Environ Monit Assess (2015) 187:98 DOI 10.1007/s10661-015-4330-z
Impact of pulp and paper mill effluents and solid wastes on soil mineralogical and physicochemical properties Gopi Adhikari & Krishna G. Bhattacharyya
Received: 23 April 2014 / Accepted: 26 January 2015 # Springer International Publishing Switzerland 2015
Abstract The present study was carried out to evaluate the impact of the effluents and the solid wastes generated by a giant pulp and paper mill in the northeastern part of India on soil mineralogy of the area. The impacts were monitored by analysis of soil samples from seven sites located in the potential impact zone and a control site where any kind of effluent discharge or solid waste dumping was absent. The soil belonged to medium texture type (sandy clay loam, sandy loam, loamy sand, and silt loam), and the soil aggregate analysis indicated higher levels of organic carbon, pH, electrical conductivity, effective cation exchange capacity, and mean weight diameter at sites receiving effluents and solid wastes from the pulp and paper mill. Depletion in soil silica level and in feldspar and quartz contents and rise in iron and calcium contents at the sites receiving effluents from the pulp and paper mill indicated significant influence on soil mineralogy. The soil contained a mixture of minerals consisting of tectosilicates (with silicate frameworks as in quartz or feldspar), phylosilicates (layered clays like kaolinite, smectite, chlorite, illite, etc.), and carbonates. Absence of pure clay minerals indicated a state of heterogeneous intermediate soil G. Adhikari Department of Chemistry, Jagiroad College, Jagiroad 782410, India e-mail: [email protected] K. G. Bhattacharyya (*) Department of Chemistry, Gauhati University, Guwahati 781014, India e-mail: [email protected]
clay transformation. The significance of the mixed mineralogy in relation to the disposal of effluents and dumping of solid wastes is discussed in details. Keywords Soil aggregate analysis . Mineralogical composition . Influence of pollutants on soil properties . Soil organic carbon . Texture analysis
Introduction Soil mineralogy is an important tool to provide information regarding fertility status, stage of weathering, etc. and is helpful in inferring the soil status (Miller and Donahue 1992). Soil clays are considered to be the most important components, as any contaminant making its way into soil has to interact with the clays (Prost and Yaron 2001). The transformation of soil mineralogical composition depends on the clay, silt, and sand fractions, which exist in a dynamic equilibrium in the soil. Clays are highly polar and are considered as the reactive component in soil. Soil clay is also well known for providing a large reactive surface area per unit weight. The polar nature of soil clay accounts for its cation exchange capacity. Amongst the most prominent cation exchangers, the naturally available alkali and alkaline earth metal ions are the pioneers in the overall weathering processes resulting in transformation of soil clay mineralogy. Pulp and paper industry is a water-intensive industry, and it generates large volumes of effluents. It is ranked at the third position in terms of fresh water consumption
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after the primary metal and chemical industries (Asghar et al. 2008). A large amount of solid wastes is also simultaneously generated, and these include the causticizing wastes (in the form of lime sludge), ash from boilers, sludge from wastewater treatment processes, and unused raw materials (such as bamboo dust) (Amini et al. 2012). On an average, a typical paper mill produces 45 kg of waste sludge per ton of paper produced (Edalatmanesh et al. 2010) and effluent generation ranges from 1.5 to 60 m3 (Thompson et al. 2001; Szolosi 2003), based on technology and nature of raw materials. Indiscriminate and unplanned waste disposal has been an unwelcome common practice with the pulp and paper mills, particularly in the developing and the underdeveloped countries, which is a matter of concern (Whitehead and Geary 2000). The waste products are always evaluated as ecological burden contributed by paper industries. The paper wastes make their way to the three major components of the environment viz. soil, air, and water. Based on the waste disposal methods, the effluents and the solid wastes have different contributions to the overall ecological health and each carries distinct ecological burden. It is frequently reported that the conventional methods of effluent treatment like the use of biological oxidation using activated sludge and aerated lagoon are often inadequate to get rid of the composite organic and inorganic mixture of pollutants (Raj et al. 2014). In many cases, the bio-solids discarded from the activated sludge treatment system are spread over agricultural fields to improve soil fertility and other physicochemical properties (Park et al. 2011). The added organic matter contains low-molecular-weight organic acids, capable of chelating Al3+ and Si4+ ions present in the clay minerals in the soil framework (Chatterjee et al. 2013). As a result of this type of chelation, the clay minerals in the soil become deficient in Al3+ and Si4+ ions that occupy the centers of the tetrahedral and octahedral basic structural units. This deficiency is adjusted by a forced rearrangement of the constituents leading to soil clay transformation. Moreover, it is known that the pulp and paper mill wastes, enriched with organic matter, are alkaline in nature, and the OH groups, contributing to alkalinity, can link the clay octahedra through the O-end in intertype and intratype of combinations. During the rearrangement processes, the inclusion and exclusion of metallic moieties that are the abundant constituents of the chemical wastes have greater chances to be inserted, resulting in the clay transformation.
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Moreover, components like organic carbon from the effluent and solid wastes in association with the soil mineral particles contribute to the lowering in the particle as well as bulk density. They contribute to higher porosity resulting into alteration of soil processes like aeration, water holding capacity, etc. Higher soil aeration increases the oxidation processes in soil, and higher water retention leads to an anaerobic situation. These are considered as the factors responsible for changes in the natural oxidation processes in soil. The altered oxidation activity, abundance of ionic species contributed by the effluents, and predominant alkaline environments are sure to alter the soil natural environment along with its clay, the most active soil component in its content and nature. The present work tries to find out the changes in soil mineralogical composition including the clay minerals upon exposure to the paper mill effluents and the solid wastes over a long period of time.
Materials and methods Soil sampling sites The site selection for soil sampling was based on the proportionate area of location of the pulp and paper mill (Nagaon Paper Mill of Hindustan Paper Corporation Limited, situated at Jagiroad, India; installed capacity 100,000 t per annum of high-quality printing paper). The soil samples were collected from eight locations (CS, S1–S7) (Table 1) that include the control site (CS) (at a distance of 1 km from the effluent treatment plant of the mill where any kind of effluent discharge or solid waste dumping is absent), two sites, S1 and S2, from solid waste dumping locations, and five sites, S3–S7, from effluent discharge locations. These are also shown in Fig. 1. The sampling sites belong to tropical rainforest climate region, subjected to a humid subtropical climate. The average rainfall in the area is 1530 mm, with average temperature 25.5–32.9 °C (summer) and 19.8– 24.8 °C (winter), with annual average of 19.8–30.4 °C. Soil sampling and preparation At each site, three soil samples were collected from a 1-m2 area up to 20-cm depth (average conventional tillage depth) using a 5-cm corer and the soil samples were homogenized to form a composite sample that
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Table 1 Location, land use pattern, and a brief description of the sampling sites Site
Soil type
Location
Description of the site
CS
Control site
26° 07′ 25.1″ N 92° 11′ 28.5″ E
Rural site away from the mill, not receiving effluent discharge or solid waste dumping
S1
Solid waste dumping
26° 07′ 43.0″ N 92° 14′ 05.6″ E
Dumping of lime waste from caustic chlorine plant near the residential colony
S2
Solid waste dumping
26° 07′ 38.5″ N 92° 14′ 30.7″ E
Dumping of coal fly ash from the mill near the residential colony
S3
Waste sludge disposal
26° 07′ 50.8″ N 92° 12′ 41.9″ E
Dumping of the sludge from the effluent treatment plant (ETP)
S4
Treated effluent discharge
26° 08′ 07.1″ N 92° 12′ 31.4″ E
Treated effluent from the ETP discharged through an underground channel to a natural wetland, the Elenga Beel
S5
Treated effluent route
26° 07′ 52.6″ N 92° 12′ 40.8″ E
Agriculture land at a distance of 50 m from S3
S6
Treated effluent route
26° 07′ 53.5″ N 92° 12′ 40.9″ E
Agriculture land at a distance of 100 m from S3
S7
Treated effluent route
26° 07′ 57.4″ N 92° 12′ 35.5″ E
Agriculture land at a distance of 500 m from S3
was likely to be representative of the specific soil type at a particular location. The samples were air-dried and passed through a 2-mm sieve, after which they were preserved for laboratory analysis. The samples were collected in three seasons viz. hot dry summer (April to June), Wet hot summer (July to September), and cold dry winter (November to February) to take into account the impact of change in climate. Analysis of soil samples Analysis of soil physicochemical parameters was done by following standard methods, i.e., soil composition with respect to sand, clay, and silt percentage by the hydrometer method; soil texture by ISSS triangle method (Reeuwijk 2002); soil organic carbon (SOC) by modified Walkley-Black method (Sarkar and Halder 2010); and electrical conductivity (EC) (1:5 soil/water suspension, Elico CM 180) (Sarkar and Halder 2010), pH (1:5 soil/water suspension, Elico LI 120) (Jackson 1958), and effective cation exchange capacity (ECEC) by ammonium acetate method (Hasse 1994). Soil aggregate analysis was done following the wet-sieving technique of Yoder 1936 (Baruah and Barthakur 1997). Soil stability was expressed in terms of percentage as well as mean weight diameter (MWD), which is defined as the sum of the product of the mean diameter, Xi, and the total sample weight, Wi, of each size fraction (MWD=∑ Xi Wi) (Baruah and Barthakur 1997). Each analysis was done
in triplicate, and the means of the three values are reported here. Portions of the soil samples were pulverized and subjected to XRF analysis to obtain soil mineralogical composition. The soil samples were soaked in water and treated with 30 % H2O2 to remove organic matter, and the soil clay was separated by dispersion and gravity separation. The clay fraction ( CS > S4 > S5 > S7 > S1 > S6 > S2
2. pH (Fig. 3): S5 > S6 > S1 > S7 > S4 > S2 > S3 > CS 3. Conductivity (Fig. 3): S3 > S7 > S5 > S4 > S6 > S1 > S2 > CS 4. ECEC (Fig. 3): S5 > S6 = S7 > S4 > S3 > S1 > S2 > CS
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S6
8
SOC and MWD
S7
Sampling sites
S5 S4 S3 S2
SOC % MWD
6 4 2 0
S1
CS
S1
S2
CS 0
10
50 0 40 30 n (%) Composition C
20
Sand (%)
Siilt (%)
600
70
80
5. Organic carbon (Fig. 4): S3 > S2 > S4 > S5 > S6 > CS > S1 6. Aggregate stability in MWD (Fig. 4): S1 > S5 > S3 > S6 > S4 > S2 = S7 > CS
pH, conductivity, CEC
Though the soil of the CS possesses higher clay content (except S3), its organic carbon content is slightly higher than S1 (waste lime dumped area). Effective cation exchange capacity (ECEC), pH, and conductivity of the soil had the minimum values in the CS. Similarly, when aggregate stabilities of the soils are compared on the basis of mean weight diameter (MWD), all the soils receiving pollutants have greater MWD, i.e., higher aggregate stability than the CS soil. This may be due to the presence of higher concentration of calcium carbonate in the effluents from causticizing plant along with higher organic matter. Calcium carbonate contributes to aggregate stability through its cementing effect, and similar enhancement is possible with high organic matter that increases overall negative charge. These
pH Conductivity dS/m CE EC cmol/ kg
30 25 20 15 10 5 0 CS
S1
S2
S3 S4 Sampling site
S6
S7
Fig. 4 Interrelationships between soil organic carbon (%) and soil aggregation (MWD)
Clay (%))
Fig. 2 Relative composition of clay, silt, and sand at the sampling sites
45 40 35
S3 S4 S5 Sampling sitees
S5
S6
S7
Fig. 3 Variation of pH, electrical conductivity, and cation exchange capacity (CEC) for the different sampling sites
observations suggest that there may be organic, alkaline, and soluble salt inputs to the sampling points along with the effluents and wastes from pulp and paper mill. Soil mineralogy The average chemical composition of the soil samples (Table 2) shows the presence of abundant amount of CaO (except at the site, S2, where coal ash is regularly dumped) and drastically reduced SiO2 in the soil of the sampling sites affected by the pulp and paper mill effluents and solid wastes. The CS had higher SiO2 content than the other sites receiving either solid wastes or treated effluent discharge from the paper mill. However, the soil from the CS had less Fe2O3 and CaO compared to the other sites. Higher CaO in the sites having impacts from the paper mill operations suggests presence of carbonates of Ca that broke down into CaO during heating to determine LOI through loss of CO2. The soil in the sites receiving pollutant loads from the mill had much higher values of loss on ignition (LOI) indicating the presence of higher amounts of organic matter and possibly carbonates. It has been shown from Si-isotopic signature studies that Si is the key factor of clay mineralogy, often induced by the climate gradient (Opfergelt et al. 2012). The observed reduction in SiO2 and, hence, Si in the present work is apparently due to the enrichment of the soil by organic wastes discarded by the paper mill, and this is likely to have important consequences for the clay mineralogy of the soil. Soil clay mineralogy When the separated clay fraction of the soil samples was subjected to FTIR and XRD measurements, the samples
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Table 2 Soil chemical composition (in weight %) and loss on ignition (LOI) from XRFS measurements Oxides
CS
S1
S2
S3
S4
S5
S6
S7
SiO2
70.83
40.48
50.37
60.21
30.8
29.8
30.13
31.85
Al2O
10.8
9.96
11.72
10.39
11.38
10.46
10.74
11.29
Fe2O
0.03
0.25
3.74
0.08
1.94
0.09
0.26
0.93
MnO
0.008
0.017
0.017
0.005
0.069
0.005
0.002
0.027
MgO
0.09
0.08
0.05
0.16
0.7
0.1
0.77
0.95
22.3
CaO
0.15
6.05
0.87
1.95
18.88
20.73
21.74
Na2O
2.12
2.17
2.16
1.99
2.19
2.08
2.08
2.16
K2O
0.63
0.28
0.74
0.33
0.65
0.38
0.43
0.71
Ti O2
0.22
0.82
0.77
0.19
0.55
0.11
0.16
0.28
P2O
0.04
0.05
0.05
0.07
0.03
0.18
0.04
LOI%
14.8
0.07
38.13
28.55
22.76
31.41
33.55
33.96
29.47
Total
99.75
98.28
99.04
98.12
98.64
98.91
99.44
99.45
were found to contain a mixture of minerals instead of pure clay minerals indicating heterogeneous intermediate metastable stages of soil clay transformations. These minerals could be classified on the basis of their classes as tectosilicates (with silicate frameworks as in quartz or feldspar), phylosilicates (layered clays like kaolinite, smectite, chlorite, illite, etc.), and carbonates. The FTIR spectra of the separated clay fractions are shown in Fig. 5a, b. The principal FTIR frequencies and their assignments (Madejová and Komadel 2001; Schroeder 2002; Pironon et al. 2003; Vaculikova and Plevova 2005; Nayak and Singh 2007; Ravisankar et al. 2010; Davarcioglu 2011) are given in Table 3. These are discussed below. Tectosilicates Quartz The abundance of this tectosilicate in the clay fraction of the sampling locations is indicated by the presence of all or some of ~1086-, ~798-, and 779-cm−1 bands (Si–O symmetrical stretching), ~694- and 538-cm−1 bands (Si–O symmetrical and asymmetrical bending), and ~468-cm−1 band (Si–O–Si deformation) in the clay fractions of soil samples from all the locations. The characteristic ~800- and ~700-cm−1 bands indicating crystallinity of quartz are also found in the soil of most of the sampling locations excepting at S1 and S4 showing poor crystalline state of quartz at these two locations.
Feldspar Two types of feldspars, viz. albite and orthoclase, could be found in the soil, based on assignment of the FTIR bands, ~779 cm−1 (Si–O sym stretching) in albite and 648 cm −1 (Si–O sym stretching) and ~536 cm−1 (Si–O asym bending) in orthoclase. Other prominent FTIR bands such as ~470 cm−1 (O–Si–O bending) and ~435 cm−1 (Si–O sym stretching) also point to the presence of orthoclase. On the other hand, the bands, ~424 cm−1 and ~408 cm−1 (O–Si–O bending) in the clay fractions of the soil samples indicate the presence of albite. Since feldspar exists as a mixture of orthoclase and albite in all the sampling locations, it is not likely to be in highly crystalline form. Phylosilicates Kaolinite The presence of the clay mineral, kaolinite, in the soil samples is indicated by the appearance of the characteristic FTIR bands: 3691 cm−1 assigned to in-phase symmetric OH stretching; ~3669- and ~3653-cm−1 bands due to anti-phase OH stretching; ~3620 cm−1 from inner hydroxyl groups lying between the tetrahedral and octahedral sheets; ~3457 cm−1 assigned to OH stretching of adsorbed water molecules; ~1635 cm−1 due to OH deformation frequency; ~1102-, 755-, and 697-cm−1 bands assigned to Si–O perpendicular stretching; ~1033, 1011, and 791 cm−1 due to in plane Si–O stretching; ~938 and ~915 cm−1 arising from OH deformation in inner surface hydroxyl groups; ~541 cm−1 from Al–O–Si deformation; ~472 cm−1 from Si–O–Si deformation; and ~432 cm−1 due to
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a 60
45
55 40
45
Transmission
Transmission
50
40
35
30
35 25 30 20
25 20 4000
3400
2800
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Wavenumber cm -1
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65
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cm -1
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35 55
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40 4000
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2800
2200
1600
Wavenumber
1000
400
cm -1
15 4000
3400
2800
2200
Wavenumber
1600
1000
400
cm -1
Fig. 5 a FTIR spectra of the clay fraction of (i) control site (CS), (ii) site S1, (iii) site S2, and (iv) site S3 (clockwise from top left). b FTIR spectra of the clay fraction of (i) site 4, (ii) site S5, (iii) site S6, and (iv) site S7 (clockwise from top left)
Si–O deformation. However, kaolinite in the soil samples is poorly crystalline form as the peaks around 3696, 3688, 3669, 3652, and 3621 cm−1 are not well resolved (Shoval et al. 1999). Illite Occurrence of illite in the soil samples is shown by the appearance of the FTIR bands ~3620 cm−1 (inner hydroxyl groups lying between the tetrahedral and octahedral sheets); ~3450 cm−1 (OH stretching in water molecule); ~1635,~688, and 622 cm−1 (OH deformation
in water); 1090 cm−1 (Si–O normal to plane stretching); 915 cm−1 (OH deformation in inner surface hydroxyl groups); ~832 cm −1 (Al–Mg–OH deformation); ~756 cm −1 (Al–O–Si inner surface vibration); ~525 cm−1 (Al–O–Si deformation); and ~472 cm−1 (Si–O–Si deformation) in the clay fraction. Chlorite The characteristic bands for chlorite were seen in the clay fraction of the soil from the location, S2 (adjacent to fly ash dumping area) only. FTIR
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b 70
46
65
41
Transmission
Transmission
60 36
31
55
50
26 45 21
16 4000
40
3400
2800
2200
1600
1000
35 4000
400
3400
Wavenumber cm -1
2800
2200
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70
63
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60
Transmission
Transmitance
58
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53
48 50
45 4000
3400
2800
2200
1600
1000
400
Wavenumber cm -1
43 4000
3400
2800
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Wavenumber cm -1
Fig. 5 (continued)
Table 3 Assignment of FTIR bands to soil clay minerals Minerals Characteristic FTIR band (cm−1) Kaolinite 3694, 3669, 3653, 3620, 3457, 1635, 1102, 1033, 1011, 938, 915, 791, 755, 697, 541, 472, 432 Illite
3622, 3450, 1633, 1090, 1031, 916, 832, 790, 756, 688, 622, 525, 468
Chlorite
3622, 3565, 3434, 988, 819, 766, 667, 543, 441
Smectite 3620, 1088, 1008, 916, 798, 525, 467 Calcite
2922, 2874, 2513, 1797, 1426, 876, 713, 693
Quartz
1086, 798, 779, 694, 538, 467
Feldspar 585, 540, 435, 405
frequencies characteristic of chlorite were ~3620 cm−1 (due to inner hydroxyl groups lying between the tetrahedral and octahedral sheets), ~3565 and ~3434 cm−1 (OH stretching), ~988 cm −1 (Si–O stretching), ~543 cm−1 (Al–O–Si deformation), and ~441 cm−1 (Si–O–Mg deformation). Smectite The presence of the clay mineral, smectite, was observed only at the location, S3 from its FTIR bands, i.e., ~3620 cm−1 (inner hydroxyl groups lying between the tetrahedral and octahedral sheets), ~1090 cm−1 (Si–O normal to plane stretching), ~1010 and 791 cm−1 (in plane Si–O stretching), ~915 cm−1
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a 30
90 80
25 Intensity counts/sec
Intensity counts/sec
70 20
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60 50 40 30 20
5 10 0 6
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Fig. 6 a XRD spectra of the clay fraction of (i) control site (CS), (ii) site S1, (iii) site S2, and (iv) site S3 (clockwise from top left). b XRD spectra of the clay fraction of (i) site 4, (ii) site S5, (iii) site S6, and (iv) site S7 (clockwise from top left)
(OH deformation in inner surface hydroxyl groups), ~525 cm−1 (Al–O–Si deformation), and ~470 cm−1 (Si–O–Si deformation). This location also showed the presence of illite-smectite mixed layer indicated by the FTIR bands, 1034, 748, 536, and 471 cm−1. Usually, when the absorption minima shift to higher than 2200 cm−1, it is considered as an indication of lower Al content in the mineral (Duke 1994). The location, S3, showed an IR absorption band at 2137 cm−1 indicating presence of Al-enriched clay mineral in the soil.
Carbonates Calcite Presence of CO3 ion is the distinguishing feature of carbonates from other phylosilicates. All the sampling locations except the CS are found to contain calcite. The bands ~2922, 2874, 2513, 1426, and 693 cm−1 (due to CO3 vibrations), which are known to be characteristic FTIR bands for calcite, were observed in all the soil samples. Other bands supporting the presence of calcite in the soil were ~1797 cm−1 (combination band of calcite), ~876 cm−1 (out of plane
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Fig. 6 (continued)
bending), and ~713 cm−1 (in plane bending). According to Clark et al. (1990), overtones of fundamental bands in IR occur in the range of 2500–2550 and 2300–2350 cm−1 and other weaker bands at 2120– 2160, 1970–2000, and 1850–1870 cm−1 indicating the presence of carbonate minerals in mixtures. Presence of these bands in the observed FTIR spectra of the clay fraction in the soils of all the locations excepting the CS definitely indicates entry of some carbonate mineral to the sites receiving the paper mill effluent or solid waste.
Powder XRD data The powder diffractograms of the separated clay fractions are shown in Fig. 6a, b. The d-spacings are assigned on the basis of literature reports (Vaculikova and Plevova 2005; Nayak and Singh 2007; Harris and White 2008; Ravisankar et al. 2010; Davarcioglu 2011; Diko and Ekosse 2012). It is reported that d (mean)–d (measured) ranges from ±0.05 to 0.01 for calcite and from ±0.2 to 0.01 for illite and kaolinite, while the deviations for smectites are very large (Olphen and Fripiat 1979).
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Table 4 Mineral assignments on the basis of the powder XRD data 2 θ (°)
d-spacing (Å )
Mineral identified
12.6±0.2
7±0.13
Kaolinite
20.8±0.6
4.3±0.1
Kaolinite
25.2±0.3
3.54±0.04
Kaolinite
09.14
9.67
Illite
18.5±0.6
4.75±0.15
Illite
26.9±0.2
3.31±0.01
Illite
14.5
6.1
Smectite
28.9
3.1
Smectite
23.25±0.1
3.82±0.02
Calcite
29.54±0.05
3.02
Calcite
20.90, 26.87±0.22
4.25 and 3.32±0.03
Quartz
27.74
3.22
Feldspar
These variations are supposed to be due to the differences in pretreatment of the soil clay or state of hydration of the clay being studied. The clay mineralogical assignments in this work are given in Table 4. The data for the clay fraction of the CS show the presence of kaolinite (7.06 and 4.35 Å) and illite (3.31 Å). Due to the possible overlapping of quartz peak (4.26 Å) with that of kaolinite (4.35 Å) and feldspar (3.19 and 3.31 Å) with illite (3.31 Å), both quartz and feldspar could not be confirmed in the clay fractions of the soil samples, but their presence was clearly indicated in the FTIR measurements. The clay fraction of the soil at S1 shows calcite (3.81 and 3.01 Å) in it while the presence of kaolinite, quartz, and feldspar could not be confirmed, possibly due to poor crystallinity of the components (Brindley et al. 1986). The diffraction pattern of the clay from the site, S2, does not show characteristic d-spacings to assign to
any particular clay minerals. The presence of kaolinite, illite, chlorite, calcite, feldspar, and quartz, shown by the FTIR measurements, might have been masked by overlapping of the bands of a large number of minerals. This may also be due to attachment of the soil clay with unburnt coal carbon (arising from dumping of coal fly ash) leading to loss of crystallinity. In the site, S3, the soil clay shows the presence of smectite (confirmed by d-spacings of 6.09 and 3.09 Å) and illite (3.32 Å) and also randomly oriented illitesmectite mixed layer (9.17 Å). The XRD of the clay fraction of the site, S4, shows the presence of calcite (3.01 Å) and illite (3.32 Å). The site, S5, had calcite (3.82 and 3.01 Å) and illite (3.32 Å), but the poor crystallinity of the clay fraction might have been responsible for not showing the characteristic d-spacings for kaolinite, quartz, and feldspar as detected by FTIR. The clay fraction from the site, S6, shows the presence of calcite (3.02 Å), illite (3.32 Å), and polygorskite or quartz (4.25 Å). The XRD data for the site, S7, show the presence of calcite (3.84 and 3.02 Å) and illite (3.32 Å). No other clay mineral could be detected. On the basis of results of FTIR and powder XRD studies, the mineralogical composition of the clay fractions in the soil of all the locations is presented in Table 5. The results indicate that the pulp and paper mill effluents and the solid wastes introduce considerable extent of organic matter and alkalinity to the exposed soil. Decomposition of organic matter is a microorganisminitiated process and releases CO2 to the atmosphere along with the formation of organic acids. The increased soil pH takes out the H+ from the acids as well as the silicate clays. As a result, the surface negative charge increases. This increase is supposed to be adjusted with the configurational rearrangements. It is observed that smectite is found
Table 5 Availability position of different soil clay minerals Site
Kaolinite
Illite
Chlorite
Smectite
CS S1 S2
Calcite
Quartz
Feldspar
+
+
−
−
−
+
+
+
−
−
−
+
+
+
+
+
+
−
+
+
+
S3
+
+
−
+
+
+
+
S4
+
+
−
−
+
+
+
S5
+
+
−
−
+
+
+
S6
+
+
−
−
+
+
+
S7
+
+
−
−
+
+
+
(+) indicates presence, (−) indicates absence of a particular mineral in the clay part
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at S3, chlorite at S2, and calcite at all the sampling sites. Under the influence of abundant water and the ionic species, it is likely that the interlayer potassium ions in illite mineral are either replaced by Na+, Ca2+, or H2O converting the mineral to smectite. Alternatively, during rearrangement of the octahedral layer in illite, potassium ions might have been replaced leading to the formation of chlorite. Carbonate minerals belong to the basic anhydrous group having a single cation in a hexagonal close packed structure. The basic anionic CO3‾ group has carbon in sp2-hybridized state resulting in a planar triangular coordination. Since carbonate is known as a gangue mineral, it is most likely to have originated from the sediments in the pulp and paper mill effluent.
Conclusions The results indicated that the sites receiving treated effluent and solid wastes from the paper mill are either water-logged or remain wet almost throughout the year, and it has resulted in the soil having less ordered clay minerals. XRD and FTIR measurements showed mixed mineral composition of the soil. In the mixed layers, the normal crystal structure of the minerals gets modified due to replacement of existing ions in the crystal lattice. The presence of carbonate minerals was observed in all the sampling sites receiving paper mill effluents and solid wastes. Since, in these sites, calcite is detected, it might be in the form of calcite mud analogous to siliciclastic sedimentary rocks with extremely fine calcite crystals. The chlorite minerals in the soil are likely to have been contributed by the fly ash discarded by the paper mill. The presence of smectite clay in the sediment contained in the effluent from the paper industry suggests an anaerobic mechanism of interconversion of either calcite or illite to smectite. Acknowledgments This work was carried out under the Faculty Improvement Programme of University Grants Commission, New Delhi, India, to one of the authors (GA).
References Amini, S., Movahedi, S.A.R., & Mashayekhi, K. (2012). Effects of paper-mill sludge as a mulch versus topsoil incorporation on potassium uptake and the grain yield of rain-fed wheat in a high specific surface loess soil with illite dominance in clay fraction. Applied and Environmental Soil Science, 1-10 (2012). doi:10.1155/2012/624824.
Environ Monit Assess (2015) 187:98 Asghar, M. N., Khan, S., & Mushtaq, S. (2008). Management of treated pulp and paper mill effluent to achieve zero discharge. Journal of Environmental Management, 88, 1285–1299. Baruah, T.C., & Barthakur, H.P. (1997). A textbook of soil analysis. Vikash Publishing House Pvt. Ltd., 576Masjid Road, Jangpura, New Delhi 110 014, p. 334. Brindley, G. W., Kao, C. C., Harrison, J. L., Lipsicas, M., & Raythatha, R. (1986). Relation between structural disorder and other characteristics of kaolinites and dickites. Clays and Clay Minerals, 34(3), 239–249. Chatterjee, D., Datta, S. C., & Manjaiah, K. M. (2013). Clay carbon pools and their relationship with short-range order minerals: avenues to mitigate climate change? Current Science, 105(10), 1404–1410. Clark, R. N., King, T. V. V., Klejwa, M., Swayze, G. A., & Vergo, N. (1990). High resolution reflectance spectroscopy of minerals. Journal of Geophysical Research, 95(B8), 12653–12680. Davarcioglu, B. (2011). Spectral characterization of non-clay minerals found in the clays (Central Anatolian-Turkey), International Journal of the Physical Sciences, 6(3), 511522, Available online at http://www.academicjournals.org/ IJPS, doi: 10.5897/IJPS10.615, ISSN 1992–1950 ©2011 Academic Journals. Diko, M. L., & Ekosse, G. E. (2012). Physicochemical and mineralogical considerations of Ediki sandstone-hosted kaolin occurrence, South West Cameroon. International Journal of the Physical Sciences, 7(3), 501–507, 16 January, 2012, Available online at http://www.academicjournals.org/IJPS, DOI: 10.5897/IJPS11.1506. Duke, E. F. (1994). Near infrared spectra of muscovite. Tschermak substitution, and metamorphic reaction progress: implication for remote sensing. Geology, 22, 621–624. Edalatmanesh, M., Sain, M., & Liss, S. N. (2010). Cellular biopolymers and molecular structure of a secondary pulp and paper mill sludge verified by spectroscopy and chemical extraction techniques. Water Science and Technology, 62(12), 2846–2853. Harris, W., & White, G. N. (2008). In A. L. Ulery & L. R. Drees (Eds.), X-ray diffraction techniques for soil mineral identification :in methods of soil analysis part 5—mineralogical methods, Chapter 4 (pp. 81–116). Madison, Wisconsin: Soil Science Society of America, Inc. Hasse, P. R. (1994). A textbook of soil analysis, 1st Indian Reprint, CBS Publishers and Distributors Pvt. Ltd., CBS PLAZA, 24 Ansari Road, Darya Ganj, New Delhi 110002, p. 520. Jackson, M. L. (1958). Soil chemical analysis (p. 484). Englewood Cliffs, N.J.: Prentice-Hall Inc. Madejová, J., & Komadel, P. (2001). Baseline studies of the clay minerals society source clays: infrared methods. Clays and Clay Minerals, 49, 410–432. Miller, R. W., & Donahue, R. L. (1992). Soils: an introduction to soils and plant growth. Englewood Cliffs, N.J.: PrenticeHall, Inc. Nayak, P. S., & Singh, B. K. (2007). Instrumental characterization of clay by XRF, XRD and FTIR. Bulletin of Materials Science, 30(3), 235–238. © Indian Academy of Sciences. Olphen, H. Van, & Fripiat, J. J. (1979). Data handbook for clay materials and other non-metallic minerals. Pergamon Press: Oxford, UK 346 pages. Opfergelt, S., Georg, R. B., Delvaux, B., Cabidoche, Y. M., Burton, K. W., & Halliday, A. (2012). Silicon isotopes and the tracing
Environ Monit Assess (2015) 187:98 of desilication in volcanic soil weathering sequences, Gaudeloupe. Chemical Geology, 326–327, 113–122. Park, J. H., Lamb, D., Paneerselvam, P., Choppala, G., Bolan, N., & Chung, J.-W. (2011). Role of organic amendments on enhanced bioremediation of heavy metal(loid) contaminated soils. Journal of Hazardous Materials, 185, 549–574. Pironon, J., Pelletier, M., De Donato, P., & Mosser-Ruck, R. (2003). Characterization of smectite and illite by FTIR spectroscopy of interlayer NH4+ cations. Clay Minerals, 38, 201–211. Prost, R., & Yaron, B. (2001). Use of modified clays for controlling soil environmental quality. Social Science, 166, 880–894. Raj, A., Kumar, S., Haq, I., & Singh, S. K. (2014). Bioremediation and toxicity reduction in pulp and paper mill effluent by newly isolated ligninolytic Paenibacillus sp. Ecological Engineering, 71, 355–362. Ravisankar, R., Senthikumar, G., et al. (2010). Mineral analysis of costal sediments of Tuna, Gujrat, India. Indian Journal of Science and Technology, 3(7), 774–780. ISSN: 0974-6846. Reeuwijk, L. P. (2002). Procedure for soil analysis (6th ed., p. 119). Wageningen, The Netherlands: International Soil Reference and Information Centre. ISBN 90-6672-044-1.
Page 13 of 13 98 Sarkar, D., & Halder, A. (2010). Physical and chemical methods in soil analysis (2nd ed., p. 211). New Delhi: New Age International Publishers. ISBN 978-81-224-2725-7. Schroeder, P. A. (2002). Infrared spectroscopy in clay science: in CMS Workshop Lectures. In A. Rule & S. Guggenheim (Eds.), Teaching Clay Science (Vol. 11, pp. 181–206). Aurora, CO: The Clay Mineral Society. Shoval, S., Yartiv, S., Michaelian, K. H., Boudeulle, M., & Panczer, G. (1999). Hydroxyl stretching Raman and infrared bands ‘A’ and ‘Z’ in spectra of kaolinites. Clay Minerals, 34, 551–563. Szolosi, O. (2003). Water cycle with zero discharge at Visy Pulp and Paper, Tumut, NSW. Water (Australia), 30, 34–36. Thompson, G., Swain, J., Kay, M., & Froster, C. F. (2001). The treatment of ulp and paper mill effluent: a review. Bioresource Technology, 77, 275–286. Vaculikova, L., & Plevova, E. (2005). Identification of clay minerals and micas in sedimentary rocks. Acta Geodynamics et Geomaterialia, 2(2 (138)), 167–175. Whitehead, J. H., & Geary, P. M. (2000). Geotechnical aspects of domestic on-site effluent management systems. Australian Journal of Earth Sciences, 47, 75–82.
Impact of pulp and paper mill effluents and solid wastes on soil mineralogical and physicochemical properties Gopi Adhikari & Krishna G. Bhattacharyya
Received: 23 April 2014 / Accepted: 26 January 2015 # Springer International Publishing Switzerland 2015
Abstract The present study was carried out to evaluate the impact of the effluents and the solid wastes generated by a giant pulp and paper mill in the northeastern part of India on soil mineralogy of the area. The impacts were monitored by analysis of soil samples from seven sites located in the potential impact zone and a control site where any kind of effluent discharge or solid waste dumping was absent. The soil belonged to medium texture type (sandy clay loam, sandy loam, loamy sand, and silt loam), and the soil aggregate analysis indicated higher levels of organic carbon, pH, electrical conductivity, effective cation exchange capacity, and mean weight diameter at sites receiving effluents and solid wastes from the pulp and paper mill. Depletion in soil silica level and in feldspar and quartz contents and rise in iron and calcium contents at the sites receiving effluents from the pulp and paper mill indicated significant influence on soil mineralogy. The soil contained a mixture of minerals consisting of tectosilicates (with silicate frameworks as in quartz or feldspar), phylosilicates (layered clays like kaolinite, smectite, chlorite, illite, etc.), and carbonates. Absence of pure clay minerals indicated a state of heterogeneous intermediate soil G. Adhikari Department of Chemistry, Jagiroad College, Jagiroad 782410, India e-mail: [email protected] K. G. Bhattacharyya (*) Department of Chemistry, Gauhati University, Guwahati 781014, India e-mail: [email protected]
clay transformation. The significance of the mixed mineralogy in relation to the disposal of effluents and dumping of solid wastes is discussed in details. Keywords Soil aggregate analysis . Mineralogical composition . Influence of pollutants on soil properties . Soil organic carbon . Texture analysis
Introduction Soil mineralogy is an important tool to provide information regarding fertility status, stage of weathering, etc. and is helpful in inferring the soil status (Miller and Donahue 1992). Soil clays are considered to be the most important components, as any contaminant making its way into soil has to interact with the clays (Prost and Yaron 2001). The transformation of soil mineralogical composition depends on the clay, silt, and sand fractions, which exist in a dynamic equilibrium in the soil. Clays are highly polar and are considered as the reactive component in soil. Soil clay is also well known for providing a large reactive surface area per unit weight. The polar nature of soil clay accounts for its cation exchange capacity. Amongst the most prominent cation exchangers, the naturally available alkali and alkaline earth metal ions are the pioneers in the overall weathering processes resulting in transformation of soil clay mineralogy. Pulp and paper industry is a water-intensive industry, and it generates large volumes of effluents. It is ranked at the third position in terms of fresh water consumption
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after the primary metal and chemical industries (Asghar et al. 2008). A large amount of solid wastes is also simultaneously generated, and these include the causticizing wastes (in the form of lime sludge), ash from boilers, sludge from wastewater treatment processes, and unused raw materials (such as bamboo dust) (Amini et al. 2012). On an average, a typical paper mill produces 45 kg of waste sludge per ton of paper produced (Edalatmanesh et al. 2010) and effluent generation ranges from 1.5 to 60 m3 (Thompson et al. 2001; Szolosi 2003), based on technology and nature of raw materials. Indiscriminate and unplanned waste disposal has been an unwelcome common practice with the pulp and paper mills, particularly in the developing and the underdeveloped countries, which is a matter of concern (Whitehead and Geary 2000). The waste products are always evaluated as ecological burden contributed by paper industries. The paper wastes make their way to the three major components of the environment viz. soil, air, and water. Based on the waste disposal methods, the effluents and the solid wastes have different contributions to the overall ecological health and each carries distinct ecological burden. It is frequently reported that the conventional methods of effluent treatment like the use of biological oxidation using activated sludge and aerated lagoon are often inadequate to get rid of the composite organic and inorganic mixture of pollutants (Raj et al. 2014). In many cases, the bio-solids discarded from the activated sludge treatment system are spread over agricultural fields to improve soil fertility and other physicochemical properties (Park et al. 2011). The added organic matter contains low-molecular-weight organic acids, capable of chelating Al3+ and Si4+ ions present in the clay minerals in the soil framework (Chatterjee et al. 2013). As a result of this type of chelation, the clay minerals in the soil become deficient in Al3+ and Si4+ ions that occupy the centers of the tetrahedral and octahedral basic structural units. This deficiency is adjusted by a forced rearrangement of the constituents leading to soil clay transformation. Moreover, it is known that the pulp and paper mill wastes, enriched with organic matter, are alkaline in nature, and the OH groups, contributing to alkalinity, can link the clay octahedra through the O-end in intertype and intratype of combinations. During the rearrangement processes, the inclusion and exclusion of metallic moieties that are the abundant constituents of the chemical wastes have greater chances to be inserted, resulting in the clay transformation.
Environ Monit Assess (2015) 187:98
Moreover, components like organic carbon from the effluent and solid wastes in association with the soil mineral particles contribute to the lowering in the particle as well as bulk density. They contribute to higher porosity resulting into alteration of soil processes like aeration, water holding capacity, etc. Higher soil aeration increases the oxidation processes in soil, and higher water retention leads to an anaerobic situation. These are considered as the factors responsible for changes in the natural oxidation processes in soil. The altered oxidation activity, abundance of ionic species contributed by the effluents, and predominant alkaline environments are sure to alter the soil natural environment along with its clay, the most active soil component in its content and nature. The present work tries to find out the changes in soil mineralogical composition including the clay minerals upon exposure to the paper mill effluents and the solid wastes over a long period of time.
Materials and methods Soil sampling sites The site selection for soil sampling was based on the proportionate area of location of the pulp and paper mill (Nagaon Paper Mill of Hindustan Paper Corporation Limited, situated at Jagiroad, India; installed capacity 100,000 t per annum of high-quality printing paper). The soil samples were collected from eight locations (CS, S1–S7) (Table 1) that include the control site (CS) (at a distance of 1 km from the effluent treatment plant of the mill where any kind of effluent discharge or solid waste dumping is absent), two sites, S1 and S2, from solid waste dumping locations, and five sites, S3–S7, from effluent discharge locations. These are also shown in Fig. 1. The sampling sites belong to tropical rainforest climate region, subjected to a humid subtropical climate. The average rainfall in the area is 1530 mm, with average temperature 25.5–32.9 °C (summer) and 19.8– 24.8 °C (winter), with annual average of 19.8–30.4 °C. Soil sampling and preparation At each site, three soil samples were collected from a 1-m2 area up to 20-cm depth (average conventional tillage depth) using a 5-cm corer and the soil samples were homogenized to form a composite sample that
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Table 1 Location, land use pattern, and a brief description of the sampling sites Site
Soil type
Location
Description of the site
CS
Control site
26° 07′ 25.1″ N 92° 11′ 28.5″ E
Rural site away from the mill, not receiving effluent discharge or solid waste dumping
S1
Solid waste dumping
26° 07′ 43.0″ N 92° 14′ 05.6″ E
Dumping of lime waste from caustic chlorine plant near the residential colony
S2
Solid waste dumping
26° 07′ 38.5″ N 92° 14′ 30.7″ E
Dumping of coal fly ash from the mill near the residential colony
S3
Waste sludge disposal
26° 07′ 50.8″ N 92° 12′ 41.9″ E
Dumping of the sludge from the effluent treatment plant (ETP)
S4
Treated effluent discharge
26° 08′ 07.1″ N 92° 12′ 31.4″ E
Treated effluent from the ETP discharged through an underground channel to a natural wetland, the Elenga Beel
S5
Treated effluent route
26° 07′ 52.6″ N 92° 12′ 40.8″ E
Agriculture land at a distance of 50 m from S3
S6
Treated effluent route
26° 07′ 53.5″ N 92° 12′ 40.9″ E
Agriculture land at a distance of 100 m from S3
S7
Treated effluent route
26° 07′ 57.4″ N 92° 12′ 35.5″ E
Agriculture land at a distance of 500 m from S3
was likely to be representative of the specific soil type at a particular location. The samples were air-dried and passed through a 2-mm sieve, after which they were preserved for laboratory analysis. The samples were collected in three seasons viz. hot dry summer (April to June), Wet hot summer (July to September), and cold dry winter (November to February) to take into account the impact of change in climate. Analysis of soil samples Analysis of soil physicochemical parameters was done by following standard methods, i.e., soil composition with respect to sand, clay, and silt percentage by the hydrometer method; soil texture by ISSS triangle method (Reeuwijk 2002); soil organic carbon (SOC) by modified Walkley-Black method (Sarkar and Halder 2010); and electrical conductivity (EC) (1:5 soil/water suspension, Elico CM 180) (Sarkar and Halder 2010), pH (1:5 soil/water suspension, Elico LI 120) (Jackson 1958), and effective cation exchange capacity (ECEC) by ammonium acetate method (Hasse 1994). Soil aggregate analysis was done following the wet-sieving technique of Yoder 1936 (Baruah and Barthakur 1997). Soil stability was expressed in terms of percentage as well as mean weight diameter (MWD), which is defined as the sum of the product of the mean diameter, Xi, and the total sample weight, Wi, of each size fraction (MWD=∑ Xi Wi) (Baruah and Barthakur 1997). Each analysis was done
in triplicate, and the means of the three values are reported here. Portions of the soil samples were pulverized and subjected to XRF analysis to obtain soil mineralogical composition. The soil samples were soaked in water and treated with 30 % H2O2 to remove organic matter, and the soil clay was separated by dispersion and gravity separation. The clay fraction ( CS > S4 > S5 > S7 > S1 > S6 > S2
2. pH (Fig. 3): S5 > S6 > S1 > S7 > S4 > S2 > S3 > CS 3. Conductivity (Fig. 3): S3 > S7 > S5 > S4 > S6 > S1 > S2 > CS 4. ECEC (Fig. 3): S5 > S6 = S7 > S4 > S3 > S1 > S2 > CS
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S6
8
SOC and MWD
S7
Sampling sites
S5 S4 S3 S2
SOC % MWD
6 4 2 0
S1
CS
S1
S2
CS 0
10
50 0 40 30 n (%) Composition C
20
Sand (%)
Siilt (%)
600
70
80
5. Organic carbon (Fig. 4): S3 > S2 > S4 > S5 > S6 > CS > S1 6. Aggregate stability in MWD (Fig. 4): S1 > S5 > S3 > S6 > S4 > S2 = S7 > CS
pH, conductivity, CEC
Though the soil of the CS possesses higher clay content (except S3), its organic carbon content is slightly higher than S1 (waste lime dumped area). Effective cation exchange capacity (ECEC), pH, and conductivity of the soil had the minimum values in the CS. Similarly, when aggregate stabilities of the soils are compared on the basis of mean weight diameter (MWD), all the soils receiving pollutants have greater MWD, i.e., higher aggregate stability than the CS soil. This may be due to the presence of higher concentration of calcium carbonate in the effluents from causticizing plant along with higher organic matter. Calcium carbonate contributes to aggregate stability through its cementing effect, and similar enhancement is possible with high organic matter that increases overall negative charge. These
pH Conductivity dS/m CE EC cmol/ kg
30 25 20 15 10 5 0 CS
S1
S2
S3 S4 Sampling site
S6
S7
Fig. 4 Interrelationships between soil organic carbon (%) and soil aggregation (MWD)
Clay (%))
Fig. 2 Relative composition of clay, silt, and sand at the sampling sites
45 40 35
S3 S4 S5 Sampling sitees
S5
S6
S7
Fig. 3 Variation of pH, electrical conductivity, and cation exchange capacity (CEC) for the different sampling sites
observations suggest that there may be organic, alkaline, and soluble salt inputs to the sampling points along with the effluents and wastes from pulp and paper mill. Soil mineralogy The average chemical composition of the soil samples (Table 2) shows the presence of abundant amount of CaO (except at the site, S2, where coal ash is regularly dumped) and drastically reduced SiO2 in the soil of the sampling sites affected by the pulp and paper mill effluents and solid wastes. The CS had higher SiO2 content than the other sites receiving either solid wastes or treated effluent discharge from the paper mill. However, the soil from the CS had less Fe2O3 and CaO compared to the other sites. Higher CaO in the sites having impacts from the paper mill operations suggests presence of carbonates of Ca that broke down into CaO during heating to determine LOI through loss of CO2. The soil in the sites receiving pollutant loads from the mill had much higher values of loss on ignition (LOI) indicating the presence of higher amounts of organic matter and possibly carbonates. It has been shown from Si-isotopic signature studies that Si is the key factor of clay mineralogy, often induced by the climate gradient (Opfergelt et al. 2012). The observed reduction in SiO2 and, hence, Si in the present work is apparently due to the enrichment of the soil by organic wastes discarded by the paper mill, and this is likely to have important consequences for the clay mineralogy of the soil. Soil clay mineralogy When the separated clay fraction of the soil samples was subjected to FTIR and XRD measurements, the samples
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Table 2 Soil chemical composition (in weight %) and loss on ignition (LOI) from XRFS measurements Oxides
CS
S1
S2
S3
S4
S5
S6
S7
SiO2
70.83
40.48
50.37
60.21
30.8
29.8
30.13
31.85
Al2O
10.8
9.96
11.72
10.39
11.38
10.46
10.74
11.29
Fe2O
0.03
0.25
3.74
0.08
1.94
0.09
0.26
0.93
MnO
0.008
0.017
0.017
0.005
0.069
0.005
0.002
0.027
MgO
0.09
0.08
0.05
0.16
0.7
0.1
0.77
0.95
22.3
CaO
0.15
6.05
0.87
1.95
18.88
20.73
21.74
Na2O
2.12
2.17
2.16
1.99
2.19
2.08
2.08
2.16
K2O
0.63
0.28
0.74
0.33
0.65
0.38
0.43
0.71
Ti O2
0.22
0.82
0.77
0.19
0.55
0.11
0.16
0.28
P2O
0.04
0.05
0.05
0.07
0.03
0.18
0.04
LOI%
14.8
0.07
38.13
28.55
22.76
31.41
33.55
33.96
29.47
Total
99.75
98.28
99.04
98.12
98.64
98.91
99.44
99.45
were found to contain a mixture of minerals instead of pure clay minerals indicating heterogeneous intermediate metastable stages of soil clay transformations. These minerals could be classified on the basis of their classes as tectosilicates (with silicate frameworks as in quartz or feldspar), phylosilicates (layered clays like kaolinite, smectite, chlorite, illite, etc.), and carbonates. The FTIR spectra of the separated clay fractions are shown in Fig. 5a, b. The principal FTIR frequencies and their assignments (Madejová and Komadel 2001; Schroeder 2002; Pironon et al. 2003; Vaculikova and Plevova 2005; Nayak and Singh 2007; Ravisankar et al. 2010; Davarcioglu 2011) are given in Table 3. These are discussed below. Tectosilicates Quartz The abundance of this tectosilicate in the clay fraction of the sampling locations is indicated by the presence of all or some of ~1086-, ~798-, and 779-cm−1 bands (Si–O symmetrical stretching), ~694- and 538-cm−1 bands (Si–O symmetrical and asymmetrical bending), and ~468-cm−1 band (Si–O–Si deformation) in the clay fractions of soil samples from all the locations. The characteristic ~800- and ~700-cm−1 bands indicating crystallinity of quartz are also found in the soil of most of the sampling locations excepting at S1 and S4 showing poor crystalline state of quartz at these two locations.
Feldspar Two types of feldspars, viz. albite and orthoclase, could be found in the soil, based on assignment of the FTIR bands, ~779 cm−1 (Si–O sym stretching) in albite and 648 cm −1 (Si–O sym stretching) and ~536 cm−1 (Si–O asym bending) in orthoclase. Other prominent FTIR bands such as ~470 cm−1 (O–Si–O bending) and ~435 cm−1 (Si–O sym stretching) also point to the presence of orthoclase. On the other hand, the bands, ~424 cm−1 and ~408 cm−1 (O–Si–O bending) in the clay fractions of the soil samples indicate the presence of albite. Since feldspar exists as a mixture of orthoclase and albite in all the sampling locations, it is not likely to be in highly crystalline form. Phylosilicates Kaolinite The presence of the clay mineral, kaolinite, in the soil samples is indicated by the appearance of the characteristic FTIR bands: 3691 cm−1 assigned to in-phase symmetric OH stretching; ~3669- and ~3653-cm−1 bands due to anti-phase OH stretching; ~3620 cm−1 from inner hydroxyl groups lying between the tetrahedral and octahedral sheets; ~3457 cm−1 assigned to OH stretching of adsorbed water molecules; ~1635 cm−1 due to OH deformation frequency; ~1102-, 755-, and 697-cm−1 bands assigned to Si–O perpendicular stretching; ~1033, 1011, and 791 cm−1 due to in plane Si–O stretching; ~938 and ~915 cm−1 arising from OH deformation in inner surface hydroxyl groups; ~541 cm−1 from Al–O–Si deformation; ~472 cm−1 from Si–O–Si deformation; and ~432 cm−1 due to
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a 60
45
55 40
45
Transmission
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50
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35 25 30 20
25 20 4000
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Fig. 5 a FTIR spectra of the clay fraction of (i) control site (CS), (ii) site S1, (iii) site S2, and (iv) site S3 (clockwise from top left). b FTIR spectra of the clay fraction of (i) site 4, (ii) site S5, (iii) site S6, and (iv) site S7 (clockwise from top left)
Si–O deformation. However, kaolinite in the soil samples is poorly crystalline form as the peaks around 3696, 3688, 3669, 3652, and 3621 cm−1 are not well resolved (Shoval et al. 1999). Illite Occurrence of illite in the soil samples is shown by the appearance of the FTIR bands ~3620 cm−1 (inner hydroxyl groups lying between the tetrahedral and octahedral sheets); ~3450 cm−1 (OH stretching in water molecule); ~1635,~688, and 622 cm−1 (OH deformation
in water); 1090 cm−1 (Si–O normal to plane stretching); 915 cm−1 (OH deformation in inner surface hydroxyl groups); ~832 cm −1 (Al–Mg–OH deformation); ~756 cm −1 (Al–O–Si inner surface vibration); ~525 cm−1 (Al–O–Si deformation); and ~472 cm−1 (Si–O–Si deformation) in the clay fraction. Chlorite The characteristic bands for chlorite were seen in the clay fraction of the soil from the location, S2 (adjacent to fly ash dumping area) only. FTIR
98
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b 70
46
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43 4000
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Fig. 5 (continued)
Table 3 Assignment of FTIR bands to soil clay minerals Minerals Characteristic FTIR band (cm−1) Kaolinite 3694, 3669, 3653, 3620, 3457, 1635, 1102, 1033, 1011, 938, 915, 791, 755, 697, 541, 472, 432 Illite
3622, 3450, 1633, 1090, 1031, 916, 832, 790, 756, 688, 622, 525, 468
Chlorite
3622, 3565, 3434, 988, 819, 766, 667, 543, 441
Smectite 3620, 1088, 1008, 916, 798, 525, 467 Calcite
2922, 2874, 2513, 1797, 1426, 876, 713, 693
Quartz
1086, 798, 779, 694, 538, 467
Feldspar 585, 540, 435, 405
frequencies characteristic of chlorite were ~3620 cm−1 (due to inner hydroxyl groups lying between the tetrahedral and octahedral sheets), ~3565 and ~3434 cm−1 (OH stretching), ~988 cm −1 (Si–O stretching), ~543 cm−1 (Al–O–Si deformation), and ~441 cm−1 (Si–O–Mg deformation). Smectite The presence of the clay mineral, smectite, was observed only at the location, S3 from its FTIR bands, i.e., ~3620 cm−1 (inner hydroxyl groups lying between the tetrahedral and octahedral sheets), ~1090 cm−1 (Si–O normal to plane stretching), ~1010 and 791 cm−1 (in plane Si–O stretching), ~915 cm−1
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a 30
90 80
25 Intensity counts/sec
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70 20
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5 10 0 6
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6
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9
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30
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Fig. 6 a XRD spectra of the clay fraction of (i) control site (CS), (ii) site S1, (iii) site S2, and (iv) site S3 (clockwise from top left). b XRD spectra of the clay fraction of (i) site 4, (ii) site S5, (iii) site S6, and (iv) site S7 (clockwise from top left)
(OH deformation in inner surface hydroxyl groups), ~525 cm−1 (Al–O–Si deformation), and ~470 cm−1 (Si–O–Si deformation). This location also showed the presence of illite-smectite mixed layer indicated by the FTIR bands, 1034, 748, 536, and 471 cm−1. Usually, when the absorption minima shift to higher than 2200 cm−1, it is considered as an indication of lower Al content in the mineral (Duke 1994). The location, S3, showed an IR absorption band at 2137 cm−1 indicating presence of Al-enriched clay mineral in the soil.
Carbonates Calcite Presence of CO3 ion is the distinguishing feature of carbonates from other phylosilicates. All the sampling locations except the CS are found to contain calcite. The bands ~2922, 2874, 2513, 1426, and 693 cm−1 (due to CO3 vibrations), which are known to be characteristic FTIR bands for calcite, were observed in all the soil samples. Other bands supporting the presence of calcite in the soil were ~1797 cm−1 (combination band of calcite), ~876 cm−1 (out of plane
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Fig. 6 (continued)
bending), and ~713 cm−1 (in plane bending). According to Clark et al. (1990), overtones of fundamental bands in IR occur in the range of 2500–2550 and 2300–2350 cm−1 and other weaker bands at 2120– 2160, 1970–2000, and 1850–1870 cm−1 indicating the presence of carbonate minerals in mixtures. Presence of these bands in the observed FTIR spectra of the clay fraction in the soils of all the locations excepting the CS definitely indicates entry of some carbonate mineral to the sites receiving the paper mill effluent or solid waste.
Powder XRD data The powder diffractograms of the separated clay fractions are shown in Fig. 6a, b. The d-spacings are assigned on the basis of literature reports (Vaculikova and Plevova 2005; Nayak and Singh 2007; Harris and White 2008; Ravisankar et al. 2010; Davarcioglu 2011; Diko and Ekosse 2012). It is reported that d (mean)–d (measured) ranges from ±0.05 to 0.01 for calcite and from ±0.2 to 0.01 for illite and kaolinite, while the deviations for smectites are very large (Olphen and Fripiat 1979).
Environ Monit Assess (2015) 187:98
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Table 4 Mineral assignments on the basis of the powder XRD data 2 θ (°)
d-spacing (Å )
Mineral identified
12.6±0.2
7±0.13
Kaolinite
20.8±0.6
4.3±0.1
Kaolinite
25.2±0.3
3.54±0.04
Kaolinite
09.14
9.67
Illite
18.5±0.6
4.75±0.15
Illite
26.9±0.2
3.31±0.01
Illite
14.5
6.1
Smectite
28.9
3.1
Smectite
23.25±0.1
3.82±0.02
Calcite
29.54±0.05
3.02
Calcite
20.90, 26.87±0.22
4.25 and 3.32±0.03
Quartz
27.74
3.22
Feldspar
These variations are supposed to be due to the differences in pretreatment of the soil clay or state of hydration of the clay being studied. The clay mineralogical assignments in this work are given in Table 4. The data for the clay fraction of the CS show the presence of kaolinite (7.06 and 4.35 Å) and illite (3.31 Å). Due to the possible overlapping of quartz peak (4.26 Å) with that of kaolinite (4.35 Å) and feldspar (3.19 and 3.31 Å) with illite (3.31 Å), both quartz and feldspar could not be confirmed in the clay fractions of the soil samples, but their presence was clearly indicated in the FTIR measurements. The clay fraction of the soil at S1 shows calcite (3.81 and 3.01 Å) in it while the presence of kaolinite, quartz, and feldspar could not be confirmed, possibly due to poor crystallinity of the components (Brindley et al. 1986). The diffraction pattern of the clay from the site, S2, does not show characteristic d-spacings to assign to
any particular clay minerals. The presence of kaolinite, illite, chlorite, calcite, feldspar, and quartz, shown by the FTIR measurements, might have been masked by overlapping of the bands of a large number of minerals. This may also be due to attachment of the soil clay with unburnt coal carbon (arising from dumping of coal fly ash) leading to loss of crystallinity. In the site, S3, the soil clay shows the presence of smectite (confirmed by d-spacings of 6.09 and 3.09 Å) and illite (3.32 Å) and also randomly oriented illitesmectite mixed layer (9.17 Å). The XRD of the clay fraction of the site, S4, shows the presence of calcite (3.01 Å) and illite (3.32 Å). The site, S5, had calcite (3.82 and 3.01 Å) and illite (3.32 Å), but the poor crystallinity of the clay fraction might have been responsible for not showing the characteristic d-spacings for kaolinite, quartz, and feldspar as detected by FTIR. The clay fraction from the site, S6, shows the presence of calcite (3.02 Å), illite (3.32 Å), and polygorskite or quartz (4.25 Å). The XRD data for the site, S7, show the presence of calcite (3.84 and 3.02 Å) and illite (3.32 Å). No other clay mineral could be detected. On the basis of results of FTIR and powder XRD studies, the mineralogical composition of the clay fractions in the soil of all the locations is presented in Table 5. The results indicate that the pulp and paper mill effluents and the solid wastes introduce considerable extent of organic matter and alkalinity to the exposed soil. Decomposition of organic matter is a microorganisminitiated process and releases CO2 to the atmosphere along with the formation of organic acids. The increased soil pH takes out the H+ from the acids as well as the silicate clays. As a result, the surface negative charge increases. This increase is supposed to be adjusted with the configurational rearrangements. It is observed that smectite is found
Table 5 Availability position of different soil clay minerals Site
Kaolinite
Illite
Chlorite
Smectite
CS S1 S2
Calcite
Quartz
Feldspar
+
+
−
−
−
+
+
+
−
−
−
+
+
+
+
+
+
−
+
+
+
S3
+
+
−
+
+
+
+
S4
+
+
−
−
+
+
+
S5
+
+
−
−
+
+
+
S6
+
+
−
−
+
+
+
S7
+
+
−
−
+
+
+
(+) indicates presence, (−) indicates absence of a particular mineral in the clay part
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at S3, chlorite at S2, and calcite at all the sampling sites. Under the influence of abundant water and the ionic species, it is likely that the interlayer potassium ions in illite mineral are either replaced by Na+, Ca2+, or H2O converting the mineral to smectite. Alternatively, during rearrangement of the octahedral layer in illite, potassium ions might have been replaced leading to the formation of chlorite. Carbonate minerals belong to the basic anhydrous group having a single cation in a hexagonal close packed structure. The basic anionic CO3‾ group has carbon in sp2-hybridized state resulting in a planar triangular coordination. Since carbonate is known as a gangue mineral, it is most likely to have originated from the sediments in the pulp and paper mill effluent.
Conclusions The results indicated that the sites receiving treated effluent and solid wastes from the paper mill are either water-logged or remain wet almost throughout the year, and it has resulted in the soil having less ordered clay minerals. XRD and FTIR measurements showed mixed mineral composition of the soil. In the mixed layers, the normal crystal structure of the minerals gets modified due to replacement of existing ions in the crystal lattice. The presence of carbonate minerals was observed in all the sampling sites receiving paper mill effluents and solid wastes. Since, in these sites, calcite is detected, it might be in the form of calcite mud analogous to siliciclastic sedimentary rocks with extremely fine calcite crystals. The chlorite minerals in the soil are likely to have been contributed by the fly ash discarded by the paper mill. The presence of smectite clay in the sediment contained in the effluent from the paper industry suggests an anaerobic mechanism of interconversion of either calcite or illite to smectite. Acknowledgments This work was carried out under the Faculty Improvement Programme of University Grants Commission, New Delhi, India, to one of the authors (GA).
References Amini, S., Movahedi, S.A.R., & Mashayekhi, K. (2012). Effects of paper-mill sludge as a mulch versus topsoil incorporation on potassium uptake and the grain yield of rain-fed wheat in a high specific surface loess soil with illite dominance in clay fraction. Applied and Environmental Soil Science, 1-10 (2012). doi:10.1155/2012/624824.
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