Reduction methods in trihalomethane formation potential (THMFP) were investigated for a treated sewage, fulvic acid in a treated sewage, fulvic acid in a leaf mold and humic acid in a leaf mold by oxidation with ozone, potassium permanganate (KMnO₄), adsorption with activated carbon and their combination.
The molecular weight distributions of the three humic substances were determined using a Sephadex G-25 or G-75 before and after the ozonation. The eluted solution was divided into four or three groups and for each THMFP per unit organic carbon was determined. THMFPs of the fulvic acid and the humic acid in leaf mold were reduced effectively by ozonation alone. On the other hand, THMFPs of the treated sewage and the fulvic acid in treated sewage were not reduced significantly by the oxidation with ozone or KMnO₄, though THMFP was reduced considerably by the adsorption with activated carbon.
The molecular weight of the fulvic acid and the humic acid in leaf mold fairly decreased by ozonation, and their THMFPs were reduced significantly since the decomposed lower molecular weight fractions had very small THMFPs per unit organic carbon. The molecular weights of the smaller fulvic acid in treated sewage were reduced more by ozonation, but the THMFP showed no significant decrease.

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Pheopigments concentrations in sestons, settling materials and bottom muds in experiment ponds were measured by HPLC. Pyropheophytin a (pptn-a) as well as pheophytin a (ptn-a), chlorophyll a(chl-a) and pyrochlorophyll a(pchl-a) were identified by using a LC/MS method. An increase of pptn-a and a decrease of pheophorbide a(pbd-a) in sestons were observed in the ponds with abundant gold fish (Carrasius auratus). This tendency was also observed in settling materials and bottom muds in the experiment ponds. The decomposition process of chl-a was suggested to be chl-a → ptn-a → pbd-a (demetalation followed by dephytylation) in the ponds without gold fish where a large amount of zooplankton was observed. On the other hand chi-a → pchl-a → pptn-a (decarbomethoxylation followed by demetalation) seemed to be the main decomposition process in the ponds with abundant gold fish with a small amount of zooplankton. Zooplankton and fish may play an important role in the dephytyl process and the decarbomethoxy process, respectively. Pheopigments concentrations in surface sediments were different between Tokyo Bay, Onjuku Reservoir and Lake Imbanuma. The pyropheophorbide a (pphd-a) concentration was high in the sediment of Tokyo Bay where settling particles would take the longest time to reach the surface sediments. High percentage of chl-a was observed in the surface sediment of Lake Imbanuma, which was a shallow eutrophic lake, and undecomposed phytoplanktons were recognized on the surface sediment.

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To reduce the diffusion of trihalomethane precursors from livestock farm, field survey and laboratory experiments were carried out concerning 1) trihalomethane precursors concentration in livestock barn wastewater and effluent of treatment facilities, 2) potential diffusion of trihalomethane precursors from manure and compost, and 3) fate of trihalomethane precursors from composted manure in soil and aquatic environments. Median value of trihalomethane formation potential (THMFP) in wastewater from 11 livestock barn was 7,700 μg·l^-1. Median value decreased to about 570 μg·l^-1 by aerobic biological treatment. THMFP of the wastewater shows significant positive correlation between TOC, BOD and COD. THMFP also correlated with 260 nm absorbance of filtrate (E₂₆₀). Since measurement of E₂₆₀ is simple and rapid, it should he suitable for rough estimation of THMFP of the wastewater. Leachable trihalomethane concentration in swine faeces was 880 μg·g^-1 dry weight. After solid composting, the concentration decreased to 130 μg·g^-1 dry weight. Slurry derived from dairy cow barn contained dissolved trihalomethane precursors of 13,500 μg·l^-1. After liquid composting by aeration, the concentration decreased to 4,400 μg·l^-1. Immediately after mixing of the solid and liquid compost with soil, leachable trihalomethane precursors decreased drastically probably due to adsorption of the precursors to soil particles. However, only slight decrease of leachable trihalomethane precursors occurred afterward. Soluble trihalomethane precursors of the solid and liquid compost were decreased only slightly during incubation after mixed with spring water. These results suggest that trihalomethane precursors diffused from solid and liquid composts are persistent against microbiological degradation in soil and aquatic environment.

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Alkylphenol polyethoxylate (APE) and their metabolites were determined in the aquatic environment in Nagoya city. The persistent metabolites of APE, namely nonylphenol tetra-,tri -,di- and monoethoxylate(NPI-4EO), nonylphenol(NP) and octylphenl(OP) were determined in effluents of municipal sewage-treatment plants and river waters by HPLC. In many samples NP1-4EO concentrations were higher than NP. It seems that a predominant source of the invesitigated compounds in river waters was the effluents of municipal sewage-treatment plants. Nonylphenol polyethoxylate (NPnEO : n≥5) was not detected in effluents of municipal sewage-treatment plants, but was detected only in river water receiving untreated municipal wastewaters.
NPnEO, NP1-4EO, NP and OP were found in sediments at concentration levels of a few hundreds times higher than those levels in river waters, indicating their accumulation in sediments. NP concentrations were higher than NP1-4EO concentrations in sediments.
These metabolites, particularly NP, are more toxic to aquatic organisms than the parent compounds, consequently there are public concerns about their environmental effects. This research demonstrates that further investigation on the behaviour of APE and their metabolites is necessary.

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Red tide outbreaks kill great number of cultured fish resulting in the serious problem for fisheries. In this study, to clarify the ability of the foam-separation system for collection of red tide plankton, the optimum conditions of this system was investigated by batch system.
The results are as follows :
(1) It was clear that the foam-separating system was very effective for collecting plankton by combined use of a coagulant (poly ferric sulfate : PFS) and protein (casein). When added PFS and casein at dosage of 40mg-Fe·l^-1 and 15mg·l^-1, respectively, the recovery of Heterosigma akashiwo, Chattonella antiqua and Gymnodinum mikimotoi were 99%, and the ratio of volume of foam waste water to total amount of red tide seawater was about eight percent. The optimum dosages of PFS and casein for collecting diatom (Pheaodactylum tricornutum, Skeletonema costatum, Chaetoceros sociale) and H. akashiwo were less than that for above two red tide species.
(2) Approximately 100% of dosed PFS and casein were recovered from the treated seawater. Furthermore, about 99% of phosphate was removed from the red tide seawater by coagulation.
(3) AGP tests showed that the growth of red tide plankton (H. akashiwo, C. antiqua and G. mikimotoi) were strongly limited in the treated seawater.

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