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SOIL SURVEY HORIZONS

Vol. 45. No. 3

Articles Trace Element Concentrations of Three Soils in Central Appalachia A. Slagle, J. Skousen, D. Bhumbla, J. Sencindiver, and L. McDonald1 Abstract

Background concentrations of trace elements in soils are important due to recent interest in contamination potential and toxic effect of these elements on humans and the environment.. We assessed the trace element content of three major soil series in Major Land Resource Area (MLRA) 126 of the Appalachian region of the USA by two extraction techniques. Three pedons each of Upshur and Vandalia (both Typic Hapludalfs), and Gilpin (Typic Hapludults) soil series in three distinct areas of this region were described and sampled. Bulk density, texture, pH, cation exchange capacity (CEC), base saturation, and total carbon were determined for each described horizon. For the A, Bt, and C horizons of each soil series, concentrations of ten trace elements (As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Se, Zn) were determined by ICPAES after microwave digestion by USEPA Method 3051 and an HF method. Trace element concentrations using USEPA 3051 were about 1.5 to 5 times lower than the amounts extracted by the HF method, except for Mn. Copper, Mn, and Ni contents were significantly higher in the Alfisols (Upshur and Vandalia) compared to the Ultisol (Gilpin) when extracted by the 3051 method, but only Ni was significantly higher in Alfisols with the HF method. No differences were found among soils for As, Ba, Cd, Cr, Pb, Se, and Zn using either extraction method. Average concentrations (mg/kg) in A horizons of these soils for both Method 3051 and HF digestion were: As below detection limits (BDL), BDL; Ba 120, 255; Cd 1.5, 3.0; Cr 17, 22; Cu 16, 31; Mn 1470, 1360; Ni 11, 19; Pb BDL, 8; Se BDL, BDL; and Zn 65, 87. Based on the HF method, no elements exceeded the cumulative loading rate concentrations allowed by the USEPA 503 regulations. However, Cd concentrations were up to ten times higher in these soils compared with similar soils in nearby areas, and exceeded the Northeastern U.S. Regional Research recommended values for waste material application. Soils vary across the landscape, therefore each soil contains unique trace element concentrations based on its parent material and other soil-forming factors that may have added or removed these elements from the soil. High background concentrations of trace elements, whether natural or anthropogenic, could result in 1

A. Slagle is Middle School Teacher, Oakland, MD; J. Skousen is Professor, D. Bhumbla is Assistant Professor, J. Sencindiver is Professor, and L. McDonald is Associate Professor in the Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV 26506-6108. Scientific contribution no. 2872 from the West Virginia Agricultural and Forestry Experiment Station, Morgantown. This research was supported by funds appropriated under the Hatch Act.

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Mobilization and release into surface and subsurface waters and subsequent incorporation into the food chain. Soil factors such as organic matter, type and amount of clay, pH and cation exchange capacity (CEC) influence the quantity of trace elements available for mobilization and release or sorption in a soil. Several studies document gradual increases in the trace element contents of agricultural and forested soils due to waste applications (Berthelsen et al., 1995; Chang et al., 1984; McBride, 1995). While essential in small quantities for plant growth, micronutrients like copper (Cu), manganese (Mn), molybdenum (Mo), and zinc (Zn) can be toxic at high concentrations in the soil. Some elements not known to be essential to plant growth, such as arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni), and selenium (Se), also are toxic at high concentrations or under certain environmental conditions in the soil. Regulators who make policy decisions on application rates for waste materials, fertilizers, and pesticides often have limited data on total amounts, plant uptake, toxicity, and fate and transport of trace elements in soils (McBride, 1995; Mermut et al., 1996; Schmidt, 1997). In addition, not much specific data on background levels of trace elements in soils are available to compare to resulting levels after waste applications to land. The U.S. Environmental Protection Agency (USEPA, 1993) regulates nine trace elements for land-applied sewage sludge: As, Cd, Cu, Pb, Hg, Mo, Ni, Se, Zn. Only six of these elements (Cu, Ni, Zn, Cd, Pb, Se) are considered to be phytotoxic (Schmidt, 1997). Accounting for element speciation, complexation, and the dynamic interaction of solid surfaces (soils, organic matter, and live plants) and water with trace elements, it is difficult to determine the maximum allowable total trace element concentrations that can exist in soils without becoming potentially toxic to plants or harming the environment. At present, USEPA regulations allow metals to be added to soils from 10 to >100 times more than estimated background concentrations in agricultural soils, but McBride (1995) states that these regulations are quite lenient when compared to international standards. Estimated background concentrations are developed from studies on trace element content of soils in some states and these background concentrations are adopted when no other data are available for soils in surrounding areas. Elemental analyses of trace metals in prominent soil series have been published in Minnesota (Pierce et al., 1982), Pennsylvania (Ciolkosz et al., 1993a,b, 1998), Oklahoma (Lee et al., 1997), Florida (Ma et al., 1997), Mississippi (Pettry and Switzer, 1993), and Tennessee (Ammons et al., 1997). During a 1995 site evaluation for application of biosolids to West Virginia farm soils, it was found that background levels of several trace elements exceeded maximum permissible levels for soils according to USEPA 503 regulations even before biosolids application. These farm soils had no history of previous biosolid or other waste applications. Therefore, without knowledge of soil background trace element content, legislators and practitioners may allow application of waste materials to soils already inherently high in trace element content and therefore exceed accepted levels given by federal guidelines. 74

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The objectives of this study were to determine the trace element concentrations by horizon of three major soil series (Upshur, Vandalia, and Gilpin) in three counties of MLRA-126 (central Appalachian region), and to compare the trace element concentrations extracted by two currently-used digestion techniques (USEPA 3051 and an HF method) to regulated levels. Materials and Methods Site Selection Three counties in West Virginia were selected to represent MLRA-126 (Fig. 1). This resource area, the Central Allegheny Plateau, comprises the western and northwestern one-third of West Virginia and extends into Ohio and Pennsylvania. The soils of this region are underlain by shale, sandstone, siltstone and some limestone sediments of younger Pennsylvanian and Permian age. Most of the area is steep or very steep except for terraces and floodplains adjacent to major drainages. Major streams include the Elk, Kanawha, Little Kanawha, Monongahela, Ohio and West Fork Rivers. While more than half of the area is wooded or reverting to woody species, small farms with agricultural crops and pasture are common in the area, and most of the land along the Ohio River is being used for agricultural, urban and industrial purposes. The growing season is about 150-185 days, and annual rainfall is about 44 in. (110 cm) (USDA-SCS, 1980). The soils selected to best represent the Central Allegheny Plateau area were Upshur, Vandalia and Gilpin series. A total of nine pedons were sampled and classified: one pedon of Upshur, Vandalia and Gilpin in each of three West Virginia counties (Clay, Doddridge, and Mason). Care was taken to select relatively pristine forest soils not contaminated by direct, anthropogenic additions of trace metals. Site selection and pedon location criteria were: 1) more than 31 miles (50 km) away from any power plant, 2) more than 109 yds (100 m) from rural roadways, 3) more than 109 yds (100 m) from any known or abandoned building site, and 4) no history of waste applications. Soil Series Descriptions Upshur soils (fine, mixed, superactive, mesic Typic Hapludalfs) are derived from clay shale residuum and are interbedded with thin layers of siltstone on ridgetops, benches and hillsides. They are deep and well drained, having slopes ranging from 0 to 70 percent. While many areas with Upshur soils are returning to mixed woodlands of oak (Quercus sp.), yellow-poplar (Liriodendron tulipifera L.) and hickory (Carya sp.), Upshur soils are often cleared and used for pasture, hay and grain crops due to their inherently high fertility. Upshur covers large areas in western and central West Virginia, southwestern Pennsylvania, southeastern Ohio and northeastern Kentucky (USDA-NRCS, 1991b). Vandalia soils (fine, mixed, active, mesic Typic Hapludalfs) are very deep and well drained. They formed in colluvium from shale, siltstone and some sandstone. Topographically, their positions are on footslopes and colluvial fans with 3 to 60 percent slopes. Cleared areas are used mostly for pasture or hay, and unmanaged 75

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Fig. 1. The area inside the dashed circle represents the location of Major Land Resource Area 126 (MLRA-126) in the Appalachian region of the eastern U.S. Soil pits for our three soil series were located in Doddridge, Mason, and Clay counties of West Virginia.

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areas of Vandalia soils are reverting to woodland of mixed hardwoods. The series covers large areas of western West Virginia, eastern Ohio, and northeastern Kentucky (USDA-NRCS, 1991c). Gilpin soils (fine-loamy, mixed, semiactive, mesic Typic Hapludults) are formed in residuum of nearly horizontal interbedded shale, siltstone and some sandstone. These soils are moderately deep, well drained, and exist on slopes ranging from 0 to 70 percent on dissected uplands. Gilpin soils are primarily used for cropland and pasture, but also support large areas of mixed oak hardwoods. They occur extensively in Pennsylvania, West Virginia, Ohio, Kentucky, Maryland, New York, Tennessee, Virginia, and Indiana (USDA-NRCS, 1991a). Sample Collection Soil pits were dug by hand to a depth of 63 inches (160 cm) or to bedrock. Soil profiles were described according to standard soil survey procedures (Soil Survey Division Staff, 1993). These descriptions are not provided here but are available in Slagle (2001). Soil samples were taken from each described horizon using plastic tools. Any non-decomposed organic material was removed prior to sampling the uppermost horizon. These bulk materials were transported in plastic bags to the laboratory and allowed to air dry for a week. Laboratory Analyses The air-dried bulk soil samples were pulverized by a wooden rolling pin to pass through a plastic, 2-mm sieve, and all analyses were performed on less than 2mm soil. Particle size distribution was determined by the pipette method (Method 3A1, Soil Survey Staff, 1996). All samples were pre-treated with H2O2 to oxidize any organic matter. Soil pH determinations were made on 1:1 water:soil suspensions using a standard pH probe (Method 8C1f, Soil Survey Staff, 1996). Total carbon was determined by mixing 200 mg of soil with 100 mg ComCat accelerator and analyzed with a Leco CNS-2000 (Leco Corp., St. Joseph, MI). Using 1.0N NH4OAc buffered at pH 7.0, exchangeable cations were replaced with NH4+ and analysis of extracted bases (Ca+2, Na+, K+ and Mg+2) was performed on an AA (Model 5000, Perkin Elmer Atomic Absorption Spectrophotometer, Norwalk, CT; Method 6N2, 6O2, 6P2, 6Q2, Soil Survey Staff, 1996). The pH 8.2 BaCl2triethanolamine (TEA) extraction measured titratable acidity (H+ and Al+3) (Method 6H5, Soil Survey Staff, 1996). Cation exchange capacity (CEC) was computed by summing NH4OAc extractable bases and BaCl2-triethanolamine (TEA) titratable acidity (H+ and Al+3) (Soil Survey Staff, 1996). Base saturation was determined by dividing the sum of extractable base cations (Ca+2, Na+, K+ and Mg+2) by CEC.

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Trace Element Analyses Soil samples were digested by two methods for trace element content: USEPA 3051 and HF acid. The methods involved closed-vessel, microwave digestion (MDS2000, CEM Corp., Mathews, NC). Extracts from the two microwave acid digestion procedures were analyzed for As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Se, and Zn by ICPAES (Model P400, Perkin Elmer Analytical Instruments, Norwalk, CT). Method 3051 of the USEPA used concentrated HNO3 acid following solid waste procedure SW 846-3051 (CEM Corp., 1991; USEPA, 1997). This method involved a closed vessel using pressure and temperature-controlled microwave heating for dissolution. The method was modified to use 1.0 g soil instead of 0.5 g in each vessel and to increase the rate at which the desired temperatures and pressures were reached for digestion of six samples per run. The HF method used a combination of three concentrated acids: HNO3, HF, and HCl (Lim and Jackson, 1982), with microwave digestion. Similarly, 1.0 g of soil was used and only six vessels were placed in the microwave per run. After dissolution of silicate minerals with these acids, excess HF was neutralized with H3BO3. Each soil sample for both methods was analyzed in triplicate, with the average values and standard deviations of the replicates reported. Statistical Analyses All statistical analyses were conducted in Microsoft Excel 97 (Microsoft Corp., Santa Rosa, CA). Means and standard deviations for A, Bt, and C horizons were computed for each trace element by series. In total, the nine pedons were represented by three horizons in each of the three series for each element. Significant differences (p < 0.05) in the same horizon across different soil series were computed by ANOVA and the means were separated by the Student’s t-test. Quality Control for Soil Analysis Standard reference soil materials (2709 and 2711) were obtained from the National Institute of Standards and Technology (NIST) and digested in triplicate and analyzed using identical procedures as stated above. Recoveries of 85 to 115% were found for trace metals in these reference soils (Table 1). Based on these recoveries of +15%, we concluded that the trace element values extracted from these soils were satisfactory. Results and Discussion Physical Properties Bulk density values increased with depth in all three soil series, increasing from 0.8 Mg/m3 in surface horizons to 1.6 Mg/m3 in subsurface horizons (Table 2). Sand generally declined with depth, while clay increased in all Bt horizons compared to A and C horizons. As expected, the clay was generally lower in all horizons of Gilpin versus Upshur and Vandalia soils. Soil pH ranged from 4.5 to 5.7 in these soils. 78

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Table 1. Recovery of trace elements using the HF extraction method on NIST Standard Reference Material 2709 (San Joaquin Soil) and 2711 (Montana Soil) compared to NIST certified concentrations. ______________________________________________________________________________ Element NIST 2709 HF Method Recovery NIST 2711 HF Method Recovery (----- mg/kg -----) (%) (----- mg/kg ------) (%) Ba Cd Cr Cu Mn Ni Pb Zn

968 0.4 130 35 538 88 19 106

997 BDL† 139 39 570 91 19 121

103 ---107 111 106 104 101 114

726 42 47 114 638 21 1162 350

784 37 40 130 734 23 1278 402

108 87 85 114 115 108 110 115

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†BDL = below detection limit.

The ability of soils to sorb elements on soil surfaces, then to release and exchange them with the soil solution is important in determining trace element mobility and bioavailability in the environment. The CEC was generally highest for the Upshur soils. The CEC decreased with depth in Upshur and Gilpin soils, but increased with depth in Vandalia soils. The reason for CEC increases with depth in Vandalia is related to the relatively high clay content in Bt and C horizons of these pedons. Base saturation was higher in Upshur and Vandalia soils than Gilpin. Base saturation increased with depth in both the Alfisols, while it slightly decreased within Gilpin (an Ultisol). Total carbon decreased with depth (Table 2) with the highest amount clearly in the A horizons. Table 2. Mean values of some physical and chemical properties of major horizons for Upshur, Vandalia, and Gilpin soil series in West Virginia. ______________________________________________________________________________

Series/Horizon

Bulk Density

Sand

Silt

Clay pH

(Mg/m3) ----------------- % -----------

CEC†

Base Total Saturation C

(s.u.) (cmolc/kg) ---- % --------

Upshur (Alfisol) A 0.8 14 59 27 5.2 35.9 39 4.4 Bt 1.3 10 47 43 4.6 28.3 34 0.2 C --1 78 21 5.6 25.7 76 0.1 Vandalia (Alfisol) A 0.8 10 64 26 4.9 21.9 31 2.8 Bt 1.6 8 55 37 4.8 23.5 42 0.2 C 1.6 4 64 32 5.7 26.5 58 0.1 Gilpin (Ultisol) A 1.0 24 64 12 4.6 21.9 17 3.1 Bt 1.5 16 63 21 4.5 12.8 14 0.3 C 1.5 33 53 14 4.6 11.8 13 0.2 †s.u. is standard unit. ‡CEC was calculated by summing the bases extracted by 1.0N NH4OAc, plus the extractable acidity (H and Al) using BaCl2-TEA extraction.

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Trace Element Concentrations by USEPA 3051 Extraction This extraction technique was designed to extract trace elements from all soil fractions except for those elements found within clay lattices. In relative terms, trace elements bound within clay minerals are less available for release into the environment and therefore pose a much lower threat. Therefore, USEPA 3051 represents amounts of elements that can be potentially labile in the environment better than the HF extraction method. Data for As, Pb, and Se, although analyzed, were not present in detectable quantities and therefore were not reported in Tables 3 and 4. Barium was found in higher concentrations in the Upshur and Vandalia soils (both Alfisols) compared to the Gilpin (the Ultisol), but the differences were not significant by ANOVA (Table 3). For Cd and Cr, slight trends were found for increasing concentrations with depth. Similar to Ba, there were no significant concentration differences for Cd or Cr among these three soil series. The Cd values in these soils were ten times higher than similar soil series in Pennsylvania using USEPA 3051 (Ciolkosz et al., 1993b), while Ba and Cr concentrations were very similar. We found significantly higher amounts of Cu and Ni in A and C horizons of the Alfisols (Upshur and Vandalia) versus the Ultisol (Gilpin). Copper concentrations increased with depth in most soils, similar to the trend and values reported in Ciolkosz et al.(1993b). The increases with depth suggest that these elements are derived from parent materials. Manganese followed a reverse trend, with significantly greater quantities of Mn in A horizons versus Bt or C horizons. Significantly more Mn was extracted from A horizons of Alfisols than the Ultisol. Zinc concentration was fairly consistent with depth, with the Alfisols showing a trend for slightly higher values than Gilpin. Statistical tests for USEPA 3051 trace element concentrations between horizons and among soil series showed that Upshur and Vandalia (the Alfisols) were not significantly different. These Alfisols, however, were significantly different from Gilpin (the Ultisol) for Cu and Ni (A and C horizons), and Mn (A horizon). Nevertheless, the Alfisols generally showed a strong trend for higher values for all trace elements than Gilpin. Average A-horizon trace element concentrations across soils are given in Table 3. Trace element concentration by the HF method Trends similar to the USEPA 3051 extraction were found for trace element concentrations among series and horizons using the HF digestion method (Table 4). There were no significant differences for any trace element concentrations between Upshur and Vandalia (the Alfisols). Only Ni was significantly different among soils using HF digestion, showing the Upshur/Vandalia soils (the Alfisols) to be significantly higher in Ni than Gilpin (the Ultisol).

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81 NS

17 (1.6) 19 (5.7) 17 (4.5)

15 (1.4) 21 (4.8) 22 (4.2)

18 (3.7) 25 (9.1) 25 (2.0)

540 (136) 190 (158) 180 (128)

2280 (1218) 510 (510) 160 (44)

1570 (929) 220 (139) 280 (73)

Up=Va>Gi§ Up=Va>Gi A & C horizon A horizon

13 (3.8) 18 (6.1) 21 (7.6)

19 (3.6) 29 (10.9) 34 (10.9)

17 (2.1) 27 (10.9) 43 (3.6)

53 (23.9) 46 (7.9) 44 (2.4)

75 (38.1) 64 (26.3) 71 (16.7)

66 (15.4) 65 (19.0) 67 (13.0)

Up=Va>Gi NS A & C horizon

8 (2.8) 11 (2.3) 10 (0.6)

14 (1.3) 15 (4.9) 18 (2.7)

11 (0.5) 15 (3.5) 27 (6.0)

Ave. Conc. in A horizon 120 1.5 17 16 1470 11 65 ____________________________________________________________________________________________________________________ _ †Concentrations of Arsenic, Lead and Selenium were below detection limits and not reported in this table. ‡NS = Means for the same horizon across soils are not significantly different by ANOVA. §Up = Upshur, Va = Vandalia, Gi = Gilpin. Means separated by the Student’s t-test.

NS

2.0 (0.6) 1.5 (0.8) 2.5 (0.8)

Gilpin (Ultisol) A 80 (28) Bt 70 (20) C 50 (7)

NS‡

1.0 (0.4) 1.5 (0.7) 3.0 (1.4)

Vandalia (Alfisol) A 180 (131) Bt 130 (82) C 120 (81)

Significance

2.0 (1.4) 2.5 (1.6) 3.0 (1.2)

Ba Cd Cr Cu Mn Ni Zn (------------------------------------------------------------ mg/kg --------------------------------------------------------------)

Upshur (Alfisol) A 100 (56) Bt 90 (54) C 140 (55)

Series/Horizon

__________________________________________________________________________________________________________________________

Table 3. Concentrations of trace elements† (means with standard deviation in parentheses) of major horizons for Upshur, Vandalia, and Gilpin soils in MLRA-126 using the USEPA 3051 extraction method.

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NS 3.0

Ave. Conc. in A horizon 255

82 22

NS 31

NS 1360

NS

19

Up=Va>Gi¶ A & C horizon

8

NS

87

NS

Trace Element Concentration Standards Total Content# 300 0.1 65.0 20.0 550 20.0 10.0 50.0 19.0 1500.0 750.0 ---260.0 150.0 1400.0 USEPA 503†† ---NE Reg. Res.‡‡ ---2.5 250.0 63.0 ---25.0 250.0 125.0 ____________________________________________________________________________________________________________________ † Concentrations of both Arsenic and Selenium were below detection limits and not reported in this table. ‡BDL = below detection limit. §NS = Means for the same horizon across soils are not significantly different by ANOVA. ¶Up = Upshur, Va=Vandalia, Gi=Gilpin. Means separated by the Student’s t-test. #The average total elemental concentration in normal, uncontaminated soils (Pais and Jones, 1997). ††Cumulative loading rates based on the final concentration in soil (mg/kg) in the upper 15 cm of soil, USEPA 503 standards (USEPA, 1993). ‡‡Cumulative loading rates based on the final concentration in soil (mg/kg) in the upper 15 cm of soil (Northeastern U.S. Regional Research, 1985).

Significance

NS§

Series/Horizon Ba Cd Cr Cu Mn Ni Pb Zn n (------------------------------------------------------------------------ mg/kg ------------------------------------------------------------------------) Upshur (Alfisol) A 240 (48) 3.0 (1.1) 27 (19.1) 29 (19.4) 1460 (640) 22(4.2) 11 (10.5) 107(10.0) Bt 130 (26) 5.0 (1.9) 54 (17.9) 44 (33.9) 330 (226) 30 (9.3) BDL‡ 107 (22.9) C 150 (15) 15.0 (7.9) 67 (2.3) 75 (9.6) 440 (144) 56 (8.9) 17 (13.6) 132 (12.0) Vandalia (Alfisol) A 270 (22) 3.0 (2.2) 27 (6.3) 37 (5.6) 1890 (1040) 23 (2.6) 6 (3.4) 90 (6.5) Bt 150 (28) 5.0 (2.6) 46 (13.1) 58 (7.8) 420 (355) 29 (7.9) BDL 97 (18.6) C 160 (32) 10.0 (4.2) 59 (14.2) 79 (18.9) 200 (16)) 35 (8.0) 6 (8.1) 126 (29.0) Gilpin (Ultisol) A 260 (14) 2.0 (0.7) 10 (9.0) 26 (10.8) 720 (211) 11 (3.5) 5 (7.2) 64 (15.2) Bt 180 (37) 4.0 (2.5) 25 (15.5) 38 (7.7) 270 (174) 18 (2.9) BDL 77 (13.1) C 140 (31) 4.0 (1.1) 20 (0.6) 44 (6.7) 160 (80) 22 (2.2) BDL 73 (6.3)

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Table 4. Concentrations of trace elements† (means with standard deviations in parentheses) of major horizons for Upshur, Vandalia, and Gilpin soils in MLRA-126 using the HF extraction method.

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Comparison of the Methods Overall, the HF method was more effective in dissolving the soil (Table 4), releasing 1.5 to 5 times more trace elements compared to the USEPA 3051 method. Concentrations of Ba, Cr, Cu, Ni, and Zn were 2 to 3 times greater by HF digestion compared to 3051 (compare Tables 3 and 4). Cadmium concentrations were up to 5 times greater with HF. Lead went from non-detectable concentrations using 3051 to 5 to 16 mg/kg with HF. The notable exception to this trend was Mn, where 3051 extractable Mn was equal to or greater than Mn extracted by HF. Therefore, these comparisons between methods suggest that a large fraction of the total trace element concentration in these soils was tied up in the crystal structures of clays. The HF method should represent a “total” quantity of trace elements present in the soil because concentrated HNO3, HF, and HCl acids cause soil components to dissolve, thereby releasing the bound elements within their structures. This method is almost always employed to determine if a soil has acceptable or unacceptable levels of trace elements (Sims et al., 1997), but few circumstances or events in the field would promote the natural dissolution of clays quickly, thereby releasing all trace elements. The HF extraction method may not be suitable to assess background levels of unpolluted soils for biosolids application programs. Therefore, a method such as USEPA 3051, rather than the HF method, should more accurately represent the worstcase scenario for mobilization of trace elements in the environment and may be more appropriate to assess the trace element concentration of soils. Comparison with Other Standard Values Several other levels of trace element concentrations are given in Table 4. The first is a measure of the average total concentration of trace elements in unpolluted soils (Pais and Jones, 1997). When compared to these average total concentrations, only Cd was much higher in our soils (up to 150 times higher). Very high concentrations of P were found in the C horizons of Vandalia and Upshur soils (data not shown), and Cd is a common component in phosphate rocks. Therefore, high Cd concentrations in these soils are of geologic origin and related to the parent material from which these soils developed. All other elements were generally within 1 to 3 times of the average values reported in Pais and Jones (1997). One reason for conducting this research was to determine whether trace element concentrations in these unpolluted soils were already higher than cumulative loading rate values promulgated by USEPA. Earlier assessments of unpolluted soils in this region showed that As and Cd were already at sufficiently high concentrations to prohibit the use of these soils for biosolid application. In comparing the concentrations in these MLRA126 benchmark soils to the USEPA 503 cumulative loading standards (Table 4), no elements are close to exceeding the maximum concentrations listed in the 503 regulations. Cadmium in two instances (the C horizons of Upshur and Vandalia soils) approached the 19 mg/kg cumulative loading rate standard. Arsenic was not detected by ICP-AES with either extraction method in these soils.

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A much more conservative maximum cumulative loading rate standard was issued by a group of scientists in the northeastern U.S. (Northeastern U.S. Regional Research, 1985). Cadmium exceeded (with one exception) the maximum concentration suggested by this group in all horizons of these soils, while Cu, Ni, and Zn exceeded these values in a few cases (especially in C horizons). In the case of using the 3051 method, Cd concentrations were close to the maximum levels, but exceeded the 2.5 mg/kg level only in C horizons. However, the large standard deviation for Cd in all horizons suggests that these soils may well exceed the guideline levels. Summary and Conclusions The elements extracted from Upshur, Vandalia, and Gilpin soils in MLRA-126 were between 1.5 to 5 times greater for the HF method compared to the USEPA 3051 method. The trace element concentrations from MLRA-126 soils using 3051 were similar to the same soil series in Pennsylvania except for Cd and Pb. In our study, Cu, Mn, and Ni were found at significantly greater concentrations in Upshur/Vandalia soils (Alfisols) versus Gilpin (an Ultisol). Using HF, only Ni was significantly different between the Alfisols and the Ultisol. In comparing the trace element concentrations from 3051 and HF extraction to cumulative loading rate standards, Cd was found to be close to or exceed the cumulative loading rate suggested by northeastern U.S. soil scientists, but neither extraction method gave elemental concentrations close to the cumulative loading rate promulgated by USEPA 503 regulations. Acknowledgments The authors thank Dr. Jim Gorman of WVU, and soil scientists Tim Dilliplane, Tony Jenkins, and Scott Hoover from the Natural Resources Conservation Service for assistance with field work. References Ammons, J.T., R.J. Lewis, J.L. Branson, M.E. Essington, A.O. Gallagher, and R.L. Livingston. 1997. Total elemental analysis for selected soil profiles in Tennessee. Bulletin 693. The Univ. of Tennessee Agric. Exp. Stn., Knoxville. Berthelsen, B.O., E. Steinnes, W. Solberg, and L. Jingsen. 1995. Heavy metal concentrations in plants in relation to atmospheric heavy metal deposition. J. Environ. Qual. 24:1018-1026. CEM Corp. 1991. SW 846-3051, microwave sample preparation note EN-4. CEM Corporation, P.O. Box 200, Matthews, NC 28106. Chang, A.C., J.E. Warneke, A.L. Page, and L.J. Lund. 1984. Accumulation of heavy metals in sewage sludge-treated soils. J. Environ. Qual. 13:87-91. Ciolkosz, E.J., A.W. Rose, W.J. Waltman, and N.C. Thurman. 1993a. Total elemental analysis of Pennsylvania soils. Agronomy Series No. 126. Dep. of Agronomy, Penn. State Univ., University Park. Ciolkosz, E.J., M.K. Amistadi, and N.C. Thurman. 1993b. Metals in Pennsylvania soils. Agronomy Series No. 128. Dep. of Agronomy, Penn. State Univ., University Park. Ciolkosz, E.J., R.C. Stehouwer, and M.K. Amistadi. 1998. Metal data for Pennsylvania soils. Agronomy Series No. 140. Dep. of Agronomy, Penn. State Univ., University Park.

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Lee, B.D., B.J. Carter, N.T. Basta, and B.Weaver. 1997. Factors influencing heavy metal distribution in six Oklahoma benchmark soils. Soil Sci. Soc. Am. J. 61:218-223. Lim, C. and M. Jackson. 1982. Dissolution for total elemental analysis. p. 1-11. In A.L. Page et al. (ed.) Methods of soil analysis. Part 2. 2nd ed. Agron. Monogr. 9. ASA and SSSA. Madison, WI. Ma, L.Q., F. Tan, and W.G. Harris. 1997. Concentrations and distributions of eleven metals in Florida soils. J. Environ. Qual. 26:769-775. McBride, M.B. 1995. Toxic metal accumulation from agricultural use of sludge: are USEPA regulations protective? J. Environ. Qual. 24:5-18. Mermut, A.R., J.C. Jain, L. Song, R. Kerrich, L. Kozak, and S. Jana. 1996. Trace element concentrations of selected soils and fertilizers in Saskatchewan, Canada. J. Environ. Qual. 25:845-853. Northeastern U.S. Regional Research. 1985. Criteria and recommendations for land application of sludges in the Northeast. U.S. Regional Research Bulletin 851. Penn. State Univ., University Park. Pais, I. and J.B. Jones. 1997. The handbook of trace elements. St. Lucie Press, Boca Raton, FL. Pettry, D.E. and R.E. Switzer. 1993. Heavy metal concentration in selected soils and parent materials in Mississippi. Bulletin 998. Office of Agricultural Communications, Mississippi State Univ., Starkville. Pierce, F.J., R.H. Dowdy, and D.F. Grigal. 1982. Concentrations of six trace elements in some major Minnesota soil series. J. Environ. Qual. 11:416-422. Schmidt, J.P. 1997. Understanding phytotoxicity thresholds for trace elements in land-applied sewage sludge. J. Environ. Qual. 26:4-10. Sims, J.T., S.D. Cunningham, and M.E. Sumner. 1997. Assessing soil quality for environmental purposes: roles and challenges for soil scientists. J. Environ. Qual. 26:20-25. Slagle, A. 2001. Background concentrations of trace elements in three West Virginia soils -- MLRA126.M.S. Thesis, West Virginia Univ. Morgantown. (Available on line at https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp_etdId=1380). Soil Survey Division Staff. 1993. Soil survey manual. USDA Handbook No. 18. U.S. Government Printing Office, Washington, D.C. Soil Survey Staff. 1996. Soil survey laboratory methods manual. Soil Survey Investigations Report No. 42, version 3.0. USDA-NRCS-National Soil Survey Center. U.S. Department of Agriculture-Natural Resources Conservation Service, U.S. Government Printing Office, Washington, DC. USDA-NRCS. (1991a) Official Soil Series Description: Gilpin Series. U.S. Department of AgricultureNatural Resources Conservation Service, Statistical Laboratory, Iowa State University. Ames, Iowa. USDA-NRCS. (1991b) Official Soil Series Description: Upshur Series. U.S. Department of AgricultureNatural Resources Conservation Service, Statistical Laboratory, Iowa State University. Ames, Iowa. USDA-NRCS. (1991c) Official Soil Series Description: Vandalia Series. U.S. Department of Agriculture-Natural Resources Conservation Service, Statistical Laboratory, Iowa State University. Ames, Iowa. USDA-SCS. 1980. General soil map of West Virginia. U.S. Department of Agriculture-Soil Conservation Service, Lanham, MD. USEPA. 1993. Clean Water Act. Standards for the use and disposal of sewage sludge. Code of Federal Regulations (CFR) Part 503, Vol. 58, No. 32. U.S. Environmental Protection Agency, Washington, DC. USEPA. 1997. Method 3051a: Microwave assisted acid dissolution of sediments, sludges, soils, and oils. 2nd ed. U.S. Environmental Protection Agency, U.S. Government Printing Office, Washington, DC.

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