**2. Sampling sites**

Two sampling sites from tidal flat areas, sample 1(S1) and sample 2 (S2) and three sampling sites (sample 3 (S3), sample 4 (S4) and sample 5 (S5)) inside the Ariake Sea were selected as the study areas. Figure 2 shows the locations of the two tidal flat areas (Higashiyoka and Iida) and the three different areas inside the sea, along with the two types (pillar type and float type) of *Porphyra* sp. cultivation areas.

The tidal currents sweep into the sea and move northwards along the eastern shoreline and create a counterclockwise water movement. This would sweep the finer suspended particles delivered by rivers on the east side towards the inland end, where sedimentation would occur. Sediments in the Ariake Sea tidal flats are medium sand to silty mud. Medium sand, which accounts for 71% of the total tidal flats, is located mainly in the east and south coast areas (Azad et al. 2005). The silty mud is mainly in the bay head. Higashiyoka tidal flat located in the bay head was chosen as a study area (S1) which is near to Chikugo River (the biggest river in Kyushu Island), Okinohota River as well as other rivers and thought to be affected by the river waters. Another study area in tidal flat was Iida (S2), which seems to be

in soils as a function of time and depth (Anandkumar et. al, 2001). In recent years, considerable efforts have gone into developing techniques to determine these properties (Ochsner et al, 2001). The propagation of heat in a soil is governed by its thermal characteristics (De Vries, 1963). Main factors influencing soil thermal properties are mineralogical composition, the organic content and water content (De Vries, 1952, Wierenga et. al, 1969). No study has been carried out before to get the information about the thermal properties as well as thermal environment of the Ariake sea mud. So the objective of this study is to assess the thermal environment of the tidal mud by getting the information of the temperature distribution in different depths and find a diurnal and seasonal profile of it in the tidal flat region, and finally thermal properties variation with respect to depth for the temperature distribution in different seasons. The thermal properties of the Ariake Sea mud collected from both tidal flat and inside the deep sea of the Ariake Sea were conducted as a

1972 1976 1980 1984 1988 1992 1996 2000 2004 2008

Two sampling sites from tidal flat areas, sample 1(S1) and sample 2 (S2) and three sampling sites (sample 3 (S3), sample 4 (S4) and sample 5 (S5)) inside the Ariake Sea were selected as the study areas. Figure 2 shows the locations of the two tidal flat areas (Higashiyoka and Iida) and the three different areas inside the sea, along with the two types (pillar type and

The tidal currents sweep into the sea and move northwards along the eastern shoreline and create a counterclockwise water movement. This would sweep the finer suspended particles delivered by rivers on the east side towards the inland end, where sedimentation would occur. Sediments in the Ariake Sea tidal flats are medium sand to silty mud. Medium sand, which accounts for 71% of the total tidal flats, is located mainly in the east and south coast areas (Azad et al. 2005). The silty mud is mainly in the bay head. Higashiyoka tidal flat located in the bay head was chosen as a study area (S1) which is near to Chikugo River (the biggest river in Kyushu Island), Okinohota River as well as other rivers and thought to be affected by the river waters. Another study area in tidal flat was Iida (S2), which seems to be

Year

*Crassostrea gigas Atrina pectinata Sinonovacula constricta*

part of thermal environmental studies of the Ariake Sea.

float type) of *Porphyra* sp. cultivation areas.

Catch (x 103kg)

Fig. 1. The graph of catch vs year

**2. Sampling sites** 

the most affected by the acid treatment practice. The other three study areas are chosen inside the Ariake Sea where all the time they are under water. The sample 1 and sample 2 (Higashiyoka and Iida) were collected during the ebb tide and the tidal flat was exposed to the sun directly. The other three mud samples (S3, S4, and S5 in Figure 2) were collected from under the sea water at different depths in different locations in the Ariake Sea. The sample collection was done in the last week of April 2006. The typical values of basic physicochemical properties of the mud samples collected from five study areas are tabulated in the Table 1.The mud samples were collected from the 0-0.2 m in the Ariake Sea.

Fig. 2. Map of the Ariake Sea & study area
