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Atmospheric deposition of lead in Norway: spatial and temporal variation in isotopic composition
Science of the Total Environment 336 (2005) 105 – 117 www.elsevier.com/locate/scitotenv
Atmospheric deposition of lead in Norway: spatial and temporal variation in isotopic composition ˚ berg b, H. Hjelmseth b E. Steinnes a,b,*, G. A a
Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway b Institute for Energy Technology, NO-2027 Kjeller, Norway Received 5 February 2004; received in revised form 29 April 2004; accepted 30 April 2004
Abstract Moss samples collected from 22 sites all over Norway at five different times during 1977 – 2000 were analysed for stable lead isotope ratios. These data together with total lead concentrations and relevant literature lead isotope data from UK, western/ central Europe and eastern Europe/Russia were used to elucidate major source regions for lead deposited in different parts of the country at different times. The southernmost part of the country was most affected from western/central Europe around 1975, but the deposition declined rapidly and UK became a more significant source region in the 1980s. Recently, the influence is mostly from Eastern Europe. In the west, UK was the dominant source region during the whole period. In the middle and northern regions, the deposition was low but also decreasing regularly, and the main source region was probably the North Atlantic. In the far north – east, influence from Russia and eastern Europe was dominant during the whole period. D 2004 Published by Elsevier B.V. Keywords: Atmospheric lead; Stable lead isotopes; Moss; Norway; Transboundary pollution; Temporal trends
1. Introduction Studies over the last 25 years have shown that terrestrial ecosystems all over Norway have been contaminated moderately to strongly by lead and other trace elements from atmospheric deposition (Steinnes, 2001). Long-range transport from other parts of Europe appears to be the main reason for this extensive lead contamination (Amundsen et al., 1992), and especially the southernmost part of the country has * Corresponding author. Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway. Tel.: +47-73-59-62-37; fax: +47-73-55-08-77. E-mail address: [email protected] (E. Steinnes). 0048-9697/$ - see front matter D 2004 Published by Elsevier B.V. doi:10.1016/j.scitotenv.2004.04.056
been strongly affected (Steinnes et al., 1992, 1994). Since the initial measurements in the 1970s (Hanssen et al., 1980; Steinnes, 1980), the lead deposition has decreased regularly all over the country (Berg and Steinnes, 1997; Steinnes et al., 2001), but the earlier deposits are retained in surface soils (Steinnes et al., 1989, 1997) and may still be a source of significant concern for considerable time in the future. Thanks to the moss biomonitoring technique, the temporal and spatial distribution of lead deposition in Norway has been monitored in great detail since 1977. This approach is especially well suited for lead since the Pb concentration measured in naturally growing terrestrial moss is closely related to the bulk deposition (Berg et al., 1995). Still the contribution of lead
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from different source regions and categories to a given site cannot be estimated from the moss technique alone. Since the ratios between the four stable lead isotopes vary in different lead deposits due to differences in the geological history, the determination of the stable isotope composition of lead using high precision thermal ionisation mass spectrometry (TIMS) has been shown to be a useful method to study the contribution from different source categories to lead pollution in various types of environmental
samples (Flegal et al., 1986; Maring et al., 1987; Smith et al., 1990; Rosman et al., 1993; Graney et al., 1995; Dunlap et al., 1999). Stable lead isotope ratios in moss samples were studied for the first time by Rosman et al. (1998) on a material from seven sites in different parts of Norway. The samples from each site had been collected at four different times, in 1977, 1985, 1990, and 1995, and they appeared to exhibit considerable temporal as well as spatial variation in lead isotope composition. The present work is an
Fig. 1. Locations of the moss sampling sites.
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Table 1 Stable lead isotope ratios in moss samples collected at five different times at 22 different localities in Norway Location
Coordinates (decimal) jN
jE
(1) Rømskog
59.68
11.82
(2) Trysil
61.42
12.38
(3) Brandbu
60.43
10.58
(4) Vang/Valdres
61.15
8.40
(5) Andebu
59.30
10.12
˚ mot/Vinje (6) A
59.50
7.97
(7) Vega˚rshei
58.97
8.93
(8) Evje
58.58
7.87
(9) Øyslebø
58.17
7.58
(10) Gya
58.60
6.37
Year
206/204
206/207
208/207
Pb Ag/g
2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977
18.012 17.835 17.795 17.664 17.796 17.947 17.908 17.653 17.714 17.724 17.873 17.613 17.766 17.656 17.730 17.880 17.677 17.702 17.632 17.711 18.089 17.979 17.882 17.731 m 18.039 17.849 17.760 17.703 17.731 18.067 17.941 17.806 m 17.777 18.238 17.889 17.725 17.553 17.887 17.937 17.872 17.648 17.553 17.685 17.800 17.614 17.449 m 17.989
1.1558 1.1468 1.1411 1.1363 1.1411 1.1523 1.1473 1.1338 1.1394 1.1379 1.1473 1.1340 1.1401 1.1335 1.1398 1.1477 1.1389 1.1375 1.1329 1.1374 1.1604 1.1550 1.1454 1.1390 m 1.1554 1.1479 1.1411 1.1373 1.1393 1.1574 1.1498 1.1431 m 1.1415 1.1678 1.1486 1.1367 1.1297 1.1374 1.1513 1.1467 1.1346 1.1268 1.1391 1.1432 1.1322 1.1221 m 1.1280
2.4294 2.4167 2.4153 2.4083 2.4182 2.4254 2.4215 2.4078 2.4087 2.4125 2.4203 2.4015 2.4133 2.4062 2.4154 2.4223 2.4082 2.4097 2.4057 2.4130 2.4350 2.4251 2.4191 2.4111 m 2.4291 2.4167 2.4110 2.4094 2.4130 2.4329 2.4234 2.4167 m 2.4180 2.4316 2.4183 2.4089 2.4004 2.4251 2.4245 2.4201 2.4071 2.4025 2.4140 2.4156 2.4042 2.3950 m 2.4141
10.9 11.9 14.5 24 49 2.01 6.9 13.7 15 35 5.6 10.3 12.5 24 50 3.6 6.7 13.5 13 38 4.6 26.1 23.5 37 123 4.9 7.4 21.6 25 19 13.9 29.9 27.1 53 112 6.2 12.5 26.8 29 50 18.1 24.4 52.3 86 148 8.7 21.6 41.7 99 106
(continued on next page)
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Table 1 (continued) Location
Coordinates (decimal) jN
Year
206/204
206/207
208/207
Pb Ag/g
2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977
17.857 17.527 17.482 17.329 17.545 17.715 17.526 17.374 17.265 17.528 17.800 17.523 17.392 17.321 17.590 17.746 17.637 17.473 17.360 17.579 17.848 17.704 17.612 17.450 17.628 17.880 17.712 17.561 17.488 17.744 18.043 17.826 17.758 17.572 17.748 17.907 17.815 17.597 m 17.678 17.899 17.833 17.601 17.641 17.828 18.011 17.862 17.589 17.532 17.730
1.1462 1.1277 1.1204 1.1133 1.1264 1.1373 1.1259 1.1174 1.1110 1.1280 1.1436 1.1246 1.1183 1.1160 1.1305 1.1413 1.1338 1.1252 1.1176 1.1323 1.1480 1.1380 1.1324 1.1246 1.1361 1.1494 1.1378 1.1305 1.1261 1.1409 1.1582 1.1443 1.1399 1.132 1.1414 1.1513 1.1435 1.1333 m 1.1402 1.1520 1.1420 1.1296 1.1351 1.1452 1.1577 1.1456 1.1273 1.1284 1.1386
2.4114 2.3988 2.3976 2.3897 2.4054 2.4118 2.3993 2.3916 2.3846 2.4023 2.4183 2.3988 2.3931 2.3879 2.4064 2.4160 2.4079 2.3983 2.3925 2.4071 2.4221 2.4094 2.4047 2.3941 2.4074 2.4229 2.4105 2.4020 2.3966 2.4152 2.4305 2.4138 2.4118 2.401 2.4144 2.4243 2.4155 2.4046 m 2.4141 2.4270 2.4171 2.4043 2.4054 2.4157 2.4335 2.4191 2.4046 2.3974 2.4108
5.5 13.5 21.2 30 49 4.9 11.3 35.5 35 30 6.7 21.8 29.7 35 47 4.4 9.1 12.5 18 19 0.94 1.5 2.9 4 8 1.38 4.4 6.0 9 26 1.16 1.9 5.9 8 4 4.8 9.3 11.7 14 37 2.5 9.3 13.4 28 18 2.1 1.9 3.4 6 5
jE
(11) Nedstrand
59.33
5.70
(12) Kvitingen
60.45
5.86
(13) Haukeland
60.83
5.58
(14) Va˚gsøy
61.98
5.17
(15) Ka˚rvatn
62.78
8.85
(16) Momyr
64.08
10.52
(17) Muru
64.47
14.12
(18) Vassvatnet
66.40
13.18
(19) Moskenes
67.92
13.05
(20) Øverbygd
69.00
18.95
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Table 1 (continued) Location
Coordinates (decimal) jN
jE
(21) Karasjok
69.45
25.78
(22) Gamvik
71.07
28.23
Year
206/204
206/207
208/207
Pb Ag/g
2000 1995 1990 1985 1977 2000 1995 1990 1985 1977
18.038 17.891 17.783 17.629 17.773 17.915 17.902 17.881 17.698 17.899
1.1569 1.1495 1.1436 1.1329 1.1452 1.1520 1.1495 1.1491 1.1373 1.1487
2.4357 2.4180 2.4132 2.4042 2.4165 2.4274 2.4259 2.4236 2.4087 2.4235
0.87 1.4 2.6 6 5 1.45 2.7 7.2 3 5
m = missing value.
extension of that work to 22 different sites covering the entire mainland of Norway and including samples from year 2000 in addition to the four previous years of sampling.
2. Materials and methods Samples of the feather moss Hylocomium splendens from 22 sites in different parts of Norway, respectively, in 1977, 1985, 1990, 1995, and 2000 were investigated in the present work. The samples had been collected as part of a national program monitoring the deposition of pollutants from longrange atmospheric transport, and the parts of the moss plant representing the incremental growth during the last 3 years preceding the year of collection were taken for analysis. The locations of the 22 sites are shown on the map in Fig. 1, and their geographical coordinates are listed in Table 1. All selected sites are located in relatively remote areas far from towns or other significant sources of air pollution. Moss samples of about 0.2 g were decomposed in a low-temperature plasma asher. The residue was dissolved in a few drops of concentrated HNO3. After evaporating the solution to dryness, the residue was dissolved in 0.2 ml 3 M HNO3 before chromatographic separation of Pb according to a modification of the method described by Horwitz et al. (1992, 1994). The sample solution was fed on a column packed with a crown ether resin. After removing most other elements by washing with 3 M HNO3, Pb was eluted with dilute ammonium carbonate solution. The analyses were performed on a Finnigan MAT 261 mass spectrometer
using single rhenium filaments and the total Pb blank was < 100 pg. Before loading the sample, 2 Al of silica gel (Merck) was evaporated to dryness on the filament at a current of 1 A. The sample was dissolved in 1 Al of 10% H3PO4, loaded onto the silica gel, and evaporated to dryness at 1 A. The current was then raised to 1.5 A for 1 min and subsequently to 2.0– 2.1 A followed by a swift raise to red glow. The turret was loaded with 12 samples and 1 NBS 981 Pb standard. Filament current during analyses varied between 1.6 and 1.8 A. Data collection was made in 10 blocks of 10 measurements. The Pb isotopic ratios were corrected for mass fractionation by repeated analyses of the NBS 981 Pb standard, which showed a reproducibility of 206Pb/ 204 Pb = 0.16%, 206 Pb/ 207 Pb = 0.06%, and 208 Pb/ 206 Pb = 0.16% at the 2s level.
3. Results and discussion Results from the lead isotope analyses, expressed by the ratios 206Pb/207Pb, 208Pb/207Pb, and 206Pb/ 204 Pb, are listed in Table 1, along with the corresponding Pb concentrations from previous analyses by electrothermal AAS (1977, 1985) or ICP-MS (1990 – 2000). Since much of the Pb isotope data for environmental samples in the literature are presented as 206Pb/207Pb, the subsequent discussion will be based on this ratio in order to make the comparison with the previous data easier. The trends apparent from the preliminary report on Norwegian mosses (Rosman et al., 1998) based on seven sites are confirmed and fortified by the present results. In general, the 206Pb/207Pb ratio drops from
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1977 to 1985 and then turns gradually to higher values during the period 1990 – 2000. The regional differences in 206Pb/207Pb however are considerable at any time, with the lowest values observed in the southwest. In order to facilitate a more detailed discussion, isopleths of the 206Pb/207Pb ratio were constructed for each of the sampling years 1977 (Fig. 2), 1985 (Fig. 3), 1990 (Fig. 4), 1995 (Fig. 5), and 2000 (Fig. 6). These dates represent the year of collection. Since the moss samples were collected in a way to represent the incremental growth during the three preceding years, the representative years for comparison with literature data (with
Fig. 2. Geographical variation of
206
the exception of Scottish moss samples) may be 1975, 1983, 1988, 1993, and 1998, respectively. Previous knowledge on contributions from different source regions to the lead deposition in Norway at different sites and times is very limited. Some evidence is available from the Birkenes station in southernmost Norway, about 40 km southwest of the present site 7, where lead and other trace elements were studied in diurnal aerosol samples collected during 1978– 1979 and 1985 – 1986 (Amundsen et al., 1992) and the corresponding air trajectories assigned to eight sectors representing different source regions. The predomi-
Pb/207Pb ratio in moss samples collected in 1977.
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Fig. 3. Geographical variation of
111
206
Pb/207Pb ratio in moss samples collected in 1985.
nant contributions came from the sectors covering the European mainland and UK. Contributions to the integrated amount of lead from the sectors covering Norwegian territory were only 11.7% and 11.8%, respectively, for the two periods (not including trajectories that could not be assigned to any particular sector). Corresponding data do not exist for other relevant sites in Norway, but since all sampling sites were quite remote from densely populated areas, it may be assumed that the contribution of lead from domestic sources did not play a major role at any site. Since long-range atmospheric transport from source regions elsewhere in Europe is the main source
of lead deposition in Norway, it seems appropriate to start the discussion by reviewing literature data for 206 Pb/207Pb in air in different potential source regions over the time period concerned. Data for aerosols as well as from analyses of precipitation and dated ice and peat cores are useful for this purpose. A survey of available literature data is presented in Table 2. The most complete data are from the UK, where relevant data exist for the entire period covered by the Norwegian moss survey. Considering all data, it appears that the 206Pb/207Pb ratio dropped by nearly 2% from the mid 1970s to the early 1980s, stayed low for some years, and then increased again from the late 1980s
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Fig. 4. Geographical variation of
206
Pb/207Pb ratio in moss samples collected in 1990.
due to the gradually increasing use of unleaded petrol after 1986 (Farmer et al., 2000). For the years represented by the Norwegian moss samples, the following approximate values may be estimated from the UK data: 1975, 1.120; 1983, 1.105; 1988, 1.125; 1993, 1.135; 1998; 1.145. This estimation does not consider the peat values from Western Scotland (Weiss et al., 2002), which are systematically higher than the other data by about 1% but show the same temporal trend. For mainland Europe, the data are relatively scarce, and the corresponding estimates are therefore presum-
ably less reliable. For western/central Europe, the 206 Pb/207Pb ratio does not show the same variation as in the UK but seems to have been of the order of 1.13– 1.14 over the entire period 1975 –1993. In some of these countries, the use of unleaded petrol started earlier than in the UK. In the western part of the Soviet Union and possibly other states in eastern Europe, a relatively stable value around 1.155 may be estimated. Leaded gasoline is still used in this part of Europe. Before entering a detailed discussion of the information carried by the present lead isotope data for
E. Steinnes et al. / Science of the Total Environment 336 (2005) 105–117
Fig. 5. Geographical variation of
113
206
Pb/207Pb ratio in moss samples collected in 1995.
mosses, some additional pieces of information need to be considered. First, although a strong and consistent decline of lead deposition all over the country is evident from the numbers for total Pb in moss in Table 1, there are distinct geographical differences in these trends, as illustrated in Fig. 7. In the 1977 survey, the observed lead deposition was far higher in the south than elsewhere, particularly in areas near the Skagerrak coast (sites 5, 7, 8, 9), but the deposition there dropped by over a factor of 3 until 1990 followed by a regular but somewhat slower decline through the 1990s. Pre-
cipitation in this region is predominantly supplied by southerly to easterly winds. Turning to the southern part of the west coast (sites 11– 14), the 1977 lead figures were only about 30% of those in the far south, but the level stayed relatively constant until 1990 after which there was a similar decay as in the south. In this area, in particular at sites approximately 20 –50 km from the coast (cf. sites 12– 13), the annual precipitation is about three times higher than at the southern coast, but the prevailing wind direction during precipitation events is south – southwest. From site 14 and
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Fig. 6. Geographical variation of
206
Pb/207Pb ratio in moss samples collected in 2000.
northward, the 1977 values were only 10– 20% of those in the far south, and a regular decline was observed over the whole period. In most of this area, precipitation is supplied mainly by westerly/north – westerly winds from the North Atlantic. Considering all the above information and relating it to the moss 206Pb/207Pb data, the following interpretations may be offered with respect to the most important source regions of lead deposition in Norway at different times: Southern – southeastern region (sites 1 – 9): This region probably received most of its lead in the past from mainland Europe. The rapid decline during the
1970s –1980s is probably to a great extent associated with early introduction of unleaded gasoline in some of the source countries. An influence from UK is also evident in this region, however, with declining 206 Pb/207Pb between 1977 and 1985 and gradually decreasing ratios toward the west at all times. Recently ratios of 1.15 –1.16 are observed in this region, indicating that a greater fraction of the recent lead from long-range transport has its origin in Eastern Europe, including Russia. West coast (sites 10– 14): Ratios here are consistently lower than elsewhere, and follow quite closely the UK trend for airborne lead. In this region, the
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Table 2 206 Pb/207Pb in aerosol and other relevant media in different parts of Europe Country, Site
Sampling medium
Year
206
Reference
UK Perth Scotland
Aerosols Moss
1994 1970 – 1979 1980 – 1989 1990 – 1999 2000 1989 – 1991 1997 – 1998 1985 1985 1971 – 1975 1976 – 1980 1981 – 1985 1986 – 1990 1975 F 2 1981 F 2 1986 F 2 1988 F 2 1991 1998
1.101 1.127(30) 1.120(10) 1.137(16) 1.151(7) 1.120(31) 1.144(145) 1.118(10) 1.108(5) 1.116(2) 1.108(2) 1.098(2) 1.128(2) 1.133 1.129 1.117 1.115 1.133 1.122(6)
Rosman et al., 1998 Farmer et al., 2002
1.132(6) 1.138(7) 1.144(3) 1.156(3) 1.137(4) 1.139(3) 1.137(2) 1.138(5) 1.130(6) 1.112(10) 1.145(6) 1.156(6)
Rosman et al., 2000
1.152(2) 1.160(6) 1.169(4) 1.153(5)
Mukai et al., 2001 Bollho¨fer and Rosman, 2002 Hopper et al., 1991
Rainwater Scotland, rural Lancashire Harpenden
Aerosols Aerosols Herbage
Scotland, western
Peat
Oxford
Aerosols
Western Europe Mont Blanc
Snow/ice
France Germany Netherlands W. Europea Avignon Grenoble Constance Poln
Aerosols Aerosols Aerosols Aerosols Aerosols Aerosols Aerosols Aerosols
1975 – 1977 1981 – 1984 1986 1990 – 1991 1994 1994 1994 1988 1998 1996 – 1998 1998 1998
Eastern Europe Moscow Moscow E. Europea W. USSR
Aerosols Aerosols Aerosols Aerosols
1994 1999 1988 1988
a
Pb/207Pb (number)
Farmer et al., 2000 Farmer et al., 2000 Farmer et al., 2000 Bacon et al., 1996
Weiss et al., 2002
Bollho¨fer and Rosman, 2002
Rosman et al., 1998
Hopper et al., 1991 Bollho¨fer and Rosman, 2002
Aerosols in southern Sweden representing air transport from the respective sectors.
dominant contribution is most probably from the UK, in particular during the 1980s. Central and northern part (sites 15 –20): In this region, the temporal variation is less pronounced than farther south. Ratios around 1.14 are typical, and the main source region is probably the North Atlantic, where even sources in North America, which have relatively high 206Pb/207Pb values, may have contributed in addition to the European ones (Rosman et al.,
1998). The UK-associated decline in 1985 however is also seen in most of this region, but less distinctly than farther south. Recent development towards values of 1.15 and above may indicate some Russian/Eastern European influence as well. Far north-eastern sites (21 – 22): Here the level stays quite stable at 1.14 – 1.15 during the entire period, with the exception of a drop in 1985. In this area, the relative importance of Russia/Eastern Europe
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Fig. 7. Time trends in atmospheric deposition of lead in three different parts of Norway as reflected by moss samples (Ag Pb/g moss). Years shown are the years of sampling.
is obviously greater than in areas farther south, at least until 1995. Since local soil dust is invariably a problem in the interpretation of data from moss surveys (Steinnes, 1995), contribution to the present data from local mineral soil particles should also be considered. The knowledge on lead isotope ratios in Norwegian bedrock is limited in general. In a recent study of stable lead isotopes in podzolic soil profiles from different parts of Norway, however, 206Pb/207Pb ratios within the range 1.20 –1.73 were observed in the C-horizon (Steinnes et al., unpublished). Thus, it seems that none of the moss data discussed in this work were appreciably influenced from the geochemical background at the sampling site.
Acknowledgements This work was supported by a grant from the Research Council of Norway.
References Amundsen CE, Hanssen JE, Semb A, Steinnes E. Long-range atmospheric transport to southern Norway. Atmos Environ 1992; 26A:1309 – 24. Bacon JR, Jones KC, McGrath SP, Johnston AE. Isotopic character of lead deposited from the atmosphere at a grassland site in the United Kingdom since 1860. Environ Sci Technol 1996;30: 2511 – 8.
Berg T, Steinnes E. Recent trends in atmospheric deposition of trace elements in Norway as evident from the 1995 moss survey. Sci Total Environ 1997;208:197 – 206. Berg T, Røyset O, Steinnes E, Vadset M. Atmospheric trace element deposition: principal component analysis of ICP-MS data from moss samples. Environ Pollut 1995;88:67 – 77. Bollho¨fer A, Rosman KJR. The temporal stability in lead isotopic signatures at selected sites in the Southern and Northern Hemispheres. Geochim Cosmochim Acta 2002;66:1375 – 86. Dunlap CE, Steinnes E, Flegal AR. A synthesis of lead isotopes in two millennia of European air. Earth Planet Sci Lett 1999;167: 81 – 8. Farmer JG, Eades LJ, Graham MC, Bacon JR. The changing nature of the 206Pb/207Pb isotopic ratio of lead in rainwater, atmospheric particulates, pine needles and leaded petrol in Scotland, 1982 – 1998. J Environ Monit 2000;2:49 – 57. Farmer JG, Eades LJ, Atkins H, Chamberlain DF. Historical trends in the lead isotopic composition of archival sphagnum mosses from Scotland (1838 – 2000). Environ Sci Technol 2002;36: 152 – 7. Flegal AR, Itoh K, Patterson CC, Wong CS. Vertical profile of lead isotope compositions in the north – east Pacific. Nature 1986; 321:689 – 90. Graney JR, Halliday AN, Keeler GJ, Nriagu JO, Robbins JA, Norton SA. Isotopic record of lead pollution in lake sediments from the northeastern United States. Geochim Cosmochim Acta 1995;59: 1715 – 28. Hanssen JE, Rambæk JP, Semb A, Steinnes E. Atmospheric deposition of trace elements in Norway. In: Drabløs D, Tollan A, editors. Ecological Impact of Acid Precipitation. Norway: ˚ s; 1980. p. 116 – 7. Oslo-A Hopper JF, Ross HB, Sturges WT, Barrie LA. Regional source discrimination of atmospheric aerosols in Europe using the isotopic composition of lead. Tellus 1991;43B:45 – 60. Horwitz EP, Chiarizia R, Dietz ML. A novel strontium selective extraction chromatographical resin. Solv Extr Ion Exch 1992; 10:313 – 36. Horwitz EP, Dietz ML, Rhoads S, Felinto C, Gale NH, Houghton J. A lead selective extraction chromatographical resin and its application to the isolation of lead from geological samples. Anal Chim Acta 1994;292:263 – 73. Maring H, Settle DM, Buat-Me´nard P, Dulac F, Patterson CC. Stable lead isotope tracers of air mass trajectories in the Mediterranean region. Nature 1987;300:154 – 6. Mukai H, Machida T, Tanaka A, Yelpatievskiy PV, Uematsu M. Lead isotope ratios in the urban air of eastern and central Russia. Atmos Environ 2001;35:2783 – 93. Rosman KJR, Chisholm W, Boutron CF, Candelone JP, Hong S. Isotopic evidence for the source of lead in Greenland snows since the late 1960s. Nature 1993;362:333 – 5. Rosman KJR, Ly C, Steinnes E. Spatial and temporal variation in isotopic composition of atmospheric lead in Norwegian moss. Environ Sci Technol 1998;32:2542 – 6. Rosman KJR, Ly C, Van de Velde K, Boutron C. A two century record of lead isotopes in high altitude Alpine snow and ice. Earth Planet Sci Lett 2000;176:413 – 24. Smith DR, Niemeyer S, Estes JA, Flegal AR. Stable lead isotopes
E. Steinnes et al. / Science of the Total Environment 336 (2005) 105–117 evidence of anthropogenic contamination in Alaskan sea otters. Environ Sci Technol 1990;1517 – 21. Steinnes E. Atmospheric deposition of heavy metals in Norway studied by analysis of moss samples using neutron activation analysis and atomic absorption spectrometry. J Radioanal Chem 1980;58:387 – 91. Steinnes E. A critical evaluation of the use of naturally growing moss to monitor the deposition of atmospheric metals. Sci Total Environ 1995;160/161:243 – 9. Steinnes E. Metal contamination of the natural environment in Norway from long range atmospheric transport. Water Air Soil Pollut., Focus 2001;1:449 – 60. Steinnes E, Solberg W, Petersen HM, Wren CD. Heavy metal pollution by long range transport in natural soils of southern Norway. Water Air Soil Pollut 1989;45:207 – 18. Steinnes E, Rambæk JP, Hanssen JE. Large-scale multi-element survey of atmospheric deposition using naturally growing moss as biomonitor. Chemosphere 1992;35:735 – 52.
117
Steinnes E, Hanssen JE, Rambæk JP, Vogt NB. Atmospheric deposition of trace elements in Norway: temporal and spatial trends studied by moss analysis. Water Air Soil Pollut 1994; 74:121 – 40. Steinnes E, Allen RO, Rambæk JP, Petersen HM, Varskog P. Atmospheric deposition of trace elements in Norway: temporal and spatial trends studied by moss analysis. Sci Total Environ 1997;205:255 – 66. Steinnes E, Berg T, Sjøbakk TE, Uggerud H, Vadset M. Atmospheric deposition of heavy metals in Norway. Nation-wide survey in 2000. State Program for Pollution Monitoring, Report 838/01. Oslo: Norwegian State Pollution Control Authority; 2001. p. 1 – 28. In Norwegian. Weiss D, Shotyk W, Boyle EA, Kramers JD, Appleby PG, Cheburkin AK. Comparative study of the temporal evolution of atmospheric lead deposition in Scotland and eastern Canada using blanket peat bogs. Sci Total Environ 2002; 292:7 – 18.
Atmospheric deposition of lead in Norway: spatial and temporal variation in isotopic composition ˚ berg b, H. Hjelmseth b E. Steinnes a,b,*, G. A a
Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway b Institute for Energy Technology, NO-2027 Kjeller, Norway Received 5 February 2004; received in revised form 29 April 2004; accepted 30 April 2004
Abstract Moss samples collected from 22 sites all over Norway at five different times during 1977 – 2000 were analysed for stable lead isotope ratios. These data together with total lead concentrations and relevant literature lead isotope data from UK, western/ central Europe and eastern Europe/Russia were used to elucidate major source regions for lead deposited in different parts of the country at different times. The southernmost part of the country was most affected from western/central Europe around 1975, but the deposition declined rapidly and UK became a more significant source region in the 1980s. Recently, the influence is mostly from Eastern Europe. In the west, UK was the dominant source region during the whole period. In the middle and northern regions, the deposition was low but also decreasing regularly, and the main source region was probably the North Atlantic. In the far north – east, influence from Russia and eastern Europe was dominant during the whole period. D 2004 Published by Elsevier B.V. Keywords: Atmospheric lead; Stable lead isotopes; Moss; Norway; Transboundary pollution; Temporal trends
1. Introduction Studies over the last 25 years have shown that terrestrial ecosystems all over Norway have been contaminated moderately to strongly by lead and other trace elements from atmospheric deposition (Steinnes, 2001). Long-range transport from other parts of Europe appears to be the main reason for this extensive lead contamination (Amundsen et al., 1992), and especially the southernmost part of the country has * Corresponding author. Department of Chemistry, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway. Tel.: +47-73-59-62-37; fax: +47-73-55-08-77. E-mail address: [email protected] (E. Steinnes). 0048-9697/$ - see front matter D 2004 Published by Elsevier B.V. doi:10.1016/j.scitotenv.2004.04.056
been strongly affected (Steinnes et al., 1992, 1994). Since the initial measurements in the 1970s (Hanssen et al., 1980; Steinnes, 1980), the lead deposition has decreased regularly all over the country (Berg and Steinnes, 1997; Steinnes et al., 2001), but the earlier deposits are retained in surface soils (Steinnes et al., 1989, 1997) and may still be a source of significant concern for considerable time in the future. Thanks to the moss biomonitoring technique, the temporal and spatial distribution of lead deposition in Norway has been monitored in great detail since 1977. This approach is especially well suited for lead since the Pb concentration measured in naturally growing terrestrial moss is closely related to the bulk deposition (Berg et al., 1995). Still the contribution of lead
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from different source regions and categories to a given site cannot be estimated from the moss technique alone. Since the ratios between the four stable lead isotopes vary in different lead deposits due to differences in the geological history, the determination of the stable isotope composition of lead using high precision thermal ionisation mass spectrometry (TIMS) has been shown to be a useful method to study the contribution from different source categories to lead pollution in various types of environmental
samples (Flegal et al., 1986; Maring et al., 1987; Smith et al., 1990; Rosman et al., 1993; Graney et al., 1995; Dunlap et al., 1999). Stable lead isotope ratios in moss samples were studied for the first time by Rosman et al. (1998) on a material from seven sites in different parts of Norway. The samples from each site had been collected at four different times, in 1977, 1985, 1990, and 1995, and they appeared to exhibit considerable temporal as well as spatial variation in lead isotope composition. The present work is an
Fig. 1. Locations of the moss sampling sites.
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Table 1 Stable lead isotope ratios in moss samples collected at five different times at 22 different localities in Norway Location
Coordinates (decimal) jN
jE
(1) Rømskog
59.68
11.82
(2) Trysil
61.42
12.38
(3) Brandbu
60.43
10.58
(4) Vang/Valdres
61.15
8.40
(5) Andebu
59.30
10.12
˚ mot/Vinje (6) A
59.50
7.97
(7) Vega˚rshei
58.97
8.93
(8) Evje
58.58
7.87
(9) Øyslebø
58.17
7.58
(10) Gya
58.60
6.37
Year
206/204
206/207
208/207
Pb Ag/g
2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977
18.012 17.835 17.795 17.664 17.796 17.947 17.908 17.653 17.714 17.724 17.873 17.613 17.766 17.656 17.730 17.880 17.677 17.702 17.632 17.711 18.089 17.979 17.882 17.731 m 18.039 17.849 17.760 17.703 17.731 18.067 17.941 17.806 m 17.777 18.238 17.889 17.725 17.553 17.887 17.937 17.872 17.648 17.553 17.685 17.800 17.614 17.449 m 17.989
1.1558 1.1468 1.1411 1.1363 1.1411 1.1523 1.1473 1.1338 1.1394 1.1379 1.1473 1.1340 1.1401 1.1335 1.1398 1.1477 1.1389 1.1375 1.1329 1.1374 1.1604 1.1550 1.1454 1.1390 m 1.1554 1.1479 1.1411 1.1373 1.1393 1.1574 1.1498 1.1431 m 1.1415 1.1678 1.1486 1.1367 1.1297 1.1374 1.1513 1.1467 1.1346 1.1268 1.1391 1.1432 1.1322 1.1221 m 1.1280
2.4294 2.4167 2.4153 2.4083 2.4182 2.4254 2.4215 2.4078 2.4087 2.4125 2.4203 2.4015 2.4133 2.4062 2.4154 2.4223 2.4082 2.4097 2.4057 2.4130 2.4350 2.4251 2.4191 2.4111 m 2.4291 2.4167 2.4110 2.4094 2.4130 2.4329 2.4234 2.4167 m 2.4180 2.4316 2.4183 2.4089 2.4004 2.4251 2.4245 2.4201 2.4071 2.4025 2.4140 2.4156 2.4042 2.3950 m 2.4141
10.9 11.9 14.5 24 49 2.01 6.9 13.7 15 35 5.6 10.3 12.5 24 50 3.6 6.7 13.5 13 38 4.6 26.1 23.5 37 123 4.9 7.4 21.6 25 19 13.9 29.9 27.1 53 112 6.2 12.5 26.8 29 50 18.1 24.4 52.3 86 148 8.7 21.6 41.7 99 106
(continued on next page)
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Table 1 (continued) Location
Coordinates (decimal) jN
Year
206/204
206/207
208/207
Pb Ag/g
2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977 2000 1995 1990 1985 1977
17.857 17.527 17.482 17.329 17.545 17.715 17.526 17.374 17.265 17.528 17.800 17.523 17.392 17.321 17.590 17.746 17.637 17.473 17.360 17.579 17.848 17.704 17.612 17.450 17.628 17.880 17.712 17.561 17.488 17.744 18.043 17.826 17.758 17.572 17.748 17.907 17.815 17.597 m 17.678 17.899 17.833 17.601 17.641 17.828 18.011 17.862 17.589 17.532 17.730
1.1462 1.1277 1.1204 1.1133 1.1264 1.1373 1.1259 1.1174 1.1110 1.1280 1.1436 1.1246 1.1183 1.1160 1.1305 1.1413 1.1338 1.1252 1.1176 1.1323 1.1480 1.1380 1.1324 1.1246 1.1361 1.1494 1.1378 1.1305 1.1261 1.1409 1.1582 1.1443 1.1399 1.132 1.1414 1.1513 1.1435 1.1333 m 1.1402 1.1520 1.1420 1.1296 1.1351 1.1452 1.1577 1.1456 1.1273 1.1284 1.1386
2.4114 2.3988 2.3976 2.3897 2.4054 2.4118 2.3993 2.3916 2.3846 2.4023 2.4183 2.3988 2.3931 2.3879 2.4064 2.4160 2.4079 2.3983 2.3925 2.4071 2.4221 2.4094 2.4047 2.3941 2.4074 2.4229 2.4105 2.4020 2.3966 2.4152 2.4305 2.4138 2.4118 2.401 2.4144 2.4243 2.4155 2.4046 m 2.4141 2.4270 2.4171 2.4043 2.4054 2.4157 2.4335 2.4191 2.4046 2.3974 2.4108
5.5 13.5 21.2 30 49 4.9 11.3 35.5 35 30 6.7 21.8 29.7 35 47 4.4 9.1 12.5 18 19 0.94 1.5 2.9 4 8 1.38 4.4 6.0 9 26 1.16 1.9 5.9 8 4 4.8 9.3 11.7 14 37 2.5 9.3 13.4 28 18 2.1 1.9 3.4 6 5
jE
(11) Nedstrand
59.33
5.70
(12) Kvitingen
60.45
5.86
(13) Haukeland
60.83
5.58
(14) Va˚gsøy
61.98
5.17
(15) Ka˚rvatn
62.78
8.85
(16) Momyr
64.08
10.52
(17) Muru
64.47
14.12
(18) Vassvatnet
66.40
13.18
(19) Moskenes
67.92
13.05
(20) Øverbygd
69.00
18.95
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Table 1 (continued) Location
Coordinates (decimal) jN
jE
(21) Karasjok
69.45
25.78
(22) Gamvik
71.07
28.23
Year
206/204
206/207
208/207
Pb Ag/g
2000 1995 1990 1985 1977 2000 1995 1990 1985 1977
18.038 17.891 17.783 17.629 17.773 17.915 17.902 17.881 17.698 17.899
1.1569 1.1495 1.1436 1.1329 1.1452 1.1520 1.1495 1.1491 1.1373 1.1487
2.4357 2.4180 2.4132 2.4042 2.4165 2.4274 2.4259 2.4236 2.4087 2.4235
0.87 1.4 2.6 6 5 1.45 2.7 7.2 3 5
m = missing value.
extension of that work to 22 different sites covering the entire mainland of Norway and including samples from year 2000 in addition to the four previous years of sampling.
2. Materials and methods Samples of the feather moss Hylocomium splendens from 22 sites in different parts of Norway, respectively, in 1977, 1985, 1990, 1995, and 2000 were investigated in the present work. The samples had been collected as part of a national program monitoring the deposition of pollutants from longrange atmospheric transport, and the parts of the moss plant representing the incremental growth during the last 3 years preceding the year of collection were taken for analysis. The locations of the 22 sites are shown on the map in Fig. 1, and their geographical coordinates are listed in Table 1. All selected sites are located in relatively remote areas far from towns or other significant sources of air pollution. Moss samples of about 0.2 g were decomposed in a low-temperature plasma asher. The residue was dissolved in a few drops of concentrated HNO3. After evaporating the solution to dryness, the residue was dissolved in 0.2 ml 3 M HNO3 before chromatographic separation of Pb according to a modification of the method described by Horwitz et al. (1992, 1994). The sample solution was fed on a column packed with a crown ether resin. After removing most other elements by washing with 3 M HNO3, Pb was eluted with dilute ammonium carbonate solution. The analyses were performed on a Finnigan MAT 261 mass spectrometer
using single rhenium filaments and the total Pb blank was < 100 pg. Before loading the sample, 2 Al of silica gel (Merck) was evaporated to dryness on the filament at a current of 1 A. The sample was dissolved in 1 Al of 10% H3PO4, loaded onto the silica gel, and evaporated to dryness at 1 A. The current was then raised to 1.5 A for 1 min and subsequently to 2.0– 2.1 A followed by a swift raise to red glow. The turret was loaded with 12 samples and 1 NBS 981 Pb standard. Filament current during analyses varied between 1.6 and 1.8 A. Data collection was made in 10 blocks of 10 measurements. The Pb isotopic ratios were corrected for mass fractionation by repeated analyses of the NBS 981 Pb standard, which showed a reproducibility of 206Pb/ 204 Pb = 0.16%, 206 Pb/ 207 Pb = 0.06%, and 208 Pb/ 206 Pb = 0.16% at the 2s level.
3. Results and discussion Results from the lead isotope analyses, expressed by the ratios 206Pb/207Pb, 208Pb/207Pb, and 206Pb/ 204 Pb, are listed in Table 1, along with the corresponding Pb concentrations from previous analyses by electrothermal AAS (1977, 1985) or ICP-MS (1990 – 2000). Since much of the Pb isotope data for environmental samples in the literature are presented as 206Pb/207Pb, the subsequent discussion will be based on this ratio in order to make the comparison with the previous data easier. The trends apparent from the preliminary report on Norwegian mosses (Rosman et al., 1998) based on seven sites are confirmed and fortified by the present results. In general, the 206Pb/207Pb ratio drops from
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1977 to 1985 and then turns gradually to higher values during the period 1990 – 2000. The regional differences in 206Pb/207Pb however are considerable at any time, with the lowest values observed in the southwest. In order to facilitate a more detailed discussion, isopleths of the 206Pb/207Pb ratio were constructed for each of the sampling years 1977 (Fig. 2), 1985 (Fig. 3), 1990 (Fig. 4), 1995 (Fig. 5), and 2000 (Fig. 6). These dates represent the year of collection. Since the moss samples were collected in a way to represent the incremental growth during the three preceding years, the representative years for comparison with literature data (with
Fig. 2. Geographical variation of
206
the exception of Scottish moss samples) may be 1975, 1983, 1988, 1993, and 1998, respectively. Previous knowledge on contributions from different source regions to the lead deposition in Norway at different sites and times is very limited. Some evidence is available from the Birkenes station in southernmost Norway, about 40 km southwest of the present site 7, where lead and other trace elements were studied in diurnal aerosol samples collected during 1978– 1979 and 1985 – 1986 (Amundsen et al., 1992) and the corresponding air trajectories assigned to eight sectors representing different source regions. The predomi-
Pb/207Pb ratio in moss samples collected in 1977.
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Fig. 3. Geographical variation of
111
206
Pb/207Pb ratio in moss samples collected in 1985.
nant contributions came from the sectors covering the European mainland and UK. Contributions to the integrated amount of lead from the sectors covering Norwegian territory were only 11.7% and 11.8%, respectively, for the two periods (not including trajectories that could not be assigned to any particular sector). Corresponding data do not exist for other relevant sites in Norway, but since all sampling sites were quite remote from densely populated areas, it may be assumed that the contribution of lead from domestic sources did not play a major role at any site. Since long-range atmospheric transport from source regions elsewhere in Europe is the main source
of lead deposition in Norway, it seems appropriate to start the discussion by reviewing literature data for 206 Pb/207Pb in air in different potential source regions over the time period concerned. Data for aerosols as well as from analyses of precipitation and dated ice and peat cores are useful for this purpose. A survey of available literature data is presented in Table 2. The most complete data are from the UK, where relevant data exist for the entire period covered by the Norwegian moss survey. Considering all data, it appears that the 206Pb/207Pb ratio dropped by nearly 2% from the mid 1970s to the early 1980s, stayed low for some years, and then increased again from the late 1980s
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Fig. 4. Geographical variation of
206
Pb/207Pb ratio in moss samples collected in 1990.
due to the gradually increasing use of unleaded petrol after 1986 (Farmer et al., 2000). For the years represented by the Norwegian moss samples, the following approximate values may be estimated from the UK data: 1975, 1.120; 1983, 1.105; 1988, 1.125; 1993, 1.135; 1998; 1.145. This estimation does not consider the peat values from Western Scotland (Weiss et al., 2002), which are systematically higher than the other data by about 1% but show the same temporal trend. For mainland Europe, the data are relatively scarce, and the corresponding estimates are therefore presum-
ably less reliable. For western/central Europe, the 206 Pb/207Pb ratio does not show the same variation as in the UK but seems to have been of the order of 1.13– 1.14 over the entire period 1975 –1993. In some of these countries, the use of unleaded petrol started earlier than in the UK. In the western part of the Soviet Union and possibly other states in eastern Europe, a relatively stable value around 1.155 may be estimated. Leaded gasoline is still used in this part of Europe. Before entering a detailed discussion of the information carried by the present lead isotope data for
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Fig. 5. Geographical variation of
113
206
Pb/207Pb ratio in moss samples collected in 1995.
mosses, some additional pieces of information need to be considered. First, although a strong and consistent decline of lead deposition all over the country is evident from the numbers for total Pb in moss in Table 1, there are distinct geographical differences in these trends, as illustrated in Fig. 7. In the 1977 survey, the observed lead deposition was far higher in the south than elsewhere, particularly in areas near the Skagerrak coast (sites 5, 7, 8, 9), but the deposition there dropped by over a factor of 3 until 1990 followed by a regular but somewhat slower decline through the 1990s. Pre-
cipitation in this region is predominantly supplied by southerly to easterly winds. Turning to the southern part of the west coast (sites 11– 14), the 1977 lead figures were only about 30% of those in the far south, but the level stayed relatively constant until 1990 after which there was a similar decay as in the south. In this area, in particular at sites approximately 20 –50 km from the coast (cf. sites 12– 13), the annual precipitation is about three times higher than at the southern coast, but the prevailing wind direction during precipitation events is south – southwest. From site 14 and
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Fig. 6. Geographical variation of
206
Pb/207Pb ratio in moss samples collected in 2000.
northward, the 1977 values were only 10– 20% of those in the far south, and a regular decline was observed over the whole period. In most of this area, precipitation is supplied mainly by westerly/north – westerly winds from the North Atlantic. Considering all the above information and relating it to the moss 206Pb/207Pb data, the following interpretations may be offered with respect to the most important source regions of lead deposition in Norway at different times: Southern – southeastern region (sites 1 – 9): This region probably received most of its lead in the past from mainland Europe. The rapid decline during the
1970s –1980s is probably to a great extent associated with early introduction of unleaded gasoline in some of the source countries. An influence from UK is also evident in this region, however, with declining 206 Pb/207Pb between 1977 and 1985 and gradually decreasing ratios toward the west at all times. Recently ratios of 1.15 –1.16 are observed in this region, indicating that a greater fraction of the recent lead from long-range transport has its origin in Eastern Europe, including Russia. West coast (sites 10– 14): Ratios here are consistently lower than elsewhere, and follow quite closely the UK trend for airborne lead. In this region, the
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Table 2 206 Pb/207Pb in aerosol and other relevant media in different parts of Europe Country, Site
Sampling medium
Year
206
Reference
UK Perth Scotland
Aerosols Moss
1994 1970 – 1979 1980 – 1989 1990 – 1999 2000 1989 – 1991 1997 – 1998 1985 1985 1971 – 1975 1976 – 1980 1981 – 1985 1986 – 1990 1975 F 2 1981 F 2 1986 F 2 1988 F 2 1991 1998
1.101 1.127(30) 1.120(10) 1.137(16) 1.151(7) 1.120(31) 1.144(145) 1.118(10) 1.108(5) 1.116(2) 1.108(2) 1.098(2) 1.128(2) 1.133 1.129 1.117 1.115 1.133 1.122(6)
Rosman et al., 1998 Farmer et al., 2002
1.132(6) 1.138(7) 1.144(3) 1.156(3) 1.137(4) 1.139(3) 1.137(2) 1.138(5) 1.130(6) 1.112(10) 1.145(6) 1.156(6)
Rosman et al., 2000
1.152(2) 1.160(6) 1.169(4) 1.153(5)
Mukai et al., 2001 Bollho¨fer and Rosman, 2002 Hopper et al., 1991
Rainwater Scotland, rural Lancashire Harpenden
Aerosols Aerosols Herbage
Scotland, western
Peat
Oxford
Aerosols
Western Europe Mont Blanc
Snow/ice
France Germany Netherlands W. Europea Avignon Grenoble Constance Poln
Aerosols Aerosols Aerosols Aerosols Aerosols Aerosols Aerosols Aerosols
1975 – 1977 1981 – 1984 1986 1990 – 1991 1994 1994 1994 1988 1998 1996 – 1998 1998 1998
Eastern Europe Moscow Moscow E. Europea W. USSR
Aerosols Aerosols Aerosols Aerosols
1994 1999 1988 1988
a
Pb/207Pb (number)
Farmer et al., 2000 Farmer et al., 2000 Farmer et al., 2000 Bacon et al., 1996
Weiss et al., 2002
Bollho¨fer and Rosman, 2002
Rosman et al., 1998
Hopper et al., 1991 Bollho¨fer and Rosman, 2002
Aerosols in southern Sweden representing air transport from the respective sectors.
dominant contribution is most probably from the UK, in particular during the 1980s. Central and northern part (sites 15 –20): In this region, the temporal variation is less pronounced than farther south. Ratios around 1.14 are typical, and the main source region is probably the North Atlantic, where even sources in North America, which have relatively high 206Pb/207Pb values, may have contributed in addition to the European ones (Rosman et al.,
1998). The UK-associated decline in 1985 however is also seen in most of this region, but less distinctly than farther south. Recent development towards values of 1.15 and above may indicate some Russian/Eastern European influence as well. Far north-eastern sites (21 – 22): Here the level stays quite stable at 1.14 – 1.15 during the entire period, with the exception of a drop in 1985. In this area, the relative importance of Russia/Eastern Europe
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Fig. 7. Time trends in atmospheric deposition of lead in three different parts of Norway as reflected by moss samples (Ag Pb/g moss). Years shown are the years of sampling.
is obviously greater than in areas farther south, at least until 1995. Since local soil dust is invariably a problem in the interpretation of data from moss surveys (Steinnes, 1995), contribution to the present data from local mineral soil particles should also be considered. The knowledge on lead isotope ratios in Norwegian bedrock is limited in general. In a recent study of stable lead isotopes in podzolic soil profiles from different parts of Norway, however, 206Pb/207Pb ratios within the range 1.20 –1.73 were observed in the C-horizon (Steinnes et al., unpublished). Thus, it seems that none of the moss data discussed in this work were appreciably influenced from the geochemical background at the sampling site.
Acknowledgements This work was supported by a grant from the Research Council of Norway.
References Amundsen CE, Hanssen JE, Semb A, Steinnes E. Long-range atmospheric transport to southern Norway. Atmos Environ 1992; 26A:1309 – 24. Bacon JR, Jones KC, McGrath SP, Johnston AE. Isotopic character of lead deposited from the atmosphere at a grassland site in the United Kingdom since 1860. Environ Sci Technol 1996;30: 2511 – 8.
Berg T, Steinnes E. Recent trends in atmospheric deposition of trace elements in Norway as evident from the 1995 moss survey. Sci Total Environ 1997;208:197 – 206. Berg T, Røyset O, Steinnes E, Vadset M. Atmospheric trace element deposition: principal component analysis of ICP-MS data from moss samples. Environ Pollut 1995;88:67 – 77. Bollho¨fer A, Rosman KJR. The temporal stability in lead isotopic signatures at selected sites in the Southern and Northern Hemispheres. Geochim Cosmochim Acta 2002;66:1375 – 86. Dunlap CE, Steinnes E, Flegal AR. A synthesis of lead isotopes in two millennia of European air. Earth Planet Sci Lett 1999;167: 81 – 8. Farmer JG, Eades LJ, Graham MC, Bacon JR. The changing nature of the 206Pb/207Pb isotopic ratio of lead in rainwater, atmospheric particulates, pine needles and leaded petrol in Scotland, 1982 – 1998. J Environ Monit 2000;2:49 – 57. Farmer JG, Eades LJ, Atkins H, Chamberlain DF. Historical trends in the lead isotopic composition of archival sphagnum mosses from Scotland (1838 – 2000). Environ Sci Technol 2002;36: 152 – 7. Flegal AR, Itoh K, Patterson CC, Wong CS. Vertical profile of lead isotope compositions in the north – east Pacific. Nature 1986; 321:689 – 90. Graney JR, Halliday AN, Keeler GJ, Nriagu JO, Robbins JA, Norton SA. Isotopic record of lead pollution in lake sediments from the northeastern United States. Geochim Cosmochim Acta 1995;59: 1715 – 28. Hanssen JE, Rambæk JP, Semb A, Steinnes E. Atmospheric deposition of trace elements in Norway. In: Drabløs D, Tollan A, editors. Ecological Impact of Acid Precipitation. Norway: ˚ s; 1980. p. 116 – 7. Oslo-A Hopper JF, Ross HB, Sturges WT, Barrie LA. Regional source discrimination of atmospheric aerosols in Europe using the isotopic composition of lead. Tellus 1991;43B:45 – 60. Horwitz EP, Chiarizia R, Dietz ML. A novel strontium selective extraction chromatographical resin. Solv Extr Ion Exch 1992; 10:313 – 36. Horwitz EP, Dietz ML, Rhoads S, Felinto C, Gale NH, Houghton J. A lead selective extraction chromatographical resin and its application to the isolation of lead from geological samples. Anal Chim Acta 1994;292:263 – 73. Maring H, Settle DM, Buat-Me´nard P, Dulac F, Patterson CC. Stable lead isotope tracers of air mass trajectories in the Mediterranean region. Nature 1987;300:154 – 6. Mukai H, Machida T, Tanaka A, Yelpatievskiy PV, Uematsu M. Lead isotope ratios in the urban air of eastern and central Russia. Atmos Environ 2001;35:2783 – 93. Rosman KJR, Chisholm W, Boutron CF, Candelone JP, Hong S. Isotopic evidence for the source of lead in Greenland snows since the late 1960s. Nature 1993;362:333 – 5. Rosman KJR, Ly C, Steinnes E. Spatial and temporal variation in isotopic composition of atmospheric lead in Norwegian moss. Environ Sci Technol 1998;32:2542 – 6. Rosman KJR, Ly C, Van de Velde K, Boutron C. A two century record of lead isotopes in high altitude Alpine snow and ice. Earth Planet Sci Lett 2000;176:413 – 24. Smith DR, Niemeyer S, Estes JA, Flegal AR. Stable lead isotopes
E. Steinnes et al. / Science of the Total Environment 336 (2005) 105–117 evidence of anthropogenic contamination in Alaskan sea otters. Environ Sci Technol 1990;1517 – 21. Steinnes E. Atmospheric deposition of heavy metals in Norway studied by analysis of moss samples using neutron activation analysis and atomic absorption spectrometry. J Radioanal Chem 1980;58:387 – 91. Steinnes E. A critical evaluation of the use of naturally growing moss to monitor the deposition of atmospheric metals. Sci Total Environ 1995;160/161:243 – 9. Steinnes E. Metal contamination of the natural environment in Norway from long range atmospheric transport. Water Air Soil Pollut., Focus 2001;1:449 – 60. Steinnes E, Solberg W, Petersen HM, Wren CD. Heavy metal pollution by long range transport in natural soils of southern Norway. Water Air Soil Pollut 1989;45:207 – 18. Steinnes E, Rambæk JP, Hanssen JE. Large-scale multi-element survey of atmospheric deposition using naturally growing moss as biomonitor. Chemosphere 1992;35:735 – 52.
117
Steinnes E, Hanssen JE, Rambæk JP, Vogt NB. Atmospheric deposition of trace elements in Norway: temporal and spatial trends studied by moss analysis. Water Air Soil Pollut 1994; 74:121 – 40. Steinnes E, Allen RO, Rambæk JP, Petersen HM, Varskog P. Atmospheric deposition of trace elements in Norway: temporal and spatial trends studied by moss analysis. Sci Total Environ 1997;205:255 – 66. Steinnes E, Berg T, Sjøbakk TE, Uggerud H, Vadset M. Atmospheric deposition of heavy metals in Norway. Nation-wide survey in 2000. State Program for Pollution Monitoring, Report 838/01. Oslo: Norwegian State Pollution Control Authority; 2001. p. 1 – 28. In Norwegian. Weiss D, Shotyk W, Boyle EA, Kramers JD, Appleby PG, Cheburkin AK. Comparative study of the temporal evolution of atmospheric lead deposition in Scotland and eastern Canada using blanket peat bogs. Sci Total Environ 2002; 292:7 – 18.