Abstract
Nine 1.5 m sediment cores from the Wilkinson Basin Geotechnical Test Area were used in an investigation of the interrelationships among geotechnical properties and major ion concentrations in the pore water. The ionic composition of the pore water in the upper 10 cm does not differ significantly from the overlying sea water. Sodium, potassium and chloride ion concentrations do not change significantly with depth in the sediment. Anaerobic oxidation of organic matter is indicated by the decrease in pore water sulfate ion concentration with increasing depth. Pore water concentrations of magnesium and calcium also decrease with depth while the carbonate mineral fraction of the sediment increases, suggesting carbonate precipitation in consequence of oxidation. Simple quantitative relationships among the measured chemical and geotechnical properties are not apparent. The normalized shear strength, Upsilon n/gamma z, decreases with decreasing sulfate ion concentration, indicating possible strengthening by labile organic matter.
