Photochemical decomposition of environmentally persistent short-chain perfluorocarboxylic acids in water mediated by iron(II)/(III) redox reactions

The photochemical decomposition of short-chain (C(3)-C(5)) perfluorocarboxylic acids (PFCAs) was investigated. Direct photolysis in water proceeded slowly with the 220- to 460-nm light emission from a xenon-mercury lamp to form F(-), CO(2), and shorter-chain PFCAs. Addition of a small amount of Fe(3+) to the aqueous solutions of the PFCAs dramatically enhanced their photochemical decomposition under an oxygen atmosphere: when the (initial PFCA)/(initial Fe(3+)) molar ratio was 13.5 (initial PFCA concentration=67.3mM), the pseudo-first-order rate constants for the PFCA decomposition were 3.6-5.3 times those with photolysis alone, and the turnover number for the catalytic PFCA decomposition [i.e., (moles of decomposed PFCA)/(moles of initial Fe(3+))] reached 6.71-8.68 after 24h of irradiation. The catalysis can be explained by photoredox reactions between PFCA, Fe(3+)/Fe(2+) and oxygen via photo-induced complexation of Fe(3+) with the PFCAs.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice plants: possible contaminated pathways

Uptake of dioxins was confirmed in rice plants. We determined (i) dioxin concentrations and isomer profiles in leaf+stem samples of rice plants grown in three soils with different dioxin concentrations and isomer profiles and (ii) temporal changes in dioxin concentrations and isomer profiles in rice grown in a paddy field on which agricultural chemicals containing dioxin impurities had been used in previous years. Principal-component and chemical mass-balance analyses of the data showed that dioxin concentrations and isomer profiles in the rice grown in the different soils were similar, even though the dioxin concentrations and isomer profiles of the soils were different. However, the dioxin concentrations in the rice were influenced by dioxin levels in the atmospheric gas phase. Changes in dioxin levels during the growing period of the rice were also strongly influenced by adhesion of the soil to plant components during the early stage of growth, but gradually the influence of the atmospheric gas phase became predominant. Calculated dietary uptake estimates indicated that, even in rice grown in Japan on soil contaminated with high concentrations of dioxins, the amount of dioxins ingested by humans from rice is extremely small, and the amount of dioxins ingested by livestock from forage rice is similar to that for other forage crops.     

Humic-like substances global levels and extraction methods in aerosols

Environmental Chemistry Letters - The abundance of humic-like substances in the atmosphere has received considerable attention since these substances play an important role in various atmospheric...     

Characterization of Photovoltaic Performance of the Dye-Sensitized Solar Cell with a Novel Ruthenium Complex Having a Bisdemethoxycurcumin as a Ligand

The first example of a ruthenium sensitizer (TUS-22) having a natural dye, bisdemethoxycurcumin, as a ligand has been synthesized. The dye-sensitized solar cell based on this novel dye showed 5.8% conversion efficiency under AM 1.5 (100 mW/cm²) irradiation.     

Techniques to separate metal from waste printed circuit boards from discarded personal computers

Waste printed circuit boards contain valuable metals such as Au, Pd, Ag, and Cu that can be reutilized and harmful elements such as Pb, Br, and Cr that must be removed from the viewpoint of environmental conservation. In this research, we examined a method that separates the materials from printed circuit boards contained in discarded personal computers. After cutting the printed circuit boards to a size of 20 × 20 mm, they were heated at 873 K under an Ar atmosphere to remove organic resins containing elements such as C, H, and N. After heat treatment, the printed circuit boards were crushed using a planetary ball mill and the pulverized powders were filtered. The fraction with a granularity of greater than 250 μm was separated into magnetic and nonmagnetic materials by a magnetic field. Because the fraction with a granularity of less than 250 μm contained 39 mass% of C, it was heated at 1273 K in an atmosphere of 95% Ar and 5% O₂ to allow carbon combustion to take place, followed by metal reduction processing at the same temperature in an atmosphere of 97% Ar and 3% H₂. The basicity of the resulting powder was adjusted and the powder was heated at 1773 K under an Ar atmosphere. The proposed method separated the slag and metal, and 80% of the valuable metals contained in printed circuit boards could be collected.     

Release of phosphorus from lake sediments

The relationship between the content of various forms of phosphorus in lakesediments and the amount of phosphorus released under aerobic and anaerobic conditions was studied. Total phosphorus content in the sediment of Lake Kasumigaura was highest at the 0–5 cm surface layer and decreased with depth. The constant value below 15 cm was consistent with the decrease of iron-bound phosphorus conent (FeP). The amount of phosphorus released from the sediments was proportional to the decrease of FeP under both aerobic and anaerobic conditions. Under anaerobic conditions, 90% of the FeP initially held in the sediments was released in 55 days. Using dialysis apparatus, maximum growth yield of algae was shown to be linearly dependent on the amount of phosphorus released under aerobic conditions.     

日本湖泊水质富营养化控制措施与政策

日本在经历了20世纪50年代和60年代的严重污染事件后,强化了环境政策.在水污染控制法中从严制定了污水排放限制和水质标准,在20世纪70年代和80年代成功地减少了污染.对"日本湖泊水质保全特别措施法"的现状、流域的点源和非点源污染负荷的削减、湖泊底泥的疏浚以及采用生态工程方法减少支流负荷等流域综合管理进行了综述和探讨,并给出了进一步改善湖泊水质的建议.     

The praying mantis (Mantodea) as predator of the poisonous red-spotted newt <Emphasis Type="Italic">Notophthalmus viridescens</Emphasis> (Amphibia: Urodela: Salamandridae)

A Chinese praying mantis, Tenodera sinensis, was observed feeding on a living red-spotted newt, Notophthalmus viridescens. Specimens of that newt’s population are known to contain high concentrations of tetrodotoxin (TTX), a specific blocker of voltage-gated sodium channels. After experimental oral administration of a TTX-solution (1 mg/ml) to adult specimens of four mantis species, all survived high TTX concentrations (up to 30.8 μg/g body mass) as revealed by analysis of their body extracts, but they are rapidly killed by intra-abdominal injection of 1 μg TTX. The toxin was found to be gradually excreted with faeces. As demonstrated by monoclonal antibody-based immunohistochemical technique, TTX does not penetrate the mid-gut membrane, since it was localized only in the gut lumen, but not in the epithelial cells. This prevents the toxin to reach its target, the sodium channels of the insect’s nervous system, and enables the mantids to feed on toxic prey without risking poisoning.     

Vibrio alginolyticus,a tetrodotoxin-producing bacterium,in the intestines of the fish Fugu vermicularis vermicularis

The influence of nutrient deprivation on cell-cycle progression was examined in two phytoplankton species, the diatom Thalassiosira weissflogii (actin) and the coccolithophorid Hymenomonas carterae (cocco II). The diatom was starved for nitrogen, silicon or both, whereas only nitrogen limitation was examined in H. carterae. In both species, nitrogen-starved cells were arrested in the early part of the cell cycle (G₁ phase). In the diatom, silicon-starvation arrested cells in late G₁ phase and also in the last part of the cell cycle (G₂+M). In all cases, cell-cycle arrest could be reversed by addition of fresh medium, but cell-cycling times during the first generation were increased in comparison to those in nutrient replete, steady-state growth conditions. These results supply evidence for simultaneous dual-nutrient limitation of population growth and provide a mechanistic interpretation for the division patterns observed in cultures where nutrients are supplied periodically.     

Evaluation of river pollution of neonicotinoids in Osaka City (Japan) by LC/MS with dopant-assisted photoionisation

An atmospheric pressure photoionisation (APPI) source for liquid chromatography/mass spectrometry (LC/MS) was applied to determine neonicotinoid pesticides in the aquatic environment. Dopant-assisted APPI was very effective in the ionisation of neonicotinoids. Neonicotinoids generated protonated molecules in APPI with high sensitivity, while adduct ions, such as sodiated molecules, were predominantly generated in conventional electrospray ionisation. The ionisation of neonicotinoids was confirmed by ultra-high-resolution MS. An analytical method coupled with solid phase extraction was developed for acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, and thiamethoxam. Method detection limits were 0.47 to 2.1 ng L(-1) for six neonicotinoids. Dinotefuran was the most frequent and highest among the neonicotinoids examined in the aquatic environment in Osaka, Japan. The maximum concentration of dinotefuran was 220 ng L(-1). Given the toxicity of neonicotinoids for aquatic creatures, the concentrations observed here were substantially low. The change in concentrations was temporally coincident with the period of the neonicotinoid application. Although rapid photodegradation and some degradation products have been elucidated, the degradation products in the aquatic environment were not identified in the present study.