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INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 5, No 5, 2015 © Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article

ISSN 0976 – 4402

Assessment of heavy metals pollution and natural radioactivity in topsoil of Savar industrial area, Bangladesh B.M.R. Faisal1, R.K. Majumder2, M. J. Uddin1, F. Deeba2, D. Paul3, M.A. Haydar3, M. I. Ali3 1-Department of Environmental Sciences, Jahangirnagar University, Dhaka-1342, Bangladesh 2-Nuclear Minerals Unit, Atomic Energy Research Establishment, Dhaka-1349, Bangladesh 3-Health Physics & Radioactive Waste Management Unit, INST, Atomic Energy Research Establishment, Dhaka-1349 Bangladesh [email protected] doi: 10.6088/ijes.2014050100091

ABSTRACT A total number of twenty topsoil samples were analyzed for heavy metals using X-ray Fluorescence System where as radioactivity levels of seven samples were determined by High Purity Germanium (HPGe) detector. The average concentrations of Mn, Zn, Cr, Co and Cu were 584.68, 213.04, 190.33, 164.63 and 100.18 mg/kg respectively in topsoil, which were much above the recommended level as well as higher than their corresponding background values thus indicating environmental pollution. The order of average heavy metal contents was Mn>Zn>Cr>Co>Cu>As>Pb in topsoil. Soil pollution assessment was carried out by using enrichment factor (EF), geoaccumulation index (Igeo), contamination factor (CF), degree of contamination (Cd) and pollution load index (PLI). The soil shows moderate enrichment of Cu and minimal enrichment with Zn, Pb, Cr, As, and Co. Whereas Igeo and CF exhibit moderate to high contamination for Mn, Zn, Cu, Cr and Co. The results of PLI of analyzed heavy metals indicate that the study area is contaminated with heavy metals like Mn, Zn, Cu, Cr and Co. Multivariate statistical analyses, principal component and cluster analysis shows significant anthropogenic intrusions of Cr, Mn, As, Pb, Co and Cu in the topsoil of the study area. The calculated average activity concentrations of radionuclides 226Ra, 232Th and 40 K in topsoil were 30.56 Bq.kg-1, 60.45 Bq.kg-1 and 706.00 Bq.kg-1 respectively. The estimated average Absorbed Dose Rate (D) and the Outdoor Annual Effective Dose (E) and the External Hazard Index (Hex) are 79.54 nGyh-1, 0.10mSvy-1 and 0.46 Bq.Kg-1 respectively. The result of Pearson linear correlation coefficient between heavy metals and the observed radionuclides shows negative or negligible correlation which means that the radioactivity level are not associated with heavy metal concentration. But significant positive correlation between 40K and Mn strongly suggests that these elements may arise from clay minerals and/or agricultural inputs in this area. Keywords: Heavy Metals, Heavy Metal Pollution Index, Multivariate Statistical Analysis, Natural Radioactivity, Radioactive Health Hazard Indices 1. Introduction The chemical composition of soil, particularly its metal content, is environmentally important, because depending on their concentrations, levels of toxic elements can reduce soil

Received on January 2015 Published on March 2015

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Assessment of heavy metals pollution and natural radioactivity in topsoil of Savar industrial area, Bangladesh

fertility, can increase input to food chain, which leads to accumulate toxic metals in foodstuffs, and ultimately can endanger human health. The industrial units in Savar area include garments, textile miles, leather goods, metal products, electronic goods, paper products, chemicals and fertilizers and miscellaneous products (Khan et al., 2011). The industrial discharge or wastes include heavy metals, toxic chemicals, dissolved lime, chromium sulfate, alkali, hydrogen sulfide, sulfuric acid, bleach, dyes, oil, formic acid, suspended solids, organic matter, pesticides, polychlorinated biphenyls (PCBs), dioxins, poly-aromatic hydrocarbons (PAHs), petrochemicals, phenolic compounds and microorganisms (Fakayode, 2005) etc. generated from the industrial activities. The industrial waste are discharged into the low lying areas in the surroundings without any prior treatment that can decrease soil quality by increasing concentrations of pollutants such as heavy metals, resulting in adverse effects on macrophytes, soil fauna and human health (Ahmed et al., 2009). Besides, the uneducated farmers randomly use fertilizers and pesticides in agricultural lands. Essential heavy metals like Copper (Cu), Zinc (Zn) and Manganese (Mn) as well as nonessential heavy metals like Cadmium (Cd), Chromium (Cr), Manganese (Mn) and Lead (Pb)) are considered highly toxic for human and aquatic life when it exceed the safe level. Due to the heavy metal pollution productivity of agricultural products may become low compare to the unpolluted area and it may disrupt the normal life of low income people of this area. Soil provides a direct source of radioactivity in food chain due to its uptake by cultivated plants. In addition to natural sources, soil radioactivity is also affected by man-made activities. The radioactivity concentration of 226Ra, 232Th and 40K above permissible level is very harmful to the human body. Hence, the present study has been initiated to (a) assess the heavy metal pollution in topsoil by calculating a number of pollution indices and statistical analysis to report the general status of soil quality in study area and (b) the assessment of natural radioactivity (238U, 232Th and 40K) concentrations and evaluation of radiation hazard in topsoil of the study area. This study can also be helpful to establish a research baseline and the results can be used as the baseline for future remediation actions in this study area. 2. Material and methods 2.1 Study area The study area is lies between 23054/47.8// to 23048/33.1// north latitude and 90014/52.6" to 90014/44.5// east longitude (Figure 1). The study area comprise of many isolated water bodies occupying the low lying and depressed areas connected or not connected to the river system. The Bansi-Daleshwari and Turag comprises the drainage network of the study area–the Bansi on the west and the Turag is away on the east. The land of Savar industrial area is composed of Pleistocene red clay and recent alluvium soil. The major part of the land is used for the cultivation of agricultural products and the rest is used for industrial activity. 2.2 Sample collection Soil samples were collected from twenty different locations by using clean stainless steel (Figure 1). The geographical location of each sampling points were determined with a handheld global positioning system (GARMIN). The soil samples were collected from agricultural fields, residential areas, industrial area, roadside area, canal bed, beside river bed and fresh agricultural fields. Two fresh samples (S-04 and S-17) were collected from agricultural land at a safe distance from the study area for background studies. About 2-3 kg of soil was taken from each sampling point and was kept in polythene bags designated with sampling location, date and sample ID. B.M.R. Faisal et al International Journal of Environmental Sciences Volume 5 No.5, 2015

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Figure 1: Showing the sampling points of study area 2.3 Measurement of physicochemical parameters For determination of pH, 10 gm the air-dried sample was mixed with 25 mL distilled water (soil: water at a ratio of 1:2.5) and the solution was stirred thoroughly and after 25-30 minutes the reading was taken (Islam and Weil, 2000). For Electrical Conductivity (EC) measurement, 10 gm air dried soil was taken and then mixed with 40 ml of deionized water in a biker (soil: water at a ratio of 1:40) and after stirring of 30 minutes reading was taken (Halim et al., 2011). In this study Total Organic Carbon (TOC) was measured by dry combustion method (Carbonell-Barrachina et al., 2007) following the equation given below;

TOC =

Final Sample Weight − Initial Sample Weight × 100%.............(1) Initial Sample Weight

2.4 Elemental analysis by PXRF method The total concentration of heavy metals of topsoil samples were measured by X-Ray Fluorescence, employing a Thermo Scientific NITON XRF analyzer; using powder pellet B.M.R. Faisal et al International Journal of Environmental Sciences Volume 5 No.5, 2015

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samples following the procedures outlined by (Tamim et al., 2012). For analyzing the soil samples in the XRF analyzer around 30 gm samples were taken in a sample container. The sample cups is need to be filled with at least 10 gm of the prepared sample and have to make sure that no voids or uneven layers are present (User Guide of NITON XL3t). Analyzed concentrations of heavy metals were within ±10% deviation from their certified values. 2.5 Radioactivity determination Radioactivity of seven topsoil samples were measured using a low level gamma counting system, a HPGe detector with a relative efficiency of 40% and energy resolution of the 1.8 keV at 1332 keV of 60Co gamma ray line. The corresponding background count for each sample has been measured for 10000s and it was subtracted from the sample activity counting. The radioactivity of 226Ra, 232Th and 40K were estimated on the assumption that they are in secular equilibrium with their respective daughter products within four weeks (Chowdhury et al., 1999). The energy regions selected for the corresponding radionuclides were 295 keV and 352 keV of 214Pb and 609 keV of 214Bi for 226Ra, 239 KeV of 212Pb, 583 keV of 208Tl, 911 keV of 228Ac for 228Th and 1460 keV for 40K. The γ- activity was calculated from the following equation:

A=

CPS .......... ( 2 ) E × I ×W

Where, A = Activity of the sample in Bq.kg-1, Cps = the net counts per second = cps for the sample- cps for background value; E = the counting efficiency of the gamma energy; I = absolute intensity of the gamma ray and w = samples net weight (in gm). 2.6 Heavy metal pollution assessment in topsoil The quality of studied topsoil samples in Savar industrial area is assessed by calculating a number of pollution indices and various statistical analyses. 2.6.1 Enrichment factor (EF) Enrichment factor (EF) was determined by calculating the amount of trace metal (CM) accumulated compared to the background concentration of the same metal (Vega et al., 2009). CM / Al( sample ) EF = ...........(3) CM / Al( Background ) Where, CM (Sample) is the measured concentration of heavy metal in the sample; CM (Background) is the background value for the same metal. Banwart and Malmstrom (2001) have distinguished five classes of enrichment factors: EF40, extremely high enrichment. The EF values close to unity indicate crusted origin, those less than 1.0 suggest a possible mobilization or depletion of metals (Zsefer, 1996) whereas EF >1.0 indicates that the element is of anthropogenic origin. (Rubio et al., 2000) recommended the use of regional background values. In this regard, the background values in the present study were calculated from the average concentrations of heavy metals in unaffected soils (S-04 and S-17) of the study area, following the approach of (Cabrera et al., 1999). In this study, Aluminium (Al) was used as the reference element for geochemical normalization because of the following reasons: (1) Al B.M.R. Faisal et al International Journal of Environmental Sciences Volume 5 No.5, 2015

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is associated with fine solid surfaces, (2) its geochemistry is similar to that of many trace metals and (3) its natural concentration tends to be uniform (Daskalakis and O’Connor, 1995). 2.6.2 Geoaccumulation Index (Igeo) Geoaccumulation index (Igeo) was calculated following the procedure proposed by Muller 1981) and (Ruiz, 2001). Geoaccumulation index provides a classification system for the degree of metal enrichment when compared to the background (Ruiz, 2001). CM ( Sample ) I geo = log 2 .......... ..( 4) 1.5 × CM ( Bankground ) Where, CM (Sample) is the measured concentration of heavy metal in the sample, CM (Background) is the background value for the same metal and 1.5 is a multiplying factor intended to offset natural variability in background data resulting from lithological variations. (Ruiz, 2001) has determined seven classes of Igeo; samples may be classified as unpolluted (0≤ Igeo), unpolluted to moderately polluted (0≤ Igeo≤1), moderately polluted (1≤Igeo≤2), moderate to strongly polluted (2≤ Igeo≤3), strongly polluted (3≤ Igeo≤4), strongly to extremely polluted (4≤ Igeo≤5), and extremely polluted (Igeo≥5). 2.6.3 Contamination Factor (CF) and Degree of Contamination (Cd) The CF is the ratio obtained by dividing the concentration of each metal in the soil by the baseline or background value (concentration in unpolluted soil). Contamination factor was determined based on the equation 5. The calculated Cd is therefore defined as the sum of the contamination factor for the pollutant species specified by (Håkanson, 1980) and was assessed by using equation 6.

CF =

C ( HeavyMetal

)

C ( Bankground

)

.......... .( 5 )

Where, C (Heavy Metal) is the measured concentration of heavy metal in the sample and C is the background value for the same metal. The Cd is aimed at providing a measure of the degree of overall contamination in surface layers in a particular sampling site. (Background)

n

i

C d = ∑ C f .......... ............(6) i =1

According to (Muller, 1969) the contamination levels may be classified based on their intensities on a scale ranging from 1 to 6 (0= none, 1= none to medium, 2=moderate, 3=moderately to strong, 4= strongly polluted, 5= strong to very strong, 6= very strong). The following terminology is adopted to describe the contamination degree for analyzed elements; CdCo>Cu>As>Pb in present study. This elevated concentration of heavy metals in this area may be harmful for the human health and environment.

3.2 Soil quality assessment The result of the present study shows that most of the metals are enriched in the studied soils (Table 2).

Table 2: Enrichment Factor (EF) and Geoaccumulation Index (Igeo) of heavy metals Pb Sample ID S- 1 S- 2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-11 S-12 S-13 S-14 S-15 S-16 S-17 S-18 S-19 S-20 Average

As

Zn

Cu

EF

Igeo

EF

Igeo

EF

Igeo

1.27 1.44 1.01 0.52 2.66 3.90 1.57 0.55 1.55 1.51 1.14 1.23 0.00 1.63 0.44 0.74 1.50 1.45 1.23 1.43 1.41

0.82 0.92 0.65 0.33 1.71 2.51 1.01 0.36 0.99 0.97 0.73 0.79 0.00 1.05 0.28 0.48 0.97 0.93 0.79 0.92 0.86

0.90 0.84 2.52 0.86 2.78 2.49 0.78 0.84 0.84 0.68 0.74 0.58 2.99 0.73 0.85 0.60 1.14 0.81 0.65 0.99 1.18

0.97 0.91 2.73 0.93 3.01 2.69 0.85 0.91 0.91 0.73 0.80 0.63 3.23 0.79 0.92 0.65 1.23 0.87 0.70 1.07 1.28

0.99 3.58 2.32 0.79 5.46 7.10 2.65 0.67 2.20 0.96 3.14 1.21 0.27 2.68 0.74 0.59 1.22 0.95 0.50 0.61 1.93

5.56 20.15 13.07 4.43 30.70 39.93 14.92 3.79 12.35 5.39 17.66 6.80 1.51 15.06 4.15 3.30 6.87 5.32 2.82 3.43 10.86

EF

Mn Igeo

EF

Cr Igeo

EF

Co Igeo

EF

Igeo

1.23 2.94 1.10 25.23 1.09 8.28 1.21 7.81 1.96 4.67 1.27 29.32 1.25 9.44 1.15 7.42 1.27 3.04 1.70 39.05 0.97 7.34 1.27 8.23 1.02 2.45 1.38 31.65 1.06 8.05 1.09 7.07 5.20 12.42 2.17 49.82 2.95 22.30 1.08 6.99 4.22 10.07 1.97 45.28 1.22 9.23 1.18 7.64 3.78 9.03 1.34 30.87 1.03 7.80 0.95 6.16 1.02 2.43 0.96 22.12 0.91 6.85 0.93 6.02 1.65 3.95 0.95 21.92 1.08 8.17 0.87 5.63 1.06 2.54 1.47 33.72 0.83 6.27 0.75 4.84 4.66 11.11 0.69 15.92 1.12 8.47 1.31 8.47 2.00 4.77 0.58 13.30 0.91 6.87 1.01 6.54 2.36 5.64 2.28 52.45 2.79 21.12 1.37 8.90 4.03 9.61 1.56 35.83 1.27 9.61 0.99 6.41 1.17 2.78 1.60 36.71 1.12 8.45 1.26 8.19 0.83 1.98 0.85 19.46 0.83 6.27 0.73 4.70 0.98 2.33 0.61 14.05 0.93 7.08 0.91 5.88 0.93 2.23 0.49 11.18 0.81 6.09 1.00 6.51 0.75 1.79 0.47 10.80 0.82 6.18 1.02 6.64 0.83 1.99 0.97 22.26 0.87 6.57 1.27 8.25 2.05 4.89 1.22 28.05 1.19 9.02 1.07 6.92

The Igeo values for the heavy metals of environmental interest ranges from 2.51-0.28 for Pb, 3.23-0.63 for As, 39.93-1.51 for Zn, 12.42-1.79 for Cu, 52.45-10.80 for Mn, 22.30-6.09 for Cr, and 8.90-4.70 for Co. The average Igeo values of Mn (28.05), Zn (10.86), Cr (9.02) and Co (6.92) indicate that the sampling sites are extremely polluted with these metals. Based on average Igeo values, the ranking intensity of heavy metal pollution of the soil sample is as B.M.R. Faisal et al International Journal of Environmental Sciences Volume 5 No.5, 2015

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follows Mn>Zn>Cr>Co>Cu>As>Pb. These results state that the soil of the study area can be categorized as follows: unpolluted to moderately polluted with Pb (0< average Igeo