Diffuse Pollution Conference, Dublin 2003
Poster Papers
CORRELATION OF IRON/IRON OXIDES AND TRACE HEAVY METALS IN SEDIMENTS
OF FIVE RIVERS, IN SOUTHERN TAIWAN
*Tsai L. J.1 , Yu K.C.1 , Ho S.T.2
1
Department of Environmental Engineering and Health, Chia-Nan University of Pharmacy and Science, Tainan 717,
Taiwan, ROC
2
Department of Industrial Safety and Hygiene, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan, ROC
ABSTRACT
The main purpose of this study is to verify the correlations between iron element/iron oxides and the aqua-regia extractable
heavy metal in depth profiles of river sediment cores. Sediments, sampled from five main rivers (the Yenshui, Tsengwen,
Chishui, Potzu, and Peikang Rivers), contaminated with different level of heavy metals pollution located in southern
Taiwan, were used to determine the average concentration ratio between each heavy metal and iron element. The influence
of total anthropogenic heavy metal concentration on the average concentration ratio also can be assessed to realize the total
binding capacity of iron element with heavy metals in high and moderate pollution level of river sediment. The correlation
coefficients between Iron element and aqua-regia extractable heavy metals (Cu, Cr, Zn, Ni, Pb, Co, and Mn) are higher
than those between Iron oxides and aqua-regia extractable heavy metals in sediments of five rivers. It indicated that the
adsorption and coprecipitation of heavy metals on the iron oxides was not the only mechanism for the accumulation of
heavy metals with iron element in sediment.
The average concentration ratio of heavy metal versus iron element was defined as the concentration (mg/kg) of each kind
of aqua regia extractable heavy metals divided by iron element (%) in sediments. The values of the average concentration
ratio for each heavy metal were found as the slope of the linear regressive line of heavy metals versus iron element and
could be used as an indicator to score the pollution degree clearly in the river sediment. The coefficients of linear
regression between the trace heavy metals and iron element in sediments of five rivers were mostly higher than 0.7,
indicating that the importance of iron element in the accumulation of heavy metals in river sediments.
*Corresponding author. E-mal;[email protected]
KEYWORDS: Correlation coefficients, Heavy metals, Iron element, Iron oxides, River sediment.
INTRODUCTION
Sediment is known as traps or sources of chemical compounds and elements from the river water. The distribution of
heavy metals in sediment can be separated as exchangeable, carbonates, oxidizing, organic matter and residual fractions
(Tessier et al., 1979; Ryssen et al., 1999; Stephens et al., 2001). The percent of metals bound to five fractions were
associated with kinds of metals (Stephens et al., 2001). The metals extracted from the oxidizing fraction including the
destruction of physical (adsorption and absorption) and chemical actions (e.g. bound to iron oxides) (Donahoe, et al.,
198).The metals in different sequential extraction can be used to realize the geochemical behavior regarding
remobilization. However, the importance of iron element or iron oxides controlling the distribution of these aqua-regia
extractable trace metals in the sediment need to be compared.
Iron element is an abundant and natural component in the sediment (Nolting et al., 1999). The main objective of this study
is to investigate the metals relationship between iron element or iron oxides and aqua-regia in high or middle heavy metal
polluted river, and to assess the availability of average concentration ratio in expression the pollution degree of metals.
MATERIALS AND METHODS
Study areas
The five main rivers (the Yenshui, Tsengwen, Chishui, Potzu, and Peikang Rivers) flow through the largest plain area of
southern Taiwan. The catchments of the Yenshui River have many industrial plants which discharge large amount of
wastewater contaminated with high concentration of heavy metals and organic matters. The major pollutions in the
catchments of the other four rivers were due to domestic and agricultural activities and contained low concentration of
heavy metals and middle concentration of organic matters.
Sediment core samples preparation
Sediment cores were sampled from the five main rivers with a hand-operated sediment corer (Wildco, U.S.A.) for
investigation in this study. The sediment cores were held vertically in 4 ice-box when taking back to our laboratory and
cut downwards from the water-sediment interface (by plastic blades) to divide the cores into several 2-cm (between 0-10
cm depth of sediment core) and 5-cm (deeper under 10 cm depth of sediment core) segments. Each sediment core segment
was air-dried at room temperature before chemical analysis.
Chemical analysis
Geochemical components in the sediment were determined using the acid hydroxylamine method for Fe-oxides (Wang,
1987). Fe in hydroxylamine solution were analyzed by atomic absorption spectrometer and expressed in % of Fe2 O3 . The
heavy metals in different depth of river sediment were released by microwave assisted strong acid digestion. 0.2-0.5 gram
of air-dried sediments was taken from each sediment segment and added to a fluorocarbon polymer vessel with 3 mL of
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Diffuse Pollution Conference, Dublin 2003
Poster Papers
nitric acid (65%) and 9 mL of hydrochloric acid (37%) (Breder, 1982). This digestion process was performed by the
Milestone MLS 1200 programmed microwave system. The temperature of the acid-sample mixture in the vessel was
brought to 170±5 in 10 minutes and maintained at this temperature for 10 minutes. The concentrations of each
extractable heavy metal (Co, Cr, Cu, Zn, Ni, Pb, Mn, and Fe) were measured by flame atomic absorption
spectrophotometer (GBC, AA960, Australia).
RESULTS AND DISCUSSIONS
Heavy metals pollution in river sediment
The different depth of sediments in Yenshui river were seriously polluted by trace heavy metals (Cu, Cr, Zn, Ni, Pb, and
Co) accumulating from river water as shown in Table 1. The mostly highest concentrations of trace heavy metals were
found in the top layer of sediment below the water sediment interface. Cu, Cr, Zn, Ni, Pb, and Co were as high as 1000,
820, 830, 430, 105, and 140 mg/kg. The concentrations of metals near the background level were also can be found in the
sediment core segments, except Cu. The concentration variation of Cu, Co, Pb, and Ni were near background level in the
four moderate heavy metal polluted river sediments, indicating that little amount of those metals were discharged in those
catchments.
Table 1 Ranges of heavy metals Concentration in highly and moderately heavy-metal
pollution river sediments
Heavy Metals Pollution Levels
Metals
High pollutiona (mg/kg)
Moderate pollutionb (mg/kg)
Cu
80-1000
5-35
Cr
15-820
13-50
Zn
45-830
43-250
Ni
15-430
15-38
Pb
10-105
10-46
Co
8-140
8-26
a Sediment core segments sampled from the Yenshui River.
b Sediment core segments sampled from the Tsengwen, Chishui, Potzu, and Peikang Rivers.
Binding capacity of iron element
The average concentration ratios between aqua-regia extractable heavy metals versus iron element mg/kg vs. % can be
used to express the binding capacity of iron element in sediment as shown in Table 2. The average concentration ratio
values increase with the level of heavy metals pollution. Those values can be used as indicator for the express of metals
pollution degree. The average concentration ratios of Cu, Cr, Ni, Pb, Co, and Zn were 298.6, 296.7, 121.9, 24.2, 16.8 and
289.7. Those values were significantly higher than the values found in the other four rivers.
Table 2 Summary of average c oncentration ratios for aqua-regia extractable heavy metals
versus iron element,mg/kg vs. %.
Rivers
The Yenshui River
The Tsengwen River
The Chishui River
The Potzu River
The Peikang River
Cu
298.6
5.4
10.1
9.1
9.1
Average Concentration Ratio
Cr
Zn
Ni
296.7
289.7
121.9
6.4
20.4
7.5
6.9
33.8
6.6
12.3
66.9
5.7
7.1
49.5
5.7
Pb
24.2
8.7
8.3
6.4
12.3
Co
16.8
4.9
4.5
3.2
5.8
Mn
89.5
163.3
96.6
89.6
131.3
Correlations of Iron element/Iron oxides and trace heavy metals
The aqua-regia extractable heavy metals (Cu, Cr, Zn, Ni, Pb, Co, Mn, and Fe) had significant linear correlation
coefficients (mostly larger than 0.90) with iron element in sediments of five rivers as shown in Table 3 and Figure 1. The
linear correlation coefficients for Ni, Pb, Co, and Mn in Yenshui River were larger than those found in the Tsengwen,
Chishui, Potzu, and Peikang Rivers. Another correlation between aqua-regia extractable heavy metals and iron oxides had
lower linear correlation coefficients than those of iron element for each metal.
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Poster Papers
Table 3. Summary of linear correlation coefficients between Iron element/ Iron oxides and aqua-regia extractable
heavy metals in sediments of five rivers
Rivers
Yenshui R.
Tsengwen R.
Chishui R.
Potzu R.
Peikang R.
Correlated
Parameters
Iron Element
Iron Oxides
Iron Element
Iron Oxides
Iron Element
Iron Oxides
Iron Element
Iron Oxides
Iron Element
Iron Oxides
Cu
0.91
0.72
0.94
0.81
0.86
0.77
0.88
0.43
0.90
0.68
Aqua-regia Extractable Heavy Metals
Cr
Zn
Ni
Pb
Co Mn
0.91 0.87 0.81 0.88 0.78 0.95
0.78 0.77 0.75 0.80 0.73 0.66
0.91 0.96 0.85 0.75 0.81 0.90
0.80 0.79 0.72 0.57 0.63 0.65
0.60 0.89 0.78 0.63 0.70 0.88
0.49 0.75 0.32 0.27 0.67 0.64
0.81 0.80 0.67 0.60 0.59 0.85
0.52 0.57 0.59 0.36 0.30 0.61
0.82 0.72 0.59 0.71 0.69 0.85
0.43 0.34 0.41 0.42 0.58 0.75
Fe
1.00
0.93
1.00
0.81
1.00
0.74
1.00
0.69
1.00
0.72
CONCLUSION
The correlation coefficients between iron element and aqua-regia extractable heavy metals (Cu, Cr, Zn, Ni, Pb, Co, and
Mn) are higher than those between iron oxides and aqua-regia extractable heavy metals in sediments of five rivers. The
average concentration ratios of Cu, Cr, Zn, Ni, Pb, and Co derived from the four moderate heavy metal pollution river
sediments were smaller than those derived from the high heavy metal contamination river sediments. It indicated the
importance of the trace heavy metals binding capacity in the fixation of metals in sediment particle.
REFERENCES
Breder R. Optimization studies for reliable trace metal analysis in sediments by atomic absorption spectrometric methods.
Fresenius’ Z. Anal. Chem., 313, 395-402.
Donahoe, R.; Liu C. (1998). Pore water geochemistry near the sediment-water interface of a zoned, freshwater wetland in
the southeastern United States. Environmental geology, 33(2/3), 143-153.
Nolting R.F., Ramkema A., Everaarts J.M. (1999). The geochemistry of Cu, Cd, Zn, and Pb insediment cores from the
continental slpoe of the Banc d’Arguin (Mauritania). Continental Shelf Research, 19, 665-691.
Ryssen, R.; Leermarkers, M., Baeyens, W. (1999). The mobilization potential of trace metals in aquatic sediments as a tool
fro sediment quality classification. Environmental Science & Policy, 2, 75-86.
Stephens S.R., Alloway B.J., Carter J.E., and Parker, A. (2001). Towards the characterization of heavy metals in dredged
canal sediments and an appreciation of availability: two examples from the U.K. Environmental Pollution, 113, 395401.
Tessier, A.; Campbell, P.G.C.; Bisson, M.(1979). Sequential Extraction Procedure for the Speciation of Particulate Trace
Metals. Anal. Chem., 51, 844−851.
Wang, C.; Schuppli, P.A.; Ross, G.J. A Comparison of Hydroxylamine and Ammonium Oxalate Solutions as Extractants
for Al, Fe and Si from Spodosols and Spodosol−like Soils in Canada. Geoderma 1987, 40, 345−355.
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Diffuse Pollution Conference, Dublin 2003
Poster Papers
Copper (Cu)
Chromium (Cr)
1000
1000
y = -447.06 + 0.029861x
R= 0.90518
y = -442.05 + 0.029673x
600
400
200
4
4
3.2 10
y = -2.4727 + 0.00053557x
4 10
4
4
35
R= 0.93715
15
4
3.2 10
y = 4.2155 + 0.00064316x
4
4 10
R= 0.91053
25
20
Tsengwen River
15
Tsengwen River
5
10
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
4
2.4 10
4
3.2 10
4
4 10
40
35
y = -13.583 + 0.0010139x
y = 2.9263 + 0.0006933x
R= 0.86275
R= 0.60109
35
30
30
25
Cr (mg/kg)
Cu (mg/kg)
4
2.4 10
30
20
20
15
10
25
20
15
10
Chishui River
5
Chishui River
5
0
0
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
40
4
2.4 10
4
3.2 10
4 10
4
70
y = -8.2676 + 0.00090306x
R= 0.87622
y = -4.713 + 0.0012301x R= 0.81358
60
30
50
Cr (mg/kg)
35
25
20
15
10
Potzu River
5
40
30
20
Potzu River
10
0
0
4
1.6 10
30
Yenshui River
1.6 10
Cr (mg/kg)
Cu (mg/kg)
4
2.4 10
10
Cu (mg/kg)
400
0
1.6 10
4
2.4 10
y = -8.9133 + 0.00091346x
4
3.2 10
4 10
4
4
1.6 10
35
R= 0.90305
4
2.4 10
4
3.2 10
y = -0.088132 + 0.00070597x
4 10
4
R= 0.81973
30
Cr (mg/kg)
25
Cu (mg/kg)
600
200
Yenshui River
0
25
R= 0.91655
800
Cr (mg/kg)
Cu (mg/kg)
800
20
15
10
Peikang River
5
25
20
15
10
Peikang River
5
0
0
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
Fe (mg/kg)
4
2.4 10
4
3.2 10
4 10
4
Fe (mg/kg)
Fig. 1(ab) Linear correlation of iron element versus trace heavy metals in different depth of sediments from
five rivers in southern Taiwan. (a) Cu; (b) Cr
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Poster Papers
Zinc (Zn)
Nickel (Ni)
600
1000
y = -387.86 + 0.028971x
R= 0.87208
y = -165.45 + 0.012191x
R= 0.81066
800
Ni (mg/kg)
Zn (mg/kg)
500
600
400
200
Yenshui River
400
300
200
100
Yenshui River
0
0
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
100
40
y = 9.0493 + 0.0020415x
R= 0.96419
Ni (mg/kg)
Zn (mg/kg)
80
70
60
Tsengwen River
50
4
3.2 10
y = -21.904 + 0.0033752x
4 10
4
R= 0.84914
30
25
20
4
Tsengwen River
4
1.6 10
35
R= 0.88715
120
30
100
25
Ni (mg/kg)
Zn (mg/kg)
4
2.4 10
80
60
40
Chishui River
20
4
2.4 10
4
3.2 10
4 10
y = 3.1513 + 0.00066259x
4
R= 0.77612
20
15
10
Chishui River
5
0
0
4
1.6 10
4
2.4 10
4
3.2 10
y = -81.639 + 0.0066941x
4 10
4
4
1.6 10
4
2.4 10
4
4
3.2 10
4 10
y = 10.915 + 0.00057178x
R= 0.66994
50
R= 0.80368
250
40
Ni (mg/kg)
Zn (mg/kg)
y = 2.8751 + 0.00075475x
4 10
10
4
1.6 10
200
150
100
30
20
10
Potzu River
50
0
Potzu River
0
4
1.6 10
200
3.2 10
15
40
300
2.4 10
4
35
90
140
4
4
2.4 10
y = -56.627 + 0.0049466x
4
3.2 10
4 10
4
4
1.6 10
35
R= 0.71806
4
2.4 10
4
3.2 10
y = 6.3667 + 0.00057239x
4 10
4
R= 0.59469
150
Ni (mg/kg)
Zn (mg/kg)
30
100
50
Peikang River
25
20
15
10
Peikang River
5
0
0
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
Fe (mg/kg)
4
2.4 10
4
3.2 10
4 10
4
Fe (mg/kg)
Fig. 1(cd) Linear correlation of iron element versus trace heavy metals in different depth of sediments from
five rivers in southern Taiwan. (c) Zn; (d) Ni
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Poster Papers
Lead (Pb)
Cobalt (Co)
100
80
y = -22.311 + 0.0024233x
R= 0.87967
70
Co (mg/kg)
Pb (mg/kg)
80
60
40
Yenshui River
4
4
2.4 10
4
3.2 10
4 10
4
R= 0.75125
4
2.4 10
4
3.2 10
y = 3.2799 + 0.00048691x
4 10
4
R= 0.81451
30
Co (mg/kg)
40
Pb (mg/kg)
Yenshui River
1.6 10
35
y = 2.5478 + 0.00086892x
30
20
10
Tsengwen River
25
20
15
Tsengwen River
10
0
5
4
1.6 10
4
2.4 10
4
3.2 10
4 10
y = 1.4005 + 0.00082522x
R= 0.62792
4
4
1.6 10
50
4
2.4 10
4
3.2 10
4 10
4
30
y = 3.5922 + 0.00044714x
R= 0.69867
25
Co (mg/kg)
40
Pb (mg/kg)
30
4
50
30
20
10
20
15
10
Chishui River
0
Chishui River
5
4
1.6 10
4
2.4 10
4
3.2 10
y = 12.75 + 0.00063544x
4 10
4
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
30
R= 0.60335
y = 8.0137 + 0.00032254x
R= 0.58749
25
Co (mg/kg)
40
Pb (mg/kg)
40
0
1.6 10
30
20
10
20
15
10
Potzu River
5
Potzu River
0
0
4
1.6 10
4
2.4 10
4
3.2 10
y = -8.1998 + 0.0012333x
4 10
4
4
1.6 10
30
R= 0.70736
4
2.4 10
4
3.2 10
4 10
4
y = -0.48888 + 0.00058329x R= 0.69194
25
Co (mg/kg)
40
Pb (mg/kg)
50
10
0
50
R= 0.77825
20
20
50
y = -11.355 + 0.0016833x
60
30
20
10
20
15
10
Peikang River
5
Peikang River
0
0
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
Fe (mg/kg)
4
2.4 10
4
3.2 10
4 10
4
Fe (mg/kg)
Fig. 1(ef) Linear correlation of iron element versus trace heavy metals in different depth of sediments from five rivers in
southern Taiwan. (e) Pb; (f) Co
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Manganese (Mn)
600
900
y = -37.636 + 0.013134x
800
Mn (mg/kg)
Mn (mg/kg)
y = 16.843 + 0.008948x R= 0.94708
R= 0.84857
500
400
300
200
700
600
500
400
300
100
Yenshui River
200
Peikang River
0
100
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
0
2.5 10
5 10
4
4
7.5 10
1 10
5
Fe (mg/kg)
500
y = 56.403 + 0.0096606x
600
R= 0.88083
y = 62.613 + 0.0089647x
R= 0.85497
500
Mn (mg/kg)
Mn (mg/kg)
450
400
350
300
250
400
300
200
100
Chishui River
200
Potzu River
0
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
Fe (mg/kg)
800
y = -6.3748 + 0.015338x
R= 0.90149
Mn (mg/kg)
700
600
Fig. 1(g) Linear correlation of iron element versus trace
heavy metals in different depth of sediments from five rivers
in southern Taiwan. (g) Mn.
500
400
300
Tsengwen River
200
4
1.6 10
4
2.4 10
4
3.2 10
4 10
4
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