Coastal Marine Environment Sustainability - Sustainable Practices in Geoenvironmental Engineering - page 277

0.7

sandy sediments

Clay

Silty-clay sediments

Summer

predicted as
sandy sediments
silt-clay sediments

0.6

Sand Initial

Ignition loss

0.5

0.4

0.3

Predicted as
sandy sediments

0.2

0.1

Sandy sediments

0.0

0 5 10 15 20

Ignition loss (%)

FIGURE 8.2
Sulide content versus ignition loss for the Harima-nada sediments. (Data from Ministry of Land, Infrastructure,
Transport and Tourism, Japan. Available at http://www.pa.cgr.mlit.go.jp/chiki/suishitu/download/input.htm.)

organic matter leads to high bacterial sulfate reduction rates, oxygen depletion, and sub-
sequent release of toxic hydrogen sulide from summer to autumn (Magni et al., 2008;
Rosenberg et al., 2001). At this stage, the ignition loss tends to decrease and the sulide con-
tent will increase (Yamamoto et al., 1997). The trend is indicated by the arrow in Figure 8.2.
The concentration of the sulide in sediments depends on many factors, such as the type
of sediment, organic content, pH, redox potential, dissolved oxygen, water and sediment
temperature, etc. The physical and chemical properties of Seto Inland Sea sediments,
reported by Yamamoto et al. (1997), are shown in Figure 8.3 plotted in terms of redox

500

400

1993 October
1994 June

300

200

100

0

-100

-200

-300

4 5 6 7 8 9

pH

FIGURE 8.3
Comparison between redox potentials in October 1993 and June 1994. (Data from Yamamoto, T. et al., Journal of
the Faculty of Applied Biological Science, Hiroshima University , 36: 43-49, 1997.)