Environmental preservation and remediation techniques in costal waters

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To assess the environmental preservation and remediation techniques of an enclosed water areas, seawater and lake water, suspended solids, settling particles and sediment were collected from Shimizu Port and Lake Sanaru. Suspended solids discharged from rivers and the biological particles produced in the port and lake caused a reduction in transparency and an increase in chemical oxygen demand. Trace metals, such as Mn, Co, and Pb, were highly concentrated in suspended solids. The results showed that these suspended particles could accumulate metals from seawater and lake water as effectively as biogenic particles. After particle deposition, trace metals are regenerated into seawater and lake water under anaerobic conditions. This process plays an important role in the accumulation of chemicals in water and sediments, especially in enclosed sea areas. The results showed that the concentrations of the heavy metals measured were relatively high. The concentrations of copper and zinc in the sediment samples were higher than the probable effect levels (PEL) of marine sediments provided by the Canadian Sediment Quality Guidelines. The high concentrations obtained were probably due to the high organic content resulting from humus.The separation of organic matter might be useful as a remediation technique for dredged materials.The applicability of steelmaking slag was examined experimentally to improve the bottom sediments in several sea areas. The experimental results showed that stone-shaped steelmaking slag controlled the occurrence of sulfide, and that the materials were available as a submerged embankment material, which can be used for a base of algae and benthonic organisms. It is also found that the particles of the steelmaking slag can be an effective base and can supply nutrients for attached algae.