As ports are located downstream of rivers, they readily show accumulation and deposition of contaminating particulate matter. Maintenance dredging is therefore essential for navigation. High levels of contamination affect physical structure of the levee of confined disposal facilities, and concentration of chemicals is one of the determining factors for identifying beneficial use. Careful handling is therefore necessary in the management of chemicals in port and harbor sediments, taking into consideration the possibility of dredging. However, there have been few studies regarding the management of hazardous chemicals in port and harbor sediments. Here, the technological tasks related to these tasks were determined. Current regulation regarding dredged material based on leachability test is inadequate when reclaimed land will be utilized for commercial purposes. Basic and academic tasks include establishment of standard method of analysis of fine chemicals, investigation of the relationships between benthic fauna and chemicals in the sediment, and grasp of the fate and transport of chemicals in ports. Practical tasks include selection of target chemicals for monitoring and establishment of on-site countermeasures, such as capping. To overcome the above challenges, field observations, laboratory experiments, and modeling analyses were performed.
　A nationwide survey indicated that heavy metal concentrations in some port sediments exceeded guidelines used in the USA. A detailed survey in Nagoya Port showed that horizontal distributions of heavy metals and polycyclic aromatic hydrocarbons (PAHs) were quite different, reflecting their non-point or point sources. We propose a new integrated indicator, which is defined as the sum of exceeding level from ERL or ERM for heavy metals. Multiple linear regression analysis clearly indicated that the number of species of benthic fauna decreases as the value of the indicator increases. A field survey in Nagoya Port and laboratory experiments on equilibrium partitioning as well as adsorption/desorption for PAHs revealed that increases in solubility due to the association with dissolved organic matter and incomplete desorption due to insufficient shaking time were the main factors influencing partitioning. Fate and transport analysis of PAHs in the port showed that PAHs with greater numbers of rings accumulated more easily in the port sediment. We propose that target chemicals for monitoring should be 11 species of metal, dioxins, and PCBs. The validity of a method to estimate leachability from its content based on equilibrium partitioning was also discussed. Selection of filter paper type affected the leachability value. Moreover, dissolved organic matter and shaking time were other influential factors, as was the case for PAHs. Revision of the solid-liquid separation procedure in the test protocol is needed to reduce the variability in results. Analysis based on a proposed diffusion model for dioxins in the sediments indicated that dioxin release rate from sediment decreased with increasing capping layer thickness. Model analysis demonstrated the effectiveness of the proposed new method for sand capping, in which organic-rich sediment contained in a thin mat was applied between contaminated sediment and the sand capping layer. Finally, the current guideline of countermeasures for dioxins was reformed to propose a new guideline applicable to other chemicals. Issues that should be examined in each step of countermeasures are also summarized.