CURRENT RESEARCH Environmental Trace Metal Contamination in Kellogg, Idaho, near a Lead Smelting Complex R. C. Ragaini”, H. R. Ralston, and N. Roberts Lawrence Livermore Laboratory, University of California, Livermore, Calif. 94550 ~~
Soil cores, grasses, and ambient air aerosols were sampled in the vicinity of a P b smelting complex in Kellogg, Idaho. Of 34 elements analyzed by instrumental neutron activation and x-ray fluorescence, Cd, Sb, Ag, Pb, Au, Zn, Se, As, In, Ni, Cu, and Hg were the most highly enriched, ranging in surface soils up to 7900 ppm Pb, 29 000 ppm Zn, and 140 ppm Cd. For grasses, P b ranged up to 10 000 ppm, Zn to 12 000 ppm, and Cd to 4400 ppm. Aerosol enrichments above contributions from local resuspended soils were 4100 for Cd, 180 for As, 110 for Pb, and 60 for Zn. These soil profiles, grass analyses, and aerosol enrichments indicate that other toxic elements, Cd, Se, As, Ni, and Hg, in addition to Pb, have significantly contaminated the Kellogg environment as a result of the smelting operations. State air pollution control agencies are increasingly concerned with the environmental impact of trace metals since, in aerosols, they are an inhalation hazard to man and animals and a stress hazard to plants. Trace metals can also function as catalysts in secondary transformation of atmospheric pollutants, e.g., in converting SO2 emissions into hazardous sulfates and sulfuric acid aerosols. Trace metals are introduced to the environment from a variety of sources: industrial emissions, fuel combustion, incineration, and transportation. In this paper we report the results of a study carried out at a mining and smelting site in Kellogg, Idaho. In 1974 it was reported ( I , 2) that two Kellogg preschool children were treated for P b poisoning and that 90% of the children subsequently tested showed abnormally high levels of P b in their blood. In 1976 the Shoshone Lead Health Project acknowledged that the center of abnormally high P b concentrations in the Valley is the smelting complex. Although leaching and wind blown dusts from tailings piles still constitute an active source, the largest active source of contamination is airborne emissions from the smelting complex ( 3 ) .However, the report did point out that the relative health significance of current emissions and previously deposited P b has not yet been established ( 3 ) .Furthermore, emissions, depositions, and effects of other toxic elements were not systematically studied. We carried out multielement analyses of thirty 24-h highvolume (Hi-Vol) air particulate filters collected over a 12month period in downtown Kellogg. T o measure the soil concentrations and to evaluate the contribution of windblown soil and tailings to local aerosols, we took soil cores along with grass samples at 12 sites, and tailings and sinter samples a t three sites. Our results constitute the most comprehensive multielement aerosol, soil, and grass analysis for Kellogg, Idaho, published to date. Further analyses of soil and vegetation should provide the necessary data base for determining the levels and rates of heavy metal deposition. These data could
be used in an assessment of the resultant biological dose to man of toxic elements other than lead and, as such, are especially important because the synergistic effects of heavy metal aerosol exposure on humans in Kellogg have not yet been addressed. Preliminary results of our analyses have been presented previously (4-7). Area Description. Kellogg, Idaho (Figure l),is located in the heart of the nation’s largest and richest mining district in the Coeur d’Alene River Basin in the panhandle region of northern Idaho. It has been the site of a heavy metals mining, smelting, and refining industry for the.past 88 years. Lead, Zn, and Ag are the principal marketed metals, along with considerable quantities of Cd, Sb, and sulfuric acid. Located in the smelter complex in Kellogg are a concentrator, P b smelter, electrolytic Zn plant, phosphoric acid/fertilizer plant, and sulfuric acid plant. The P b smelter has been in operation since 1916, and the Zn plant since 1926. The operation employs about 2300 out of a population of 3900 in Kellogg. The geomorphology of the valley is one of high, steep mountains (up to 6300 ft) enclosing a narrow y!- to Yz-rnilewide valley at an elevation of 2200 ft. The valley extends 6 miles in an east-west direction following the Coeur d’Alene River. The valley floor is filled in with river alluvium that may reach several hundred feet deep. Mine tailings and slag wastes that were discharged directly into the river before 1968 have formed a layer of silt over much of the valley floor downstream from the mining operations. These tailings have been used as land fill in various parts of the valley. The valley rocks are primarily from the Precambrian Belt, fine-grained argillites and quartzites. The winds aloft follow a prevailing west-to-east pattern in the summer, switching over to an east-to-west pattern in the winter. A diurnal pattern for the ground-level winds is structured on top of the seasonal prevailing winds: westerly morning winds gradually becoming northerly and finally easterly in the evening. Inversion conditions occur frequently in the fall. Smelting Process. The principal source of heavy metal aerosols in the ambient air is the main stack of the P b smelter s-.
-
~
R.R. Coeur d ’ A l e n e River T a i l i n g s ponds 1 . 5 . 95 S a i l sampling s i t e s
t 4
Zinc p i a n t
‘
1mi
Figure 1. Map of Kellogg Valley showing sampling locations Volume 11, Number 8, August 1977
773
(3).Average emissions of P b from the main smelter stack were estimated to have been 8.3 metric tons per month from 1955 through 1964 and 11.7 metric tons per month from 1965 through 1973 (3).There are a number of steps in the smelting process that could also serve as sources of fugitive emissions. After the crude ores, principally PbS and ZnS, are crushed, screened, and blended, they are pulverized and dumped into flotation cells along with reagents. The Pb-bearing minerals are skimmed off as a froth. The other reagents are added, and Zn-bearing minerals are likewise separated. The slurries are then dried, becoming concentrates that are mixed with crude ores and fluxes, and pelletized. These mixtures are roasted to remove S, creating sinter, which is fired along with coke in the lead smelter, forming P b bullion and waste slag. Lead bullion carries along Cu, Au, As, Sb, and Bi. Zinc is then separated from the slag in a slag fuming furnace. Later the Cu, As, Sb, Ag, and Au are refined. The blast furnace and refinery area gases containing the metal oxides are conveyed via a flue to a baghouse where 2800 1.5 X 30 ft bags filter the dust. The collected dust is then treated to remove Cd and other metals. The Zn concentrates are refined in the electrolytic Zn plant. The SO1 flue gases are captured in HzS04units that are used in a H3P04 and (NH4)3P04 fertilizer plant. Other sources of metals related to the smelting operation include spills of concentrate from ore trains and trucks, resuspended dust from tailings and sinter piles, and leaching of tailings piles.
Sampling and Analysis Sampling Procedures. Air particulate samples were collected on top of the Kellogg City Hall by personnel from the
Idaho Department of Public Health at approximately 8-day intervals from January 29 to December 18, 1972. Whatman 4 filters were used with a recording flow meter and a 20 cfm pump running for 24 h per sample, generally from 3:OO p.m. to 3:OO p.m. Mass loadings as determined by the Idaho Department of Public Health ranged from 60 to 251 pg/m3, as shown in Table I. Soil cores (26 cm) were taken by driving a steel cylindrical corer, containing an interchangeable plastic liner, into the soil. Upon removal the liner was capped to protect the core. Three core increments were analyzed: 0-2,lO-12, and 20-22 cm. The cores were air dried, and 50-g samples were ground to less than 200 mesh. Triplicate samples were analyzed; 25 mg were used for a short neutron irradiation and 200 mg were used for a long irradiation. The grass samples were taken at the same locations as the soil cores. The grass samples were analyzed without washing to include the surface-deposited dust in the analysis. They were dried at 60 OC in a forced air oven and then ground. Neutron Activation Analysis. Analyses of the trace elements of interest were performed with instrumental neutron activation analysis (INAA) and x-ray fluorescence analysis (XRFA).The INAA was performed by irradiating the samples in the 3-MW Livermore Pool-Type reactor (LPTR). Table I1 shows the irradiation and counting procedure that was followed. For the 2-min irradiations, Ti flux monitors were irradiated simultaneously with the samples in precleaned polyethylene vials and counted later. The flux monitors had been previously irradiated along with elemental standards for calibration. The elemental concentrations in the sample were calculated by
Table 1. Collection Data for Hi-Vol Samples Taken in Kellogg, Idaho
774
Sample no.
Collection date
Total aitiiow, m3
Paltlculate wt, mg
Concn in air, fig/m3
% Day wind from west
2 3 4 5 8 9 10 11 12 13 14 15 16 18 20 21 27 28 30 31 33 34 36 38 39 40 41 42 43 44
01-29 01-31 02-07 02-15 03-16 03-24 04-03 04- 13 04-24 05-05 05-1 1 05-19 05-30 06-19 07-06 07-13 08-15 08-2 1 09-1 1 09-17 10-0 1 10-05 10-24 11-03 11-14 11-24 12-04 12-06 12-13 12-18
1269 1390 J 129 1190 1220 1423 1256 1403 1395 1330 1354 1280 1403 1618 1656 958 1585 1654 1657 1419 1283 1240 1181 1353 1160 1484 1450 1635 1192 1319
159.5 135.1 133.6 114.4 235.5 128.5 244.5 218.9 230.7 155.2 241.1 198.0 267.4 261.7 235.7 216.3 223.8 199.6 198.5 255.0 260.3 203.2 300.2 122.7 250.6 189.7 86.4 109.2 199.8 158.5
125.7 97.2 118.3 96.1 193.1 90.3 194.6 156.0 165.4 116.7 178.1 154.7 190.6 161.7 142.3 225.7 141.2 120.7 119.8 179.7 202.9 163.9 254.2 90.7 216.1 127.8 59.6 66.8 167.6 120.2
...
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Environmental Science & Technology
... 20 20 70 75 90 80 60 30 90 30 20
50 80 100 70 50 60 90 70 65 30 80 55 90 0 0 80 80
comparison with the elemental standard normalized by the ratio of the Ti monitor's activation. For the 12-h irradiations elemental standards were irradiated simultaneously with the samples in rotating polyethylene containers and counted later. Triple-distilled water and specpure or reagent grade chemicals were used in the preparation of the elemental standards. A 45-cm3 Ge(Li) detector with a resolution (full width a t half maximum) of 2.3 keV for the 1332-keV y-ray detection was used for the y-ray spectroscopy. The spectral data were accumulated in a 4096-channel pulse height analyzer, recorded on computer-compatible magnetic tape, and reduced using peak analysis computer codes (8).The accuracy and precision of the INAA system at Lawrence Livermore Laboratory (LLL) have been verified by analysis of National Bureau of Standards Reference Materials and by participation in interlaboratory comparison studies (9). X-ray Fluorescence Analysis. The XRFA system consisted of an 80-mm2 Si(Li) detector with a resolution of 190 eV for the 5.90-keV x-ray line from 55Fe. Fluorescence spectra were obtained with a lo9Cdring source as the exciter in a 180' geometry. Spectra were taken in 1000-s exposures and were stored in a 1024-channel block in a minicomputer. Calibration techniques, data reduction, and standardizations have been previously described (10). The XRFA system was used to analyze for Fe, Cu, Zn, Br, Sr, and P b in the Hi-Vol filters and for P b in the soils and grass samples. The filter samples actually analyzed were 29-mm-diam discs cut out of the 8 X 10 in. high-volume filters. Homogeneous deposition on the filters was verified by repeatedly analyzing replicate discs cut from the same filter. A series of 40 soil samples was prepared for XRFA by fusion with nine parts lithium metaborate to one part soil in a Pt-Au alloy crucible at about 900 "C. The fusion melt was cooled, weighed, reheated, and cast into 1-in.-diam preweighed A1 rings, giving a glass-like disc about 1.4 mm thick. Standards for comparison were prepared by adding known weights of PbO to high-purity Si02, preparing 9:l fusion mixtures, and casting standard discs. A blank was prepared with Si02. Iron, Cu, Zn, and Br were determined in the aerosols by both INAA and XRFA and provided an internal check on our analyses. The agreement between the INAA and XFRA filter data is shown by linear correlation coefficients for Cu, Br, Fe, and Zn of 0.98,0.96,0.93, and 0.97, respectively.
Results Soils. Figure 1 shows the soil sampling locations in the study. Table I11 lists the designations and locations of the sites. Sites 4, 8, and 10 are listed as other sites because they do not fit the designations of representative valley site or background site. Site 4 (Kellogg Cemetery) is located on a hill overlooking the valley and is subject to quite different wind conditions and fallout patterns. Sites 8 and 10 are located in the town of Wallace and near the Sunshine Mine, respectively. The trace metal soil concentrations at these sites were appreciably higher than those at the background sites (#7, #9), indicating they were exposed to different sources and unsuitable in our scheme. Sites 13-15 were the existing dumping locations. Two surface samples were taken from each of these three sites; core samples were taken from sites 1-12. Table IV shows the surface (0-2 cm) soil concentrations of the most enriched elements Cd, Sb, Ag, Pb, Au, Zn, Se, and As. The P b data agree with the analyses in ref. 3. The surface concentrations of the tailings (and sinter) piles (sites 13-15) are included for comparison. The surface layer metal concentrations are highest at the sampling sites closest to the smelter, Nos. 11, 12, and 2. In general, the elemental concentrations in the tailings are in the same range as those in the surface soil fraction. This
Table II. Neutron Irradiation and Sample Counting Schedule for This Study Irradla- Neutron Countflux tlon Cooling Ing time n/cml-s time time
2 min
2X 1013
4 min 500
Elements detected
AI, V, Cu, Ti, Ca
S
20 min 1000 Na, Mg, CI, Mn, Br, I, Ba, In S
12h
4X
lo'*
20-30 h 6-10 days 20-30 days
2000 As,W,Ga,K,Cd S
100 min 8-12 h
Sm, Au, Hg, La, Sb Fe, Cr, Co, Zn, Hg, Se, Ag, Sb, Ce, Eu, Sc, Th, Ni, Ta, Hf, Ba, Rb
Table 111. Kellogg Valley Soil/Vegetation Sample Site Designations Distance from smelter, miles
7.8 E
No. 7
w
No. 9
3.3
Background sites Osburn Pinehurst Representative Valley sites
1.5 E
No. 1
Cor. Railroad and Hill Streets
0.7 E
No. 2
West Ridge Road
2.0 E
No. 3
Cor. 3rd and Gold Streets
2.0 E
No. 5
Chestnut St.
1.8 E
No. 6
Kellogg Medical Center
0.27 W
No. 11
Silver King School
0.66 W
No. 12
Smelterville Park Contaminated Valley sites
0.7 E
No. 2
West Ridge Road
2.0 E
No. 3
Cor. 3rd and Gold Streets
1.8 E
No. 6
Kellogg Medical Center
0.27 W
No. 11
Silver King School Other sites
2.3 E
No. 4
Kellogg Cemetery
11.8 E
No. 8
Wallace
No. 10
Big Creek
5.0 E
Tailings sites No. 13
Sinter pile
No. 14
Smelterville tailings pond
No. 15
Kellogg tailings pond
agreement makes it difficult to distinguish them as separate sources. The maximum concentrations of the enriched elements do not occur at the same site: however, four valley sites, nos. 2,3,6, and 11,can be classified as the most contaminated. Sites 2,3, and 11were vacant lots; site 6 was a grassy lawn. T o compare our data to soil data at other locations and to intercompare our soil, tailings, and filter data, we have calculated enrichment factors relative to average crustal abundances. The enrichment factor (EFi)for a given element of a single site (i) is expressed as follows: EFi = Ri (Site)/R (Earth's crust) Volume 11, Number 8, August 1977
(1) 775
Table IV. Kellogg Valley Trace Element Concentrations in Surface Soils (0-2 cm) (ppm) a Sitea
Distance from smelter, miles
1.5 0.7 2.0 2.3 2.0 1.8 7.8 11.8 3.3 5.0 0.27 0.66
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 a
Cd
Sb
Ag
Pb
Au
Zn
...
32 150 260 28 72 104 20 40 18 20 155 5 52 70 79
6.0 25 31 2.7 14 24 3.7 10 2.8 3.6 30 9.3 3.2 13 24
1700 7600 6700 2000 170 5300 890 2200 1000 300 7900 3200 290 3700 7900
0.07 0.37 0.22
970 4 300 1400 200 2 600 5 700 804 3 000 940 320 13 000 870 29 000 3 200 7 500
140 32
... 65 82
... ... 18
... a3 25
... 26 37
... 0.47 0.25
... ... 0.06
... 0.23 0.12
... 0.12 0.24
Se
... 6.7 5.1
... 3.4 1.6
... ...
... ... 4.6 0.76 5.5
... 0.75
AS
69 93 94 24 44 110 24 37 36 53 100 49 18 210 260
See Figure 1 and Table Ill for sampling locations.
Table"' Mean Surface 'Oil Concentrationsat Seven Kellogg Valley Sites: Enriched Elements Element
Cd
Sb Ag Pb Au Zn
Se As
w In Ni
cu I Br Hg
Crustal (Wedepohl), ppm
Concn,a PPm
70.9f 41.0 1 1 1 f 86 20.0 f 10.2 4640 f 3030 0.25f 0.14 4160 f 440 3.69 f 2.23 80.3f 26.3 90.0f 44.8 2.05 f 1.33 1200 f 670 278 f io8 4.9 f 0.3 16.6f 9.3 0.112 f 0.093
0.1 0.2 0.06 15 0.004 60 0.09 1.7 1.3 0.07 44 30 0.5 2.9 0.03
EFw
1540 1150 680 560 160 130 100 86 86 70 39 24 16 13 9.3
Contamlbkgd
5.6 13.0 11.0 9.4 5.2 8.5 8.5 4.1 2.6 12.0
... >1.5 >0.68 >0.74 13.0
a Mean values of concentrations at sites 1-3. 5, 6, 11, and 12. Ratio of average surface concentrationsat contaminatedsites 2,3,6, and 11to average background sites 7 and 9.
where R is the ratio of the concentration of a given element to that of Sc. If one calls Ri the elemental ratio, then the average element ratio R over all valley sites is: 1 ni when n is the number of sites. We redefine the average valley soil enrichment factor (EF,) as: R EF, = (3)
R=-CRi
R,
where R, is the ratio of the element to Sc for crustal rock using the values of Wedepohl ( 2 1 ) . Elemental enrichment factors are used for analysis because absolute concentrations are affected by winds, precipitation, inversions, etc. Ratioing absolute elemental concentrations to another single element removes variations caused by particulate loading changes. A second normalization to soil 776
Environmental Science & Technology
abundances allows the determination of the relative amounts of soil particulate and nonsoil particulate loadings on the air filters. We selected Sc as the normalizer element because it is detected with high accuracy and precision and because the only reasonable source of Sc was the soil. Other studies have normalized to A1 (12). Since A1 might possibly be emitted from the smelter operations, however, we chose Sc as a better soil indicator element. Table V contains the mean surface-soil concentrations of those elements having EF, values greater than 10. The elemental data from sites 1-3,5,6,11, and 12 were averaged to represent valley soil. The variations represent one standard deviation from the mean values. Elements with EF > 10 were arbitrarily considered enriched relative to crustal abundances; those with EF < 10 as nonenriched elements. Table VI shows similar data for nonenriched elements. The scandium EF, is by definition, unity. The cutoff between enriched and nonenriched elements is arbitrary; however, elements with EF < 10 appear nonenriched on the aerosols, as discussed below. An additional indicator of contamination is the surface-soil concentrations at the valley sites compared to those at the background sites. The ratio contamhkgd in Tables V and VI are ratios of the averages of the elemental surface-soil concentrations at the most contaminated valley sites 2,3,6, and 11to the average of the nonvalley background sites 7 and 9. All of the calculated ratios are greater than four for the enriched metals with the exception of W (2.6), whereas all the nonenriched elements have ratios less than four. The rare earths have EF, values and contamhkgd values near one, as expected. Since a high enrichment or a high contamhkgd factor does not necessarily prove an unnatural source of an element, it is worthwhile to examine the soil profiles of the elements. Figure 2 shows some typical profiles of selected elements taken at sites 2,3,9, and 12. Sites 2 and 3, vacant lots, are contaminated valley sites. Site 12, a valley site, is a grassy lawn area and appears to have been disturbed in some fashion. Site 9 is a background site. At sites 2 , 3 , and 9 the enriched elements Pb, As, Ag, Sb, Br, Hg, Cd, In, Se, Ni, and Au show a sharp decrease with depth. The only enriched metal element that shows a zero slope is W . The high EF, indicates a concentration higher than Wedepohl's, but the zero slope and the low contamhkgd ratio (2.6)
Table VI. Mean Surface Soil Concentrations at Seven Kellogg Valley Sites: Nonenriched Elements Element
5.37 f 2.82% 10.1 f 3.7 2090 f 2881 20.7 f 21.4 21.7 f 8.5 4.57 f 3.17% 5.93 f 2.35 62.8 f 23.9 213 f 133 504 f 204 1.16 f 0.47 8.57 f 3.58 31.9 f 4.5 44.6 f 22.0 8.14 f 2.81 1.52 f 0.41 % 2.49 f 0.96 1.34 f 1.56% 43.8 f 7.5 3.27 f 1.23% 0.544 f 0.249%
Mg Hf Mn co
Ga Fe Sm Ce CI Ba Eu Th La Cr sc K Ti
Ca V AI Na a
Crustal (Wedepohl), ppm
Concn, ppm
1.39% 3.0 690.0 12.0 17.0 3.54% 6.6 75.0 320.0 590.0 1.4 11.0 44.0 70.0 14.0 2.82% 4700.0 2.87% 95.0 7.8% 2.45%
pk
Contam/bkgda
EF,
6.6 5.8 4.9 3.0 2.8 2.1 1.6 1.4 1.4 1.4 1.4 1.4 1.2 1.1 1.0 0.93 0.93 0.79 0.79 0.71 0.38
1.5 0.93 2.9 3.0 1.4 2.1 0.89 0.90 >2.0 0.91 1.1 0.86 0.94 1.3 0.92 0.92 0.97 3.8 1.3 0.79 0.75
Ratio of average surface concentrations at contaminated sites 2, 3, 6, and
11 to average background sites 7 and 9.
S i t e No. 2
Ag
E
S i t e :lo.
3
Table VII. Surface Soil, Tailing, and Sinter Enrichments (EF,) Element
soils
Talllngs
Slnter
Cd
1540 1150 680 560 160 130 100 86 86 70 39 24 16 13
1210 1360 1250 1430 190 370 32 530 41 67
