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Assessment of Heavy Metal Contamination and Sediment Quality in the Buriganga
River, Bangladesh
P. K. Saha
Lecturer, Department of Civil Engineering
Bangladesh University of Engineering & Technology
Dhaka-1000, Bangladesh
e-mail: provat_ce@yahoo.com
M.D. Hossain
Professor, Department of Civil Engineering
Bangladesh University of Engineering & Technology
Dhaka-1000, Bangladesh
e-mail: delwar@ce.buet.ac.bd
Abstract—Concentrations of five heavy metals (Pb, Cd, Cr, Cu,
and Zn) for sediment from the Buriganga River and for the
portion of sediment which passing through the #200 sieve were
determined in this study to evaluate their levels and spatial
distribution. The ranges of the measured concentrations in the
total sediments are as follows: 60.3-105.6 mg/kg for Pb, 0.4-1.6
mg/kg for Cd, 52.8-139.6 mg/kg for Cr, 70-346 mg/kg for Cu
and 245-984.9 mg/kg dry weights for Zn and fine portion of
sediments contain higher heavy metal concentration compared
to total sediments. To assess metal contamination in sediment,
US environmental Protection Agency’s (USEPA) Guidelines
were applied. The concentrations of Pb, Cu, and Zn in all
sediment samples are above the EPA guideline for heavily
polluted sediment and the concentration of Cd and Cr are fall
in the criteria of moderately to highly polluted range. The
metals contamination in the sediments were also evaluated by
applying Index of geo-accumulation (Igeo), contamination
factor (Cf) and toxicity characteristics leaching procedure test
(TCLP test).TCLP test results showed that the Buriganga
River sediments are not likely to leach hazardous
concentrations of particular toxic constituents into the
environment as a result of improper management. Sieve
analysis of sediment samples, moisture content and organic
matter content test were also performed in this study to
determine the physical characteristic of sediment samples.
Keywords-sediment; heavy metal; contamination; organic
content; contamination factor; geo-accumulation index ;TCLP
test
I. INTRODUCTION
The River Buriganga running by the side of the Dhaka
City, the capital of Bangladesh, is one of the most polluted
rivers in Bangladesh. Many industries have set up in and
around the Dhaka city during the last decade, and the number
of new industries are continually increasing. The river
Buriganga is increasingly being polluted with the city’s
thousands of industrial units and sewerage lines dumping
huge volumes of toxic wastes which contain lots of heavy
metal into it day and night (Islam et al., 2006). Heavy metals
contamination in aquatic environment is of critical concern,
due to toxicity of metals and their accumulation in aquatic
habitats. Trace metals in contrast to most pollutants, not bio-
degradable, and they undergo a global ecological cycle in
which natural water are the main pathways. Of the chemical
pollutants, heavy metal being non-biodegradable, they can be
concentrated along the food chain, producing their toxic
effect at points after far removed from the source of pollution
(Tilzer and Khondker, 1993). Exposure to heavy metals has
linked to several human diseases such as development
retardation or malformation, kidney damage, cancer,
abortion, effect on intelligence and behavior, and even death
in some cases of exposure to very high concentrations.
The aim of this study is to assess the level of heavy metal
concentrations and sediment quality in surface sediments of
the Buriganga River and to explore the natural and
anthropogenic input of heavy metals and to assess the
pollution status on the area and to highlight relationships
among metals pollution.
II. METHODS AND MATERIALS
Sediments sample were collected from five sites along
the Buriganga River as showing in Fig.1 Latitude and
Longitude for each site were illustrated in Table I. The
sediment samples were directly collected from the Buriganga
River during the dredging of Buriganga bed sludge. The
samples were carried by polythene bag. After collection,
some portion of sediment samples were dried in a vacuum
oven at 105ºC until constant weight, lightly ground in an
agate mortar for homogenization and prepared for analysis of
heavy metal and some portion of samples were prepared for
sieve analysis, moisture content and organic content test. For
heavy metal test, 5 gm of dried sample was digested with
acid and prepared 500 ml solution. Finally, five heavy metals
(Pb, Cd, Cr, Cu, and Zn) concentration were determined in
the environmental engineering laboratory, BUET by using
atomic absorption spectrophotometer (AAS). To determine
the physical characteristics of sediment, moisture content,
organic matter content and sieve analysis test were also
performed. Toxicity characteristics leaching procedure
(TCLP) test for sediment samples were performed for five
heavy metals (Pb, Cd, Cr, Cu and Zn) to determined the
readily toxicity level of heavy metals. Heavy metal
concentration for the fine portion of sediment samples
(sample which passing through # 200 sieve) were also
performed in this study.
TABLE I. LOCATION OF SEDIMENT SAMPLE COLLECTION
Station
No Location Latitude Longitude
1 Wachpur Ghat 23°44'41.6"N 90°20'35"E
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2011 2nd International Conference on Environmental Science and Technology
IPCBEE vol.6 (2011) © (2011) IACSIT Press, Singapore
2 Kolatiya Para 23°44'17.2"N 90°21'1.8"E
3 kamrangirchar(End) 23°42'37.4"N 90°23'20.9"E
4 Kamrangirchar(North) 23°44'1.4"N 90°21'21.1"E
5 Badamtoli Ghat 23°42'37"N 90°24'1.3"E
Figure 1. Map showing the sampling location
III. RESULTS AND DISCUSSIONS
A. Heavy Metal Concentrations
The total metal concentrations for each sampling site
found in sediments in this study are shown in Table II. Metal
contents were ranging over following intervals: Pb: 60.3-
105.6 mg/kg; Cd: 0.4-1.6 mg/kg; Cr: 52.8-139.6 mg/kg; Cu:
70- 346 mg/kg; Zn: 245-984.9 mg/kg dry weights. Mean
concentration of the metals were: Pb: 79.4 mg/kg; Cd: 0.82
mg/kg; Cr: 101.2 mg/kg; Cu: 184.52 mg/kg; Zn: 502.26
mg/kg dry weights, allowing to arrange the metals from
higher to lower mean content in this area as: Zn > Cu > Cr>
Pb > Cd.
Pearson's correlation coefficient matrix among the
selected heavy metals is presented in Table III. Significant
correlations between the contaminants of Cd and Zn
(r=0.987), Cd and Cu (r=0.976), Zn and Cu (r=0.965), Pb
and Zn (r=0.892), Pb and Cr (r=0.853), Cd and Pb (r=0.823),
Pb and Cu (r=0.801), Cr and Cu (r=0.753) could indicate the
same or similar source input. The metal concentrations for
the sediment passing through the No. 200 sieve are shown in
Table IV. Metal contents were ranging over following
intervals: Pb: 62.5-128.5 mg/kg; Cd: 0.2-1.1 mg/kg; Cr: 55-
160.4 mg/kg; Cu: 95.6- 426.6 mg/kg; Zn: 227.9-950.1 mg/kg
dry weights. Mean concentration of the metals were: Pb:
85.72 mg/kg; Cd: 0.54 mg/kg; Cr: 107.86 mg/kg; Cu: 233.12
mg/kg; Zn: 528.28 mg/kg dry weights. By comparing the
result obtain from metal concentrations of total sediment
(without sieve) and metal concentration of the sediment
which passing through No. 200 sieve (fine portion), it is
shown that the average concentration for all the metal in fine
portion is higher than total sediment except Cd. It is also
shown in this study, the standard deviation (SD) between the
concentrations of metal at different sites are very high that
may indicate the spatial distribution of metal contamination
is not uniform.
TABLE II. CONCENTRATION OF HEAVY METALS (MG/KG DRY WEIGHT)
Station No.
Concentration of heavy metal (mg/kg dry weight)
Pb Cd Cr Cu Zn
1 82.3 0.4 129.9 107.7 329.6
2 70.4 0.5 57.9 85 276
3 60.3 0.4 52.8 70 245
4 80.6 1.2 125.8 313.4 675.8
5 105.6 1.6 139.6 346 984.9
Mean 79.8 0.8 101.2 184.4 502.3
Max 105.6 1.6 139.6 346 984.9
Min 60.3 0.4 52.8 70 245
SD 16.9 0.55 42.2 133.8 320.3
Background 20 0.2 97 32 129
TABLE III. CORELATION MATRIX BETWEEN HEAVY METALS IN
SEDIMENT SAMPLES FROM THE BURIGANGA RIVER
Pb Cd Cr Cu Zn
Pb 1
Cd 0.823 1
Cr 0.853 0.662 1
Cu 0.801 0.976 0.753 1
Zn 0.892 0.987 0.741 0.965 1
TABLE IV. CONCENTRATION OF HEAVY METALS (MG/KF DRY WEIGHT)
SEDIMENTS WHICH PASSING THROUGH #200 SIEVE
Station No.
Concentration of heavy metal (mg/kg dry
weight)
Pb Cd Cr Cu Zn
1 62.4 0.2 113.7 146.9 359.3
2 77.4 0.3 62.4 147.3 337.4
3 46.3 0.2 55 95.9 227.9
4 114 0.9 160.4 348.9 766.7
5 128.5 1.1 147.8 426.6 950.1
Mean 85.7 0.6 107.9 233.1 528.3
Max 128.5 1.1 160.4 426.6 950.1
Min 62.5 0.2 55 95.9 227.9
SD 34.6 0.4 48.1 145.3 312.3
B. Physical Characteristic of Sediment (Sieve analysis,
Moisture content & Organic Content)
Moisture content and organic matter content result of
sediment sample is presented in table V and sieve analysis
result of sediment sample is presented in the table VI
Average in all sites, 1.75% materials retain on #4 and above
sieve and 25.34 % materials passing through the #200 sieve
whereas 72.90% materials retain on #8 to #200 sieves that
indicate the sediment size of the Buriganga River ranges
over medium to fine size and it contains a significant amount
of fine particle. The average moisture content and organic
matter content of the sediment sample are 82.26% and 7.12%
respectively. A relationship is found between the moisture
content and organic matter content. Higher moisture content
in the sediment sample shows the higher organic matter
content. There is another relationship found in this study, the
sites which contain higher organic matter shows higher
heavy metal concentration .For example, Station No. 4 and 5
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which contain higher organic matter (10.14% and 12.2%
respectively) showed higher heavy metal content.
TABLE V. MOISTURE CONTENT AND ORGANIC CONTENT OF
SEDIMENT SAMPLES OF THE BURIGANGA RIVER
Moisture Content and Organic matter Content of Sediment
Sample(% of dry sample)
Station No. Moisture Content Organic Content
1 64.33 4.11
2 43.15 5.52
3 38.11 3.61
4 100.21 10.14
5 165.5 12.2
Average 82.26 7.12
TABLE VI. SIEVE ANALYSIS RESULT OF THE SEDIMENT SAMPLE OF
THE BURIGANGA RIVER
Sieve Analysis result of Sediment Sample
Station 1 Station 2 Station 3 Station 4 Station 5
Sieve
Size %
materials %
materials %
materials %
materials %
materials
(ASTM
) retains retains retains retains retains
(gms) (gms) (gms) (gms) (gms)
1/4" 0.75 1.06 1.17 0.47 0
No 4 1.38 1.38 1.44 0.76 0.37
No 8 9.07 6.96 7.02 9.23 4.96
No 16 15.14 10.26 11.59 16.89 11.36
No 30 10.35 6.82 8.45 14.03 10.6
No 40 4.06 4.12 3.77 7.18 4.51
No 50 4.95 5.25 5.41 7.03 5.61
No 100 17.5 22.59 17.56 13.64 17.52
No 200 13.95 17.84 15.14 9.82 14.33
PAN 22.86 23.71 28.44 20.95 30.74
TOTAL 100 100 100 100 100
%
Coarse 2.13 2.44 2.61 1.23 0.37
%
Medium 75.02 73.84 68.94 77.82 68.89
% Fine 22.86 23.71 28.44 20.95 30.74
IV. ASSESSMENT OF HEAVY METAL CONTAMINATION
A. Assessment According to United States Environmental
Protection Agency (USEPA)
The chemical contaminations in the sediments were
evaluated by comparison with the sediment quality guideline
proposed by USEPA. These criteria are shown in Table VII.
Present study shows that all the sites are heavily polluted for
Pb, Cu and Zn while for Cr, sites 2 and 3 are moderately
polluted and sites 1, 4, 5 are heavily polluted. For Cd, all the
sites are ranges over not polluted to moderately polluted
condition.
B. Assessment According to Geo-accumulation Index (Igeo)
A common criterion to evaluate the heavy metal
pollution in sediments is the geo-accumulation index (Igeo),
which was originally defined by Muller (1979) to determine
metals contamination in sediments, by comparing current
concentrations with pre-industrial levels and can be
calculated by the following equation (Muller 1979)
2
. (1)
Where, Cn is the concentration of element ‘n’ and Bn is
the geochemical background value [In this study, consider
Bn=world surface rock average given by Martin and
Meybeck (1979)]. The factor 1.5 is incorporated in the
relationship to account for possible variation in background
data due to lithogenic effect. The geo-accumulation index
(Igeo) scale consists of seven grades (0-6) ranging from
unpolluted to highly pollute (shown in Table VIII).
According to the Muller scale, the calculated results of Igeo
values ( Shown in Table IX) indicate, for Pb sediment
quality be considered as moderately polluted (1≤Igeo<2) for
all stations while for Cr sediment quality was recorded
unpolluted for all stations (Igeo<0). For Cu and Zn, sites 5 are
ranges from moderately to strongly polluted sediment quality.
From unpolluted to moderately polluted situation was
recorded for Cd, Cu, and Zn for station No. 1, 2, 3 (except
station No 1 for Cu which Igeo is 1.17 that indicates
moderately polluted situation).Higher Igeo values are showed
for Station No 4 and 5 which sediment quality ranges from
moderately polluted to strongly polluted for most of the
tested heavy metals. On the basis of the mean values of Igeo,
sediments are enriched for metals in the following order: Cd >
Cu > Pb > Zn > Cr.
TABLE VII. EPA GUIDELINES FOR SEDIMENTS (MG/KG DRY WEIGHTS)
Metal Not
polluted Moderately
polluted Heavily
polluted Present
study
Pb <40 40-60 >60 60.3-105.6
Cd …. … >6 0.4-1.6
Cr <25 25-75 >75 52.8-139.6
Cu <25 25-50 >50 70-346
Zn <90 90-200 >200 245-984.9
TABLE VIII. MULLER’S CLASSIFICATION FOR THE GEO-ACCUMULATION
INDEX
I
g
eo Value Class Sediment Quality
≤0 0 Unpolluted
0-1 1 From unpolluted to moderately polluted
1-2 2 Moderately polluted
2-3 3 From moderately to strongly polluted
3-4 4 Strongly polluted
4-5 5 From strongly to extremely polluted
>6 6 Extremely polluted
TABLE IX. GEO-ACCUMULATION INDEX VALUES FOR THE SEDIMENTS
SAMPLES OF THE BURIGANGA RIVER
Station I
g
eo
V1-386
Pb Cd Cr Cu Zn
1 1.46 0.42 -0.16 1.17 0.77
2 1.23 0.74 -1.33 0.82 0.51
3 1.01 0.42 -1.46 0.54 0.34
4 1.43 2 -0.21 2.71 1.80
5 1.82 2.42 -0.06 2.85 2.35
Mean 1.39 1.97 -0.65 1.62 1.15
C. Assessment According to Contamination Factor
The contamination factor (Cf) or enrichment ratio(ER)
and the degree of contamination (Cd) are used to determine
the contamination status of sediment in the present study. Cf
values for describing the contaminations level are shown in
table X .The contamination factor are calculated according to
the eq.2 and the degree of contamination (Cd) was defined as
the sum of all contamination factors. Calculated
contamination factor (Cf) and degree of contamination (Cd)
for this study is shown in the table XI.
(2)
Where, Background value of the metal= world surface
rock average given by Martin and Meybeck (1979).
In the present study, maximum contamination factor was
found in the station No. 5 where the degree of contamination
is 33.16.Contamination factor, Cf>6 (indicate very high
contamination) are found in station No 4 for Cd , Cu and
station No. 5 for Cd, Cu and Zn. All the station has a
contamination factor (Cf)>1 for all tested heavy metals
except station 2 and 3 for Cr. The mean value of the Cf are
found: Pb: 3.99 (considerable contamination); Cd: 4.1
(moderate contamination); Cr: 1.043 (moderate
contamination); Cu: 5.76 (considerable contamination); Zn:
3.89 (considerable contamination) .On the basis of the mean
values of Cf, sediments are enriched for metals in the
following order: Cu> Cd > Pb >Zn > Cr.
D. Assessment According to Toxicity Charateristics
Leaching Procedure (TCLP)
Toxicity Characteristics Leaching Procedure (TCLP) is a
very important tool for assessing readily contaminated heavy
metal for sediment samples. In this study, heavy metal
concentrations from leachate of Buriganga River Sediments
were tested in the laboratory and pollution levels of leachate
were assessed with comparison of EPA standard. Results of
the TCLP test are presented in the Table XII. For all the sites,
concentrations of heavy metal in leachate are not exceeded
the permissible EPA standard. That indicate regarding the
readily toxicity pollution by heavy metal, Buriganga River
Sediment condition is not the severe state.
TABLE X. CONTAMINATION FACTOR AND LEVEL OF CONTAMINATION
(HAKANSON 1980)
Contamination Factor (Cf) Level of Contamination
Cf < 1 low contamination
1≤ Cf < 3 moderate contamination
3≤ Cf < 6 considerable contamination
Cf > 6 very high contamination
TABLE XI. CONTAMINATION FACTOR VALUES FOR THE SEDIMENT
SAMPLE OF THE BURIGANGA RIVER
Sample
Location
Enrichment Ratio (ER) or
Contamination Factor (Cf)
Degree of
contamination
Pb Cd Cr Cu Zn
1 4.11 2 1.33 3.365 2.5 13.3
2 3.5 2.5 0.59 2.656 2.1 11.41
3 3.01 2 0.54 2.187 1.89 9.64
4 4.03 6 1.29 9.793 5.23 26.35
5 5.28 8 1.43 10.812 7.6 33.16
Mean 3.99 4.1 1.04 5.76 3.89 18.8
TABLE XII. TCLP TEST RESULT FOR THE SEDIMENT SAMPLE OF THE
BURIGANGA RIVER
Concentration of heavy metal in mg/l
Station No Pb Cd Cr Cu Zn
1 0.101 0.015 0.053 0.344 9.43
2 0.125 0.011 0.022 0.202 6.25
3 0.185 0.012 0.029 0.118 4.193
4 0.131 0.023 0.042 0.274 18.961
5 0.173 0.024 0.045 0.246 26.09
Mean 0.143 0.017 0.0382 0.237 12.99
Max 0.185 0.024 0.053 0.344 26.09
Min 0.101 0.011 0.022 0.118 4.193
SD 0.031 0.0055 0.011 0.0752 8.28
EPA
Standard 5 1 5
V. CONCLUSIONS
The results of this study supply valuable information
about metal heavy contents and physical characteristics of
sediment from different sampling stations of Buriganga
River. The order of the mean concentrations of tested heavy
metals: Zn > Cu > Cr> Pb > Cd and it is found in this study
that, the fine portion of the sediment (sediment. which
passing through #200 sieve) are contain more heavy metal
contents than total sediments. USEPA guideline, Geo-
accumulation Index, contamination factor and degree of
contamination, TCLP are successfully applied for the
assessment of contamination. According to USEPA: for Pb,
Cu and Zn, the sediment samples are heavily polluted
whereas for Cd, Cr, the sediments samples are moderate to
heavily polluted; according to Igeo: the sediments quality is in
moderately polluted condition for Pb, Cd, Cu, Zn while
according to contamination factor (Cf): Pb, Cd, Cu and Zn
are responsible for considerable contaminations. TCLP test
showed that there is no considerable risk of contaminations
from leachate of Buriganga River Sediments. Considering all
assessment criteria, Pb, Cu and Zn are responsible for
considerable or significant amount of heavy metal
contaminations while Cr and Cd are responsible for moderate
to high level contaminations. Station 5 (Badamtoli Ghat)
contains highest amount of heavy metal contamination and
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station 3 (Kamrangirchar-End) contains lowest amount of
heavy metal contamination.
ACKNOWLEDGMENT
The authors realized thanks to the BUET Authority and
the staffs of the BUET Environmental Engineering
laboratory, for providing all kinds of assistance to conduct
this research work.
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