A simple method of determining the degree of PAH (polycyclic aromatic hydrocarbon) pollution was developed. The concentration of each PAH was determined by decomposing the fluorescence spectrum into individual PAH spectra. There was a good relationship of the fluorescence method with GC/MS results although most results overestimated PAH concentrations. This method was successfully applied to various kinds of PAH-polluted soils and sediments. The major advantage of this method is that sophisticated tools used to separate PAHs (GC or HPLC) are not required. From a viewpoint of environmental management, this method is extremely useful since these tools are not yet common used today and its maintenance and operational cost is low. Conducting the initial screening using this technique leads to the efficient analysis of ubiquitous PAHs in polluted environments.

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The objective of this study is to clarify the effect of light reduction by sediment deposition on leaves and sand movement on eelgrass distribution for obtaining fundamental knowledge on the formation of the eelgrass (Zostera marina L.) habitat. We investigated light regime and sediment deposition on leaves near the lower edge of an eelgrass bed, and monitored sand movement and transplanted eelgrass in an unvegetated site near the higher edge. The average light intensity through sediment deposition on eelgrass leaves was estimated to be approximately 3 E·m^-2·d^-1 at a low depth limit. As sediment deposition on leaves was 0.7 mg·cm^-2 <, the light intensity required by eelgrass might be 4 E·m^-2·d^-1 <. Sand movement at the unvegetated site ranged from -10 cm to 12 cm and was more unstable than that at a natural site. Scouring for two months reached up to 10 cm, and seedlings disappeared at the unvegetated site near the higher edge. However, the number of vegetative shoots in the unvegetated site steadily increased. These results suggest that vegetative shoots can survive within 10 cm washouts and the growth of eelgrass near the higher edge of an eelgrass bed is restricted to vegetative reproduction.

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This research showed that the addition of KCI to piggery wastewater and the application of electrolytic treatment enables the removal of nitrogen together with phosphorus from that wastewater, which is something that previous biological treatment methods were unable to accomplish. It also showed that the addition of an aerobic treatment method employing and activated sludge as a first step prior to electrolytic treatment results in a more efficient system for the removal of nitrogen and phosphorus from piggery wastewater than electrolytic treatment alone. This research showed clearly that (1) polarity switching removes scale that forms on the iron electrode, making nitrate reduction also possible with piggery wastewater, (2) it is difficult to generate hypochlorous acid with the platinum-wire electrode for nitrogen removal even when using polarity switching due to the formation of stubborn scale, (3) electrolysis of piggery wastewater using polarity switching can reduce the amount of nitrogen and phosphorus in the wastewater to virtually zero if the frequency of the switching is optimized, and (4) the amount of electric power used to remove nitrogen and phosphorus from piggery wastewater can be reduced significantly by conducting electrolysis after biological treatment rather than just electrolysis alone.

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It is well known that a hydrotalcite-like compound is a layer structure inorganic ion exchanger and has a high selectivity for certain anions. The authors clarified that the synthetic Mg-A-Cl form hydrotalcite (HT) has a high selectivity and a large adsorbing capacity for phosphate ions. It is estimated that HT has a high selectivity for anions, such as arsenate, arsenite, selenate and selenite ions, that have the same size and properties as phosphate ions. Therefore, we examined the adsorption capacities of HT to AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- in order to remove these anions using HT from the waste water. The obtained results were as follows. HT rapidly adsorbed AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- at the anion concentrations of 0.2 to 100 mg·l^-1. The selectivity of AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- on the HT is very high. The removal mechanism of HT for AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- was ion exchange for Cl^-. Furthermore, HT had a high ion exchange capacity for AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- under the condition of coexistence with other anions. Moreover, the concentrations of AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- in all treated water samples were below 0.1 mg·l^-1, which is the waste water quality standard of As and Se. These results showed that HT is an effective adsorbent for the removal of AsO₄^3-, AsO₃^3-, SeO₄^2- and SeO₃^2- in the waste water.

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“Daphnia sp. acute immobilisation test” is a typical ecotoxicity test for chemicals. In the test procedures, the most troublesome operation is separating and collecting hundreds of water fleas in preparing the test. In this study, the automatic water flea separator and collector have been developed to simplify the test. Using the separator, 95% of the population of targeted individual Daphnia were separated from the untargeted Daphnia. Using the collector, the separated individual water fleas were collected in groups of 5 (average: 5.2, standard deviation: 0.8). The toxicity tests for potassium dichromate were performed and the efficacy of the device was evaluated. According to the results of the Daphnia sp., Acute Immobilisation Test, major damage was not observed in the individual Daphnia separated and collected automatically.

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The grain-size distribution of turbidity, water chemistry, and the size of fine particles associated with contaminants in turbid groundwater were investigated in existing monitoring wells. Groundwater monitoring wells are used in obtaining general information on groundwater quality and specific information on concentrations and specification of mobile contaminants in the vicinity of a monitoring well. This information is used in determining whether a given facility is currently in compliance with regulations. Turbidity (fine particles) are present in monitoring wells as a result of well installation in a stratum containing many fine particles (e.g., clay and silt) at a depth of less than GL-10m, well development, prior purging, sampling events, and natural colloidal transport and deposition over time. It is crucial that samples obtained from monitoring wells accurately reflect in situ mobile contaminant concentrations. The filtration of groundwater samples may remove both mobile fine particles/colloids and artifact particles. The most common groundwater purging method is to purge a monitoring well using bailers or pumps to remove 3 to 5 casing volumes to obtain formation water. In this paper, the concept and numerical formulas of a well-purging model are introduced and discussed. The calculation result shows that prepurging more than 3 casing volumes ensures a sampling of well water which is similar to formation water. The differences between filter pack and gravel pack (filter media #2 - #4) and the method of selecting the sizes of filter media were surveyed and discussed with the aim of installing a monitoring well in a stratum containing many fine particles.

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