The chemical and mineralogical behaviour of Pb in shooting range soils from central Sweden

Environmental

Pollution. Vol. 89, NO. 3, pp. 30%3@, 1995 Copyright 0 1995 Elsevier Science Ltd

Printed in Great Britain. All rights resewed. 0269-7491/95/%07.00 0269-7491(94)00068-9

ELSEVIER

THE CHEMICAL IN SHOOTING

AND MINERALOGICAL BEHAVIOUR OF PB RANGE SOILS FROM CENTRAL SWEDEN

Zhixun Lin,” Blake Comet,b Ulf Qvarfort’ & Roger Herbert’ “Environmental Geology, Institute of Earth Sciences, Uppsala University, Norbyvtigen 18B, S-752 36 Uppsala, Sweden ‘8rebro

County Board, Environmental Unit, 701 86 drebro, Sweden

(Received 13 June 1994; accepted 30 August 1994)

1991). Jsrgensen and Willems (1987) reported that the amount of Pb used in shotgun ammunition in Denmark is 800 tons annually, compared with 250 tons of Pb used annually as additives in automobile fuel. Studies of Pb pollution in Finnish shooting ranges show that many tons of lead have been spread from these sources into the environment (Tanskanen et al., 1991; Manninen & Tanskanen, 1993). According to calculations of Mukherjee (1993), in 1990 about 563 tons of Pb was shot in Finland. Hockin (1989) investigated the Pb content in the shooting range soils of Sweden and the United Kingdom. The latest estimate shows that 500-600 tons of Pb are used annually in shotgun ammunition in Sweden (Comet, 1992). The annual flux of Pb-pellets and bullets on the shooting range soils is significant, and has begun to arouse concern regarding the contamination of soils and ground water by lead. The purpose of the present study is to investigate the transformation of Pb-pellets and bullets in the environment of some shooting ranges in Sweden and to evaluate the chemical mobility of Pb in the soils.

Abstract Recently investigations have shown that the annual flux of lead from shotgun pellets to shooting range soils is sig@cant in some countries. This paper presents the data of chemical and mineralogical analyses of soils and Pb-pellet crusts from jiveshooting ranges in Sweden and, based on these results, evaluates the retention of lead in these shooting range soils. In the soils, Pb-pellets and bullets are readily decomposed and transformed to crust materials composed of Pb-bearing minerals. The trans,formation products in the crust materials, identified by X-ray d@iaction, are predominantly hydrocerussite [Pb,(COJ2 (OH),], ussociated with cerussite (PbCO,) and anglesite (PbSO,). In a period of 20-25 years, an average of 4??% metallic lead in the pellets has been transformed to lead carbonate and lead sulphate, where the former is the more stable mineral in the surface environment. However, in soils relatively rich in humus an average of 156% metallic lead in the pellets was transformed to secondary leud compounds in the same period. The results of the chemical analyses indicate that Pb is rather immobile in the soil profile. The surjcial horizon contains higher concentrations of lead (52-3400 mg kg-‘), while lower concentrations of lead were found in the E and B horizons where the total Pb concentrations (8-37 mg kg-‘) are within about one standard deviation of the mean reference sample concentration. An inverse relationship is revealed between the aluminium hydroxide content of the soil fraction and EDTA-extractable Pb, which suggests that these compounds have affected the retention of lead. Keywords: Shooting range soils, hydrocerussite,

SAMPLING LOCATIONS Soil samples containing Pb pellets and bullets were collected from five shooting ranges in Brebro county, central Sweden, during July 1992 (Fig. 1). These shooting ranges are located in Munkatorp, Ingvaldstorp, L&m& Dimbo, and Hbghult. The Haghult site includes both Hiighult and Heghult (B). Shooting practice at these ranges consists primarily of skeet training, where Pb-shot (pellets) is used. However, L&m& Dimbo and Hijghult (B) are rifle-shooting ranges for elk-hunting training where jacketed bullets are used. The bullets consist of a Pb core with a copper-alloy cover. Several pits were dug with a spade at each site. The sampling locations within each soil profile and site are shown in Table 1. In addition to the samples collected from the shooting range soils, reference samples (see columns labelled ‘Reference’ in Table 1) have been collected from each sampling site from an area outside of the shooting range, in an area unaffected by firing activities. Composite soil samples (M06, 109 and H08) were collected from the Munkatorp, Ingvaldstorp, and Hiighult sites, respectively, in order to determine the

angle-

site, lead, soil chemistry. INTRODUCTION Although there are numerous reports of Pb pollution in soils, only a limited number have investigated Pb contamination in shooting range soils. In some countries the use of Pb-containing ammunition, i.e. pellets and bullets, for hunting and sport is a significant source of Pb pollution. A new pellet contains mainly lead (97%), antimony (2%), arsenic (0.5%) and sometimes nickel (0.5%). The metals of jacketed bullets contain lead (90%), copper (9%) and zinc (1%) (Tanskanen et al., 303

304

Z. Lin et al.

Fig. 1. Map showing the locations of the studied shooting ranges.

general mineralogy of the soils. Samples HKOl and LDOl, were collected from Hijghult (B) and L&-m& Dimbo, respectively. In these rifle-shooting ranges, bullets were collected from the man-made butts that are earth mounds mixed with woody sawdust which serve as the shooting targets for elk-hunting training. Therefore, the two samples from the butts cannot be directly compared to samples collected from specific soil horizons, as presented in Table 1. The shooting ranges in this investigation lie on podsol soils. Samples from the Munkatorp site were collected from the 0 horizon (depth interval O-4 cm) and the A horizon (410 cm), where all the Pb pellets were located. The Munkatorp shooting range has been used since 1970, with about 100 000 firings annually (data from 1992). Samples from the Ingvaldstorp site were collected from the 0 horizon (depth interval O-2 cm), A horizon (2-6 cm), E horizon (611 cm) and B horizon (11-51 cm). The Pb pellets were mainly found in the upper part of the A horizon. The site has been used as a

shooting range since 1970, with 10000 firings annually. L&m& Dimbo, where bullets are used, has been a shooting range since 1941, and has about 8000 firings annually (data from 1992). The bullets were collected from man-made shooting butts with no identifiable soil horizons. Samples from Hijghult were collected from both soils and shooting butts. The sampled soil horizons were the 0 horizon (depth interval O-6 cm), A horizon (6-16 cm), E horizon (16-18 cm) and the B horizon (1843 cm). The Pb pellets were found in the 0 horizon and the upper part of the A horizon, which is rich in humus. This shooting range is used from May to October and has about 25000 firings annually. The bullets were collected from shooting butts at another location in Hoghult (hereafter called Hoghult (B)), where about 15 000 firings are reported annually. ANALYTICAL METHODOLOGY In order to separate the pellets and bullets from the

Table 1. Location of sampling locations within the soil profiles

0 A E B C

Organic matter Organo-mineral Eluvial horizon Illuvial horizon Parent material

Ingvaldstorp

Munkatorp

FAO classification Pit 1

Pit 2

Ref

Pit 1

MO1 MO3

MO2

MO4 MO5

101 103 104 IO.5

Haghult

Pit 2

Ref

Pit 1

102

I07 108

HO1 HO3 HO4 HO5

106

Pit 2

Ref

HO2

HO6 HO7

305

Behaviour of Pb in shooting range soils

surrounding soil, each sample was air-dried and separated by dry sieving into three fractions (>2 mm, 2-0.6 mm and ~0.6 mm). After sieving, the Pb pellets and bullets were separated from the soil samples by hand. The Pb pellets were visibly corroded and covered by a crust of white, gray and yellow material. Most of the pellets are about 2-2.5 mm in diameter; a few pellets are smaller indicating that weathering and breakage has reduced their size in the soils. The crust material was removed from the pellets by placing them in distilled water and treating them in an ultrasonic bath at 30 kHz until no further crust material could be removed. The resulting suspension was centrifuged and decanted. The crust materials were dried in an oven at 80°C for XRD analysis. Crust material on the bullets was collected in the same way. Mineralogical identification of the crust materials on pellets and of soil samples was performed by X-ray diffractometric (XRD) analysis using a Philips PW diffractometer. In addition, the clay fraction (~2 pm) from samples MOl, M02, 101, 102, and the composite samples was obtained by sedimentation (Galehouse, 1971) and was then dried by freeze-drying to avoid the problem of shrinkage associated with oven-drying (Bennett & Hulbert, 1986). Random orientation specimens were prepared and continuously scanned in the range 4-70” 28 at a rate of 2” min ‘, using Cu Ka radiation (wavelength 1.5419 A). Quantification of the soil mineral content was performed according to the method described by Chung (1974). The mineral compositions of the crust material from pellets and bullets were semi-quantitatively estimated according to the method of Groff (1973). Chemical analyses were performed on bulk soil samples. The soil pH, total exchangeable acidity (TA) and exchangeable Al in the soils were determined by the following procedure. A suspension of 20 g soil with 100 ml 1 M KC1 was shaken for 2 h, and then filtered. Each clean filtrate was divided into two subsamples and 50 ml of the clean filtrate was titrated with 0.02 M NaOH to pH 8.2. To this solution, 10 ml of 4% NaF was added, then the solution was titrated back to pH 8.2 with 0.02 M HCl. The amounts of NaOH and HCl consumed were calculated for the TA value and exchangeable Al value, respectively. The pH was measured in the other subsample by a pH-82 standard pH meter. Exchangeable K, Na, Ca, Mg and Cu concentrations were determined by shaking 20 g soil with 100 ml 1 M ammonium acetate (pH 48) solution in a 250 ml plastic bottle for 1 h, the suspension was filtered, and analysed with a flameless atomic absorption spectrophotometer. Loss on ignition (LOI) is determined as the sample’s loss of mass after heating the sample at 550°C for 6 h. It is assumed that the organic matter content is directly related to the LOI value. In order to understand the concentrations of Pb bound in various phases, namely, water-soluble, organic matter/adsorption complexes, and solid phases, soil samples were extracted by (i) distilled water, (ii) EDTA, and (iii) aqua regia, respectively. The distilled water extraction removes water-soluble Pb phases from

the soil sample. The suspension with the ratio of 1: 4 (mass : water) was shaken for 1 h. The EDTA solution was used to extract water-soluble Pb compounds, adsorbed Pb, and organically-bound Pb. The EDTA-Pb was determined by extracting 20 g soil with 100 ml 0.02 M EDTA buffered to pH 4.6 by ammonium acetate for 2 h. Lead extracted by hot dissolution in an aqua regia solution is assumed to constitute the total Pb content of the soil sample, including all of the above-mentioned Pb forms plus mineral-bound Pb. All filtrates were analysed by AAS. The ratio of the distilled water plus EDTA-extractable Pb to the total Pb content related to the proportion of the total soil Pb pool distributed within the different fractions. CHEMICAL

AND MINERALOGICAL

RESULTS

Soil

The results of the chemical analyses for the shooting range soils and reference samples are shown in Table 2. The results indicate that there is significant chemical variation in samples from different sites and sampling horizons. In general, the Munkatorp soils are characterized by a high total exchangeable base cation content (BC; i.e. the sum of Ca, Mg, Na and K concentrations), a low total acidity (TA), and a high base saturation (BS) in both the 0 and A horizons. For the Ingvaldstorp and Hoghult soils, where the sampling also included the E and B horizons of the soil profile, there is a marked decrease in base saturation from the 0 horizons (5060%) to the E horizons (0.5-5%), and then an increase in the B horizons. The samples from L&-m& Dimbo and Hiighult (B) were collected from the shooting butts and cannot, therefore, be directly compared to the results from the podzol horizons. However, similar geochemical processes can be expected to be found in both sampling media (e.g. mineral precipitation and adsorption phenomena). The results of the analyses for total Pb in the soils (Table 2) indicate that there is large variation in the data. The Pb concentrations in the 0 and A horizons from the shooting ranges, where most of the Pb pellets were found, ranged from 52 to 3400 mg kg-‘. However, the mean total Pb concentration in these six samples is 618 mg kg ’ with a standard deviation of 1363 mg kg-‘. This large standard deviation is larger than the mean itself, indicating that the number of shooting range samples is too small for statistical calculations. The reference samples from the 0 and A horizons from the same sites ranged in total Pb concentration from 14 to 100 mg kg-‘, with a mean value of 48 mg kg-’ and a standard deviation of 30 mg kg-‘. The Pb in the reference samples may be derived from the weathering of the local bedrock, or from atmospheric deposition. Although average background Pb concentrations in soils derived from granitic bedrock are about 18 mg kg-’ (Cannon et al., 1984). Comet (1992) reports background Pb concentrations in Swedish forest soils to be in the region of 40 mg kg-’ where the Pb is mainly derived from atmospheric deposition.

306

Z. Lin et al. Table 2. Analytical results of chemical analyses

Site

Sampled horizon

LOI PHKCI wd

-

Exchangeable (meq kg-‘) TA

Al

BC

Cu

Pb (mg kg-‘) Total

EDTA-

Water-

EDTA/Total

Munkatorp

MO1 MO3 MO4 MO5

0 A 0 A

8.02 4.01 6.04 2.69

4.02 4.53 4.16 4.05

8.36 2.44 9,56 7.76

1.96 1.03 2.00 4.06

227.43 76.49 30.73 182.66

0.033 0.032 0.028 0,028

96.45 96.91 76.28 95.92

73 52 54 39

17.5 < 0.05 8.95 < 0.05

0.30 n.a. n.a. n.a.

0.24 0.00 0.17 0.00

0 A E B A

6.04 7.34 0.26 0.69 15.38 1.37

3.11 3.03 4.00 4.52 3.47 4.08

17.72 14.96 6.98 10.08 61.82 21.52

6.01 6.64 6.94 8.28 0.00 17.05

17.91 7.41 0.34 3.11 3508 2.36

0.014 0.017 0.011 0.016 0.03 0.011

50.27 33.14 4.66 23.61 36.2 9.88

69 61 8 18 55 14

43.25 33.40 < 0.05 < 0.05 9.80 < 0.05

0.70 n.a. n.a. n.a. na. n.a.

0.63 0.55 0.00 0.00 0.18 0.00

0 A E B 0 A

11.34 2.67 - 0.73 2.01 12.03 2.03

3.43 4.05 4.36 4.55 3.18 4.38

54.26 18.76 12.92 9.68 37.40 14.84

25.2 14.08 11.18 8.06 11.02 12.64

89.56 0.67 0.09 15.27 23.10 0.72

0.022 0.014 0.024 0.016 0.022 0.024

62.27 3.5 0.72 61.21 38.18 4.61

3400 55 18 37 100 26

475 138 35.25 0.50 20.70 < 0.05

0.75 n.a. n.a. n.a. n.a. n.a.

0.14 2.51 1.96 0.01 0.21 0.00

7.35

6.79

2.32

1.42

2.91

55.81

9.0(%)

83(%)

1.70

0.92

1.39

6.95

0.08

0.04

0.99

55.41

350

65.75

0.72

0.19

Ingvaldstorp

101 103 104 105 107 IO8 Hdghult

HO1 HO3 HO4 HO5 HO6 HO7

0

Liinniis Dimbo

LDOI

29.9

Hiighult (B)

HKOl

1,259

Samples in italics are reference samples. n.a. means not analysed. LOI: loss on ignition (o/o);TA: Total acidity (meq kg ‘); BC: sum of exchangeable Ca, Mg, Na, K (meq kg-‘); BS: Base saturation = (BC x lOO)/(BC + TA).

The content of extractable-Pb present in the EDTAPb fraction, and water-soluble fraction is presented in Table 2. In all cases, the EDTA-Pb fraction far exceeds the water-soluble fraction. The water-soluble Pb fraction probably consists of hydrated Pb ions that are loosely adsorbed to mineral surfaces as outer sphere complexes (Sposito, 1989). Since the Pb retained in this fraction is very small in comparison to the EDTA-Pb fraction, it is not considered a significant sink for Pb in soils and will not be discussed further in this paper. The final column of Table 2 refers to the ratio of EDTA-Pb to the total Pb content. According to XRD analytic data, the mineralogy of the bulk composite soil samples are as follows. Munkatorp: quartz, 60%, potassium feldspars, 16%, plagioclase feldspars, 14%, and chlorite, 10%; Ingvaldstorp: quartz, 90%, potassium feldspars, 6%, and plagioclase

feldspars, 4%; Hdghult: quartz, 72%, potassium feldspars, 1O%, plagioclase feldspars, 13%, chlorite, 3%, and hornblende, 2%. The mineral content of the clay fraction (~2 pm) from these shooting ranges is shown in Table 3. In general, the clay fractions contain quartz, potassium feldspars, plagioclase feldspars, muscovite, gibbsite, and the clay minerals chlorite and kaolinite. Smectite in the MO1 sample was identified as a mixed-layer chlorite-smectite, showing a broad 001 reflection on the XRD diagram. While gibbsite in the Munkatorp samples exhibited rather well-defined peaks on the XRD patterns, gibbsite in the Ingvaldstorp samples showed broader and more blurred reflections, indicating a more poorly-ordered crystal structure. Pellet and bullet crust material

The semi-quantitative

estimates of crust material min-

Table 3. Mineral composition of shooting range soils for the grain-size fraction c 2 pm (%) Sample

Quartz

K-feldspars

Munkatorp

MO1 MO2 Comp

Plagioclases

Chlorite

17 27 34

7 15 14

7 14 14

66 38 57

11 21 10

7 15 8

11

5 12 4

62

8

9

10

3

12

Ingvaldstorp

101 102 Comp

6

Hiighult”

Comp

Muscovite

“Hbghult composite sample also contains 1% amphibole.

10 6 10

Kaolinite

Smectite 7

3 3

3 3

Gibbsite 52 35 13

8 8 7 7

307

Behaviour of Pb in shooting range soils

MO2

A--

I

k

MO1

101

HOI

HO2

LDOI

HKOl

Sampling Location 0

Hydrocerussite

Cerussite

H Anglesite

/

Fig. 2. The content of Pb compounds in the crust materials of pellets from different shooting ranges

eralogy are presented in Fig. 2, and examples of the XRD patterns are shown in Fig. 3. According to the XRD analyses, the pellet crust material consists predominantly of hydrocerussite [Pb,(CO,),(OH),], with small amounts of cerussite (PbC03) and anglesite (PbSOJ. The mineral composition of the bullet crust material is mainly hydrocerussite, with small amounts of cerussite and anglesite, as well as feldspars, quartz, kaolinite, muscovite, hematite and copper compounds (probably copper nickel carbonate hydroxide and copper iron oxide). DISCUSSION

AND CONCLUSIONS

Lead is one of the heavy metals causing damage to the environment. A number of sources of Pb contamination to soils have been recognised. Discharges of lead to the soil in the vicinity of a shooting range through shotgun cartridges, although restricted to a small area, presents a potential negative impact on soils. For example, about 135 000 shotgun cartridges, each with 28 g of lead pellets, are fired annually in only three shooting ranges, namely, Munkatorp, Ingvaldstorp and Hiighult. The annual lead load to the soil is around 3780 kg, which is not a small figure if all shooting ranges in Sweden are considered. Under the surficial conditions, pH in the range 3.03455 (Table 2), it is possible that lead is released from pellets and causes high concentrations of lead in the soil. The principal environmental problems with heavy metals are their concentrations in soils and water. The results of this investigation have primarily shown that the flux of lead to soil and water would be effectively controlled by many factors, including soil chemistry, the rate of pellet decomposition, attenuation by adsorption with clays, organic substance and solid phases in the soil. The results of the chemical analyses indicate that Pb in the soil is partitioned primarily in EDTA- and aqua regia-extractable fractions (Table 2). As shown in the last column of the Table 2, the amount of Pb adsorbed to minerals surfaces and organically-bound ranges

between 0 and 92% of the total Pb in the sample. The variation in these data suggests that the retention of Pb is probably site dependent and is determined by a complex combination of the soil pH, organic matter content, soil cation exchange capacity, and soil leaching rate. The results of chemical analyses revealed the enrichment of lead in the uppermost part of the soil profile. The lower concentration of lead in the E and B horizons where the total Pb concentrations (8-37 mg kg-‘) are within about one standard deviation of the mean reference sample concentration, may suggest that the downward movement of lead may be retarded. In addition, the total Pb content in most of the samples from the shooting ranges is within the range of the values found in the reference samples. Only a few of the samples (i.e. HOl, LDOl, HKOl) contained total Pb concentrations significantly above the levels found in the reference samples. This suggests that the weathering products of the Pb pellets may be retained primarily in the weathering crusts by secondary mineral phases. These secondary lead compounds will become a potential source of lead contamination when change in the surficial soil conditions take place. Lead not extracted by the EDTA solution is either specifically adsorbed to surfaces through inner-sphere complexes or present in mineral lattices. The mineralogical analyses of the pellet and bullet crust material show that Pb is at least partially retained in the soils as Pb carbonates and sulphates. In addition, Pickering (1983) suggested that heavy metals, including Pb, could be coprecipitated with Fe and Al oxides (e.g. AI(O FeOOH). One sink for the mineral-bound Pb is gibbsite (Al(OH),), which was detected in several soil samples. As shown in Fig. 4, there is an inverse relationship between the gibbsite content of the soil fraction and EDTA-Pb. Lead either specifically adsorbed to, or coprecipitated with, gibbsite is firmly retained by the soil and is not extractable with EDTA. It is possible that Pb is also precipitated as Pb carbonates and sulphates, as identified in the pellet and bullet crust

308

Z. Lin et al.

masses of metallic Pb in pellets, plus Pb in the crust and extractable Pb in soil. The decomposition of the pellets and bullets is controlled by a complex combination of environmental factors, such as soil pH, organic matter content, soil leaching rate and ligands. It was observed in this investigation that the pellets collected from Hoghult shooting range soils have decomposition ratios of 18-24%, where the soils are relatively rich in organic matter. Comparatively, Munkatorp and Ingvaldstorp shooting range soils have relatively low decomposition ratios (Table 4) and lower organic matter contents (see column headed LOI, Table 2). The mass of crust materials relative to the mass of pellets (‘crust materials’) refers to the degree of transformation of metallic Pb in pellets to Pb minerals. The decomposition of the pellets and bullets has released Pb into the soils; a fraction of the Pb has remained in contact with the pellets and bullets as a weathering crust, and the remaining fraction has entered the soil matrix. The results of the mineralogical analysis of the crusts indicate that anglesite (PbSO& cerussite (PbCO,), and hydrocerussite [Pb,(CO,),(OH),] have formed. The relative distribution of these minerals varies between site and sample, and may be determined by soil pH and the abundance of CO,2- and SO:- ligands. Cerussite formation is apparently favoured over anglesite formation in samples LDOI and HKOl, while anglesite is favoured over cerussite for the remaining samples. Samples LDOl and HKOl have near-neutral pH while the other samples were collected from acidic horizons (pH < 4.5) suggesting a relationship with soil pH. In addition, at pH below 4.3, the dominating carbonate species in soils is carbonic acid (H&O,) and not the carbonate ion (CO,*-). Therefore, while hydrocerussite is still the dominating species in the soils, depletion of the carbonate ligand allows the sulphate ion to compete as a complexing agent. Jorgensen and Willems (1987) reported that cerussite was found in samples with pH 7.4, but only smaller amounts were found in samples having pH 5.5. As shown in Table 2, samples LDOl and HKOl have significantly different levels of EDTA-Pb and exchangeable Cu, while the total bullet mass and sample size of these samples was approximately the same (data not shown). LDOl contains more than 200 times the EDTA-Pb and more than 20 times the Cu than that of HKOl . According to XRD diagrams, LDOl contains a greater content of Pb compounds than HKOl. These compounds, however, are probably not EDTA extractable. Under an optical microscope, it is observed that sample LDOl also contains sawdust fragments, which are not present in sample HKOl. The sawdust has a structure similar to that of charcoal, i.e. having a great number of microcells. Lead and Cu may be retained by these microcells resulting in very high concentrations of exchangeable Cu and EDTA-Pb. In contrast, Pb and Cu compounds may be retained primarily by surface adsorption to soil minerals in sample HKOl. material

Hc

Hc

:

LS

35

25

28

Fig. 3. XRD diffraction diagrams showing the mineral compounds in the crust materials of Pb pellets (Cu Ka, degree 20). Hc: hydrocernssite; An: anglesite; C: cernssite; Q: quartz; F: feldspars.

but these minerals were not detected in the soils by XRD analysis, due possibly to poor crystallinity and low contents.

material,

In the samples collected, Pb is found as metallic Pb in the pellets and bullets, and as Pb minerals in the crust covering the pellets and bullets, and as extractable Pb in the soil. A decomposition ratio can therefore be

defined as the mass of the crust material to the summed

Behaviour

309

of Pb in shooting range soils

60 ??MO1

??MO2

,

0. 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.6

0.9

1

EDTA-Pb/Total Pb

Fig. 4. The relationship

between EDTA-Pb and gibbsite content.

Table 4. Measured mass of Pb in pellets, in crust materials, and in extractable-Pb in soil for each sample. The decomposition ratio is calculated and compared to the percentage of crust materials for each sample Sample

Extractable-Pb in soils (8)

Decomposition ratio’ (%)

Crust materials

(8)

Pb in crust materials (8)

4.01 8.34

0.11 0.39

0.03 0.04

3.45 5.13

2.90 4.80

5.49 4.53

0.24 0.31

0.09 0.19

591 10.57

4.50 6.90

4.01 4.05

0.71 0.54

0.35 0.22

24.25 1844

17.70 13.50

Pb in pellets

(%)

Munkatorp

MO1 MO2 Invaldstorp

101 102 Hoghult

HO1 HO2 “Decomposition

ratio= PL,,

matenaN’bpel~ets + Pbcrust matetial

+

REFERENCES Bennett, R. H. & Hulbert, M. H. (1986). Clay Microstructure. International Human Resources Development Corporation, Boston, USA, pp. 10610. Cannon, H. L., Connally, G. G., Epstein, J. B., Thorton, I. & Wixson, B. G. (1984). Geochemistry and the Environment, Vol. 3. National Academy of Sciences, Washington, D. C., USA, pp. 17-3 1. Chung, F. E. (1974). Quantitative interpretation of X-ray diffraction patterns of mixture: Adiabatic principle of X-ray diffraction analysis of mixture. J. Appl. Cryst., 7, 526-31. Comet, B. (1992). Fdrekomst och Upptradande av bly i Mark vid Skjutbanor i Grebro Kommun. Rapport Dnr 54/92, Miljo-Halsoskydd, City of Orebro (in Swedish). Galehouse, J. S. (1971). Sedimentation analysis. In Procedures in Sedimentary Petrology, ed. R. E. Carver. WileyInterscience, New York, USA, pp. 69-94. Groff, D. W. (1973). Quantitative mineral exploration. Quart. Colorado Sch. Mines, 66, 61-85.

Hockin, D. C. (1989). Spent Shotgun in the Countryside: An Evaluation of the Environmental Conditions of a Number of Clay Pigeon Shooting Schools in the United Kingdom

Pb,,,J.

and Sweden. Final report of stage one studies to British Assoc. for Shooting & Conservation, RPS Environmental Sciences Ltd, UK. Jorgensen, S. S. & Willems, M. (1987). The fate of lead in soils: The transformation of lead pellets in shooting-range soils. Ambio, 16, 11-15. Mam-iinen, S. & Tanskanen, N. (1993). Transfer of lead from shotgun pellets to humus and three plant species in a Finnish shooting range. Arch. Environ. Contam. Toxicol., 24,41614.

Mukherjee, A. B. (1993). The use and the emissions of lead in Finland. In Znt. Conf Heavy Metals in the Environment, 12-16 September 1993, Toronto, Canada. Pickering, W. F. (1983). The role of chemical equilibria in the leaching of metal ions from soil components. In Leaching and Dtzusion in Rocks and their Weathering Products, ed. S. S. Augustithis. Theophrastus Publications, Athens, Greece, pp. 463-504. Sposito, G. (1989). The Chemistry of Soils. Oxford University Press, Oxford, UK, 277 pp. Tanskanen, H., Kukkonen, I. & Kaija, J. (1991). Heavy Metal Pollution in the Environment of a Shooting Range. Geological Survey of Finland, Special Paper 12, pp. 187-93.