of start-up and/or date of shut down, and current status are as follows: (1) Great Detroit Resource Recovery Authority (GDRRA), 83,160 kg h- z, 1990, operating; (2) Grosse Point-Clinton Refuse Disposal Authority, 22,680 kg h- 1, 1972, operating; (3) Central Wayne County Sanitation Authority, 18,900 kgh-1, 1964 (from 1985 to 1987 the plant was shut down), operating; (4) Southeast Oakland County Research Recovery Authority, 22,680 kgh-Z, 1956, not operating since June 1988; (5) Detroit Department of Public Work, 21,500kgh -1, 1965, operating; (6) Detroit Sewage Treatment Plant, 13,600 kg h- 1, 1940, operating; (7) Wyandotte Wastewater Plant, 8330 kg h- 1, 1939, operating; (8) Warren Wastewater Treatment Plant, 3130kgh -1, 1959, operating; (9) City of Trenton, 2730kgh -1, 1970, operating; (10) Pontiac Sewage Treatment Plant, 1820 kgh-1, 1962, operating; (11) Chrysler Sterling Stamping, 1200 kg h-1, 1986, not operating; (12) Veteran's Administration, 910 kg h-1, 1986, operating.
way be construed to imply reduced risks of ecological damage by Hg pollution, especially at the local and regional scales. On the contrary, the data tend to suggest that ecosystems are susceptible to inputs of even small quantities of anthropogenic mercury. Furthermore, it is quite common to see urban trends in Hg emissions and ambient levels that are quite different from the continental and global patterns. The city of Detroit, Michigan, illustrates the contrasting local vs global and regional trends. Atmospheric concentrations of particulate Hg were measured in Detroit on a weekly basis from 1982 to 1992 at nine sites located in residential, commercial and industrial areas (Pirrone et al., 1995b, c). Particulate Hg generally represents only 1-10% of the total atmospheric Hg with elemental mercury in the vapor phase being the dominant (90-95%) form present (Fitzgerald, 1986; Gill
and Fitzgerald, 1987; Lindqvist, et al., 1991). The particulate phase was studied because it has a much shorter lifetime in the atmosphere and ambient particulate Hg levels are thus more reflective of emissions from local sources. The trend in observed ambient air concentration of particulate Hg from 1986 to 1992 is compared with the reported coal consumption for the state of Michigan and the total target capacity of incineration plants (TCIP) in the city (Fig. 1). Detroit has over 1650 incinerators with target capacities in the range of a few kg h - 1 to 90,000 kg h - a (International Joint Commission, 1990) and the top 12 incinerators shown in Fig. 2 account for about 50% of the total mass of wastes disposed of by this particular process. During the 1986-1992 period, the 16% annual increase in the atmospheric concentration of particulate
2986
N. PIRRONE et al.
Hg in Detroit can generally be accounted for by a 11 °/o annual increase in the quantity of wastes being incinerated in the city and a 5% annual increase in Hg emissions to the atmosphere from other sources (e.g. primary and secondary pyrometallurgical processes, miscellaneous category). The shut down of the second largest incinerator at the end of 1988 is clearly reflected by a reduction in Hg level in 1989-90 (Fig. 1). The start-up of the big ( T C I P of 83,160 k g h - 1 ) Greater Detroit Resource Recovery Authority incinerator in 1990 is followed by a sharp increase in the Hg levels in Detroit. These data demonstrate that the levels (and emissions) of Hg in Detroit have increased by about 16% y r - 1 since 1989 in contrast to a nearly constant trend in N o r t h America as a whole. The need to focus more attention on incinerators as sources of mercury pollution, especially in urban areas, is also clearly highlighted. Acknowledoements--The authors would like to thank the anonymous reviewer and Jozef Pacyna for their thoughtful and thorough review of this paper.
REFERENCES
Benoit J. M., Fitzgerald W. F. and Damman A. W. H. (1994) Historical atmospheric mercury deposition in the midcontinental U.S. as recorded in an ombrotrophic peat bog. In Mercury pollution: Integration and synthesis (edited by Huckabee J. and Watras C.), pp. 187-202. Lewis Publishers, Chelsea, Michigan. Bloom N. S. and Prestbo E. M. (1993) A new survey of mercury in U.S. fossil fuels. In Proc. Coal-Energy and Env., Int. Pittsburgh Coal Conf., Pittsburgh, Pennsylvania, 12-16 September, Vol. 1, pp. 563-568. Chu P. and Porcella D. B. (1995) Mercury stack emissions from U.S. electric utility power plants. Wat. Air Soil Pollut. 80, 135-144. Cointreau S. J. (1986) Environmental Manaoement of Urban Solid Wastes in Developing Countries. The World Bank, Washington, District of Columbia. Cole H. S., Hitchcock A. L. and Collins R. (1992) Mercury Warnino: The Fish You Catch May be Unsafe to Eat. Clean Water Fund, Washington, District of Columbia. Delfino J. J. and Crisman T. L. (1993) Spatial and temporal distribution of mercury in Everglades and Okefenokee wetland sediments. Department of Environmental Engineering Sciences, University of Florida, GainnesviUe. EIA, Energy Information Administration (1991) International Energy Annual 1991. Washington, District of Columbia. EIA, Energy Information Administration (1992) International Eneroy Annual 1992. Washington, District of Columbia. EIA, Energy Information Administration (1994) Estimates of U.S. Biomass Energy Consumption 1992. Department of Energy, Washington, District of Columbia. Engstrom D. R., Swain E. B. and Brigham M. E. (1994) In Abstracts with Prooram, Int. Conf. on Mercury as a Global Pollutant. Whistler, British Columbia. Fitzgerald W. F. (1986) Cycling of mercury between the atmosphere and the oceans. In The Role of Air-Sea Exchange in Geochemical Cycling (edited by Buaat-Menard P.), pp. 363-408. NATO Advanced Institute Series, Reidel, Dordrecht. Fitzgerald W. F. (1995) Is mercury increasing in the Atmosphere? The need for an Atmospheric Mercury Network (AMNET). Wat. Air Soil Pollut. g0, 245-254.
Fitzgerald W. F., Mason R. P., Vandal G. M. (1991) Atmospheric cycling and air-water exchange of mercury over mid-continental lacustrine regions. Wat. Air Soil Pollut. 56, 745-767. Gill G. A. and Fitzgerald W. F. (1987) Mercury in surface waters of the open ocean. Global Biogeochemical Cycles 1, 199-212. Huckabee J. and Watras C. (1994) Mercury pollution: Inte Oration and synthesis. Lewis Publishers, Chelsea, Michigan. Hudson R. J. M., Gherini S. A., Fitzgerald W. M. and Porcella D. B. (1995) Anthropogenic influences on the global mercury cycle: a model-based analysis. Wat. Air Soil Pollut. 80, 265-272. International Joint Commission, Detroit-Windsor-Port Huron-Sarnia Air Pollution Advisory Board (1990) Report to the International Joint Commission. Windsor, Canada~ Iverveldt A., Munthe J., Brosset C. and Pacyna J. M. (1995) Long-term changes in concentration and deposition of atmospheric mercury over Scandinavia. Wat. Air Soil Pollut. 80, 227-233. Johnson M. G. (1987) Trace element loadings to sediments of fourteen Ontario lakes and correlation with concentrations in fish. Can. J. Fish. Aquatic Sci. 44, 754-762. Keeler G. J., Glinsorn G. and Pirrone N. (1995) Particulate mercury in the atmosphere: its significance, transport, transformation and sources. Wat. Air Soil Pollut. 80, 159-168. Keeler G. J., Hoyer M. E. and Lamborg C. H. (1994) Measurements of atmospheric mercury in the Great Lakes basin. In Mercury pollution: Integration and synthesis (edited by Huckabee J. and Watras C.), pp. 231-241. Lewis Publishers, Chelsea, Michigan. Kemp A. L. W., Williams J. D. H., Thomas R. L. and Gregory M. L. (1978) Impact of man activities on the chemical composition of the sediments of Lakes Superior and Huron. Wat. Air Soil Pollut. 10, 381-402. Khalil M. A. K. and Rasmussen R. A. (1994) Global decrease in atmospheric carbon monoxide concentration. Nature 370, 639-41. Lantzy R. J. and MacKenzie F. T. (1979) Atmospheric trace metals: global cycles and assessment of man's impact. Geochim. Cosmochim. Acta 43, 511-525. Lindqvist O. (1991) Mercury in the Swedish environment. War. Air Soil Pollut. 55, 7-17. Lindqvist O., Johansson K., Antrap M., Anderson A., Bringwork L., Hovsenius G., Hakanson L., Iverfoldt A., Meil M. and Timm B. (1991) War. Air Soil Pollut. 55(1-2), 30. Lockhart W. L. (1994) Implications of chemical contaminants for aquatic animals in the Canadian Arctic: some review comments. Sci. Total Envir. (in press). Mason R. P., Fitzgerald W. F., Morel F. M. M. (1994) The biogeochemical cycling of elemental mercury: anthropogenic influences. Geochim. Cosmochim. Acta 58, 3191-3198. Meij R. (1991) The fate of mercury in coal-fired power plants and the influence of wet flue-gas desulphurization. Wat. Air Soil Pollut. 56, 21-33. Mudroch A. (1993) Lake Ontario sediments in monitoring pollution. Envir. Monit. Assess. 28, 117-129. Novelli P. C., Masarie K. A., Tans P. P. and Lang P. M. (1994) Recent changes in atmospheric carbon monoxide. Science 263, 1587-1590. NREL, National Renewable Energy Laboratory (1993) Mercury Emissions from Municipal Solid Waste Combustors. U.S. Department of Energy, Washington, District of Columbia. Nriagu J. O. (1984) Changing Metals Cycle and Human Health. Springer, Berlin. Nriagu J. O. (1989) A global assessment of natural sources of atmospheric trace metals. Nature 338, 47-49. Nriagu J. O. and Pacyna J. M. (1988) Quantitative assessment of worldwide contamination of air, water and soils by trace metals. Nature 333, 134-139.
Worldwide emissions of mercury Pacyna J. M. (1986) Emission factors of atmospheric elements. In Toxic Metals in the Atmosphere (edited by Nriagu J. O.), pp. 1-32. Wiley, New York. Pacyna J. M. (1989) Technological parameters affecting atmospheric emissions of trace elements from major anthropogenic sources. In Control and Fate of Atmospheric Trace Metals (edited by Pacyna J. M. and Ottar B.), pp. 15-29. Kluwer Academic Publishers, Dordrecht. Pacyna J. M. and Munch J. (1991) Anthropogenic mercury emission in Europe. Wat. Air Soil Pollut. 56, 51-61. Pacyna J. M. and Keeler G. J. (1994) Sources of mercury in the Arctic. War. Air Soil Pollut. 80, 621-632. Pacyna J. M., Voldner E., Keeler G. J. and Evans G. (1993) In Proc. First Workshop on Emissions and Modelling of Atmospheric Transport of Persistent Organic Pollutants and Heavy Metals, Durham, North Carolina, 6 7 May. Pirrone N., Glinsorn G. and Keeler G. J. (1995a) Ambient levels and dry deposition fluxes of mercury to lakes Huron, Erie and St. Clair. War. Air Soil Pollut. 80, 179-188. Pirrone N., Keeler G. J. and Warner P. O. (1995b) Trends of ambient concentrations and deposition fluxes of particulate trace metals in Detroit from 1982 to 1992. Sci. Total. Envir. 162, 43-61. Pirrone N., Keeler G. J., Nriagu J. O. and Warner P. O. (1995c) Historical trends of airborne trace metals in Detroit from 1971 to 1992. War. Air Soil Pollut. (in press). Rea A. W., Keeler G. J. and Scherbatskoy T. (1995) The deposition of mercury in throughfall and litterfall in the Lake Champlain Watershed. Atmospheric Environment (submitted). Sabbioni E., Goetz L., Springer A. and Pietra R. (1983) Trace metals from coal-fired power plants: derivation of an average data base for assessment studies of the situation in the European communities. Sci. Total. Envir. 29, 2 l 3-227.
2987
Schroeder W. H. and Larkes J. (1994) Measurements of atmospheric mercury concentrations in the Canadian environment near Lake Ontario. J.G.L.R. 20, 240-259. Slemr F. and Langer E. (1992) Increase in global atmospheric concentrations of mercury inferred from measurements over the Atlantic Ocean. Nature 355, 434-437. Smith I. M. (1986) Trace Elements from Coal Combustion Emissions. lEA Coal Research, London, U.K. Swain E. B., Engstrom, D. R., Brigham M. E., Henning T. A. and Brezonik P. L. (1992) Increasing rates of atmospheric mercury deposition in Midcontinental North America. Science 257, 784-787. Swaine D. J. (1990) Trace Elements in Coal. Butterworths, London, U.K. United Nations (1992) Statistical Yearbook. Washington, District of Columbia. U.S. Bureau of Mines (1987) Minerals Yearbook, Metals and Minerals, Vol. 1. U. S. Government Printing Office, Washington. U.S. Bureau of Mines (1993) Minerals Yearbook, Metals and Minerals, Vol. 1. U. S. Government Printing Office, Washington. U.S. Department of Commerce (1993) Statistical Abstract of the United States, 1993. Economics and Statistics Administration, Bureau of the Census, Washington, District of Columbia. U.S. Environmental Protection Agency (1993) Locating and Estimating Air Emissions for Sources of Mercury and Mercury Compounds. Interim Report. U.S. Environmental Protection Agency (1994) Mercury Study Report to Congress. Vol. 1, EPA/600/P-94/002Aa. Interim Report. Voldner E. and Smith L. (1989) Production, Usage and Atmospheric Emissions of 14 Priority Toxic Chemicals. Water Quality Board, International Joint Commission on the Great Lakes, Windsor, Ontario.
Atmospheric Environment Vol. 30, No. 17, pp. 2981 2987, 1996 Copyright © 1996 Published by Elsevier Science Ltd Printed in Great Britain. All rights reserved 1352-2310/96 $15.00 + 0.00
1352-2310(95) 00498-X
REGIONAL DIFFERENCES IN WORLDWIDE EMISSIONS OF MERCURY TO THE ATMOSPHERE N I C O L A P I R R O N E , G E R A L D J. K E E L E R a n d J E R O M E O. N R I A G U Department of Environmental & Industrial Health, School of Public Health, The University of Michigan, Ann Arbor, MI 48109-2029, U.S.A. (First received 18 December 1994 and in final form 30 November 1995)
Abstract--Annual emissions of anthropogenic Hg to the atmosphere in different regions of the world during the last decade show an interesting dichotomy: the emissions in the developed countries increased at the rate of about 4.5-5.5°/'0 yr-1 up to 1989 and have since remained nearly constant, while in developing countries the emissions continue to rise steadily at the rate of 2.7-4.5% yr- 1. On a global basis, however, thetotalanthropogenicemissionsofHgincreasedbyabout4% yr -1 duringthe 1980s, peakedin 1989 at about 2290 t and are currently decreasing at the rate of about 1.3% yr-1. Solid waste disposal through incineration processes is the dominant source of atmospheric mercury in North America ( ~ 40%), Central and South America ( ~ 34%), western Europe ( ~ 28 %) and Africa ( ~ 30%), whereas coal combustion remains the dominant source in Asia (~42%) and eastern Europe and the former USSR (~40%). Mining and smelting of Zn and Pb represent the major industrial source of Hg in Oceania (~35%). Copyright © t996 Published by Elsevier Science Ltd Key word index: Mercury, emission source, atmosphere, trend, incinerator, emission factor, urban area, global scale, regional scale, Detroit.
INTRODUCTION Mercury is a highly toxic element that has been present at varying concentrations in air, water and soil ecosystems as well as in biota (Lindqvist, 1985; Nriagu, 1989). Studies in various parts of the world show that dangerous imbalances have occurred in the global mercury cycle because human activities redistribute this element in a manner that results in elevated concentrations in the food chain (Lindqvist, 1985; Nriagu and Pacyna, 1988; Nriagu, 1989; U.S.EPA, 1994). The rate at which the concentration of mercury is increasing in the atmosphere is of considerable environmental interest and is receiving intensive scrutiny. From measurements on seven Atlantic oceanographic cruises during 1977-1990, Slemr and Langer (1992) estimated the annual increase in atmospheric Hg levels to be 1.5% in the Northern Hemisphere and 1.2% in the Southern Hemisphere. Swain et al. (1992) reported a 2% yr-X increase in Hg deposition rates in remote lakes in Wisconsin and Minnesota. Increases of 1-2% have been observed in lake and peat sediments of Alaska (Engstrom et al., 1994), Arctic Canada (Lockhart, 1994), northern Ontario (Johnson, 1987), and Scandinavia (Lindqvist et al., 1991). Mason et al. (1994) inferred a 0.6% yr -1 increase in atmospheric Hg levels from geochemical model calculations. Increases much higher than 2% y r - ~ have been reported in sediments of Florida
wetlands (Delfino and Crisman, 1993) and the Great Lakes (Kemp et al., 1978; Mudroch, 1993). By contrast, the deposition rate of atmospheric Hg observed by Iverfeldt et al. (1995) in southwestern Sweden dropped (nearly 60%) from an average of 27/.tgm -2 y r - 1 during the 1985-1989 to 10 #g m -2 y r - 1 during the 1990-1992. The gaseous Hg levels in air dropped from 3.2 ng m - 3 during the 1985-1989 to 2.7 ng m - 3 during the 1990-1992, showing a decrease (nearly 18%) much lower than that observed in deposition rate of total Hg. Whether the atmospheric Hg concentrations have increased continuously or declined in recent years remains equivocal. This paper presents annual inventories of anthropogenic Hg emissions to the atmosphere during the last decade in North America, South and Central America, western Europe, eastern Europe and the former USSR, Africa, Asia, and Oceania. Mercury emissions from coal, oil and wood combustion, incineration of medical and solid waste, pyrometallurgical processes for Pb and Zn production, and a miscellaneous category which includes chlor-alkali plants, degassing of latex paint, crematoria, fluorescent lamp breakage, dental laboratory, cement manufacturing, primary and secondary mercury production, and other coal uses are included in the calculations. Differences between the trends in industrial emissions of mercury from local (Detroit, Michigan) and global sources have also been discussed.
2981
2982
N. PIRRONE et al. METHODS
Estimates of Hg emissions from power plants are based on average Hg concentrations and annual combustion of hard coal, lignite and brown coal in electric power plants as well as for industrial, commercial and residential purposes (Sabbioni et al., 1983; Smith, 1986; Swaine, 1990; Meij, 1991; EIA, 1991, 1992; Pacyna et al., 1993; U.S.-EPA, 1993). The average Hg concentrations in coals used in the calculations (and the reported ranges) were 0.18 (0.01-3.3) #g g- ~ for North America, 0.29 (0.1-2.0)#gg-1 for western Europe, 0.3 (0.15-1.8) #gg- 1 for eastern Europe and the former U.S.S.R, 0.18 (0.08-7.0) #g g- 1 for Africa, and 0.2 (0.02-1.3) #g g- 1 for Oceania (Sabbioni et al., 1983; Smith, 1986; Swaine, 1990; Meij, 1991; Pacyna et al., 1993; U.S.-EPA, 1993; Bloom and Prestbo, 1993; Chu and Porcella, 1995). Based on these regional average Hg concentrations, the uncontrolled emission factors were estimated to be 12, 11.2, 7, 7, and 7.7 #gMJ -~ for eastern Europe and former U.S.S.R., western Europe, North America, Africa, and Oceania, respectively. In the absence of reliable data for the local coals, the uncontrolled emission factor for Central and South America was estimated to be 7.0 pg M J - t using the average Hg concentration in North American coals. The uncontrolled emission factor for Asia (12#gMJ -1) was based on the Hg contents of coals of eastern Europe and former U.S.S.R. The Hg emission estimates assume a 40% control efficiency for Hg release from coal-fired power plants in the developed countries (U.S.-EPA, 1993), mostly due to the installation of control equipments which remove sulfur and nitrogen compounds from exhaust gases and to coal cleaning (U.S.-EPA, 1994; Pacyna and Keeler, 1994). No control was assumed for the developing countries (Nriagu, 1984; Nriagu and Pacyna, 1988). Because many old coal combustion plants in eastern Europe and the former U.S.S.R. have been shut down due to the decline in economic growth at the beginning of the 1990s, a 30% control efficiency was applied in estimating the Hg emissions to the atmosphere during the period of 1990-1992, but no controls were assumed before then. Mercury emissions from the incineration of municipal (MSW) and medical (MDW) solid wastes were derived assuming a waste generation rate (U.S.-Department of Commerce, 1993; U.S.-EPA, 1994) of 1-1.8 and 0.02kg d - 1person- 1, respectively, for developed countries, whereas for developing countries a waste generation rate of 0.6 kg d-Xperson-lfor MSW and 0.005kgd-~person -~ for MDW was assumed (Cointreau, 1986). The Hg content in MSW ranges from 0.3 to 9 gt -1 in Europe (Pacyna, 1986; NREL, 1993) and from 0.36 to 5.8 gt -~ in North America (NREL, 1993; U.S.-EPA, 1993). The Hg concentrations in MDW may be 10 to 50 fold higher than that found in MSW (U.S.-EPA, 1993, 1994). An emission factor of 1.2 gt -1, assuming a 60% emission control efficiency, was adopted for MSW incinerators in developed countries (U.S.-EPA, 1993), while an emission factor of 1.0 gt-1 without emission control was assumed for garbage burning in the developing countries. Estimates of Hg emissions from MDW incinerators assume emission factors of 30 g t- ~ in developed countries (U.S.-EPA, 1994) and 10-20 gt-1 in developing countries. The uncontrolled emission factors for oil-burning power plants vary from 3.1 ngBtu-~for distilled oils to 3.3ng Btu-1 for residual oils (U.S.-EPA, 1993). An average emission factor of 2.2 ng Btu- 1 for both distilled and residual oil assuming a 25% emission control efficiency was adopted for the developed countries (U.S.-EPA, 1993), and for the developing countries which generally have limited emission controis, an average factor of 3.0 ng Btu- ~ was used. Fuel wood consumption data for various countries were obtained from the United Nations (1992) and EIA (1994) compilations. An emission factor of 0.03gt-lof wood burned (U.S.-EPA, 1993) was used for all the countries assuming no emission control.
Many zinc and lead smelters (especially in the developing countries) rely almost exclusively on electrostatic precipitators for air pollution control. This device removes very limited amounts of gas phase mercury. We have adopted the emission factors 3 gHgt-1of Pb produced and 25 g H g t of Zn produced reported in Nriagu and Pacyna (1988). The amounts of Pb and Zn produced in various countries were obtained from the U.S. Bureau of Mines (1987, 1993) compilations. The miscellaneous category includes emissions from the chlor-alkali plants (still used in the developing countries), degassing of latex paint, crematoria, fluorescent lamp breakages, dental laboratory, cement manufacturing, primary and secondary mercury production and other coal uses e.g. byproduct coke production, carbon black production. The emission factors for these sources are derived from Cole et al. (1992) and U.S.-EPA (1993, 1994).
RESULTS AND DISCUSSION Table 1 shows the annual emissions of Hg in different regions of the world during the last decade. The table provides the first published inventories for anthropogenic Hg emissions in Africa, South America and Asia. Our data are in reasonable agreement with the recent inventories for Europe during the 1980s (Pacyna, 1989; Lindqvist et al., 1991; Pacyna and Munch, 1991) which generally fall in the range of 390-1100 t y r - L Industrial emissions of Hg in the United States alone during the 1980s have been reported to be 448 t y r - 1 (Voldner and Smith, 1989), 540 t y r - 1 (Cole et al. 1992) and 600 t y r - 1 (Johnson, 1987). These values are higher than our estimate for all of N o r t h America. The total (worldwide) industrial emissions fall in the range of 910-6,200tyr -1 reported by Nriagu and Pacyna (1988) for 1983/1984, and are lower than the previously reported average values of 4 5 0 0 t y r -1 by Lindqvist et al. (1991) and Johnson (1987) for the 1980s and the 11,000 t y r -1 by Lantzy and MacKenzie (1979) for the mid-1970s. The incineration of solid wastes and garbage (MSW + M D W ) is the dominant anthropogenic source of atmospheric mercury in N o r t h America ( ~ 40%), Central and South America ( ~ 34%), Africa ( ~ 30%) and western Europe ( ~ 28%). The coal combustion in electric power plants and industrial utilities is the dominant source in the developing countries of Asia ( ~ 4 2 % ) and eastern Europe and the former U.S.S.R. (58% during 1983-1989, and 40% during 1990-1992). Mining and smelting of Zn and Pb represent the dominant industrial source of Hg in Oceania, while the burning of fuel wood is an important source of atmospheric mercury in the developing countries of Africa ( ~ 16%) and Central and South America ( ~ 11%). Oil combustion accounts for a significant fraction (4-16%) of Hg emitted in each region. Asia is implicated as the leading source of anthropogenic mercury in the atmosphere and accounts for about 46% of the global total. The strong Asian source strength is rarely given due consideration in the discussion of global mercury pollution. Eastern
W o r l d w i d e e m i s s i o n s of m e r c u r y
2983
Table 1. Worldwide mercury emissions to the atmosphere by region and by source category (t yr-1) Region
Source category
North America
Western Europe
Eastern Europe and former U.S.S.R.
Africa
1984
1985
1986
1987
1988
1989
1990
1991
1992
68.4 91.1 24.6
73.7 92.7 25.5
75.0 94.4 25.6
73.7 96.2 26.3
76.5 105.0 27.0
80.6 117.1 28.2
81.4 122.1 28.3
81.4 127.2 27.9
80.6 128.6 27.5
81.3 129.4 28.2
27.5 4.4 4.4 33.1
29.3 4.4 4.6 34.5
30.0 4.8 4.9 35.2
29.2 4.4 5.1 35.2
28.3 4.6 5.3 37.0
38.5 5.9 5.6 41.4
41.1 5.9 5.6 42.7
42.0 6.3 4.4 43.4
40.9 5.9 4.4 43.2
39.6 6.2 4.4 43.4
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes ~n production - - P b production Wood combustion Miscellaneous Total
Central and South America
1983
254
62
65
66
69
95.1 76.6 33.8
88.4 77.0 33.9
101.2 75.6 33.8
101.4 78.2 34.9
96.0 83.7 35.1
95.5 91.4 35.8
44.4 3.6 1.4 38.3
46.4 3.9 1.5 37.7
48.3 3.8 1.5 39.6
48.3 3.8 1.6 40.2
49.7 3.8 1.6 40.5
62.2 4.9 1.7 43.7
7.9 0.56 9.5 8.3 64
7.9 0.60 9.4 8.5
5.3 23.0 11.6
327
4.8 23.4 11.7
7.8 0.59 9.3 8.6
333
6.0 23.8 11.8
9.9 0.68 9.1 9.0
331
332
5.6 24.2 11.8
6.2 24.7 12.0
6.2 24.8 12.1
11.1 0.74 8.7 9.3
11.0 0.80 8.2 9.4
11.0 0.79 8.2 9.5
71
71
72
73
94.5 94.2 36.0
95.4 97.1 36.2
95.6 97.6 37.3
94.6 99.0 37.6
65.0 5.1 1.6 44.5
67.7 5.0 1.6 45.5
67.7 5.0 1.6 45.7
68.5 5.0 1.6 46.0
9.9 0.78 9.4 9.2
Total
293
289
304
308
310
335
341
348
351
352
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes - - Z n production - - P b production Wood combustion Miscellaneous
247.2 37.9 41.1
246.7 38.4 40.9
251.0 39.0 41.1
259.6 39.3 41.1
264.0 39.5 41.2
267.0 39.7 40.7
262.8 40.0 40.0
166.6 40.4 38.2
130.4 40.7 37.0
114.4 41.0 29.9
34.5 3.5 3.9 55.2
35.5 3.6 4.0 55.4
35.5 3.7 4.0 56.1
35.7 3.7 4.1 57.5
36.6 3.6 4.1 58.4
48.3 4.7 4.2 60.7
49.7 4.8 3.9 60.2
49.6 4.9 3.6 45.5
49.9 4.9 3.6 40.0
51.3 4.8 3.6 36.8
Total
423
424
430
441
447
465
461
349
307
282
22.0 25.8 6.1
23.1 27.0 6.3
23.9 28.2 6.5
24.3 29.4 6.5
25.2 30.3 6.6
25.9 31.2 6.8
25.2 32.2 7.1
24.6 34.2 7.5
29.7 34.0 7.7
28.7 35.0 8.0
5.4 0.4 13.9 11.0
5.5 0.4 14.6 11.5
5.4 0.4 15.4 12.0
5.1 0.5 16.1 12.3
5.4 0.5 16.9 12.7
7.6 0.6 17.6 13.4
7.6 0.5 18.0 13.6
7.6 0.6 18.5 14.0
7.1 0.6 18.5 14.6
7.6 0.6 18.5 14.8
85
88
92
94
98
103
104
107
112
113
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes - - Z n production - - P b production Wood combustion Miscellaneous
282.0 239.8 46.6
301.0 246.6 48.0
331.4 253.2 48.6
348.4 260.5 50.3
369.6 264.5 52.0
379.2 275.5 55.3
410.4 282.3 59.0
412.0 288.9 61.5
417.6 296.8 63.8
420.0 300.5 68.4
29.4 2.0 26.8 94.0
28.7 2.2 27.6 98.1
36.7 2.4 28.4 105.1
37.5 2.6 29.3 109.3
39.8 2.6 30.1 113.8
41.2 2.7 30.9 117.7
40.2 3.0 31.5 124.0
51.3 3.1 31.8 127.3
52.4 3.5 32.0 129.9
55.7 3.5 32.0 132.0
Total
721
806
838
872
903
950
976
996
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes Zn production - - P b production Wood combustion Miscellaneous
and the former 20-22%
7.1 0.59 9.6 8.1
5.2 22.5 11.2
317
61
Total
Europe
5.0 22.1 10.5
284
Coal combustion Solid waste incineration Oil combustion Pyrometallurgieal processes ~n production - - P b production Wood combustion Miscellaneous
World total
about
4.7 21.7 10.6
270
Total
7.1 0.51 9.7 8.0
Total
Oceania
270
4.2 21.3 10.5
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes - - Z n production - - P b production Wood combustion Miscellaneous
Asia
265
Coal combustion Solid waste incineration Oil combustion Pyrometallurgical processes Zn production - - P b production Wood combustion Miscellaneous
release from this region
Hg
emissions
has declined
5.3 5.2 1.2
6.1 5.3 1.2
6.9 5.8 1.2
7.4 6.5 1.3
8.1 6.7 1.3
8.1 7.0 1.4
7.0 7.2 1.4
8.6 7.3 1.4
7.4 1.2 0.30 3.2
7.6 1.2 0.31 3.1
7.2 1.2 0.32 3.1
7.7 1.1 0.33 3.3
7.8 1.2 0.34 3.5
10.4 1.6 0.35 4.1
10.6 1.6 0.35 4.3
10.1 1.6 0.35 4.3
10.7 1.4 0.35 4.2
10.9 1.7 0.35 4.5
25
24
24
25
27
32
33
33
32
35
1905
1989
2042
2104
2224
2288
2217
2201
2199
but
to about
1012
5.1 5.2 1.2
1861
U.S.S.R. used to account
of the global
752
6.3 5.1 1.1
for
North
the
16%
13%.
America and
mercury
15%, to
the
and western Europe respectively, global
contribute
of the
atmosphere.
about
anthropogenic Anthropogenic
2984
N. PIRRONE et al.
sources in Africa ( ~ 5%), Central and South America ( ~ 3 % ) , and Oceania ( ,-~ 1.5%) together account for < 10% of the annual global emission of atmospheric mercury. There are a number of interesting temporal differences in the regional emission patterns. The emissions in Asia, Oceania, Africa and Central and South America continue to rise steadily at annual rates of about 4.5%, 4.4%, 3.7% and 2.7%, respectively (with 1983 as the base year). By contrast, the emissions in Western Europe and North America increased at the rate of 5.5°,/o yr -~ and 4.8% yr -1 up to 1989 and have since remained nearly constant (Table 1). The sharp (nearly 40%) drop in industrial emissions from Eastern Europe and the former U.S.S.R. between 1990 and 1992 can be attributed to the social and economic upheaval in the region. It is significant that a sharp drop in Hg deposition rates (nearly 60%) and gaseous Hg (nearly 18%) levels were observed in the southwestern Sweden over the period 1990-1992 compared to the levels of the 1985 1989 (Iverfeldt et al., 1995). It is likely that the combined effects of the reduction in atmospheric Hg emissions in eastern Europe and former U.S.S.R. and the occurrence of the long-range transport of mercury from this region to Scandinavia, may explain the reduced Hg deposition rates. Worldwide, the steady increase in emissions which began before 1983 peaked in 1989 at 2290 t and subsequently declined to about 2200 t in 1992. The rate of increase up to 1989 was about 4% y r - 1, a figure that is higher than the 1-2% y r - 1 reported in many parts of Europe and North America (see above). Global emissions are currently decreasing at a rate of 1.3% yr -1, It is interesting to note that the levels of carbon monoxide, another man-made trace gas released from many sources similar to those of Hg, also increased worldwide at a rate of about 1.2% y r during the 1980s (Khalil and Rasmussen, 1994) and
declined by about 2 to 6% yr-1 between 1988 and 1993 (Khalil and Rasmussen, 1994; Novelli et al., 1994). Recent measurements of atmospheric Hg distribution in many parts of the world provide a check on the veracity of the current inventory. Assuming that most of the anthropogenic Hg is in elemental form in the atmosphere, distributed uniformly throughout the troposphere (of volume 3.1 x 1018 m3), and that the lifetime of elemental mercury in the global atmosphere is one year (Lindqvist et al., 1991), the average ambient Hg concentration is estimated to be 0.71 ng m-3. Average Hg emission from natural sources has been estimated to be 2500 t y r - 1 (Nriagu, 1989) which is equivalent to 0.81 ng m - 3 in ambient air; the range in reported natural flux is 2200-3200tyr -~ or 0.7-1.0 ng m - 3. The calculated average (natural + anthropogenic) concentration of Hg in the atmosphere thus is about 1.5 ng m-3, in excellent agreement with the 1-2 ngm 3 found in many parts of the world (Fitzgerald, 1986; Gill and Fitzgerald, 1987; Lindqvist et al., 1991; Fitzgerald et al., 1991; Keeler et al., 1994; Mason et al., 1994; Schroeder and Markes, 1994; Pirrone et al., 1995a; Rea et al., 1995). The Hg concentration in the preindustrial atmosphere has been estimated to be 0.3ngm -3 (Mason et al., 1994). The difference (nearly 0.5 n g m -3) between the calculated total Hg concentration (1.5 ng m - 3) and the contributions from industrial sources (0.71 ng m-3) and baseline natural sources (0.3 n g m -3) can be attributed to recycled anthropogenic mercury. In view of the inherent errors in these calculations, one can conclude that natural sources, industrial sources and the recycling of anthropogenic mercury each contribute about one-third of the current Hg ° burden in the global atmosphere. The emission data presented here, though lower than those reported by previous authors, should in no
,-- 4 0 .
-
"7
30
400
300
m
i,
I
-r
20
200
10
100
I1)
[~::~Coal Consumption I T C I P D
0 1986
l
1987
'-I
1988
-~r[Hg]p
"1
l
l
1989
1990
1991
]
0
1992
Fig. 1. Trends of: ([~) coal consumption in the state of Michigan (10 6 tyr- i); (11) total target capacity of incineration plants (TCIP) operating in Detroit, Michigan (104 kg h- ~);(A) arithmetic mean of the airborne particulate Hg concentration ([Hg]p) in Detroit, Michigan (pg m-3).
~
Worldwide emissions of mercury
2985
elO
- ' ~ s , , . . 2 zl ea e4 DETROIT eS~
eS4 el v~-~
e3
.jr 2
eSl
"
b
LAKE
r
St, CLAIR
$30 4~S29"e
°S o12 ~$32
-~S12 WINDSOR DEARBORN
15kin !
!
Fig. 2. Locationofsamplingsites(~)andtop 12 major incinerators (O) in Detroit. The name ofeach plant, target capacity, date of start-up and/or date of shut down, and current status are as follows: (1) Great Detroit Resource Recovery Authority (GDRRA), 83,160 kg h- z, 1990, operating; (2) Grosse Point-Clinton Refuse Disposal Authority, 22,680 kg h- 1, 1972, operating; (3) Central Wayne County Sanitation Authority, 18,900 kgh-1, 1964 (from 1985 to 1987 the plant was shut down), operating; (4) Southeast Oakland County Research Recovery Authority, 22,680 kgh-Z, 1956, not operating since June 1988; (5) Detroit Department of Public Work, 21,500kgh -1, 1965, operating; (6) Detroit Sewage Treatment Plant, 13,600 kg h- 1, 1940, operating; (7) Wyandotte Wastewater Plant, 8330 kg h- 1, 1939, operating; (8) Warren Wastewater Treatment Plant, 3130kgh -1, 1959, operating; (9) City of Trenton, 2730kgh -1, 1970, operating; (10) Pontiac Sewage Treatment Plant, 1820 kgh-1, 1962, operating; (11) Chrysler Sterling Stamping, 1200 kg h-1, 1986, not operating; (12) Veteran's Administration, 910 kg h-1, 1986, operating.
way be construed to imply reduced risks of ecological damage by Hg pollution, especially at the local and regional scales. On the contrary, the data tend to suggest that ecosystems are susceptible to inputs of even small quantities of anthropogenic mercury. Furthermore, it is quite common to see urban trends in Hg emissions and ambient levels that are quite different from the continental and global patterns. The city of Detroit, Michigan, illustrates the contrasting local vs global and regional trends. Atmospheric concentrations of particulate Hg were measured in Detroit on a weekly basis from 1982 to 1992 at nine sites located in residential, commercial and industrial areas (Pirrone et al., 1995b, c). Particulate Hg generally represents only 1-10% of the total atmospheric Hg with elemental mercury in the vapor phase being the dominant (90-95%) form present (Fitzgerald, 1986; Gill
and Fitzgerald, 1987; Lindqvist, et al., 1991). The particulate phase was studied because it has a much shorter lifetime in the atmosphere and ambient particulate Hg levels are thus more reflective of emissions from local sources. The trend in observed ambient air concentration of particulate Hg from 1986 to 1992 is compared with the reported coal consumption for the state of Michigan and the total target capacity of incineration plants (TCIP) in the city (Fig. 1). Detroit has over 1650 incinerators with target capacities in the range of a few kg h - 1 to 90,000 kg h - a (International Joint Commission, 1990) and the top 12 incinerators shown in Fig. 2 account for about 50% of the total mass of wastes disposed of by this particular process. During the 1986-1992 period, the 16% annual increase in the atmospheric concentration of particulate
2986
N. PIRRONE et al.
Hg in Detroit can generally be accounted for by a 11 °/o annual increase in the quantity of wastes being incinerated in the city and a 5% annual increase in Hg emissions to the atmosphere from other sources (e.g. primary and secondary pyrometallurgical processes, miscellaneous category). The shut down of the second largest incinerator at the end of 1988 is clearly reflected by a reduction in Hg level in 1989-90 (Fig. 1). The start-up of the big ( T C I P of 83,160 k g h - 1 ) Greater Detroit Resource Recovery Authority incinerator in 1990 is followed by a sharp increase in the Hg levels in Detroit. These data demonstrate that the levels (and emissions) of Hg in Detroit have increased by about 16% y r - 1 since 1989 in contrast to a nearly constant trend in N o r t h America as a whole. The need to focus more attention on incinerators as sources of mercury pollution, especially in urban areas, is also clearly highlighted. Acknowledoements--The authors would like to thank the anonymous reviewer and Jozef Pacyna for their thoughtful and thorough review of this paper.
REFERENCES
Benoit J. M., Fitzgerald W. F. and Damman A. W. H. (1994) Historical atmospheric mercury deposition in the midcontinental U.S. as recorded in an ombrotrophic peat bog. In Mercury pollution: Integration and synthesis (edited by Huckabee J. and Watras C.), pp. 187-202. Lewis Publishers, Chelsea, Michigan. Bloom N. S. and Prestbo E. M. (1993) A new survey of mercury in U.S. fossil fuels. In Proc. Coal-Energy and Env., Int. Pittsburgh Coal Conf., Pittsburgh, Pennsylvania, 12-16 September, Vol. 1, pp. 563-568. Chu P. and Porcella D. B. (1995) Mercury stack emissions from U.S. electric utility power plants. Wat. Air Soil Pollut. 80, 135-144. Cointreau S. J. (1986) Environmental Manaoement of Urban Solid Wastes in Developing Countries. The World Bank, Washington, District of Columbia. Cole H. S., Hitchcock A. L. and Collins R. (1992) Mercury Warnino: The Fish You Catch May be Unsafe to Eat. Clean Water Fund, Washington, District of Columbia. Delfino J. J. and Crisman T. L. (1993) Spatial and temporal distribution of mercury in Everglades and Okefenokee wetland sediments. Department of Environmental Engineering Sciences, University of Florida, GainnesviUe. EIA, Energy Information Administration (1991) International Energy Annual 1991. Washington, District of Columbia. EIA, Energy Information Administration (1992) International Eneroy Annual 1992. Washington, District of Columbia. EIA, Energy Information Administration (1994) Estimates of U.S. Biomass Energy Consumption 1992. Department of Energy, Washington, District of Columbia. Engstrom D. R., Swain E. B. and Brigham M. E. (1994) In Abstracts with Prooram, Int. Conf. on Mercury as a Global Pollutant. Whistler, British Columbia. Fitzgerald W. F. (1986) Cycling of mercury between the atmosphere and the oceans. In The Role of Air-Sea Exchange in Geochemical Cycling (edited by Buaat-Menard P.), pp. 363-408. NATO Advanced Institute Series, Reidel, Dordrecht. Fitzgerald W. F. (1995) Is mercury increasing in the Atmosphere? The need for an Atmospheric Mercury Network (AMNET). Wat. Air Soil Pollut. g0, 245-254.
Fitzgerald W. F., Mason R. P., Vandal G. M. (1991) Atmospheric cycling and air-water exchange of mercury over mid-continental lacustrine regions. Wat. Air Soil Pollut. 56, 745-767. Gill G. A. and Fitzgerald W. F. (1987) Mercury in surface waters of the open ocean. Global Biogeochemical Cycles 1, 199-212. Huckabee J. and Watras C. (1994) Mercury pollution: Inte Oration and synthesis. Lewis Publishers, Chelsea, Michigan. Hudson R. J. M., Gherini S. A., Fitzgerald W. M. and Porcella D. B. (1995) Anthropogenic influences on the global mercury cycle: a model-based analysis. Wat. Air Soil Pollut. 80, 265-272. International Joint Commission, Detroit-Windsor-Port Huron-Sarnia Air Pollution Advisory Board (1990) Report to the International Joint Commission. Windsor, Canada~ Iverveldt A., Munthe J., Brosset C. and Pacyna J. M. (1995) Long-term changes in concentration and deposition of atmospheric mercury over Scandinavia. Wat. Air Soil Pollut. 80, 227-233. Johnson M. G. (1987) Trace element loadings to sediments of fourteen Ontario lakes and correlation with concentrations in fish. Can. J. Fish. Aquatic Sci. 44, 754-762. Keeler G. J., Glinsorn G. and Pirrone N. (1995) Particulate mercury in the atmosphere: its significance, transport, transformation and sources. Wat. Air Soil Pollut. 80, 159-168. Keeler G. J., Hoyer M. E. and Lamborg C. H. (1994) Measurements of atmospheric mercury in the Great Lakes basin. In Mercury pollution: Integration and synthesis (edited by Huckabee J. and Watras C.), pp. 231-241. Lewis Publishers, Chelsea, Michigan. Kemp A. L. W., Williams J. D. H., Thomas R. L. and Gregory M. L. (1978) Impact of man activities on the chemical composition of the sediments of Lakes Superior and Huron. Wat. Air Soil Pollut. 10, 381-402. Khalil M. A. K. and Rasmussen R. A. (1994) Global decrease in atmospheric carbon monoxide concentration. Nature 370, 639-41. Lantzy R. J. and MacKenzie F. T. (1979) Atmospheric trace metals: global cycles and assessment of man's impact. Geochim. Cosmochim. Acta 43, 511-525. Lindqvist O. (1991) Mercury in the Swedish environment. War. Air Soil Pollut. 55, 7-17. Lindqvist O., Johansson K., Antrap M., Anderson A., Bringwork L., Hovsenius G., Hakanson L., Iverfoldt A., Meil M. and Timm B. (1991) War. Air Soil Pollut. 55(1-2), 30. Lockhart W. L. (1994) Implications of chemical contaminants for aquatic animals in the Canadian Arctic: some review comments. Sci. Total Envir. (in press). Mason R. P., Fitzgerald W. F., Morel F. M. M. (1994) The biogeochemical cycling of elemental mercury: anthropogenic influences. Geochim. Cosmochim. Acta 58, 3191-3198. Meij R. (1991) The fate of mercury in coal-fired power plants and the influence of wet flue-gas desulphurization. Wat. Air Soil Pollut. 56, 21-33. Mudroch A. (1993) Lake Ontario sediments in monitoring pollution. Envir. Monit. Assess. 28, 117-129. Novelli P. C., Masarie K. A., Tans P. P. and Lang P. M. (1994) Recent changes in atmospheric carbon monoxide. Science 263, 1587-1590. NREL, National Renewable Energy Laboratory (1993) Mercury Emissions from Municipal Solid Waste Combustors. U.S. Department of Energy, Washington, District of Columbia. Nriagu J. O. (1984) Changing Metals Cycle and Human Health. Springer, Berlin. Nriagu J. O. (1989) A global assessment of natural sources of atmospheric trace metals. Nature 338, 47-49. Nriagu J. O. and Pacyna J. M. (1988) Quantitative assessment of worldwide contamination of air, water and soils by trace metals. Nature 333, 134-139.
Worldwide emissions of mercury Pacyna J. M. (1986) Emission factors of atmospheric elements. In Toxic Metals in the Atmosphere (edited by Nriagu J. O.), pp. 1-32. Wiley, New York. Pacyna J. M. (1989) Technological parameters affecting atmospheric emissions of trace elements from major anthropogenic sources. In Control and Fate of Atmospheric Trace Metals (edited by Pacyna J. M. and Ottar B.), pp. 15-29. Kluwer Academic Publishers, Dordrecht. Pacyna J. M. and Munch J. (1991) Anthropogenic mercury emission in Europe. Wat. Air Soil Pollut. 56, 51-61. Pacyna J. M. and Keeler G. J. (1994) Sources of mercury in the Arctic. War. Air Soil Pollut. 80, 621-632. Pacyna J. M., Voldner E., Keeler G. J. and Evans G. (1993) In Proc. First Workshop on Emissions and Modelling of Atmospheric Transport of Persistent Organic Pollutants and Heavy Metals, Durham, North Carolina, 6 7 May. Pirrone N., Glinsorn G. and Keeler G. J. (1995a) Ambient levels and dry deposition fluxes of mercury to lakes Huron, Erie and St. Clair. War. Air Soil Pollut. 80, 179-188. Pirrone N., Keeler G. J. and Warner P. O. (1995b) Trends of ambient concentrations and deposition fluxes of particulate trace metals in Detroit from 1982 to 1992. Sci. Total. Envir. 162, 43-61. Pirrone N., Keeler G. J., Nriagu J. O. and Warner P. O. (1995c) Historical trends of airborne trace metals in Detroit from 1971 to 1992. War. Air Soil Pollut. (in press). Rea A. W., Keeler G. J. and Scherbatskoy T. (1995) The deposition of mercury in throughfall and litterfall in the Lake Champlain Watershed. Atmospheric Environment (submitted). Sabbioni E., Goetz L., Springer A. and Pietra R. (1983) Trace metals from coal-fired power plants: derivation of an average data base for assessment studies of the situation in the European communities. Sci. Total. Envir. 29, 2 l 3-227.
2987
Schroeder W. H. and Larkes J. (1994) Measurements of atmospheric mercury concentrations in the Canadian environment near Lake Ontario. J.G.L.R. 20, 240-259. Slemr F. and Langer E. (1992) Increase in global atmospheric concentrations of mercury inferred from measurements over the Atlantic Ocean. Nature 355, 434-437. Smith I. M. (1986) Trace Elements from Coal Combustion Emissions. lEA Coal Research, London, U.K. Swain E. B., Engstrom, D. R., Brigham M. E., Henning T. A. and Brezonik P. L. (1992) Increasing rates of atmospheric mercury deposition in Midcontinental North America. Science 257, 784-787. Swaine D. J. (1990) Trace Elements in Coal. Butterworths, London, U.K. United Nations (1992) Statistical Yearbook. Washington, District of Columbia. U.S. Bureau of Mines (1987) Minerals Yearbook, Metals and Minerals, Vol. 1. U. S. Government Printing Office, Washington. U.S. Bureau of Mines (1993) Minerals Yearbook, Metals and Minerals, Vol. 1. U. S. Government Printing Office, Washington. U.S. Department of Commerce (1993) Statistical Abstract of the United States, 1993. Economics and Statistics Administration, Bureau of the Census, Washington, District of Columbia. U.S. Environmental Protection Agency (1993) Locating and Estimating Air Emissions for Sources of Mercury and Mercury Compounds. Interim Report. U.S. Environmental Protection Agency (1994) Mercury Study Report to Congress. Vol. 1, EPA/600/P-94/002Aa. Interim Report. Voldner E. and Smith L. (1989) Production, Usage and Atmospheric Emissions of 14 Priority Toxic Chemicals. Water Quality Board, International Joint Commission on the Great Lakes, Windsor, Ontario.