Identification of 2,6-diisopropylnaphthalene metabolites in carp part 1. In vivo experiment

The metabolism of diisopropylnaphthalene (DIPN) in fish was studied from an ecotoxicological viewpoint to clarify the environmental fate of DIPN, a solvent of carbonless paper which is widely used as a substitute for PCB. This study identified the following metabolites in carp by in vivo experiment; 2-(1-hydroxy-1-methyl) ethyl-6-isopropylnaphthalene, 2-(1-methyl-2-hydroxyethyl)-6-isopropyl-naphthalene, 2,6-(1-hydroxy-1-methyl) ethyl-naphthalene, 2-(1-hydroxy-1-hydroxymethyl) ethyl-6-isopropylnaphthalene and α-[2-(6-isopropylnaphthyl)] propionic acid. Identification was based on UV, IR, MS, and NMR analyses. The metabolism of 2,6-DIPN in carp was concluded to mainly through oxidation of the isopropyl chain.     

Mathematical model of phosphorus release from lake sediment

This paper reports the results of a study on the phosphorus release mechanism of lake sediment, primarily by examining the relationship between release rates and sediment depth. Sediment samples from Lake Nakanoumi were used to examine the relationship between phosphorus content and sediment depth and to measure the release quantities of nutrients, specifically phosphorus. From these data, a model of phosphorus release rates was conceived and evaluated. This study concludes that phosphorus release rates from sediment depend primarily on phosphorus content of the sediment.     

Gas-particle partitioning of PCDD/Fs in Nagoya urban air, Japan

Polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) in the atmosphere were sampled by a high-volume filter/sorbent air sampler at an urban (Nagoya, Japan) site from May 2000 to January 2001 under the average ambient temperatures ranging from 1 degrees C to 33 degrees C. The gas and particle phase concentrations of PCDD/Fs were measured and then the field gas-particle partitioning data were used to assess the Junge-Pankow adsorption model and the K(OA) absorption model. For both PCDDs and PCDFs, passable agreement was obtained between the measured and predicted particulate-band fraction (phi) values by the Junge-Pankow model, but the model tends to overpredict phi for all individual Cl4-8DD/F congeners, especially for the lower chlorinated congeners. On the other hand, good agreement was obtained between the measured and predicted log K(p) values by the K(OA) model for both PCDDs and PCDFs. However, the K(OA) absorption model did not fit the field data at low ambient temperature below 5 degrees C. The disagreement at low ambient temperatures was estimated to arise from the gas adsorption artifacts during the sampling. From the validation by the field measurement data in Nagoya urban air, it is found that the K(OA) absorption model is capable of predicting more accurately gas-particle partitioning of PCDD/Fs than the Junge-Pankow adsorption model.     

The redox combustion of carbon monoxide for recovering pure carbon dioxide by using molten (Na+,K+)2(CO32-,SO42-) mixtures

Large-scale combustion systems, such as thermal power plants, emit large amounts of carbon dioxide, which can increase global warming. A molten salt redox combustion system was proposed to recover pure carbon dioxide exhausted from the combustion of fossil fuels. This system is composed of two successive processes by using reactions occurring in a molten salt. The molten salt is the mixture of the molten alkali metal sulfates and carbonates. The sulfate ions oxidize the fuels in first processes, being changed to reductive species such as sulfide ions. In this process, carbon dioxide and water are exclusively exhausted. The reductive species of sulfur compounds are oxidized to regenerate the sulfate ions by air in the second process. In this study, these above two processes were tried by using molten [(Na(+))(0.5),(K(+))(0.5)](2)[(CO(3)(2-))(0.9),(SO(4)(2-))(0.1)] alternatively. The oxidation of carbon monoxide as fuel by sulfate ions and the regeneration of sulfate ions by air were investigated in the temperature range of 700-950 degrees C, respectively. These reactions were exothermic. The rate of the regeneration of the sulfate ions was extremely high. During the oxidation of carbon monoxide, the reaction was first order in carbon monoxide with an activation energy of 101 kJ mol(-1). The optimum condition to recover pure carbon dioxide on practical operation was discussed.     

Uranium Accumulation of Crop Plants Enhanced by Citric Acid

Citric acid was applied to soil to enhance U accumulation in four crop plants. While the highest enhanced U accumulation of aboveground tissues (a.c. 2000 mg kg⁻¹ dry weight) occurred in the leaves of Indian mustard (Brassica juncea), the highest enhanced U accumulation of roots (a.c. 3500 mg kg⁻¹ dry weight) occurred in canola (Brassica napus var. napus). Uranium translocation among tissues of test plants is in the relation of roots>shoots ≅ leaves. The flowers of sunflower (Helianthus annuus) contained similar or higher U concentrations than those found in shoots, but concentrations in seeds are close to zero. In conclusion, Indian mustard is recommended as a potential species for phytoextraction for U-contaminated soil due to its high U accumulation of aboveground biomass (a.c. 2200 μg per plant). There is no evidence that two types of soils cause a significant difference of the enhanced U accumulation (p<0.05). Results, however, indicate that additional citric acid may result in downward U migration that may contaminate groundwater. Speciation of U that is taken up by plants is also discussed in the end.     

Environmental behavior of antibiotic monensin: preliminary studies in Argentina

The increase of intensive bovine production systems in Argentina involves the use of therapeutic agents and growth promoters that reach the environment through animal excreta. The growth promoter most widely used in Argentina is monensin, an ionophore polyether antibiotic produced by Streptomyces cinnamoniensis. Here, the behavior of monensin in different solid environmental matrices is analyzed, and preliminary results that suggest a strong dependence of monensin retention with the organic matter content of the matrix are discussed.     

Triterpenoid and caffeic acid derivatives in the leaves of ragweed, <Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis> L. (Asterales: Asteraceae), as feeding stimulants of <Emphasis Type="Italic">Ophraella communa</Emphasis> LeSage (Coleoptera: Chrysomelidae)

Summary. The leaf beetle Ophraella communa infests almost exclusively Ambrosia artemisiifolia in the fields of Japan, even though it normally feeds on several Asteraceous plants. A filter paper bioassay showed that the feeding of O. communa is strongly stimulated by methanolic extracts of A. artemisiifolia. The feeding stimulants for O. communa have been isolated from methanolic extracts of A. artemisiifolia. -Amyrin acetate, -amyrin acetate, 5-caffeoylquinic acid (chlorogenic acid) and 3,5-dicaffeoylquinic acid from A. artemisiifolia have been identified as feeding stimulants for O. communa. Triterpenoid derivatives (-amyrin acetate or -amyrin acetate) and caffeic acid derivatives (3, 5-dicaffoylquinic acid or 5-caffeoylquinic acid) showed feeding stimulant activity when mixed together.     

Simulation of dioxin accumulation in human tissues and analysis of reproductive risk

Polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran and dioxin-like polychlorinated biphenyl concentrations in human liver, kidney, fat, blood, muscle, richly perfused tissue (brain, lung etc.) and skin were simulated to assess the health risk for Japanese fetuses. A 40-year time course of dioxin accumulation via food ingestion was simulated using a physiologically based pharmacokinetic (PBPK) model. In richly perfused tissue, the concentration estimated by the PBPK model showed better agreement with measured concentrations than that calculated by the one-compartment model. Fetal dioxin concentration was simulated based on the assumption that the fetal concentration was almost equal to the concentration in the mother's richly perfused tissue. To assess the reproductive risk, the estimated concentration in human fetus was compared with that in rat fetus in which reproductive function showed signs of alteration by 2,3,7,8-TCDD in previous reports [Toxicol. Appl. Pharmacol. 114 (1992) 118; 146 (1997) 11; Toxicol. Sci. 53 (2000) 411; 57 (2000) 275]. The present daily intake of 2,3,7,8-TCDD is approximately 1/50 of the amount that leads to possible reproductive toxicity in the next generation. However, when 29 kinds of dioxin congeners are considered, the present level is 1/5 of the hazardous levels. For species extrapolation of dioxin risk, further study on tissue concentration versus toxicity is required.     

Metabolites of diisopropylnaphthalene in carp Part 2. Invitro experiment

This study described an $\text{in}$$\text{vitro}$ experiment on biotransformation of 2,6-DIPN in carp hepatopancreas. It has already been revealed by the previous $\text{in}$$\text{vivo}$ studies to be metabolized with enzymatic oxidation in the liver and been postulated a metabolic pathway. These results were confirmed by means of incubation with 2,6-DIPN in carp hepatic microsome preparation with NADPH, and G-6-P as co-factor. It was suggested that DIPN may be mainly metabolized in the hepatic cytochrome P-450 in the microsomes system. The kinetic parameters i.e. apparent Michaelis constant (Km) and maximum velocity (Vmax), in the metabolites formation were also calculated.