Effects of wavelength and water quality on photodegradation of N-Nitrosodimethylamine (NDMA)

N-Nitrosodimethylamine (NDMA) is a potent carcinogen that yields a cancer risk of 10⁻⁶ at concentrations as low as 0.7 ng L⁻¹. Tentative guideline values are set at 3 ng L⁻¹ in California, USA; 9 ng L⁻¹ in Ontario, Canada; 40 ng L⁻¹ nationwide in Canada; and 100 ng L⁻¹ by the World Health Organization. NDMA is a great concern in treating reclaimed water as well as drinking water. UV degradation can be considered effective degradation method. A 1-log reduction of NDMA is achieved by 1000 mJ cm⁻² of a 254-nm low pressure (LP) mercury UV lamp. However, a higher degradation efficiency than that provided by LP lamps is desired in practical treatment. In this study, the effects of wavelength and water quality were investigated to achieve higher degradation efficiency. The effects of wavelength were examined by comparing three UV lamps: a 222-nm Kr Cl Excimer UV lamp, a 254-nm LP mercury UV lamp, and a 230- to 270-nm filtered medium pressure (FMP) mercury UV lamp. The 222-nm lamp and FMP lamp achieved 4 times and 2.8 times higher degradation efficiency, respectively, than the conventional 254-nm LP lamp. Effects on water quality were also simulated by using absorption spectrum data of nitrate solutions and process water from a drinking-water treatment plant. In the simulation, the 222-nm lamp was affected by UV-absorbing compounds in the water, whereas the FMP lamp showed more stable degradation efficiency. Appropriate use of these three types of lamps could enhance the efficiency of degradation of NDMA.     

Determination of dioxin concentrations in fish and seafood samples using a highly sensitive reporter cell line, DR-EcoScreen cells

There is a strong need for the development of relatively rapid and low-cost bioassays for the determination of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in environmental and food samples. In this study, we applied a reporter gene assay using DR-EcoScreen cells (DR-cell assay), which is highly sensitive to dioxins, to the determination of PCDD/Fs and dl-PCBs in fish and seafood samples. The PCDD/Fs and dl-PCBs were extracted from homogenated samples (10 g) of 30 fish and shellfish, purified by clean-up procedure using a multilayered silica gel column and an alumina column, and applied to DR-cell assay. Interestingly, the bioanalytical equivalent (BEQ) values obtained from the DR-cell assay [<0.1 ∼ 5.4 pg BEQ g⁻¹ wet weight (ww)] were closely correlated with the toxicity equivalent (TEQ) values from conventional high-resolution gas chromatography/high-resolution mass spectrometry (HRGC-HRMS) analysis (r² = 0.912), and the slope of regression line was 0.913. Therefore, we multiplied the BEQ values from the DR-cell assay by a conversion coefficient (1.095, the reciprocal of 0.913) to approximate the TEQ values from the HRGC-HRMS analysis. Furthermore, we used this DR-cell assay to perform a prescreening test of PCDD/Fs and dl-PCBs in 16 fish and seafood samples purchased from a supermarket, revealing that a sample from the fatty flesh of a bluefin tuna exceeded 8 pg TEQ g⁻¹ ww (the European Union-tolerance limit). Taken together, these results suggest that the DR-cell assay might be applicable as a rapid and low-cost prescreening method to determine dioxin levels in fish and seafood samples.     

Surface ozonation of polyvinyl chloride for its separation from waste plastic mixture by froth floatation

Selective surface modification of polyvinyl chloride (PVC) by ozonation was evaluated to facilitate the separation of PVC from other heavy plastics with almost the same density as PVC, especially polyethylene terephthalate (PET), by the froth flotation process. The optimum froth flotation conditions were investigated, and it was found that at 40°C, 90% of PVC and PET plastics floated. The bubble size became larger and the area covered with bubbles on the plastic surface was reduced with increasing temperature. Optimum PVC separation was achieved with the flotation solution at 40°C and mixing at 180–200 rpm, even for sheet samples 10 mm in size. Combined treatment by ozonation and froth flotation is a simple, effective, and inexpensive method for PVC separation from waste plastics.     

Detecting deforestation with a spectral change detection approach using multitemporal Landsat data: a case study of Kinabalu Park, Sabah, Malaysia

Tropical deforestation is occurring at an alarming rate, threatening the ecological integrity of protected areas. This makes it vital to regularly assess protected areas to confirm the efficacy of measures that protect that area from clearing. Satellite remote sensing offers a systematic and objective means for detecting and monitoring deforestation. This paper examines a spectral change approach to detect deforestation using pattern decomposition (PD) coefficients from multitemporal Landsat data. Our results show that the PD coefficients for soil and vegetation can be used to detect deforestation using change vector analysis (CVA). CVA analysis demonstrates that deforestation in the Kinabalu area, Sabah, Malaysia has significantly slowed from 1.2% in period 1 (1973 and 1991) to 0.1% in period 2 (1991 and 1996). A comparison of deforestation both inside and outside Kinabalu Park has highlighted the effectiveness of the park in protecting the tropical forest against clearing. However, the park is still facing pressure from the area immediately surrounding the park (the 1km buffer zone) where the deforestation rate has remained unchanged.     

Photodegradation fates of cis-chlordane, trans-chlordane, and heptachlor in ethanol

cis-Chlordane, trans-chlordane, and heptachlor were photodegraded in ethanol, and their degradation fates and degradation products were determined by a computational chemical method. The most degradable material was heptachlor (first-order reaction constant k=0.13 min(-1)). Chlorine balances changed during UV irradiation, and the chlorine atoms in chlordane and heptachlor were eventually mineralized. cis-Chlordane, trans-chlordane and heptachlor each generated two di-dechlorinated products. Reactivities at various positions in these compounds were predicted on the basis of bond dissociation energies calculated by nonempirical molecular orbital calculation (Gaussian 98W).     

Degradation of a Terephthalate-containing Polyester by Thermophilic Actinomycetes and <Emphasis Type="Italic">Bacillus</Emphasis> Species Derived from Composts

We intended to find thermophilic degraders of terephthalate-containing Biomax^® films. Films in mesh bags were buried in composts (inside temperature: approximately 55–60 °C), resulting in the degradation of them in 2 weeks. Fluorescent microscopy of films recovered from composts showed that microorganisms gradually covered the surface of a film during composting. DGGE analysis of microorganisms on the composted film indicated the presence of Bacillus species as main species (approximately 80% of microbial flora) and actinomycetes (approximately 10–20%) as the second major flora. Isolation of Biomax^®-utilizing bacteria was focused on these two genera: two actinomycetes and one Bacillus species were isolated as pure best degraders from the composted polymer films, which were fragmented into small pieces. All the strains were thermophilic and identified, based on their 16S rDNA analyses. Degradation of polymer films was confirmed by (1) accelerated fragmentation of films in composts, compared with a control (no inoculum) and resultant decrease in molecular weights, (2) growth in a powdered Biomax^® medium, compared with a control without powdered Biomax^®, and (3) production of terephthalate in a powdered Biomax^® medium. In this way, we concluded that these bacteria were useful for degradation of thermostable Biomax^® products.     

Polychlorinated dibenzothiophenes in Japanese environmental samples and their photodegradability and dioxin-like endocrine-disruption potential

Polychlorinated dibenzothiophenes (PCDTs) in sediment, soil, and fly ash samples collected in Japan were analyzed and their dioxin-like endocrine-disruption potential and photodegradability investigated. PCDTs were detected in all three types of sample, although the concentrations were lower than those of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). An Ah-immunoassay confirmed that 2,3,7,8-TeCDT, 1,2,3,7,8-PeCDT, 1,2,3,7,8,9-HxCDT, and 1,2,3,4,7,8,9-HpCDT had Ah receptor-binding activities, which means that these PCDTs have the potential to cause dioxin-like endocrine-disruption. Photodegradation of PCDTs by UV irradiation was accompanied by dechlorination. The photodegradation rates of 2,3,7,8-TeCDT and OCDT were lower than the rates for the corresponding PCDF isomers (2,3,7,8-TeCDF and OCDF), which indicates that PCDTs are more stable than PCDFs to photodegradation.     

Different uses of plant semiochemicals in host location strategies of the two tachinid parasitoids

Some members of the family Tachinidae (Insecta: Diptera) deposit numerous very small eggs, termed “microtype” eggs, on the food plants of their caterpillar hosts. Parasitization is successful only when the hosts ingest these eggs. To increase the chance of hosts encountering the eggs, microtype tachinid parasitoids have to choose a suitable plant that harbors hosts and lay their eggs near the hosts. In their host location process, semiochemicals emitted by host-infested plants offer the tachinids a reliable cue. We investigated the behavioral responses of two microtype tachinid parasitoids, Pales pavida and Zenillia dolosa, to maize plants infested with their caterpillar host, Mythimna separata, in a wind tunnel. P. pavida females showed a significantly higher rate of landing on caterpillar-infested plants than on mechanically wounded or intact plants, whereas Z. dolosa landed on both the caterpillar-infested and mechanically wounded plants at significantly higher rates than on intact plants. We also examined which part of a caterpillar-infested maize leaf induces oviposition. P. pavida deposited eggs on the margin of the leaf, whereas Z. dolosa preferentially laid eggs around a caterpillar-infested area or a mechanically wounded spot. P. pavida eggs retained their parasitization ability for more than 15?days after they were deposited, whereas the eggs of Z. dolosa could not survive more than 5?days after oviposition. Our results suggest that each tachinid parasitoid employs a different host location strategy to exploit semiochemicals coming from plant–herbivore interaction as cues in order to increase their parasitization success.     

Environmental concern, attitude toward frugality, and ease of behavior as determinants of pro-environmental behavior intentions

This study investigates relations between environmental concern, attitude toward frugality, perceived ease of behavior, and stated intentions to engage in four different types of pro-environmental behavior, i.e., reductions in electricity and gas use, garbage, and automobile use, using data from 341 Japanese respondents. Environmental concern, attitude toward frugality and perceived ease of implementation were considered possible determinants. A structural equation analysis indicated that perceived ease of implementation had effects for all of the pro-environmental behaviors. It also indicated that environmental concern had a positive effect solely for garbage reduction, while attitude toward frugality had positive effects for gas and electricity reduction. For automobile use reduction, neither environmental concern nor attitude toward frugality had significant effects. The relationship between attitude toward frugality and mottainai, that is a Japanese concept indicating respect for resources, is then discussed, and it is suggested that educating people to have not only a high level of environmental concern but also a positive attitude toward frugality would be an effective means of promoting pro-environmental behavior.     

Studies with natural and anthropogenic iodine isotopes: iodine distribution and cycling in the global environment

Iodine is an important trace element in geological and biological processes. We summarize here recent results and new data of experiments and observations carried out to improve the understanding of concentration levels and behavior of natural and anthropogenic iodine nuclides in the global environment. The distribution of stable iodine in the Earth's crust was estimated using concentration data in a suite of representative samples and the influence of subduction on the marine iodine cycle was investigated using (129)I systematics on iodine-rich brines from Japan. The importance of microorganisms for the natural iodine cycle is shown in recent studies of iodine sorption on soil and of iodine volatilization from terrestrial and marine environments. Levels of anthropogenic (129)I were measured in samples collected around a spent fuel reprocessing plant in Japan.