The consultants analysed the same set of samples used for the peroxide experiments for major element composition by x-ray fluorescence (Table 12, 13), as well as some addition samples of dike materials and ash from a brick manufacturing plant (Table 14). The dike soils and sediments from Gelang Patah had relatively high concentration of total sulphur and iron, with the sediments higher than the dike soil, suggesting some net transport of iron and sulfide minerals into the ponds in addition to leaching of acidic solutions from the dikes. Both calcium and phosphorus were very low in the Gelang Patah soil and sediments, although the sediments appear to still contain some of the Ca delivered to Pond 29 by limestone applications in January, 1981. The commercial pond area dike soil in southeastern Johore State had even higher sulphur and iron concentrations but the Thailand soils were lower in sulphur than those at Gelang Patah. The quantities of total sulphur in the Thailand soils are still considerably greater than would be found in areas not affected by marine sulphur mineralization. Red minerals from Gelang Patah dike soils were predominantly iron (Table 14), as would be expected, while some yellowish solids with a strong resinous odor were primarily organic materials, rather than mineral. Ash from wood burning was very high in calcium, potassium and phosphorus (Table 14), suggesting its potential as a fertilizer for depleted soils, such as those of the Gelang Patah dikes. All of the soils the consultants analysed had total organic matter of 5–6 percent by weight, except for the new commercial ponds area which was 32 percent by weight organic matter. If all the potential acidity from the peroxide oxidation experiments were derived quantitatively from FeS2 (4 meq of H+ per mM FeS2), the pyrite weight percentages would range from 0.3 to 4 percent in the soil and sediments analysed, except for the Thailand soils which had <0.01 percent equivalent pyrite (Table 15). Thus, the Thailand soils had essentially no potential acidity, despite a significant amount of sulphur and quite high iron levels. These data are interpreted as indicating the soils in this area of Thailand have been extensively leached of pyrite from a long history of use for sea salt crystallization and later for aquaculture over periods of decades to centuries.
