Degradation of pentachlorophenol in a contaminated soil suspension using hybrid catalysts prepared via urea�Cformaldehyde polycondensation between iron(III)-tetrakis(p-hydroxyphenyl)porphyrin and humic acid

Hybrid catalysts were synthesized by attaching iron(III)-tetrakis(p-hydroxyphenyl)porphyrin (FeTPP(OH)₄) to humic acid (HA) via urea–formaldehyde polycondensation. FTIR spectra of the prepared catalysts indicated that the catalysts prepared via urea–formaldehyde polycondensation contained cross-links between the phenolic groups of FeTPP(OH)₄ and HA, which contains aliphatic amine functional groups. The prepared catalysts were examined for their ability to catalyze the oxidative degradation of pentachlorophenol (PCP) in a contaminated soil suspension. The levels of PCP degradation and dechlorination for the hybrid catalysts were significantly higher than those for the non-modified catalyst, FeTPP(OH)₄.     

Elemental composition of sediments in Lake Jinzai, Japan: Assessment of sources and pollution

Bottom sediments from Lake Jinzai in southwest Japan were analyzed to determine their chemical compositions and to assess the potential for ecological harm by comparison with sediment quality guidelines. The pollution status of lake sediments was evaluated by employing contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I(geo)), focusing on a suite of elements in lakebed and core sediments. Elevated concentrations of As, Pb, Zn, Cu, TOC, N, and P were present in several layers of the upper core and other surface sediments. The elevated metal concentrations are likely related to the fine-grained nature of the sediments, reducing bottom conditions produced by abundant organic matter, and possibly minor non-point anthropogenic sources. Moreover, correlations between the concentrations of trace metals and organic carbon, nitrogen, phosphorus, and iron, suggest that these elements play a role in controlling abundances. Calculated CF, PLI, and I(geo) indicate that the sediments are strongly polluted with respect to As, moderately to strongly polluted with Zn, and moderately polluted with Pb and Cu. Metal concentrations exceed the New York State Department of Environmental Conservation (NYSDEC) lowest effect level and the Canadian Council of Ministers of the Environment (CCME) interim sediment quality guidelines that indicate moderate impact on aquatic organisms in the study area.     

Mitigation of peroxidative stress for barley exposed to cadmium in the presence of water-extractable organic matter from compost-like materials

The effects of water-extractable organic matter (WEOM) from compost-like materials on peroxidative stress were investigated for hydroponic culture of barley exposed to Cd. In the presence of WEOM, lipoxygenase activity and malondialdehyde, indices of peroxidative stress in barley, were significantly reduced, compared to those with Cd alone (5 μM) for a 30-d culture (p < 0.05). In addition, Cd uptake in the presence of WEOM samples was significantly lower than that in their absence (p < 0.05). These results indicate that the addition of WEOM can be effective in mitigating the peroxidative stress in barley exposed to Cd. Of the total Cd in the solution, 7–8% was complexed with WEOM, indicating that the complexation of Cd with WEOM is a minor factor in reducing Cd-induced stress in barley. The WEOM sample was purified by cation-exchange column and ultrafiltration to remove the nutrient minerals, such as Ca, Mg and Fe. When the purified WEOM was employed for hydroponic culture in the presence of Cd, significant decreases in peroxidative stress and Cd uptake were observed (p < 0.05). These results show that the organic components in WEOM contribute to the mitigation of peroxidative stress in barley exposed to Cd.     

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.     

Influence of chemical characteristics of humic substances on the partition coefficient of a chlorinated dioxin

The partition coefficients (Koc) of 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) with respect to a variety of humic substances (HSs) were evaluated by a method involving solid-phase microextraction and gas chromatography-electron capture detection. The log Koc values for each of the HS samples were in the range of 6.4-7.7. The log Koc values for HAs from tropical peat, brown forest and ando soils were in the range of 7.3-7.6, similar to the calculated value for the octanol-water partition coefficient (log Koc=7.56). In contrast, the log Koc values for FAs and peat HAs were 0.5-1 unit lower than the calculated value. The parameters for the polarity of HSs, as calculated from (N+O)/C, O/C atomic ratios and the carboxyl group content, were numerically similar related to the log Koc for HpCDD. These results show that the Koc values for HpCDD are significantly influenced by the polarity of HSs.     

Removal of Cr(VI) from contaminated soil by electrokinetic remediation

A new process for the removal of hexavalent chromium [Cr(VI)] contaminated soil is described. The process provides for an efficient removal of anionic chemicals from contaminated soils. Chromate anions were removed from the soil to the anodic reservoir by the moving force of electromigration. In this process, the chromate anions that accumulate in the anodic reservoir are simultaneously eliminated by using a column packed adsorbent. The adsorbent (immobilized tannin) used was chemically incorporated into cellulose. Cr(VI) was found to be adsorbed to this adsorbent efficiently. In the electrokinetic process, the pH of the aqueous solution in the anodic reservoir was decreased by the electrolysis of water. In the present study, the pH of the solution in the anodic reservoir is maintained at pH 6 by the addition of an aqueous alkaline solution during the electrokinetic process. The advantage of pH control is that it promotes the release of Cr(VI) from the soil by electromigration, thus permitting the maximum adsorption of Cr(VI) on the immobilized tannin. Simultaneous collection of Cr(VI) from the anodic reservoir leads to the protection from secondary contamination with Cr(VI).     

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.     

Changes in Age-Related Reproductive Tactics in the Female of the Butterfly, Eurema hecabe

The occurrence of mate solicitation by virgin females was investigated in the butterfly Eurema hecabe. Young (1-day-old) virgin females rarely showed mate solicitation to male model, however, old (at least 6-day-old) virgin females frequently showed such flight. The duration of solicitation was significantly longer in older females than in younger ones. The age-related behavioral change occurs with female oogenesis (Hiroki and Kato 1996), and such behavior may thus be a result of female adaptation to maximize their fecundity. Received: 6 November 1997 / Accepted in revised form: 29 June 1998     

Effective diffusivity of the uranyl ion in a granite from Inada, Ibaraki, Japan

The effective diffusivity of uranium(VI) in Inada granite has been determined by through-diffusion. Experiments were performed at room temperature (20–25°C) in a 0.1 mol 1⁻¹ KCl solution where uranium is present predominantly as the poorly sorbing UO₂²⁺. An effective diffusivity (D_e) of (3.6 ± 1.6) × 10⁻¹⁴ m² s⁻¹ was obtained, close to that for uranine (nonsorbing organic tracer), but one order of magnitude lower than those obtained for Sr²⁺ and NpO₂⁺, and two orders of magnitude lower than that obtained for I⁻. According to well established theory, a proportional relationship exists between D_e and the diffusivity in the bulk of the solution (D_v). The effective diffusivity obtained in granite was not proportional to D_v. This agrees with results obtained for effective diffusivity in a Swedish granite. The ratio D_e/D_v was found to be not constant but increased with D_e or D_v. This result suggests a limit to the application of the theory.