Unexpected release of HNO<Subscript>3</Subscript> and related species from UV-illuminated TiO<Subscript>2</Subscript> surface into air in photocatalytic oxidation of NO<Subscript>2</Subscript>

We have discovered that HNO₃ and related species are released from the TiO₂ surface into air in the TiO₂ photocatalytic oxidation of NO₂ (1 ppm) under continuous UV light illumination (1 mW cm⁻²) by dehumidifying the outlet gas of the reaction and analyzing the recovered condensate liquid by ion chromatography. The origin of the HNO₃ recovered in the dehumidifier could not be explained by a simple desorption of HNO₃ overproduced on the TiO₂ surface. The produced HNO₃ must be activated on the TiO₂ surface and causing the unidentified reaction.     

Polybrominated, polychlorinated and monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans and dioxin-like polychlorinated biphenyls in marine surface sediments from Hong Kong and Korea

In this study we investigated occurrences and distribution patterns of dioxin-related compounds (DRCs) such as polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans (MoBPCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in marine surface sediments collected from the coastal waters of Hong Kong and Korea. In most sampling sites, concentrations of PCDDs were the highest, followed by DL-PCBs, PCDFs, PBDFs, PBDDs, MoBPCDDs and MoBPCDFs in this order. Levels of PBDD/Fs were generally 1-2 orders of magnitude lower than chlorinated analogues. Levels of PCDDs are higher than PCDFs in Hong Kong while levels of PBDFs are higher than PBDDs in Korea (p < 0.05). Report of PBDD/Fs and MoBPCDD/Fs in sediments from East Asian countries is novel and original. Environmental levels of PBDD/Fs are supposed to start increasing in accordance with rising production, use and disposal of brominated flame retardants (BFRs) and recycling processes of e-waste in Asian developing countries.     

Manganese toxicity as indicated by visible foliar symptoms of Japanese white birch (Betula platyphylla var. japonica)

For the purpose of a field diagnosis of Mn toxicity, we showed the possibility of using visible foliar symptoms of Japanese white birch (Betula platyphylla var. japonica Hara) as indicator. To examine the relationship between the expression of visible symptoms and leaf Mn concentrations, white birch seedlings were grown under four different Mn levels: 1 mg Mn l-1 as control, 10, 50 and 100 mg Mn l-1. Foliar symptoms of Mn toxicity for white birch were: (1) chlorosis at entire young leaves in the 50 and 100 mg Mn l-1 treatments; and (2) brown speckles at the leaf marginal and interveinal area for old leaves in the treatments greater than 1 mg Mn l-1. Mn preferably accumulated into the leaf marginal and interveinal area, where the brown speckles were observed. The mechanism determining the expression of symptoms seems to be associated with the physiological state related to leaf age as well as Mn distribution and concentration within a leaf.     

Microbial dynamics in the process of restoration of groundwater contaminated by chlorinated ethene in the presence of Escherichia coli

This study investigated the effects of hygiene indicator bacteria during the biostimulation of groundwater contaminated with chlorinated ethene. We showed the state of dechlorination activity and behavior of microbial structure by the addition of Escherichia coli (E. coli) as hygiene indicator bacteria in a contaminated groundwater sample. Dechlorination of tetrachloroethene and trichloroethene to cis-1,2-dichloroethene (cis-DCE) within 14 days took place similarly both with and without the addition of E. coli. This indicated that inhibition of against dechlorinating activity of corresponding dechlorinating bacteria was not caused by E. coli. Structural change of the bacterial community was analyzed both before and after dechlorination using a denaturing gradient gel electrophoresis (DGGE) and clone library. The result of DGGE detected E. coli only at day 0. A sample at day 14 after dechlorination detected Pseudomonas putida, Anaerosinus glycerini, and Clostridium genus but not E. coli. The result of the clone library also showed an identical profile. Detection of E. coli using desoxycholate media was decreased from 2.3 × 10⁶ cells/ml to 6.0 × 10³ cells/ml during day 14. These results suggest that biostimulation of groundwater contaminated by chlorinated ethene in the presence of hygiene bacteria caused the dechlorination without activity inhibition and decrease of dechlorinating bacteria.     

Role of the bivalveCorbicula japonica in the nitrogen cycle in a mesohaline lagoon

The effect of the bivalveCorbicula japonica on the nitrogen cycle in Lake Shinji, a mesohaline brackish lagoon in Japan, was examined quantitatively based on field surveys and laboratory experiments carried out in the summer of 1982 and 1983. The biomass of the flesh ofC. japonica comprised 97% of the total biomass of the macrozoobenthos in summer. Total biomass ofC. japonica in the lake was estimated 30 986 t fresh wt. The concentration of suspended solids immediately above the lake bottom, whereC. japonica filters the water, was 1.5 to 4 times higher than that in the surface water. In laboratory experiments, the filtration rate was 5.0 litres g dry flesh wt^-1 h^-1, the excretion rates of ammonia and of feces and pseudofeces ofC. japonica were 200×10^-6 g N g dry flesh wt^-1 h^-1 and 33.4 mg dry wt g dry flesh wt^-1 h^-1, respectively at 27°C, the average summer water temperature in the lake. From our study, we estimated thatC. japonica filters almost the same amounts of particulate organic nitrogen produced in the lake by phytoplankton and that supplied from rivers, and that it excretes 30% of filtered nitrogen as feces or pseudofeces and 18% as ammonia.     

Algal growth inhibition by river water pollutants in the agricultural area around Lake Biwa, Japan

An ecotoxicological study of river water discharged from the agricultural area around Lake Biwa was performed by using algal bioassays to guide chemical analysis. Water samples were collected once a week, at least, for 1 year starting in April 1997 and continuing until April 1998. The toxicities of the dissolved and particulate-adsorbed extracts of water samples were evaluated by the algal growth inhibition test and concentrations of individual pesticides were determined. Most of the river water that was collected during the periods when pesticides were applied to the paddy fields caused algal growth inhibition. Some extracts were found to contain herbicides (molinate, mefenacet, simetryn, or esprocarb) as major compounds. According to chemical assay and bioassay, simetryn was identified as the most toxic compound that caused algal growth inhibition.     

Decolorization of mixtures of different reactive textile dyes by the white-rot basidiomycete Phanerochaete sordida and inhibitory effect of polyvinyl alcohol

We tried to decolorize mixtures of four reactive textile dyes, including azo and anthraquinone dyes, by a white-rot basidiomycete Phanerochaete sordida. P. sordida decolorized dye mixtures (200 mg l-1 each) by 90% within 48 h in nitrogen-limited glucose-ammonium media. Decolorization of dye mixtures needed Mn2+ and Tween 80 in the media. Manganese peroxidase (MnP) played a major role in dye decolorization by P. sordida. Decolorization of dye mixtures by P. sordida was partially inhibited by polyvinyl alcohol (PVA) that wastewaters from textile industries often contain. This was caused by an inhibitory effect of PVA on the decolorization of Reactive Red 120 (RR120) with MnP reaction system. Second addition of Tween 80 to the reaction mixtures in the presence of PVA improved the decolorization of RR120. These results suggest that PVA could interfere with lipid peroxidation or subsequent attack to the dye.     

A comprehensive assessment system for the maritime traffic environment

It is desirable when drawing up a maritime traffic environmental project or a project for consolidating port and harbour facilities, that the safety of the maritime environment for shipping-traffic is assessed quantitatively, and that the rationale of a given project and the proposed safety measures are evaluated in an objective manner.In this report, the system flow and procedures to integrally assess the safety of the maritime traffic environment by systematically combining various simulation techniques are discussed first.Subsequently, the quantitative risk evaluation procedure for collisions of ships in waters with a high traffic density, among the assessment procedures above, and an outline of the shipping traffic flow simulation capable of reproducing ships′ movements, are described. In evaluating the results of simulations, a method introducing Subjective Judgement values (SJ-values) as indexes manifesting the subjective degree of danger felt by shiphandlers, is shown. The SJ-values were experimentally determined from simulator experiments using parameters representing the relation ship with other ships proceeding in the vicinity.Finally, some of the results of studies conducted for the recent construction of new LNG berths in Tokyo Bay are introduced as an example of practical safety assessment in this field.     

Fluorinated alkyl compounds including long chain carboxylic acids in wild bird livers from Japan

A wide range of fluorinated alkyl compounds (FACs) has been reported in wildlife in various locations in the world. However, such information regarding Japanese wildlife is rarely found. In the present study, we investigated the occurrence of 21 FACs, including perfluorinated alkyl sulfonates (PFASs), perfluorinated carboxylates (PFCAs), and fluorotelomer acids, in the livers of 10 wild bird species from two regions in northern Japan. To avoid interferences, FACs were quantified by a recently developed method using acetonitrile and solid-phase extraction followed by an ion exchange HPLC column separation. Apart from perfluorooctane sulfonate (PFOS), which was found at the highest levels of all the compounds detected, several long chain perfluorinated carboxylates (PFCAs) from C8 to C16, particularly perfluorotetradecanoic acid (PFTeDA) and perfluorohexadecanoic acid (PFHxDA), were detected for the first time. Additionally, 7:3 FTCA, a fluorotelomer acid, was also detected in most swan livers from Miyagi prefecture and all the birds from Tochigi prefecture. However, none of the sulfonamides and unsaturated telomer acids were detected in any species. Swans seem to be the least exposed wild birds to FACs among the investigated birds, signifying that feeding habits may reflect FAC accumulation in wild birds. The highest total concentration of detected FACs was 405 ng g⁻¹ wet wt., which was found in a Japanese sparrowhawk, indicating that the top predatory wild birds can accumulate several long chain carboxylic acids. However, the current FAC concentrations found in livers may suggest that these compounds alone would not cause a severe toxic effect in these species.     

Occurrence of tributyltin (TBT)-resistant bacteria is not related to TBT pollution in Mekong River and coastal sediment: with a hypothesis of selective pressure from suspended solid

Tributyltin (TBT) is organotin compound that is toxic to aquatic life ranging from bacteria to mammals. This study examined the concentration of TBT in sediment from and near the Mekong River and the distribution of TBT-resistant bacteria. TBT concentrations ranged from <2.4 to 2.4 ng/g (dry wt) in river sediment and <2.4-15 ng g(-1) (dry wt) in harbor sediment. Viable count of total bacteria ranged from 2.0 x 10(4) to 1.4 x 10(7)cfu/g, and counts of TBT-resistant bacteria ranged <1.0 x 10(2) to 2.5 x 10(4)cfu/g. The estimated occurrence rate of TBT-resistant bacteria ranged from <0.01 to 34% and was highest in upstream sites in Cambodia. The occurrences of TBT in the sediment and of TBT-resistant bacteria were unrelated, and chemicals other than TBT might induce TBT resistance. TBT-resistant bacteria were more abundant in the dry season than in the rainy season. Differences in the selection process of TBT-resistant bacteria between dry and rainy seasons were examined using an advection-diffusion model of a suspended solid (SS) that conveys chemicals. The estimated dilution-diffusion time over a distance of 120 km downstream from a release site was 20 days during dry season and 5 days during rainy season, suggesting that bacteria at the sediment surface could be exposed to SS for longer periods during dry season.