Environ. Sci. Technol. 2005, 39, 8712-8718
Sorption and Displacement of Pyrene in Soils and Sediments X I L O N G W A N G , * ,†,‡ T . S A T O , ‡ A N D BAOSHAN XING† Department of Plant, Soil and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, Massachusetts 01003, and Institute of Nature and Environmental Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
Sorption isotherms of pyrene on soils and sediments were examined to understand its sorption behavior. All systems examined exhibited nonlinear sorption. Sorption nonlinearity was found to be a function of the polarity index of soil/sediment organic matter (SOM), suggesting that the degree of condensation of SOM, characterized by its polarity index, was correlated with the sorption behavior of pyrene. The polarity index of SOM could be a new factor for explaining the sorption nonlinearity. The sorption affinity of two soils and two sediments for pyrene increased with decreasing SOM polarity. A higher sorption affinity in the two soils was associated with a higher degree of condensation of SOM compared to that of the two sediments. A displacement test was performed after pyrene sorption using phenanthrene as a displacer. Pyrene was displaced in all systems examined, and nonlinearity became less pronounced after displacement. Such an increase in isotherm linearity implied that sorption site energies became more homogeneous after displacement. Furthermore, the site energy distribution F(E*) derived from the Freundlich model parameters showed that energy reduction of high-energy sites was more significant than that of low-energy sites after displacement. In addition, a decrease in sorption capacity after displacement could be ascribed to the partial depletion of sorption sites by the displacer. The displacement data indicated that the cocontaminant can have potential effects on the fate and bioavailability of anthropogenic organic pollutants sorbed in soils and sediments, thus affecting their exposure risks.
Introduction Soil and sediment particles contain minerals and/or organic matter (SOM). These materials consist of different domains that play different roles in the sorption of organic contaminants (1). SOM has been identified as a predominant sorbent (2) unless the organic carbon content is below 0.1% by mass (3). Therefore, the mechanism of hydrophobic organic chemicals (HOCs) sorption to SOM has gained increasing attention owing to its importance to the transport, fate, bioavailability, and toxicity of these compounds (4-7). It was proposed that SOM comprises two principal heterogeneous sorption domains, namely, soft and hard carbon domains (1, 6, 8-10). The former one can be * Corresponding author phone: (413)545-2860; fax: (413)5453958; e-mail:
[email protected]. † University of Massachusetts. ‡ Kanazawa University. 8712
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envisioned as the geologically immature amorphous carbon, analogous to rubbery polymers. In contrast, the latter one is the diagenetically condensed or thermally altered SOM, similar to glassy polymers (11). Specifically, the difference between soft and hard carbon is that the latter one has a higher degree of aromaticity and rigid hydrophobic micropores in the SOM matrix (12). These micropores in the SOM have been observed using scanning tunneling microscopy (13) and measured in humic substances using N2 and CO2 adsorption (14, 15). The (O + N)/C atomic ratio of SOM was defined as its polarity index, and it has been used to characterize the degree of condensation of SOM (10, 16, 17). Mechanisms controlling HOCs sorption by SOM include absorption in the soft carbon domain and adsorption in hydrophobic micropores in hard organic carbon (4, 18). Absorption in soft SOM is a partitioning process and is always described by a linear isotherm (10), while adsorption in the hard organic carbon domain is described by nonlinear isotherms (19). Much work has been performed to elucidate the sorption mechanisms of HOCs by SOM. Young and Weber (20) found nonlinear sorption of phenanthrene on soils and shales while Chiou et al. (21) observed a linear sorption isotherm of PAHs (e.g, naphthalene, phenanthrene, and pyrene) on soils and sediments. The disparate reports in the literature may be due to different sorption mechanisms dominating soil/sediment-water sorption systems. Thus, further research is required to address the sorption behavior of HOCs in soils and sediments. It was reported that every sorption isotherm has an assumption of an underlying distribution of site energies (22). According to this theory, isotherm parameters should be closely related to particular site energy distributions, and the experimentally determined values can be explained with respect to the energy character of a sorbent. Competitive sorption has also been used to examine the sorption behavior of HOCs, but this has produced inconsistent results. For example, it was reported that competition between simultaneously sorbing cosolutes sometimes occurred and one sorbed solute was displaced by another displacer (5, 19). However, the presence of trichloroethene did not show a competitive effect on tetrachloroethene sorption (23). These results revealed that the competition effect depends on a few factors, for instance, whether the adsorption mechanism takes place or not in the sorption process. The chemical properties of the solutes and the conformation of the SOM also determine whether competitive sorption and displacement will occur. In view of the discrepant findings regarding the sorption behavior of HOCs in soils and sediments, an examination of how the site energy distribution of a sorbent changes before and after introducing a displacer would be helpful for better understanding the mechanisms underlying the displacement effect. Therefore, the objectives of this study were to (i) examine the relationship between the degree of SOM condensation, characterized by the polarity index with the porosity of solid particles, and sorption behavior of HOCs, e.g., pyrene, and (ii) interpret the mechanism of displacement from the energy heterogeneity changes of the sorption sites before and after the displacement process.
Experimental Section Sorbents Characteristics and Reagents. Black and Toyama soil samples were collected from surface horizons (0-20 cm) in Hokkaido and Ishikawa Counties, Japan, respectively. The two bed sediment samples were taken from the top 0-20 cm of the sediments; they were from Biwa Lake and Kanazawa River, respectively. Soil and sediment samples were air-dried, 10.1021/es050107s CCC: $30.25
2005 American Chemical Society Published on Web 10/11/2005
TABLE 1. Properties of Soil and Sediment Samples sorbents
C (%)
H (%)
O (%)
N (%)
(O+N)/C
ash
Biwa Lake sediment Kanazawa sediment Black soil Toyama soil
3.26 ( 0.26a 1.06 ( 0.06 8.23 ( 0.23 6.21 ( 0.24
0.63 ( 0.04a 0.39 ( 0.04 1.22 ( 0.04 1.01 ( 0.05
4.30 ( 0.18a 2.60 ( 0.05 5.78 ( 0.56 3.59 ( 0.25
0.29 ( 0.09a 0.41 ( 0.03 0.82 ( 0.04 0.52 ( 0.05
1.07 2.17 0.61 0.50
91.53 ( 2.23a 95.57 ( 1.69 83.96 ( 0.27 88.68 ( 0.21
a
Standard errors of the mean.
ground, and homogenized to pass a 250 µm sieve. The elemental composition (C, H, and N) of the organic fraction was determined by an elemental analyzer (Corder, MT-5) in triplicate, after treating the samples with 1 M HCl at a solidto-solution ratio of 1:20 to drive off inorganic carbon as CO2, followed by washing 5 times with deionized water to remove residual acid. Elemental measurement was performed immediately after freeze-drying for 4 days and oven-drying (100 °C) for 12 h to minimize the effect from moisture interference on H and O. The ash content of the samples was determined in triplicate by loss of mass after heating samples at 750 °C for 4 h (24). The oxygen content of the SOM was derived by mass difference as done by Xing et al. (25). Averaged data of elemental composition and ash content and their standard errors are presented in Table 1. The BET-based porosity of the samples was determined by a surface area analyzer (Coulter SA-3100, Coulter Co.) using N2 as the sorbate at 77 K (15) after drying the samples in an oven at 80 °C for 24 h and vacuum outgassing at 100 °C for 8 h; this drying and outgassing method was used by Chiou (26) and was proved to be sufficient to completely remove water from the samples. The total pore volume Vt (mL/g) of the samples was derived from a single-point adsorption at a relative pressure (P/P0) of 0.99 (expressed as v0.99, in mL STP/g) by converting the volume of the adsorbed gas to the volume of the liquid adsorbate: Vt ) v0.99Cf. Here, Cf is a conversion factor between the volume of the gas and liquid adsorbate with a value of 0.0016 for nitrogen at 77 K (27). The meso- and macropore volume of the samples was directly obtained from the surface area analyzer using the BJH model, and the difference between the total pore volume and the sum of the meso- and macropore volumes was attributed to the micropore volume of the individual samples. Pyrene and phenanthrene (superior grade, 98+% in purity) were purchased from Wako chemical Co. and used as received. Sorption Experiment. Sorption isotherms were obtained using a batch equilibration method (21). Approximately 50 mg of soil or sediment was added into a 50 mL screw-capped glass centrifuge tube, which was tested to achieve 25-80% uptake of pyrene in the preliminary experiments. An aqueous solution containing 0.005 M CaCl2 to suppress organic matter dissolution (28) and 100 mg/L HgCl2 to minimize biological activity was prepared, with its pH adjusted to 6 using 0.1 M HCl or 0.1 M NaOH. Such a concentration level of CaCl2 and HgCl2 was also used by others (25, 28). A volume of 20 mL of solution was added into each tube containing the test solid sample, followed by addition of 50 µL of pyrene/ methanol stock solutions with concentrations ranging from 4.4 to 44 mg/L at 14 levels. All tubes were hand-shaken for a few minutes to make them uniformly mixed. Then, the tubes were immediately sealed tightly with screw caps with Teflon liners. The solute concentrations in the test solution varied from 8% to 80% pyrene aqueous solubility, and the methanol content of 0.25% (by volume) in the test solution should not have led to any cosolvent effect (29, 30). As such, the composition of each sample in the series was identical in every respect except for the solute concentrations. The tubes were horizontally placed on a constant temperature water bath shaker oscillating at 150 rpm for 7 days at 25 °C, since our preliminary test showed that apparent
equilibrium was reached by 5 days (mass loss of pyrene Biwa Lake sediment > Kanazawa sediment (Table 2), consistent with the organic carbon content in the samples (Table 1). This implied that soil/sediment organic matter (SOM) functioned primarily as a sorption medium (21) for pyrene. To interpret the sorption mechanism of pyrene by these sorbents, we visualize that soil/sediment particles comprise three domains: (i) an exposed mineral domain; (ii) a rubbery/ amorphous SOM domain; (iii) a glassy/condensed SOM domain. The contribution from unexposed mineral surfaces to sorption was not included due to their low accessibility (8). The appropriateness of this model can be found in the relevant literature (8). Each domain has distinct characteristics (e.g., energetics and affinity) and therefore different roles in HOCs sorption. Xing and Pignatello (9) showed a decrease in Freundlich N and increase in sorption coefficient KF for describing the sorption of 1,3-dichlorobenzene, 2,4dichlorophenol, and the herbicide metolachlor onto a Pahokee peat soil and a mineral soil over an experimental duration of 1-180 days. Weber and Huang (8) also reported similar changes over times ranging from 1 min to 14 days for phenanthrene onto four mineral soils. These data indicated that solute diffusion into condensed SOM and intradomain is a slow process (20). In some cases, it takes a long time for sorbate molecules to access the condensed SOM domain associated with soil and sediment aggregates, and the time required to achieve apparent equilibrium sorption is closely correlated with the properties of the pores connecting intraparticle and within condensed SOM (8). Figure 2 presents the N2 sorption isotherm on soil and sediment samples used for this study. The pores were classified into three groups in terms of pore diameter, namely micropore (50 nm) (36). For materials containing pores of diameter smaller than 2 nm, the BET-N2 surface area and volume can
FIGURE 1. Isotherms of pyrene sorption in two soils and two sediments before and after phenanthrene addition. The sorption isotherm data are indicated by open circles and displacement data by solid circles. The lines in the figure represent the data fit with the Freundlich model.
TABLE 2. Model Parameters of Pyrene Sorption before and after Phenanthrene Addition (i.e., Displacement)a Freundlich model sorbents
Linear model
logKF
b
N
R2
F value
Kd
R2
Biwa Lake sediment
sorption displaced
3.00 ( 0.04b 2.99 ( 0.08
2.01 0.75
0.899 ( 0.04b 0.921 ( 0.06
0.994 0.970
0.002 0.005
1360 564
0.968 0.945
Kanazawa sediment
sorption displaced
3.01 ( 0.02 3.00 ( 0.06
0.24 0.19
0.937 ( 0.02 0.956 ( 0.04
0.985 0.991
0.003 0.002
210 174
0.972 0.986
Black soil
sorption displaced
3.69 ( 0.02 3.64 ( 0.04
1.68 0.54
0.861 ( 0.04 0.891 ( 0.05
0.986 0.961
0.003 0.005
5920 1890
0.961 0.946
Toyama soil
sorption displaced
3.45 ( 0.03 3.30 ( 0.09
2.62 0.36
0.808 ( 0.05 0.863 ( 0.08
0.986 0.956
0.004 0.006
4520 568
0.971 0.934
a
Units: b (L/µg); KF (µg/kg); Kd (L/kg).
b
Standard error; F value is the F test result.
TABLE 3. Porosity of Samples Used in This Study
FIGURE 2. N2 adsorption isotherms of four samples at 77 K. (]) Black soil; (4) Toyama soil; (O) Kanazawa sediment; (0) Biwa Lake sediment. be overestimated because of capillary condensation at low relative pressures (37) or underestimated when pores have constrictions smaller than approximately 0.5 nm (38). But N2 adsorption was recommended as a standard method to measure the surface area and pore volume of SOM (39). Since N2 diffusion into micropores at 77 K is a slow process, it takes over 6 weeks to reach equilibrium, we calculated the micropore volume from the difference between total pore volume and the sum of the meso- and macropore volumes as stated in the Experimental Section. The macro-, mesoand micropore volumes of the samples are presented in Table 3. The micropore volume of our samples was comparable with that of peat and humic acid samples determined using CO2 as the sorbate at 273 K (4) and soil and sediment samples employing argon as the sorbate at 87 K (1). The highest
sorbents
macropore (mL/g)
mesopore (mL/g)
micropore (mL/g)
Biwa Lake sediment Kanazawa sediment Black soil Toyama soil
0.004 0.007 0.011 0.009
0.011 0.020 0.027 0.022
0.002 0.0002 0.011 0.004
adsorption amount at individual relative pressures (P/P0) for Black soil (Figure 2) indicates its highest porosity among all samples; the similar macro- and mesoporosity (diameter >50 nm and 2-50 nm, respectively) of Toyama soil and Kanazawa sediment (Table 3) was in accordance with the nearly overlapped isotherms of these two samples (Figure 2). Interestingly, the shapes of the pore volume distribution of the samples were quite similar, with a peak at a pore diameter of 44 nm in the range of 7.6-52.7 nm demonstrating the mesopores and the other one at a pore diameter of 87 nm in the range of 52.7-182 nm displaying the macropores. Table 3 showed that Black and Toyama soils had higher macro- and mesopore volume compared to Biwa Lake and Kanazawa sediments. A higher abundance and good connection of macro- and mesopores would facilitate solute molecules to access the sorption sites in the micropores. Consistently, the sample with the higher meso- and macropore volume also had the higher micropore volume. More important is that two soils of higher organic content VOL. 39, NO. 22, 2005 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 3. Relationship between nonlinearity, N, and the polarity index of SOM. and lower SOM polarity (Table 1) had higher micropore volume, reflecting that a majority of the micropores could be attributed to the small voids in the condensed regions of SOM, thus leading to more significant sorption nonlinearity of two soil samples (Tables 2 and 3). Further, it was found in this study that the magnitude of the micropore volume was positively correlated with the degree of SOM condensation. For example, the SOM in the two sediments might have a lesser degree of condensation in terms of their higher polarity in comparison to the soil samples, thus, having lower micropore volume and nonlinearity (6). The variation in composition and structure of SOM was assumed to cause the different sorptive properties for HOCs (40). Variability in polarity and aromatic carbon content appears to be significant in controlling reactivity with HOCs (2, 4). Huang and Weber (16) reported that diagenesis of SOM usually leads to a decrease in its polarity and an increase in its aromaticity. To examine the origin of the sorption isotherm nonlinearity, the relationship between the Freundlich N and the polarity index of SOM was plotted (Figure 3), showing that the nonlinearity decreased with increasing polarity index of SOM. This indicates that the polarity or condensation degree of SOM is correlated with the nonlinear sorption behavior of HOCs, e.g., pyrene. In addition, the H/C atomic ratio of the two soils used in this study was in the range of 1.77-1.95; these values are comparable with the values within 1.50-1.59 for humic acids extracted from sediments (41) and 1.83 for a chitin sample (25). The relationship between the Freundlich N and the O/C atomic ratio using phenanthrene as the adsorbate obtained by Huang and Weber (16) was described as N ) 0.704(O/C) + 0.409. According to this equation, the predicted Freundlich N values of Black and Toyama soils and Biwa Lake sediment were comparable with the experimentally determined values from this work. Young and Weber (20) and Grathwohl (40) also found that the sorption of HOCs by condensed SOM was energetically more favorable and more nonlinear than that by the rubbery/amorphous SOM domain, which they ascribed to the more heterogeneous composition of condensed SOM. Xing (24) found a positive correlation between aromaticity of humic samples and isotherm nonlinearity, from which he speculated that the condensed SOM domain was primarily composed of aromatic moieties. However, adsorption of SOM by minerals may also create condensed domains (e.g., in soil humin) due to strong interactions between SOM and the minerals (42, 43) regardless of structures. It is plausible that in different cases, the appropriate isotherm model for data fitting is sometimes different. However, the magnitude of the sorption capacity when the liquid-phase concentration, Ce, approaches its solubility (Sw) could be the same regardless of what models are selected for data fitting. In our case, the value of the Freundlich model expression KF(bCe)N when Ce equals the pyrene solubility (135 µg/L; ref 44) was employed to describe the sorption capacity. For comparison, the capacity of individual samples was normalized with the organic carbon content (foc). The foc8716
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FIGURE 4. Relation between sorption affinity (Koc) and the polarity index (O + N)/C of SOM. Open circles refer to the Koc derived based on equilibrium concentrations of individual sorption systems with an initial concentration of 11 µg/L; solid circles are those corresponding to the high initial concentration (110 µg/L). normalized capacities of two soils (6290 mg/kg for Black soil and 5180 mg/kg for Toyama soil) were much higher than those of the two sediments (4780 mg/kg for Biwa Lake sediment and 2530 mg/kg for Kanazawa sediment). The difference in sorption capacity suggested that the more condensed SOM in the soil samples had more high-energy sorption sites. Johnson et al. (12) also found the increase in sorption capacity and nonlinearity with increasing degree of diagenesis. To better understand the correlation between pyrene sorption affinities and the degree of SOM condensation, the organic-carbon-normalized sorption coefficients (Koc) were derived from the equilibrium pyrene concentrations corresponding to its highest and lowest initial concentrations (11 and 110 µg/L, respectively) for each system using eq 1. The relation between Koc and (O + N)/C was plotted (Figure 4). A decrease in Koc with increasing (O + N)/C may be attributed to the lesser compatibility (similarity of solubility parameters) of SOM with sorbate molecules. A similar phenomenon was also observed by others (7, 25). In addition, a strong correlation between the pyrene binding coefficient and the aromatic carbon content of the sorbent was observed by Chin et al. (45). As reported, SOM evolves from highly oxidized and amorphous biopolymers to relatively reduced and condensed macromolecules, even to highly reduced, condensed kerogens during the geological period (16), thus exhibiting varying chemical compositions, e.g., polarity, elemental contents, and conformation. As a result, the sorption affinity of SOM for HOCs could be enhanced during SOM evolution (Figure 4). Displacement. The decrease in both the KF and Kd of the Freundlich and linear models for each sample after phenanthrene addition indicated the decrease of the sorption affinity for pyrene by SOM. Because the phenanthrene displacement was tested after pyrene sorption without decanting off the test solution, the data presented in Figure 1 revealed that a fraction of sorbed pyrene molecules were desorbed by phenanthrene in all systems examined. Among the two soils and two sediments examined, Toyama soil showed the most significant displacement, which is consistent with the lowest Freundlich N of the sorption isotherm in the single-solute system, thus suggesting the most evident contribution from adsorption and the least contribution from absorption. In addition, the lowest polarity of SOM in Toyama soil also reflected the most evident condensation of its SOM thus showing the most significant competition once encountering the displacer phenanthrene. Since the Freundlich N has been used to characterize the energy distribution of sorption sites (46), and the SOM matrix usually becomes swelled and softened after HOCs sorption (11, 16), an increase in N after displacement for all samples means that the energy of the sorption sites became more homogeneous due to the SOM swelling and/or occupation of “hole” sites in the condensed domain by phenanthrene (47). A similar increase in isotherm linearity using phenanthrene as the principal solute and
FIGURE 5. Site energy distributions of pyrene sorption before and after being displaced by phenanthrene. The sorption isotherm data are characterized by open circles; displacement data by solid circles. pyrene as the competitive solute was observed by Gunasekara et al. (32). Xing and Pignatello (9) interpreted the linearizing effect resulting from the cosolute as the result of the occupation and blocking of the adsorption sites while leaving the partition domain unaffected. The results presented in Figure 5 in the form of F(E*) versus the corresponding E* can be used for site energy distribution comparison after displacement, thereby facilitating our understanding of the nature of the displacement effect. Note that the E* range in this figure is limited to the experimental solute concentrations. Although it is practically difficult to determine the exact energy distribution of a sorbent over an experimental solute concentration range, it is possible to examine the relative changes in energy distribution before and after being displaced over an experimental concentration range. Due to the limited number of high-energy sites in the glassy (condensed) SOM domain, a greater proportion of pyrene would preferentially occupy these sites at low concentrations. When the displacer phenanthrene was introduced to the system, a larger percentage of pyrene would be displaced at low concentrations as compared to that at high concentrations. Our data showing the higher relative displacement percentage at low concentration than that at high concentration agreed well with observations of Gunasekara et al. (32) and Yuan and Xing (48). At moderate to high solute concentrations, a fraction of condensed SOM may convert to the rubbery state by a softening or “plasticization” effect, which was speculated by Huang and Weber (49), showing that high phenanthrene concentration reached equilibrium more quickly than at low concentration. This softening effect was hypothesized to be enhanced by the presence of displacer. The “plasticization” will increase the diffusivity of the principal solute molecules, since the diffusivity in the rubbery domain is generally much greater than in the condensed/glassy domain (11). However, more expanded domains created by this effect weaken the competitive sorption. Further analysis showed that, in all cases, the energy reduction after displacement was more significant for the high-energy sites (Figure 5), which is consistent with the findings of Yuan and Xing (48). This implied that the energy of the sorption sites will be more homogeneous after displacement, which is also clearly reflected by the increase in the Freundlich N and decrease in b after this process (Table 2). The magnitude of the displacement effect may likely depend on the extent of overlap between the hole-filling domain for the principal solute and that of the displacer molecules. The sorption capacity was reported to be closely related to the maximum number of sorption sites of sorbents, and
the total number of sorption sites can be characterized by the area under the site energy distribution F(E*) (33). It can be derived from the isotherm parameters listed in Table 2 that the change in organic-carbon-normalized sorption capacity for the Toyama soil sample before and after displacement was the largest, with the value decreasing from 5180 to 914 mg/g. Such a change for the Kanazawa sediment was the lowest, with the value from 2530 to 2120 mg/g. The result was consistent with the information illustrated in Figure 2 and Tables 1 and 3 and suggested that Toyama soil contained appreciable condensed SOM domain, thus exhibiting the strongest competitive sorption, while the condensed SOM content of Kanazawa sediment was the lowest. The decrease in the sorption capacity of all sorbents after displacement indicated that the displacer phenanthrene partially depleted a proportion of the sorption sites. The higher the condensed SOM content, the more visible is the depletion effect. In summary, the correlation between sorption nonlinearity of HOCs and the polarity index of SOM associated with soils and sediments provided additional evidence for understanding the relationship between the sorption behavior of HOCs and the chemical composition of SOM. A higher sorption affinity may decrease the bioavailability of pollutants, thus leading to difficulties in bioremediation and likely enhancing their sequestration in soil and sediment matrix. As a first attempt, the displacement test was performed by directly introducing a structurally analogous displacer (phenanthrene) to the system after pyrene sorption without decanting the test solution, which was of importance for distinguishing between desorption and displacement. The results showed that pyrene was displaced by phenanthrene in all systems. This finding implies that a cocontaminant of similar structure would liberate or facilitate the mobility and enhance the bioavailability of a contaminant previously sorbed by soils and sediments, thus posing a much more severe health threat to exposed organisms. In addition, comparison of the site energy distribution changes before and after displacer addition would provide a useful approach for interpreting the mechanism of displacement.
Acknowledgments We very much thank three anonymous reviewers for their helpful and constructive comments and Mr. Tamamura Shuji at Kanazawa University, Japan for his assistance with elemental composition determination. The study was supported by the 21st century COE (Center of Excellence) program of the Japanese Ministry of Education, Culture, Science and Technology and a USDA Competitive Grant (2002-35107-12544).
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Received for review January 17, 2005. Revised manuscript received August 7, 2005. Accepted September 2, 2005. ES050107S
