189
Journal of Chemistry, Vol. 40, No. DB, P.189 - 193, 2002
Mercury pollution due to gold mining activities in
the North of Viet Nam
Received 06-8-2002
Trinh Xuan Gian, Le Lan Anh, Vu Duc Loi, Tran Van Huy
1
, Hirokatsu
Akagy
2
, Mineshi Sakamoto
2
1
Institute of Chemistry, Viet Nam National Center for Natural Science and Technology
2
National Institute for Minamata dissease, Japan

Summary
To obtain the basic information on human exposure to mercury (Hg) due to gold mining
activities in North of Viet Nam, total mercury was determined for human hair and blood
samples collected from population living in gold mining area. The results indicate that the
mercury concentrations measured in 98 blood samples with ranging from 1.128 to 22.751 ppb
and 65 hair samples with ranging from 0.379 to 2.440 ppm, the good correlation between
concentration of mercury in hair and blood samples was found in people and the ratios of hair
Hg to blood hair were 195 for males and 142 for females

I - Introduction
Environmental mercury pollution due to
gold mining in the North of Viet Nam has been
concerned in recent years. In the gold mining
processes an enormous amount of metallic Hg

1. Samples
Human hair and blood were used in this
study, blood samples were collected from the
inhabitants living near gold mining of
Vietnamese North. The subjects consisted of 82
males and 16 females. The personal data (age,
190
sex, address and occupation) were obtained at
the time of sampling.
2. Analytical procedures for mercury
In the present work, the determination of
total mercury was made with sensitive and
reliable methods recently developed in National
institute for Minamata disease (H. Agaki et al
2001)
Total mercury analysis in hair samples: The
procedure for total mercury in hair is shown in
figure 1. A known amount of 10 mg hair
sample was placed in a 50 ml volumetric flask,
to which 1 ml of water, 2 ml concentrated
sulfuric acid were added and heated at 200
o
C
on a hotplate for 30 min. After cooling until the
room temperature, the digested sample was
made up to 50 ml with mercury-free water. An
aliquot of sample solution was introduced into
an automated circulating air flow system with
the addition of 10% stannous chloride solution
(SnCl

C to
free the mercury vapor and measured by CV-
AAS. The procedure for analyzing total
mercury by sample combustion method is
following.
The 5-mg hair sample was placed to quartz
combustion boat, 1 drops additive was added.
Place the boat in a combustion furance, heat at
800
o
C while introducing oxygen at 0.5 l/min to
release mercury which can then be collected in
a golden tube. Heat the golden tube to 700
o
C to
produce mercury vapor and measured by a
CVAA analyzer. Accuracy of method was
assesed with certified reference material NIES,
No 13 - Human hair (National institute for
environmental studies, Environment agency,
Japan). A recovery of Hg is 98.65%.
III - Results and discussion
1. Concentration of mercury in hair samples
The comparison of T-Hg measurement in
hair samples by two different methods showed
fairly good agreement, as is shown in figure 3.
There indicated that not only the two difference
analytical procedures gave comparable data,
but also mercury was lost during digesting
samples. The concentration of T-Hg is shown in

counting vial
Blood sample, 500 mg or less

H
2
O, 1 ml
Conc. HNO
3
- HClO
4
(1:1), 2 ml
Conc. H
2
SO
4
, 5 ml
Heat at 200
o
C for 30 min
Hair sample, 10 - 20 mg Digested sample

H
2
O, 1 ml
Conc. HNO
3
- HClO
4
(1:1), 2 ml
Conc. H

Base on the results of mercury analyses in
blood samples, the relationships between T-Hg
in blood and hair were investigated. The
correlation between T-Hg in blood and hair was
found, with the correlation coefficient r = 0.405
times for male and 142 for females. These
ratios were not only different to people living
near gold mining in Tapaijos river basin,
Amazon of Brazil (250 times) but also different
to between males and females (H. Akagi et al
1998). The difference between concentration of
T-Hg in males and females was found, the
contents in females were about 1.5 times lower
than in males. The sex difference in mercury.
Concentration in blood (Nishima et al.,
1976) and the hair (Shimomura et al. 1980;
Nakano and Wakisaka, 1976; Ando, 1998) has
been reported. This diference may be explained
by the amount of fish consumption, monthly
blood loss among females, and mercury
metabolism. Futashuka et al (1982) reported
that males consumed larger amount of fish and
and shellfish. Miettinen et al. (1997) found that
methyl mercury was excreted with a mean
biological half-time of 79 days for males and
71 days for females and that inorganic mercury
was excreted for 48 days by females and 37
days by females.
192
Fig. 3: Correlation of T-Hg determination in

that mercury concentration in hair and blood
was high. The comprasion between the control
group and studying group is different; the
control group is (about 2.5 - 5.0 times) lower
than studying group.
The correlation between concentration of T-
Hg in hair and blood was found. T-Hg in hair is
about 195 times (Males) and 142 times
(Females) higher than blood.
Accuracy of method was assesed with
certified reference material NIES, No 13 -
Human hair (National institute for
environmental studies, Environment agency,
Japan). A recovery of Hg is 98.65%.
There are a need more to investigate
concentration of mercury in these areas.
Inorganic mercury and methyl mercury in fish
also should be often determined.
References
1. H. Akagi. Study on mercury pollution in
Amazon, Brazil. Golbal Environmental
research Vol. 2, No. 2, P. 193 - 202 (1998).
2. H. Akagi et al. Human exposure to
mercury due to gold mining in tapajos river
basin, Amazon, Brazil: Speciation of
mercury in human hair, blood and urine.
Water, air, soil pollution 80: 85 - 94 (1995).
3. Mineshi Sakamoto et al. Ecotoxicology and
evironmental safety 22, P. 58 - 66 (1991).
4. H. Akagi, H. Nishimura. Advances in