Factors controlling chromium release from chromate containing soils.
Chromium exists in two forms in nature as [Cr.sup.3+] and [Cr.sup.6+], and among those [Cr.sup.6+] is highly toxic and is documented as high priority pollutant (Sharma et. al., 2007). Not only the toxicity of Cr but also its aqueous concentration and its mobility in different geologic environments are dependent on its oxidation state (Rai et al., 1989). Hexavalent Cr is one of the most poisonous chemical states in the environment. In Japan, [Cr.sup.6+] bearing waste from factory caused serious environmental problem in urban area. For example, about 36 years ago at the Kazenohiroba, Edogawa area in Tokyo, the [Cr.sup.6+] bearing waste was reduced by [Fe.sup.2+] (FeS[O.sub.4]) and disposed in shallow underground (1-2 m depth) and covered by volcanic soil. However, [Cr.sup.6+] containing groundwater migrated to the surface and inputted into the Arakawa River which is located close to the disposal site. In order to solve this sort of environmental problem caused by the contamination, it is necessary to elucidate the Cr behavior during soils-groundwater interaction. It is inferred that behavior depends on the site characters; especially the role of soils controlling the Cr behavior is important and has to be studied. However, a few studies on the Cr behavior in the Japanese soils-groundwater interaction have been carried out. Thus, the present study was conducted to know the interaction between Cr containing soil and aqueous solution to consider the factors controlling the Cr release from Cr contaminated soil by using the volcanic soil (andosol and loam), which is a typical and widely distributed soil in Japan.
The contaminated soils was collected from factory ruins in Chiba Prefecture, Japan and the standard soils (JSO-1 & JSO-2) from the Geological Survey of Japan. Experiment was conducted in the Laboratory of Geochemistry, School of Science for Open & Environmental Systems, Faculty of Science and Technology, Keio University, Japan.
Materials and Methods
Three types of samples were used for the experimental study. These were a contaminated soil collected from the ruins of the certain chemical factory, JSO-1 and JSO-2 (standard soil samples provided by the Geological Survey of Japan). The JSO-1 is uncontaminated loam soil and JSO-2 is contaminated soil, and these two samples were used by mixing at a ratio of 1:4, respectively. Chromium was added 1000 [micro]g [g.sup.-1] in the contaminated soil and in mixed soil (JSO-1: JSO-2) in the form of [K.sub.2]Cr[O.sub.4] which implies that almost all chromium was in the [Cr.sup.6+] form. It is confirmed the existence form of the trace element, and the source soil becoming the raw materials is the andosol soil, which was collected from the Tsukuba City outskirts. The basic material is the volcanic ash which comes from the Fuji or Hakone volcanoes.
Reagents and instrumentation
All chemicals and reagents were of analytical reagent grade quality (Sigma-Aldrich, USA and Wako, Japan). Millipore water was used throughout all the experiments. Before use, all glass and plastic ware were soaked in 14% ultrapure [HNO.sub.3] for 24 hrs. The washing was completed with Millipore water rinse. The pH, EC (electrical conductivity) and ORP (oxidation-reduction potential) were measured by using Towa DKK HM-20P pH meter, Towa DKK CM-21P EC meter and Towa DKK RM-20P ORP meter, respectively.
Major elemental constituents of the sample was determined by X-ray Fluorescence spectroscopy, employing a Rigaku RIX 1000 (Tokyo, Japan) XRF. For the preparation of beads, 0.4000 [+ or -] 0.0005 g dry oxidized (at 900[degrees]C for 14 hrs) samples, lithium tetraborate (4.0 g) and lithium iodide (50 mg) were mixed together and used a Bead Sampler NT-2100 (Tokyo, Japan). Plate calibration was performed using geological standards of Geological Survey of Japan (JB-3, JF-1, JG-2, JGb-2, JH-1 and JSy-1) following the manufacturer's recommendations.
The concentrations of Cr were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) at National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan following JIS K 0102 (JIS, 2008). A Bruker AXS: D-8 Advance (Berlin, Germany) X-ray Diffractometer was employed for XRD (X-Ray Diffraction) analysis.
Five kinds of solution with pH 3, 5, 7, 9 and 11 were used in the experiments for each soil. Nitric acid (HN[O.sub.3]) and [Na.sub.2]C[O.sub.3] were used into Millipore water to adjust pH of the initial solution. Exactly, 0.5 g soil and 20 ml solution were mixed in 50 ml polypropylene centrifuge tubes (Nalgene, New York). After shaking for 0, 1, 3, 7 and 10 days, it was filtrated through Millipore filter (0.45[micro]m), and the filtrate was collected in a polyester container. After each step, pH, EC, and ORP were measured in the filtrate and then the solutions were prepared for ICP-MS measurement following the manufacturer's recommendations.
Sequential extraction experiments
Recently Zakir and Shikazono (2008) conducted a comparative assessment of four commonly used sequential extraction procedures for trace metal partitioning in different types of sediments and reported that Hall scheme (Hall et al., 1989) recovered the maximum trace metal content. But in Hall scheme, they combined exchangeable and carbonate bound phases as AEC (adsorbed, exchangeable and carbonate bound) fraction. However, another widely used Tessier scheme (Tessier et al., 1979) has the opportunity to get specific information on exchangeable and carbonate bound fractions. Due to reasons mentioned above, present study has adopted from Hall and Tessier schemes as described in Fig. 1.
[FIGURE 1 OMITTED]
Experiments on the types of iron in soil
We carried out the analysis according to the type of the iron (each iron type) based on JIS method. This test method is established as a Japanese standard test method and it is called a JIS (Japanese industrial test method). In this study, we selected the JIS M 8312 (JIS, 1997). This analysis is the method how left [Fe.sup.3+] demands it from a calculation after having measured separately the total iron and [Fe.sup.2+]. The detailed procedure is as follows.
(1) Procedure of Total iron analysis
The melting for sample 2g with mixed reagent 5g (sodium carbonate anhydride and the sodium peroxide) under the heating condition.
(a) After the melting, it makes the water solution with sulfuric acid(1+1) 50m1 and warm water 80m1.
(b) After the addition of the hydrogen peroxide (1+9) 2m1 and heating with solution.
(c) After heating, this solution does cool.
(d) The heat again after adding hydrochloric acid (1+1) 10ml to a sample and let it add titanium (III) chloride promptly and reduce iron to its elements.
(e) After the indigo carmine, that did drip till a color of the solution changes into blue from colorlessness in [K.sub.2][Cr.sub.2][O.sub.7] standard solution.
(f) Finally it substitute measurement numerical value for a calculating formula and decide all iron.
(2) Procedure of [Fe.sup.2+] analysis
(a) After take the new sample Ig and adding the water 10ml and sulphuric acid (1+1) 20m1.
(b) Several times (5-7minutes) heating the sample solution with carbon dioxide gas flowing.
(c) If the dissolution is possible, it cools off. And hydrofluoric acid 10ml is added and heated again for 10minute.
(d) This solution does titration of diphenyl amine-4-sulfuric acid sodium with [K.sub.2][Cr.sub.2][O.sub.7] standard solution as the indicator.
(e) The numerical value got by this operation experiments at the [Fe.sup.2+].
(3) Procedure of [Fe.sup.3+] analysis
(a) [Fe.sup.2+] is provided by multiplying conversion rate to the content that does deducts [Fe.sup.2+] from total iron.
The analysis of amorphous substance materials in the soil
We carried out the analysis of amorphous substance materials based on Parfit and Wilson (1985) and Blakemore et al. (1981). The experiment increases oxalic acid--oxalic ammonium buffer solution to dry sample 1g and lets concussion while doing slanting rays of light for 4 hours. After concussion, the sample added macromolecule flocculant and 10 minutes. It confirmed the allophone materials while analyzing AAS (Atomic Absorption spectrometry) about the supernatant liquid.
Results and Discussion
Major chemical constituents and trace elements in the sample
The major chemical constituents and trace element concentrations of the soils used in the study are presented in Table 1. Major component concentrations suggest, besides the obvious presence of quartz, other aluminosilicate minerals, as well as the presence of iron oxides, and to a lesser extent, calcium, magnesium, titanium and phosphorus containing mineral phases. However, iron and aluminum oxides were almost twice in JSO-1 and JSO-2 soil than contaminated soil. On the other hand calcium and magnesium oxides were higher in contaminated soil than standard JSO-1 and JSO-2 (Table 1).
JSO-1 and JSO-2 used in the present study are standard soils, and among those JSO-1 is uncontaminated loam soil and JSO-2 is contaminated soil. It is employed as a rock standard sample widely. Analytical data on the soils used in this study i.e., the standard rocks of Geological Survey of Japan (JSO-1, JSO-2, Basalt (JB-3), Andesite (JA-1), Rhyolite (JR-1), Granodiorite (JG-1)) and contaminated soil are plotted in ([Na.sub.2]O+[K.sub.2]O)-Si[O.sub.2] and [Al.sub.2][O.sub.3]-[Fe.sub.2][O.sub.3] diagram (Figs.2 and 3, respectively). It is evident from both the figures that the analytical data of studied soils were close to basalt data, but different from the other rocks. Thus, the source rock of these samples is considered to be mostly of basaltic source. Si[O.sub.2] and ([Na.sub.2]O+[K.sub.2]O) contents of contaminated soil plot closer to the basalt than JSO-1 and JSO-2, suggesting these standard samples were suffered weathering more intensely which caused dissolution of [Na.sub.2]0, [K.sub.2]O and Si[O.sub.2] than the contaminated soil (Fig.2).
[FIGURE 2 OMITTED]
Mineralogy of the studied samples was obtained by XRD analysis, and the results are presented in Table 2. Quartz is common in the JSO-1: JSO2 mixed soils including the plagioclase and gibbsite (Terashima et al. 2000). However, orthopyroxene, olivine and mangnetite were also detected in contaminated soils including allophane and quartz (Table 2). Allophane was identified based on the methods by Parfitt and Wilson (1985) and Blakemore et al. (1981), is also presented in Table 2. Allophone is abundant in JSO-1:JSO-2 mixed soils and it is contained in contaminated soils.
Effect of shaking time and solution condition on pH and Eh
The changes of pH and Eh due to shaking time along with solution condition were plotted in Figs. 3 and 4. It is evident from the Fig. 3 (A) that the pH of JSO-1: JSO-2 mixed soils were almost 7 after 1 day shaking (except pH 11 solution). On the other hand, pH of the contaminated soil also changed within 1 day, and all solutions became alkaline (pH 10-11) (Fig. 3 B). The results inferred that the reason might be due to the different composition of the soils. But incase of Eh, shaking time and most of the solution type showed almost similar effect on both soils and the average Eh value was near about 400 mV after 1 day shaking (Fig. 4 A and B).
[FIGURE 3 OMITTED]
[FIGURE 4 OMITTED]
Relation between Eh and pH
To study the relation between the Eh and pH, the data obtained by this study were plotted in the Eh-pH diagram for chromium as described by Zachara et al. (1989) (Fig. 5). The pH of the JSO-1: JSO-2 mixed soil solution shifted towards neutral (pH 7) within 1 day shaking (Fig. 4A). The Eh of the same mixed soil solution lies close to Cr[O.sub.4.sup.2-]/Cr[(OH).sub.3][degrees] boundary and most of the data are plotted in Cr[(OH).suh.3] [degrees] dominant region (Fig. 5). On the other hand, pH of the contaminated soil solution showed almost a constant value after 1 day shaking and became more alkaline (pH 10-11). And the data are plotted in Cr[O.sub.4.sup.2-] region of the Eh-pH diagram (Fig. 5).
[FIGURE 5 OMITTED]
It should be mentioned here, even if the first solution pH was strong acid (pH=3) for the JSO-1: JSO-2 mixed soils, it has been migrated to the neutrality to slightly alkaline after 1 day shaking (Fig. 3 A). On the hand, the same strong acid solution for the contaminated soils has been migrated to strong alkaline after 1 day shaking (Fig. 3 B). These results inferred that [Cr.sup.6+] [Cr[O.sub.4.sup.2-] region] is reduced to its elements i.e. [Cr.sup.3+] [Cr[(OH).sub.3] region] by iron oxides (FeO) present in basaltic glass and adsorption of [Cr.sup.3+] by weathering product (e.g. allophane, iron hydroxide) in the soils (Figs. 6 & 7).
[FIGURE 6 OMITTED]
[FIGURE 7 OMITTED]
Relation between Cr concentration and pH
The relation between Cr concentration and pH are shown in Fig. 8. These data indicate that the Cr concentration decreases with shaking time. The Cr concentration for JSO-1: JSO-2 mixed soils varied widely. It is also evident from the Fig. 7 that the Cr concentration in alkaline solutions tends to be higher than in acidic solution both for JSO-1: JSO-2 and contaminated soils.
[FIGURE 8 OMITTED]
Hexavalent chromium ([Cr.sup.6+]) reacts with numerous reducing agents commonly found in the environment. Rai et al. (1989) reported that [Cr.sup.6+] is reduced within a few seconds by reaction with [Fe.sup.2+], and in a matter of hours to days by [Fe.sup.2+] containing oxide and silicate minerals (Venkateswaran and Palanivelu, 1977). Hexa-valent chromium ([Cr.sup.6+]) adsorption was greatest in lower pH materials enriched in kaolinite and crystalline iron oxides. Over a range in pH, [Cr.sup.6+] adsorption to subsoil was similar to that observed for pure-phase oxides (Davis et al., 1980). These results clearly indicate that the Cr concentration for JSO-1: JSO-2 mixed soil is distinctly lower than that for contaminated soil series. This difference could be explained in three possible mechanisms: 1) reduction of [Cr.sup.6+] released from the soils to [Cr.sup.3+] at initial stage; 2) adsorption of [Cr.sup.3+] on the mineral surfaces, and 3) ion exchange of [Cr.sup.6+] in solution with [Fe.sup.3+] in soils. The reduction of [Cr.sup.6+] could occur by [Fe.sup.2+] in soil. There are several reports stated that [Cr.sup.3+] is adsorbed by mineral solids that have exposed inorganic hydroxyl groups on their surfaces, including iron and aluminium oxides (Khanodhiar et al., 2000; White and Peterson, 1996). As shown in Table 1, T-[Fe.sub.2][O.sub.3] (FeO + [Fe.sub.2][O.sub.3]) of JSO-1: JSO-2 is higher (10.38 wt %) than that of contaminated soil (4.5 wt %), suggesting JSO-1: JSO-2 mixed soil has higher capability of reduction of [Cr.sup.6+] than contaminated soils. This result is at par with the findings of Eary and Kine (1989). The changes of Eh and pH from initial to final stage of the experiments are schematically shown in Figs. 6 and 7.
Relation between Cr concentration and the form of Fe in the samples
Experimental studies demonstrate that structural Fe(III) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions all the oxide surfaces over a pH range of 1-7 at 25[degrees]C. For an aqueous transition metal m , such reactions are
3[[Fe.sup.2+] [Fe.sup.3+]][O.sub.4(magnetite)]+ 3/n [m.sup.Z] [right arrow] 4[[Fe.sub.2.sup.3+]] [O.sub.3(maghemite)]+ [Fe.sup.2+] + 2/n [m.sup.Z-n]
3[[Fe.sup.2+] Ti][O.sub.3(ilmenite)]+ 2/n [m.sup.Z] [right arrow] 4[[Fe.sub.2.sup.3+]] [O.sub.3(maghemite)]+ [Fe.sup.2+] + 2/n [m.sup.Z-n],
where z is the valance state and n is the change transfer number(White et. al., 1996). It is clear from the above results and discussion that the iron content in the soil affects the oxidation-reduction reaction of the chromium. This study also determined the different forms of iron ([Fe.sup.2+] and [Fe.sup.3+]) in the soils and the results are summarized in Fig. 9, which clearly indicates that Total- Fe, [Fe.sup.2+] and [Fe.sup.3+] contents of JSO-1: JSO-2 soils are higher than those of contaminated soils.
[FIGURE 9 OMITTED]
On the basis of XRD data, the existence of clay minerals in both soils is not clear, suggesting the amorphous phases are present in the soils. According to Marumo (2003), secondary minerals and amorphous phases (e.g. allophane, iron oxyhydroxide) in Japanese soils have high adsorption capacity. In order to know the degree of weathering which is reflected by proportion of secondary phases, CIA (Chemical Index of Alteration) ([Al.sub.2][O.sub.3] / [Al.sub.2][O.sub.3] + CaO + [Na.sub.2]O + [K.sub.2]O in wt %) was calculated, and the values were 0.822 and 0.453 for JSO-1: JSO-2 and contaminated soils, respectively. Therefore, adsorption of [Cr.sup.3+] in secondary phases, ion exchange of [Cr.sup.3+] for [Fe.sup.3+] and [Al.sup.3+] in secondary phases are considered to be important mechanisms of [Cr.sup.3+] removal from the solution particularly by JSO-1: JSO-2 soils.
Result and consideration of the extraction experiments of the Cr
The results of the extraction experiments are presented in Fig. 10. It was apparent from the results of both samples the maximum Cr were present in bound to Fe-Mn oxide phase and bound to organic matter phase. In case of JSO-1: JSO-2 mixed soil Cr content was very low in exchangeable and silicates and residual phase. The reason may be due to very high content of Cr is included with allophane and iron in the soils. The extraction experimental results also support the findings stated above. It is apparent that the Cr in the JSO-1:JSO-2 mixed soil were the mixed substance of the Fe-Mn oxide mineral and organic compound.
[FIGURE 10 OMITTED]
Experimental studies on the interactions of basaltic soils (JSO-1: JSO-2 mixed soil and contaminated soil, in which [K.sub.2]Cr[O.sub.4] was added) and aqueous solutions with different pH (3, 5, 7, 9 and 11) were conducted at 25[degrees]C. The study indicates that pH, Eh and Cr in solution increased very rapidly (within 1 day) and became nearly constant values after three days. The Eh and pH data for JSO-1: JSO-2 experiments lie parallel to Cr[O.sub.4.sup.2-]/ Cr[(OH).sub.3][degrees] boundary indicating pH and Eh values were controlled by these Cr species. The study results indicate that [Cr.sup.6+] in the soils released rapidly to the solution and was reduced to Cr 3' by the soils. The capability of the reduction of [Cr.sup.6+] and fixation of Cr by JSO-1: JSO-2 mixed soil were higher than contaminated soil.
These differences in the features of both types of soils controlling the Cr behavior between the soils and aqueous solution interactions are considered to be controlled by FeO and the degree of weathering (CIA) of the soils. Generally, [Cr.sup.6+] concentrations under acidic to slightly alkaline conditions are primarily controlled by adsorption--desorption reactions. The site concentration of a given adsorbent is controlled by its exposed surface area, because hydroxyl groups typically occur at a fixed concentration per unit of surface. At a fixed site concentration for each adsorbent (aluminum oxide, iron oxide), iron oxides exhibit the strongest adsorptive for Cr[O.sub.4.sup.2-], and adsorbed Cr[O.sub.3.sup.2-] may be easily reduced to [Cr.sup.3+] by [Fe.sup.2+] present in minerals, volcanic glass and amorphous phase. Ion exchange of [Cr.sup.3+] in solution for [Fe.sup.3+] and [Al.sup.3+] in secondary phases may also be possible mechanism of [Cr.sup.3+] removal from the solution.
The experimental results showed that the level of Cr in the aqueous solution was less than the stipulated values (average concentration of Cr in Japanese soils is 25-60mg [kg.sup.-1]; Asami, 2001). The highly weathered volcanic soils studied, particularly JSO-1: JSO-2 soil, which contains high amounts of [Fe.sup.2+], total Fe and amorphous phase, and is intensely weathered may be useful to remove Cr from the solution and prevent the [Cr.sup.6+] release from the highly contaminated soil.
We thank Dr. K. Minoshima, AIST, Tsukuba, Japan for her kind assistance in ICPMS analysis.
 Asami, T., 2001, "Harmful heavy metal pollution of the Japanese soil," AGUNE Publication Center Ltd, 195-212.
 Davis, J. A. and Leckie, J. O., 1980, "Surface ionization and complexation at the oxide / water interface," Journal of Colloid and Interface Science, 74 (1), 32-43.
 Eary, L. E. and Kine, D. R., 1989, "Kinetics of chromate reduction by ferrous ions derived from hematite and biotite at 25[degrees]C ," Am. J. Sci., 289, 180-213.
 Hall, G. E. M., Vaive, J. E., Beer, R. and Hoashi, M. 1996, "Selective leaches revisited, with emphasis on the amorphous Fe oxyhydroxide phase extraction," Journal of Geochemical Exploration., 56, 59-78.
 JIS (Japanese Industrial Standard), 2008, "Testing methods for industrial wastewater," Japanese Industrial Standards Committee, Tokyo, Japan, 260-267.
 JIS (Japanese Industrial Standard), 1997, "Methods for determination of iron in titanium ores," Japanese Industrial Standards Committee, Tokyo, Japan, 114.
 Khanodhiar, S., Azizan, M. F., Osathaphan, K., and Nelson, P. O. 2000, "Copper, chromium, and arsenic adsorption and equilibrium modeling in an iron-oxide-coated sand background electrolyte system," Water, Air & Soil Pollution., 119, 105-120.
 Marumo, K. 2003," The geological feature of pollution purification using mineral materials, "The 50th Anniversary of the Society of Resource Geology Foundation Memory," The Society of Resource Geology, 393-398.
 Parfitt, R.L., Wilson, A.D. and Hutt, L. 1985, "Estimation of allophone and halloysite in three sequences of volcanic soils, New Zealand ," Catena Suppl , 7, 1-8.
 Rai, D., Eary, L. E. and Zachara, J. M. 1989, "Environmental chemistry of chromium," Science of The Total Environment, 86, 15-23.
 Sharma, Y. C., Uma, Srivastava, V., Srivastava, J., Mahto, M., 2007, "Reclamation of Cr (VI) rich water and wastewater by wollastonite," Chemical Engineering Journal, 127, 151-156.
 Terashima, S., Imai., N., Tominaga, M., Hirata , S. and Taniguchi , M., 2000, "Preparation of a new GSJ geochemical reference material : JSO-2 soil," Bunseki Kagaku, 49 (5), 319-324.
 Tessier, A., Campbell, P. G. C. and Bisson, M., 1979, "Sequential extraction procedure for the speciation of particulate trace metals," Analytical Chemistry, 51 (7), 844-851.
 Venkateswaran, P. and Palanivelu, K., 2005, "Studies on recovery of hexavalent chromium from plating wastewater by supported liquid membrane using tri-n-butyl phosphate as carrier," Hydrometallurgy, 78: 107-115.
 White, A. F. and Peterson, M. L., 1996, "Reduction of aqueous transition metal species on the surfaces of Fe (II)-containing oxides," Geochimca et Cosmochimica Acta, 60 (20), 3799-3814.
 Zachara, J. M., Ainsworth, C. C., Cowan, C.E. and Resch, C. T., 1989, " Adsorption of chromate by subsurface soil horizons," Soil Sci. Soc. Am. J., 53, 418-428.
 Zakir, H. M. and Shikazono, N., 2008, "Metal fractionation in sediments: a comparative assessment of four sequential extraction schemes," Journal of Environmental Science for Sustainable Society, 2, 1-12.
Kazuo Otomol *, Jayank Srivastava (1), H. M. Zakir (2), K. M. Mohiuddin (1,2) and Naotatsu Shikazonol
(1) Laboratory of Geochemistry, School of Science for Open & Environmental Systems, Faculty of Science and Technology, Keio University,
Hiyoshi 3-14-1, Yokohama 223-8522, Japan.
E-mails: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org
(2) Department of Agricultural Chemistry, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.
Table 1: Major chemical constituents (wt %) and trace element concentrations ([micro]g g-1) of the soil. Major JSO-1 * JSO-2 * JSO- contaminated soil chemical 1:JSO-2 No addition Addition consti- of Cr of Cr tuents Si[O.sub.2] 38.37 42.24 41.46 47.65 47.61 Ti[O.sub.2] 1.23 1.14 0.19 0.38 0.37 [Al.sub.2] [O.sub.3] 18.06 21.34 20.68 9.06 9.05 T-[Fe.sub.2] [O.sub.3] * 11.1 10.2 10.38 4.55 4.54 MnO 0.20 0.18 0.18 0.84 0.83 MgO 2.11 1.66 1.75 3.23 3.21 CaO 2.55 1.09 1.38 8.13 8.12 [Na.sub.2]O 0.67 1.03 0.95 1.29 1.28 [K.sub.2]O 0.34 1.55 1.07 1.54 1.56 [P.sub.2] [O.sub.5] 0.48 0.15 0.21 0.18 0.17 LOI *** 33.49 23.58 32.48 36.54 36.29 Trace elements As 8.1 1076 862 1.73 1.73 Co 32 1071 863 0.66 0.66 Cr 71 1118 909 85.96 1034.4 Cu 169 1276 1055 20.15 20.12 Ni 39 1070 864 29.85 29.82 Pb 13 1087 872 34.69 34.64 Zn 105 1174 792 136.5 136.2 * analyzed by Geological Survey of Japan (Terashima et al. 2000). ** T-[Fe.sub.2][O.sub.3] = FeO + [Fe.sub.2][O.sub.3] *** LOI means loss of ignition. Table 2: Mineral constituents in the studied sample. MINERALS Level of abundance JSO-1/JSO-2 JSO-2 * Contamination soils Allophane +++ +++ + Quartz + + - + Plagioclase - + X K-feldspar X - X Augite - + X Gibbsite + - + X Hematite - - X Magnetite - - + 7A halloysite X - X Orthopyroxene X X + - Hydrated halloysite X - X Olivine - - + Glass + - + - +++ abundant; + -: common; +: existent; -: rare, X: not detected * Terashima et al., (2000).
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|Author:||Otomo, Kazuo; Srivastava, Jayank; Zakir, H.M.; Mohiuddin, K.M.; Shikazono, Naotatsu|
|Publication:||International Journal of Applied Environmental Sciences|
|Date:||Jun 1, 2009|
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