5.4 Elemental Analysis by Scanning Electron Microscopy
with Energy Dispersive Spectroscopy (SEM-EDS)
The elemental composition of sclerotia grains (n ¼ 5) from the 3A horizon of the
Myoko soil profile was determined with thermal field emission scanning electron
microscopy (SEM; JSM-7001F, JEOL, Tokyo, Japan; accelerating voltage, 15 kV)
and energy dispersive spectroscopy (EDS; JED-2300 Analysis Station with the ZAF
method standardless quantitative analysis program, JEOL). Grains were sliced in
half with a sterilized knife so that the elemental composition of the outer, middle, and
inner sections of each grain could be determined (Fig. 5.4). The elemental compositions of the transverse cell walls of the sclerotia samples are summarized in
Table 5.2. Overall, the C and O contents ranged from 61 to 62 wt% and 33 to
34 wt%, respectively. The P, Al, and Fe contents were 0.06, 3.4–4.3, and
0.46–0.56 wt%, respectively. No significant difference was observed between the
elemental composition of the outer, middle, and inner sections. Aluminum was the
dominant metal.
5.5 Major Elements Analysis
The C, H, and N contents of sclerotia grains (2 mg powdered sample, 6 repeats) were
measured using a C-H-N analyzer (MT-6, Yanaco Corp., Kyoto, Japan). Oxygen
contents were evaluated as the difference between the original sample weight (2 mg)
and the total weight of the ash plus the sum of C, H, and N contents. Water contents
were obtained by subtracting the weights of samples dried in an oven at 105
C for
24 h from those of air-dried samples. The O/C and H/C ratios were calibrated on
water- and ash-free bases.
Fig. 5.3 Relationships between diameter, volume, and weight of sclerotia grains from the
Mt. Myoko 3A horizon. Open circles (○) indicate spherical sclerotia and cross marks (Â) indicate
sclerotia with other features
5 Chemical Characterization of Sclerotia Grains Collected from a Volcanic Ash. . .
81
with Energy Dispersive Spectroscopy (SEM-EDS)
The elemental composition of sclerotia grains (n ¼ 5) from the 3A horizon of the
Myoko soil profile was determined with thermal field emission scanning electron
microscopy (SEM; JSM-7001F, JEOL, Tokyo, Japan; accelerating voltage, 15 kV)
and energy dispersive spectroscopy (EDS; JED-2300 Analysis Station with the ZAF
method standardless quantitative analysis program, JEOL). Grains were sliced in
half with a sterilized knife so that the elemental composition of the outer, middle, and
inner sections of each grain could be determined (Fig. 5.4). The elemental compositions of the transverse cell walls of the sclerotia samples are summarized in
Table 5.2. Overall, the C and O contents ranged from 61 to 62 wt% and 33 to
34 wt%, respectively. The P, Al, and Fe contents were 0.06, 3.4–4.3, and
0.46–0.56 wt%, respectively. No significant difference was observed between the
elemental composition of the outer, middle, and inner sections. Aluminum was the
dominant metal.
5.5 Major Elements Analysis
The C, H, and N contents of sclerotia grains (2 mg powdered sample, 6 repeats) were
measured using a C-H-N analyzer (MT-6, Yanaco Corp., Kyoto, Japan). Oxygen
contents were evaluated as the difference between the original sample weight (2 mg)
and the total weight of the ash plus the sum of C, H, and N contents. Water contents
were obtained by subtracting the weights of samples dried in an oven at 105
C for
24 h from those of air-dried samples. The O/C and H/C ratios were calibrated on
water- and ash-free bases.
Fig. 5.3 Relationships between diameter, volume, and weight of sclerotia grains from the
Mt. Myoko 3A horizon. Open circles (○) indicate spherical sclerotia and cross marks (Â) indicate
sclerotia with other features
5 Chemical Characterization of Sclerotia Grains Collected from a Volcanic Ash. . .
81