• Economic and Environmental Geology
• /
• v.42 no.2
• /
• pp.121-131
• /
• 2009

The distribution characteristics of heavy metals for surface sediments in east oceanic dumping area (EDA) and west oceanic dumping area (WDA) are evaluated by grain sizes, minerals, sedimentation rates and compositions of heavy metals. The mean grain sizes in EDA and WDA range from $7.95{\Phi}$ to $8.51{\Phi}$ and $7.42{\Phi}$ to $8.15{\Phi}$, respectively. These are mostly belonging to the M (mud) type. Minerals in the surface sediments consist of illite with chlorite, smectite, and kaolinite. Sedimentation rates estimated by $^{210}Pb$ method in EDA and WDA are 1.11 mm/yr$\sim$1.73 mm/yr and 1.87 mm/yr, respectively. According to the interrelationship, concentrations of Ni, Cu, Cr, and Zn are closely associated with mean grain size, Al, and Fe, whereas concentrations of Cd and Pb are poorly associated with ones. The enrichment factors of these elements are higher than 1.5, suggesting that the concentrations of Cd and Pb in the surface sediments are affected by anthropogenic sources. The $I_{geo}$-class numbers of Cd and Pb in the surface sediments are mostly classified in 2 to 4, showing moderate to strongly polluted. These numbers in EDA are higher than that of WDA, and the highest number is 4, indicative of the strongly polluted class. Our results show that the disposed wastes at EDA include mineralogical wastes, dredged materials from sewage disposals, and sludges from constructions having materials of WDA. The annual amount of oceanic dumping in EDA is double than that in WDA.