Prediction of pesticide concentrations in the atmosphere using an atmospheric diffusion model (linear source plume model)

The foundational model to predict concentration of pesticides in the atmosphere outside of the sprayed area was developed using the results of measured concentration in the atmosphere, in reference to the atmospheric diffusion model utilized for the air pollution prediction model. The atmospheric diffusion model assumes that the applied area was a topographically flat farmland, that wind direction and wind speeds were constant, and the pesticide was constantly discharged from the emission line sources. Therefore the linear source plume model (LSPLM) was developed. The concentration in the atmosphere was predicted by assigning the property of the pesticides and various conditions of measurements of the model, and compared with the measured them, then the adaptability of the model was examined. As a result, the correlation between the measured value and the predicted value in paddy and forested areas was significant (P < 0.01) although deviations in the order of tens were observed, the measured value and the predicted value were generally in agreement.     

Experimental verification for real-time environmental emergency response system: WSPEEDI by European tracer experiment

Japan Atomic Energy Research Institute has developed an emergency response system WSPEEDI to forecast long-range atmospheric dispersions of radionuclides discharged into the atmosphere. The latest version of WSPEEDI consists of an atmospheric dynamic model MM5 for calculating meteorological fields and a particle random-walk model for atmospheric dispersion. The performance of WSPEEDI was evaluated by data obtained from a field tracer experiment over Europe (ETEX) in this paper. The model validation was done with respect to the following points: (1) the dependence of model accuracy on the temporal and spatial resolutions of the meteorological fields and (2) the superiority of an atmospheric dynamic model over a mass-consistent wind model. Regarding (1), it was shown that the calculation accuracy of the new version with high temporal resolution was improved, especially at the edge of the plume. Moreover, although the increase in horizontal spatial resolution of the old version had no substantial effect on the model performance, increase in horizontal resolution of the new version contributed to the significant improvement of the calculation accuracy. These results showed that the dynamically calculated meteorological field with the spatial resolution of the meso-β–γ scale greatly improved calculation accuracy.     

Remediation of soil contaminated with dioxins by subcritical water extraction

The effectiveness of subcritical water extraction (SCWE) was examined for removing dioxins from contaminated soil. Most dioxins in the soil sample were reduced at 300 degrees C or more, but decreased dioxin concentrations were also observed at 150 degrees C. After 4 h of extraction, 99.4%, 94.5% and 60% of PCDDs were removed from samples at 350, 300 and 150 degrees C, respectively. It was also determined that degradation of dioxins had occurred, since the sum of dioxins in the soil plus water extracts after the experiments had considerably decreased. This study revealed that pressurizing is not essential for the removal of dioxins. Reduction was complete within 30 min at 350 degrees C; however, it took a much longer time at lower temperatures. The results of addition experiments in which OCDDs were added to different types of soil samples have shown that dechlorination is one of the major reaction pathways. After addition of OCDD to soil samples, experiments were carried out to examine in detail the degradation pathways of PCDDs. The removal rates and congener profiles varied among soil types. Although it was previously assumed that removal rates and congener profiles depended on the chemical components in soil, nonparametric statistical analysis revealed no significant relationship between the rate of reduction and elements present in the soil. It was confirmed from isomer patterns that dechlorination of the 2,3,7,8-positions in PCDDs takes place somewhat faster than for the 1,4,6,9-positions.     

Residual organic fluorinated compounds from thermal treatment of PFOA,PFHxA and PFOS adsorbed onto granular activated carbon (GAC)

Perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonate (PFOS) adsorbed onto granular activated carbon (GAC) were thermally treated in N₂ gas stream. The purpose was to assess the fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) during thermal regeneration of GAC, which had been used for water treatment. Mineralized F, residual PFASs including short-chained species, and volatile organic fluorine (VOF) were determined. In a temperature condition of 700 °C, VOF were 13.2, 4.8, and 5.9 % as for PFOA, PFHxA, and PFOS. However, the VOF decreased to 0.1 %, if the GAC and off-gas were kept at 1000 °C. No PFASs remained in GAC at 700–1000 °C; at the same time, short-chained PFASs were slightly detected in the aqueous trapping of off-gas at 800 and 900 °C conditions. The destruction of PFASs on GAC could be perfect if the temperature is higher than 700 °C; however, the process is competitive against volatile escape from GAC. Destruction in gaseous phase needs a temperature as high as 1000 °C. Destruction of PFASs on the surface of GAC, volatile escape from the site, and thermolysis in gas phase should be considered, as to thermal regeneration of GAC.     

Evaporation characteristics of multi-component liquid

Evaporation rate of multi-component liquid such as motor gasoline is expected to change greatly with progress of evaporation because its composition changes. Therefore it is difficult to predict accurately amount of generated combustible vapor in the case that a multi-component liquid is spilt on a floor. Then, we assumed an evaporation model that composition of the vapor obeys the Raoult's law which considers the activity coefficient. Using the model, we calculated the vapor composition, the vapor pressure and the evaporation rate of the liquid. Then, comparison was done between the calculated values and the measured values obtained in this study. “Weight loss fraction” was used as a parameter signifying the progress of evaporation. The variations of the evaporation property were accurately predicted by the model. We derived a prediction model of the amount of generated combustible vapor from the relation between weight loss fraction and evaporation rate. It was found that the amount of generated vapor was expressed as a logarithmic function of time in case of a five-component liquid. Furthermore, we showed that the predicted flash point of a liquid using the composition obtained from the model was in good agreement with an experimental result.     

Growth and Nitrogen Availability of Red Pine Seedlings under High Nitrogen Load and Elevated Ozone

To evaluate the effect of increasing nitrogen (N) deposition and tropospheric ozone (O₃) concentrations on N-saturated forest ecosystems, we investigated the response of Japanese red pine (Pinus densiflora), an N-saturation sensitive tree species, to increasing N load under elevated O₃ concentrations. One-year-old seedlings of red pine were treated with three levels of N supply (0, 50 and 100 mg N L^-1 fresh soil volume) under two levels of atmospheric O₃ concentration (< 5 and 60 ppb) for two growing seasons. Nitrogen treatment did not stimulate dry matter production of the seedlings. Growth inhibition was observed in the highest N treatment under low O₃ and in the two higher N treatments under elevated O₃. Irrespective of the O₃ concentration, increasing N supply negatively affected root growth and mycorrhizal development in fine roots, resulting in a reduction in P and Mg uptake from the soil. Net photosynthetic rate was significantly reduced by both the highest N treatment under low O₃ and the two higher N treatments under elevated O₃, together with decreased N-availability to Rubisco. Nitrogen assimilated from NO₃ ^- to amino acid in the needles was not affected by the treatments. However, needle protein concentration was reduced by the highest N-treatment under low O₃ and by the two higher N-treatments under elevated O₃. These results suggest that elevated O₃ potentially disturbs the N-availability in the form of protein including Rubisco, and may advance the negative effects of excessive N-deposition on N-sensitive plant species in N-saturated forests.     

Can’t See the Forest for the Rice: Factors Influencing Spatial Variations in the Density of Trees in Paddy Fields in Northeast Thailand

The widespread presence of trees in paddy fields is a unique feature of Northeast Thailand’s agricultural landscape. A survey of spatial variability in the density of trees in paddy fields in the Northeast Region was conducted utilizing high resolution satellite images and found that the mean density in the whole region was 12.1 trees/ha (varying from a high of 44.6 trees/ha to a low of 0.8 trees/ha). In general, tree densities are higher in the southeastern part of the region and much lower in the northern central part. Tree density was influenced by multiple factors including: (1) the history of land development, with more recently developed paddy fields having higher densities, (2) topography, with fields located at higher topographical positions having a higher mean density of trees, (3) access to natural forest resources, with fields in areas located close to natural forests having higher densities, (4) amount of annual rainfall, with fields in areas with higher average annual rainfall having higher tree densities, and (5) landholding size, with fields in areas with larger-sized landholdings having more trees. However, there is a considerable extent of co-variation among these factors. Although trees remain an important element of the paddy field landscape in the Northeast, it appears that their density has been declining in recent years. If this trend continues, then the vast “invisible forest” represented by trees in paddy fields may truly disappear, with negative consequences for the villagers’ livelihoods, biodiversity conservation, and carbon sequestration in the rural ecosystem.     

Improved method for the formation of recycled resins from depolymerized products of waste fiber-reinforced plastics: simple and effective purification of recovered monomers by washing with water

The synthesis of recycled plastics from recovered monomeric materials obtained from the depolymerization reaction of fiber-reinforced plastics (FRP) was examined. The depolymerization reaction of FRP in the presence of N,N-dimethylaminopyridine (DMAP) smoothly yielded the corresponding monomers, which mainly consisted of dimethyl phthalates. The polymerization reaction with this monomer failed to form the corresponding unsaturated polyesters due to contamination by N-methyl-4-pyridone, a decomposition product of DMAP. An efficient purification of the recovered monomer was achieved by washing with water, and the purified monomer successfully yielded the corresponding polymers. A hardness test revealed that the polymers were as hard as the polyester made from virgin materials. The present modification provides a practical method for the preparation of recycled plastics from depolymerized plastics.     

Evaluation of mitogen-induced responses in marine mammal and human lymphocytes by in-vitro exposure of butyltins and non-ortho coplanar PCBs

The effects of exposure to butyltin compounds (BTs: tributyltin; TBT, dibutyltin; DBT and monobutyltin; MBT) and non-ortho coplanar PCBs (IUPAC 77, 126 and 169) on marine mammals and human lymphocyte were evaluated. Peripheral blood mononuclear cells (PBMCs) isolated from Dall's porpoises (Phocoenoides dalli), bottlenose dolphins (Tursiops truncatus), a California sealion (Zalophus californianus), a larga seal (Phocoa largha) and humans (Homo sapiens) were exposed at varying concentrations of BTs and coplanar PCBs. Concanavalin A (Con A)-stimulated mitogenesis found significantly suppressed (P<0.01) when the cells were exposed at 300 nM (89 ng/ml) of TBT and 330 nM of DBT (77 ng/ml), while MBT showed little cytotoxicity at treatment levels of up to 3,600 nM (620 ng/ml). BTs concentrations in the liver of Dall's porpoises from Japanese coastal waters ranged between 81-450 ng/g for TBT and 200-1,100 ng/g (wet wt.) for DBTs, which is greater than the cytotoxic levels registered in this study. In contrast, non-ortho coplanar PCBs did not suppress cell proliferation at concentrations of up to 30 nM (10 ng/ml). The residue levels of coplanar PCBs in the blubber of Dall's porpoises were 0.12-1.3 ng/g, which were one order of lower than those levels that do cell proliferation. When cells were exposed to a mixture of TBT/DBTand coplanar PCBs, the proliferation was significantly reduced to 33 nM DBT plus 34 nM CB-77 and 33 nM DBT plus 28 nM CB-169 mixtures, respectively. The investigations relating the contaminant-induced immunosuppression in marine mammals have been focused on persistent organochlorines such as PCBs. pesticides and dioxin compounds. However, this study suggested the possibility of BTs could also pose a serious threat to the immune functions in free-ranging marine mammals and humans.     

Trace elements accumulation and their variations with growth, sex and habitat: effects on Formosan squirrel (Callosciurus erythraeus)

Formosan squirrels are considered a useful bio-indicator because their habitat exists within that of humans. Therefore, concentrations of 19 trace elements were determined in tissues of this species for assessment of environmental pollution in urban Kamakura and rural Izuohshima. Results of analyses revealed high Cu concentrations in the livers of Formosan squirrels. Moreover, concentrations of some trace elements from automobile exhausts-V, Zn, Cu and As-in the specimens from Kamakura were higher than those from Izuohshima. These results reflect the presence of pollution caused by human activities in Kamakura.