Photon Factory Activity Report 2004 #22 Part B (2005)
Chemistry

7C, 9A, 12C/2004G302

Chemical speciation of sulfur in the Yatsu tideland sediments
Masaki KATAOKA*1 and Motoyuki MATSUO2
1Graduate School of Science, The University of Tokyo,
3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
2
Graduate School of Arts and Sciences, The University of Tokyo,
3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan

36

Users' Report

distribution of the sulfide was abounding over the middledeep layer. This distribution was found to be similar tothat of iron sulfide, which was most common in thesediments as heavy metal sulfide, except for surface layer.
The surface layer accumulation is seemed to be MnS andunstable sulfides which are temporally supplied withsurface water.
Normalized absorption coefficient

1.20
0-3cm
12-15cm
24-27cm
36-39cm
48-51cm
Na2SO4PYRRHOTITE

1.00
0.80
0.60
0.40
0.20
0.00
2.45

2.47

2.49

2.51
Energy/keV

2.53

2.55

Fig. 1. Normalized sulfur XANES spectra of the Yatsutideland sediments and standard materials

The peak rat io
0.0

0.5

1.0015Depth/ cmIntroductionIn estuary and tideland, sedimentation rate is quite
high, because salting-out of organic substances andsuspended solids is occurred and inclination is gentle.
Therefore, the sediment of such areas has a very
complicated system. Under anaerobic environments inthe sediments, the sulfate ion from seawater is reduced,
and then various sulfides have been formed in thesediments. We have already studied the chemical state ofheavy metals in the sediment of estuary and tideland, andrevealed that several heavy metals such as iron,manganese and zinc exist in a form of sulfide [1] [2]. In
order to obtain further information on the sulfides in thesediments, the vertical distribution of sulfides wasinvestigated by means of the chemical state analysis ofsulfur by XAFS in this study.
Experimental
We collected sediments vertically in Yatsu tidelandwhich is located at the east part of Tokyo and the tidelandis assumed to be a non-polluted area. The collected
sediments were cut at every 3-5 cm length immediately,
and then porewater was extracted by pressure filtration (5atm, N2). Approximately 100mg of each sample wasmounted in a prolene film. The X-ray absorption
measurement was made with synchrotron radiation byusing XANES facilities on the beam line 9A. Theradiation was monochromatized by Si (111) double
crystals. The spectra were collected in fluorescence modeusing Lytle-type detector at room temperature in thehelium atmosphere.
Results and Discussion
Figure 1 shows the normalized sulfur XANES
spectra of the Yatsu tideland sediments from different
depth and standard materials of sulfur. The XANES
spectrum of sulfur in the sediment shows two sharp peakswhich have the different energies. According to thecomparison with standard materials, the position of peak
top of these two peaks in the sediments agreed with thatof sulfur compounds. The spectra of sulfate had only one
peak of high-energy side; on the contrary, the spectrum of
sulfide had both peaks. Therefore, this fact means thatthe relative amount of the sulfide in the sediment can be
estimated by observing the peak ratio. We alreadystudied the sediments in Arakawa River which is locatedat east part of Tokyo, and the distribution of the sulfide inthe sediments was estimated by this method [3]. The
vertical distribution of the peak ratio obtained by thisoperation is shown in Fig.2. It was estimated that the304560

Fig. 2. The vertical distribution of the peak ratio of thetwo sharp peaks in sulfer XANES spectra of the Yatsutideland sediments
References[1] M. Kataoka et al., PF Activity Report, 20B, 21 (2003)[2] M. Kataoka et al., J. Radioanal. Nucl. Chem., 255,283-286 (2002)[3] M. Kataoka et al., PF Activity Report, 21B, 28 (2004)*kataokai@dolphin.c.u-tokyo.ac.jp