A whole-cell bacterial biosensor was developed for detecting low concentrations of organomercurials in the environment. The sensor plasmid for bioavailable Hg²⁺ (pHYRnLux) was constructed by fusing the mercury inducible promoter and its regulatory gene, merR, from Pseudomonas strain K-62 with the reporter genes luxAB from Vibrio harveyi. Another plasmid carrying the organomercurial lyase gene, merB3, from Bacillus megaterium MB1 was also constructed and transformed into Escherichia coli DH5 α with pHYRnLux. The resulting bacterial biosensor carrying these two plasmids responded to a various organomercurials including methylmercury chloride (MMC), ethylmercury chloride (EMC), phenylmercury acetate (PMA) and thimerosal. Under a 10-minute exposure condition, the lowest detectable concentrations of MMC and PMA were 3nM and 30nM, respectively. However, increasing the exposure time to 60 minutes allowed the detection of 300pM MMC and 3nM PMA. Thus, the constructed bacterial biosensor allows the detection of a various organomercurials from the picomolar level to the nanomolar level within 60 minutes and may be useful for monitoring bioavailable organomercurials in environmental samples.

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The processing performance of a high-strength-wastewater treatment system was investigated by feeding the system with sugar-containing synthetic wastewater for more than one year. The system consisted of a (35°C) mesophilic upflow anaerobic sludge blanket (UASB) reactor for pretreatment, and an ambient UASB reactor and a downflow hanging sponge (DHS) reactor for post-treatment. The DHS reactor was constructed using a liquid distributor and a packing material made with sponge cubes. A portion of the final effluent was recycled to the inlet of post-treatment with a recirculation ratio in the range of 2.0-0.3. The synthetic wastewater was made with organic waste from a food factory; it consisted of about 3,000mg of COD_Cr · l^-1, 2,000mg of BOD · l^-1 and 500mg of SS · l^-1. The system exhibited excellent performance in organic removal, achieving 98% COD_Cr and 96% SS removal rates (final effluent: 43mgCOD_Cr · l^-1, 12mgBOD · l^-1 and 15mgSS · l^-1) with 75% of the methane recovered from the removed COD_Cr under conditions of 24hrs of HRT, a COD_Cr volumetric loading rate of 3.0 kg · m^-3 · d^-1 (35°C UASB as pretreatment, 1.4 kg · m^-3 · d^-1; post-treatment, 1.6 kg · m^-3 · d^-1), and low final effluent temperatures such as 1-10°C. The proposed system effectively saves energy and decreases the amount of excess sludge. It is considered as a novel process to treat high-strength wastewaters up to a discharge quality level.

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Since the 1990s, population decreases, reproductive anomalies and malformations of highly aquatic animals have been increasingly reported. One possible cause is considered to be endocrine disruptive effects induced by environmental contaminants through a direct interaction with nuclear receptors, not only with steroid hormone receptors but also with other ones. In this study, we examined the binding affinities of 20 chemicals, which are registered in the Japanese Pollutant Release and Transfer Register (PRTR) and have been abundantly discharged into aquatic environments to eight human nuclear receptors and assessed their potential endocrine disruptive effects. Of the 20 PRTR chemicals tested, nonylphenol diethoxylate, telephthalic acid (TPA), and linear dodecyl-benzensulfonate (DBS) bound to at least two receptors at high concentrations. TPA and DBS enhanced the activities of both retinoic acid receptor (RAR) γ and vitamin D receptor (VDR) in a dose-dependent manner. This suggests that TPA and DBS may disturb the vitamin D endocrine functions mediated by a VDR-VDR homodimer or a VDR-RAR heterodimer. Also, our results indicate that endocrine disruptors unsuspected under the current assessment criteria could potentially bind to various nuclear receptors and disrupt endocrine systems mediated by such receptors.

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To carry out the decomposition of chlorinated aromatic compounds such as dioxins, which are hard to decompose at room temperature, nanoscale α-Fe · Fe₃O₄ composite particles were synthesized via α-FeO(OH) obtained by the reaction of ferrous sulfate and sodium carbonate aqueous solutions and contained 0.25 wt% precious metals (Pt, Pd, Rh and Ru). As the result of the decomposition of chlorobenzene (CB) using the composite particles containing precious metals, it was shown that Rh · α-Fe · Fe₃O₄ and Ru · α-Fe · Fe₃O₄ composite particles exhibit superior dechlorination function. Ru · α-Fe · Fe₃O₄ composite particles were selected because of their low price. For the application of dioxin decomposition at room temperature in contaminated soil, an extractive reagent was selected. Successively, the decomposition of dioxins in extracted-reagent- suspended soil using Ru · α-Fe · Fe₃O₄ composite particles was carried out at room temperature for seven days, and the initial Toxicity Equivalency Quantity (TEQ) values of dioxins in the solvents and soils decreased to 41-63% after the decomposition.

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Estrogenic activity on the surface of Songhua River, China water was investigated. The estrogenic activity was detected in some samples by yeast two-hybrid assay, and natural estrogen (estrone) was detected by gas chromatography-tandem mass spectrometry (GC/MS/MS). The natural estrogen seemed to originate from fecal contamination. On the basis of this supposition, we attempted to detect 10 fecal sterols in these estrogenic samples by GC/MS. The results varied depending on the source of samples and the season. However, sample C collected in January showed a high concentration of β sitosterol. This implied that there are large dairy farming or stockbreeding sites along Nenjiang River in comparison with those along Di'er Songhua River. These results were consistent with those reported in literature and showed the possibility of determining the origin of fecal contamination by fecal sterol analysis.

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