The contamination of arsenic (As) and other heavy metal (HMs) in soil causes serious health hazard to the ecosystem. In this work, the contamination of As and other heavy metals ( i.e. Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb) in rhizospheric soil of 14 plants of the severely As contaminated area of Central India is described. Among them, high content of As in the rhizospheric soils was observed, ranging from 0.22 to 4.60 g/kg with mean value of 1.6 ± 0.7 g/kg. The concentration variation, enrichment indices and toxicities of the metals in the soil are described.
Arsenic and its compounds are especially potent poisons linking with a broad variety of neurologic, cardiovascular, dermatologic, and carcinogenic effects; including peripheral neuropathy, diabetes, ischemic heart disease, melanosis, keratosis, and impairment of liver function [
The sampling network for the soil collection is presented in
(21˚6'N & 81˚2'E) as prescribed in the literature [
The soil sample (10 g) was mixed with 20 mL of deionized water in a 100-mL conical flask and allowed to stand for overnight. The pH value of the extract was measured by Hanna pH meter type-HI991300.
The Bruker S2 Picofox TXRF portable spectrometer equipped with poly capillary lens and the X-ray beam was used for the analysis of the elements in soil. A suspended solution was prepared by mixing 10 mg of soil sample with 10 mL of a water solution containing 1% (w/v) triton in ultrasonic bath for 15 min. Gallium was added to suspensions as an internal standard with a concentration of 10 mg/L. For each measurement, 10 μL of sample solution was sprayed on the quartz filter with subsequent drying. The X-ray source was focused on the filter for quantification of the elements. The peak area of the signal was computed. The three replicate measurements for each sample were carried out. The content of 14 elements (i.e. Al, P, K, Ca, As, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb) in each soil was analyzed. The standard soil sample (NCS DC 73382 CRM) was used for the quality control.
The pollution indices i.e. enrichment factor (EF), contamination factor (CF) and geo-accumulation index (GI) are used to determine element concentration in the soil samples with respect to the base line concentration. These relate the concentration of an element to a crustal element (e.g. Al) in the soil sample, and this ratio is then normalised to the ratio of those elements in the earth’s crust. The following equations are used for the calculation of the pollution indices [
where, Xs, Als, Xe and Ale are concentrations of metal and Al in the soil and earth crust, respectively.
The traditional and botanical name of the plants selected for the proposed studies is presented in
High content of metals i.e. K, Ca, Al, Fe and Ti was present in the bulk soil. Among them, Fe exhibited the highest content in the soil, followed by Al, K and Ca. The mean concentration of Fe, Al, K, Ca, Ti and P in the soil was found to be 203, 114, 75, 52, 31 and 1.6 g/kg respectively. The mean value of other HMs i.e. Mn, Cr, Zn, V, Ni, Cu, As and Pb in the bulk soil was 5.93, 0.88, 0.60, 0.51, 0.38, 0.36, 0.20 and 0.04 g/kg, respectively. The As content in the field soil of the study area was found to be much higher than in the soil of other countries i.e. Bangladesh, Nepal and China [
Similarly, elevated level of metals i.e. Fe, Al, K, Ca and Ti in the rhizospheric soils was observed, ranging from, 115 - 322, 64 - 226, 26 - 147, 19 - 99 and 18 - 52 g/kg with mean value of (at 95% probability) 212 ± 28, 121 ± 28, 87 ± 19, 56 ± 16 and 35 ± 5 g/kg, respectively. Other elements i.e. Mn, Cr, P, As, Zn, V, Ni, Cu and Pb was
S. No. | Type | Traditional name | Botanical name |
---|---|---|---|
1 | Herb | Bhengraj | Eclypta alba (EA) |
2 | Herb | Dhania | Coriandrum sativum (CS) |
3 | Herb | Pudina | Mentha spicata (MS) |
4 | Herb | Tulsi | Ocimum santum (OS) |
5 | Herb | Doobgrass | Cynodon dactylon (CD) |
6 | Herb | Bhaskatia | Solenum surratense (SS) |
7 | Herb | Dhatura | Dhatura metel (DM) |
8 | Herb | Akartara | Anacyclus pyrethrum (AP) |
9 | Herb | Kukurmuta | Spiranthes indium (SI) |
10 | Herb | Apamarg | Achyranthes aspera (AA) |
11 | Herb | Makoy | Solenum nigrum (SN) |
12 | Tree | Neem | Azadirechta indica (AI) |
13 | Tree | Palas | Butea monosperma (BM) |
14 | Tree | Chiku | Manilkara zapota (MZ) |
found to be present in the rhizospheric soils at the moderate levels, ranging from 3.4 - 12.6, 0.78 - 3.01, 1.2 - 2.7, 0.2 - 4.6, 0.70 - 1.79, 0.28 - 1.49, 0.23 - 0.93, 0.36 - 0.64, and 0.0179 - 0.331 g/kg with mean value of 7.4 ± 1.5, 1.69 ± 0.42, 1.6 ± 0.2, 1.6 ± 0.7, 1.07 ± 0.16, 0.71 ± 0.16, 0.58 ± 0.16, 0.48 ± 0.05, and 0.08 ± 0.052 g/kg, respectively
Remarkably high content of the As (4.60 g/kg) was seen in the rhizospheric soil of Mentha spicata (MS), may be due to interaction of As with the carvone [
The concentration of metals i.e. As, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb in the earth crust reported was 4.8, 3840, 97, 92, 774, 34900, 47, 28, 67 and 17 mg/kg, respectively [
The allowable limits reported for the HMs i.e. As, Cr, Mn, Cu, Ni, Zn and Pb in the soil are 5, 200, 55, 50, 50, 400 and 70 mg/kg, respectively [
M | EA | CS | MS | OS | CD | SS | DM | AP | SI | AA | SN | AI | MZ | BM |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
As | 2.81 | 2.32 | 4.60 | 3.72 | 0.30 | 1.99 | 0.26 | 0.96 | 0.67 | 0.22 | 0.48 | 1.35 | 0.32 | 3.00 |
V | 0.28 | 0.86 | 0.52 | 0.63 | 0.89 | 0.62 | 0.79 | 0.29 | 0.53 | 0.53 | 1.49 | 1.05 | 0.81 | 0.58 |
Cr | 0.99 | 1.22 | 1.17 | 2.02 | 3.01 | 1.10 | 2.69 | 0.90 | 0.78 | 2.99 | 1.42 | 0.83 | 2.65 | 1.94 |
Mn | 3.43 | 8.06 | 9.91 | 5.70 | 7.87 | 7.52 | 8.08 | 3.67 | 4.88 | 6.44 | 12.00 | 8.07 | 12.61 | 5.70 |
Ni | 0.23 | 0.38 | 0.56 | 0.64 | 0.87 | 0.36 | 0.90 | 0.27 | 0.29 | 0.90 | 0.70 | 0.35 | 0.78 | 0.93 |
Cu | 0.36 | 0.57 | 0.36 | 0.41 | 0.49 | 0.52 | 0.41 | 0.37 | 0.64 | 0.45 | 0.57 | 0.47 | 0.64 | 0.49 |
Zn | 1.19 | 1.04 | 0.91 | 1.31 | 0.89 | 1.07 | 0.70 | 0.90 | 1.24 | 0.70 | 1.79 | 0.97 | 0.90 | 1.40 |
Pb | 0.116 | 0.042 | 0.071 | 0.080 | 0.048 | 0.065 | 0.030 | 0.032 | 0.019 | 0.020 | 0.331 | 0.041 | 0.144 | 0.085 |
EA = Eclypta alba, CS = Coriandrum sativum, MS = Mentha spicata, OS = Ocimum santum, CD = Cynodon dactylon, SS = Solenum surrantense, DM = Dhatura metel, AP = Anacyclus pyrethrum, SI = Spiranthes indium, AA = Achyranthes aspera, SN = Solenum nigrum, AI = Azadirechta indica, BM = Butea monosperma, MZ = Manilkara zapota.
M | EA | CS | MS | OS | DM | AA | CD | SS | AP | SN | SI | AI | MZ | BM |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
As | 337 | 375 | 785 | 604 | 40 | 25 | 40 | 431 | 125 | 58 | 171 | 203 | 32 | 526 |
Ti | 6.7 | 10.2 | 10.5 | 6.5 | 5.8 | 6.2 | 8.4 | 15.3 | 5.7 | 6.0 | 9.0 | 9.8 | 5.0 | 6.3 |
V | 4.2 | 7.3 | 7.4 | 5.3 | 4.0 | 3.7 | 8.6 | 9.7 | 3.1 | 7.5 | 7.3 | 7.5 | 3.9 | 4.8 |
Cr | 6.9 | 11.2 | 24.3 | 9.0 | 20.6 | 21.0 | 22.6 | 13.5 | 6.4 | 9.3 | 11.2 | 6.7 | 14.3 | 18.4 |
Mn | 3.9 | 12.6 | 11.5 | 12.4 | 10.3 | 7.5 | 9.9 | 15.4 | 4.4 | 13.2 | 11.4 | 11.5 | 12.0 | 9.5 |
Fe | 3.7 | 11.8 | 12.3 | 5.0 | 7.6 | 6.5 | 7.7 | 14.8 | 5.0 | 8.2 | 13.2 | 11.6 | 6.2 | 9.3 |
Ni | 2.6 | 7.0 | 13.6 | 8.4 | 12.8 | 11.8 | 12.7 | 9.2 | 4.0 | 8.6 | 7.8 | 5.7 | 8.4 | 17.7 |
Cu | 8.7 | 17.8 | 15.4 | 9.5 | 9.7 | 8.9 | 12.0 | 19.6 | 9.1 | 12.6 | 26.7 | 13.5 | 12.3 | 16.5 |
Zn | 9.6 | 10.9 | 18.4 | 7.9 | 6.2 | 5.7 | 7.9 | 15.8 | 7.5 | 13.9 | 19.6 | 9.8 | 6.1 | 16.5 |
Pb | 4.0 | 1.8 | 4.7 | 2.5 | 1.1 | 0.7 | 1.8 | 4.2 | 1.0 | 10.5 | 1.3 | 1.7 | 4.0 | 4.2 |
M | EA | CS | MS | OS | DM | AA | CD | SS | AP | SN | SI | AI | MZ | BM |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
As | 583 | 479 | 958 | 771 | 63 | 42 | 63 | 417 | 208 | 104 | 146 | 281 | 67 | 625 |
Ti | 11.6 | 12.9 | 10.3 | 10.3 | 8.9 | 10.5 | 13.2 | 14.7 | 9.5 | 10.8 | 7.6 | 13.7 | 10.3 | 7.5 |
V | 7.2 | 9.3 | 8.2 | 7.2 | 6.2 | 6.2 | 13.4 | 9.3 | 5.2 | 13.4 | 6.2 | 10.8 | 8.4 | 6.0 |
Cr | 11.8 | 14.1 | 14.1 | 23.5 | 31.8 | 35.3 | 35.3 | 12.9 | 10.6 | 16.5 | 9.4 | 9.8 | 31.2 | 22.8 |
Mn | 6.8 | 16.2 | 19.8 | 11.4 | 16.2 | 12.8 | 15.8 | 15 | 7.4 | 24 | 9.8 | 16.14 | 25.22 | 11.4 |
Fe | 6.6 | 15.3 | 8.0 | 12.3 | 12.0 | 11.3 | 12.3 | 14.6 | 8.5 | 15.0 | 11.4 | 16.1 | 12.9 | 11.0 |
Ni | 4.5 | 9.1 | 13.6 | 13.6 | 20.5 | 20.5 | 20.5 | 9.1 | 6.8 | 15.9 | 6.8 | 8.0 | 17.7 | 21.1 |
Cu | 16 | 24 | 16 | 16 | 16 | 16 | 20 | 20 | 16 | 24 | 24 | 18.8 | 25.6 | 19.6 |
Zn | 16.9 | 14.1 | 12.7 | 18.3 | 9.9 | 9.9 | 12.7 | 15.5 | 12.7 | 25.4 | 16.9 | 13.7 | 12.7 | 19.7 |
Pb | 7.1 | 2.4 | 4.1 | 4.7 | 1.8 | 1.2 | 2.9 | 4.1 | 1.8 | 19.4 | 1.2 | 2.4 | 8.5 | 5.0 |
M | EA | CS | MS | OS | CD | SS | DM | AP | SI | AA | SN | AI | MZ | BM |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
As | 8.6 | 8.3 | 9.3 | 9.0 | 5.4 | 8.1 | 5.2 | 7.1 | 6.5 | 4.9 | 6.1 | 7.6 | 5.5 | 8.7 |
Ti | 2.4 | 2.7 | 2.5 | 2.6 | 2.6 | 2.6 | 2.8 | 1.6 | 1.7 | 2.7 | 3.2 | 3.1 | 2.7 | 2.3 |
V | 0.9 | 2.6 | 1.8 | 2.1 | 2.6 | 2.1 | 2.4 | 1.0 | 1.9 | 1.9 | 3.4 | 2.9 | 2.5 | 2.0 |
Cr | 2.8 | 3.1 | 3.1 | 3.9 | 4.4 | 3.0 | 4.3 | 2.7 | 2.5 | 4.4 | 3.4 | 2.6 | 4.3 | 3.8 |
Mn | 1.6 | 2.8 | 3.1 | 2.3 | 2.8 | 2.7 | 2.8 | 1.7 | 2.1 | 2.5 | 3.4 | 2.8 | 3.4 | 2.3 |
Fe | 2.1 | 3.3 | 2.4 | 3.0 | 3.0 | 3.3 | 3.0 | 2.5 | 2.9 | 2.9 | 3.6 | 3.4 | 3.1 | 2.9 |
Ni | 1.7 | 2.4 | 3.0 | 3.2 | 3.6 | 2.3 | 3.7 | 1.9 | 2.0 | 3.7 | 3.3 | 2.3 | 3.5 | 3.7 |
Cu | 3.1 | 3.8 | 3.1 | 3.3 | 3.5 | 3.6 | 3.3 | 3.1 | 3.9 | 3.4 | 3.8 | 3.5 | 3.9 | 3.5 |
Zn | 3.6 | 3.4 | 3.2 | 3.7 | 3.2 | 3.4 | 2.8 | 3.2 | 3.6 | 2.8 | 4.2 | 3.3 | 3.2 | 3.8 |
Pb | 2.2 | 0.7 | 1.5 | 1.7 | 0.9 | 1.4 | 0.3 | 0.4 | -0.4 | -0.3 | 3.7 | 0.7 | 2.5 | 1.8 |
The higher content of the As and other HMs was more enriched in the rhizospheric soil than the bulk soil due to biological interactions. The HMs (i.e. As, Mn, Cu, Ni and Zn) content in the rhizospheric soil was found above the permissible limits. Among them, As is extremely enriched in the soil. The higher content of HMs (i.e. As, Cr, Mn, Cu, Ni, Zn and Pb) in the rhizospheric soil of herbs i.e. MS and OS was observed.
We are thankful to the Italian Ministry of Education, Rome for granting the research project to Prof. E. Bontempi for the collaborative work.
Khageshwar SinghPatel,Bharat LalSahu,ShobhanaRamteke,Nitin KumarJaiswal,LauraBorgese,AlessandraGianoncelli,ElzaBontempi, (2015) Contamination of Arsenic and Other Heavy Metals in Rhizospheric Soil. American Journal of Analytical Chemistry,06,822-829. doi: 10.4236/ajac.2015.610078