426
A. Matsuyama et al.
2.5
Method for Total Mercury Analysis in the Soils
After collecting a fixed amount (0.2-0.5 g) of sample material for analysis, 2 ml
of a mixed solution (HN0 3 + HCI0 4 = 1:1), 5 ml of sulfuric acid, and 1 ml of H2 0
were added to the samples and digested at 230-250 °C on a hot plate for 20 min.
The mixture was cooled to room temperature, and distilled water was added to
the digested sample solution, which made the solution 50 ml. Then the mercury
in the solution was gasified by reduction with stannous chloride and measured
through cold-vapor atomic absorption analysis (Akagi and Nishimura 1991).
2.6
Method for Removing Iron Oxide from the Soil
The method used to remove iron oxide from the soil conforms with the Aguirera
and Jackson method. (Aguilera et al. 1953; Oba 1966) For 1 g of sand, 1 g of
sodium
dithionite
(Na2 S2 0 4 ),
and
30 ml
of
sodium
citrate
(Na 3 C6 H 5 0 7 ' 2H20)solution of 0.3 mol w/v were added, and the mixture was
heated and stirred in a water bath (70-80 0c) for 20 min. After the supernatant
was removed with the gradient method, once again distilled water was added, the
mixture was stirred, and the supernatant was removed. These washing
procedures were repeated several times. Then the sand from which iron was
removed was dried with a fan drier (105°C) to create soil for the test.
2.7
Analysis of Crystal Structures in the Soils and Element Analysis of the Soils
Before heating, the required amounts of artificially contaminated soils made for
the tests were collected and powdered with an agate mortar. After heating, the
samples were taken out of the reaction furnace and cooled to room temperature
in a desiccator. Then the required amounts of sample material were collected and
powdered with an agate mortar. The powdered samples were analyzed with Xrays and X-ray fluorescent tests.
3
Results and Discussion
3.1
Heating of Artificially Contaminated Soils Made for the Tests
Based on the results of the heating tests conducted on the minerals described
above, the standard sand (weathered granite), the quartz sand which was the
primary component of granite, and volcanic ash soil, were used for testing and
A. Matsuyama et al.
2.5
Method for Total Mercury Analysis in the Soils
After collecting a fixed amount (0.2-0.5 g) of sample material for analysis, 2 ml
of a mixed solution (HN0 3 + HCI0 4 = 1:1), 5 ml of sulfuric acid, and 1 ml of H2 0
were added to the samples and digested at 230-250 °C on a hot plate for 20 min.
The mixture was cooled to room temperature, and distilled water was added to
the digested sample solution, which made the solution 50 ml. Then the mercury
in the solution was gasified by reduction with stannous chloride and measured
through cold-vapor atomic absorption analysis (Akagi and Nishimura 1991).
2.6
Method for Removing Iron Oxide from the Soil
The method used to remove iron oxide from the soil conforms with the Aguirera
and Jackson method. (Aguilera et al. 1953; Oba 1966) For 1 g of sand, 1 g of
sodium
dithionite
(Na2 S2 0 4 ),
and
30 ml
of
sodium
citrate
(Na 3 C6 H 5 0 7 ' 2H20)solution of 0.3 mol w/v were added, and the mixture was
heated and stirred in a water bath (70-80 0c) for 20 min. After the supernatant
was removed with the gradient method, once again distilled water was added, the
mixture was stirred, and the supernatant was removed. These washing
procedures were repeated several times. Then the sand from which iron was
removed was dried with a fan drier (105°C) to create soil for the test.
2.7
Analysis of Crystal Structures in the Soils and Element Analysis of the Soils
Before heating, the required amounts of artificially contaminated soils made for
the tests were collected and powdered with an agate mortar. After heating, the
samples were taken out of the reaction furnace and cooled to room temperature
in a desiccator. Then the required amounts of sample material were collected and
powdered with an agate mortar. The powdered samples were analyzed with Xrays and X-ray fluorescent tests.
3
Results and Discussion
3.1
Heating of Artificially Contaminated Soils Made for the Tests
Based on the results of the heating tests conducted on the minerals described
above, the standard sand (weathered granite), the quartz sand which was the
primary component of granite, and volcanic ash soil, were used for testing and