Influence of microorganisms on the behavior of technetium and other elements in paddy soil surface water

Insolubilization patterns of technetium (Tc) and other trace elements (Sc, Co, Zn, Se, Rb, Sr, Y, Nb, Ce, Pm, Gd, Lu, Hf, and Re) in surface water covering paddy fields were compared to gain insight into the behavior of Tc in an agricultural environment. The insolubilization of Tc, which did not pass through a 0.2-microm-pore-size filter, was mainly caused by bacteria. Among the 14 other elements investigated, Nb was insolubilized by bacteria and the amounts of insoluble Nb were positively correlated with those of Tc. Although Re is a chemical analog of Tc, no similarity was observed. These results suggest that Tc behaves similarly to Nb in the insolubilization in surface water covering paddy fields.     

Thermal remediation of PCDD/Fs contaminated soil by zone combustion process

A new thermal process has been proposed for remediating soils contaminated by chlorinated organic compounds, e.g., PCDD/Fs and PCBs. This is to apply the "zone combustion process" which utilizes stable combustion of coke particles in the packed bed to soils with air flow across the bed. The usefulness and validity were obtained the results showing that more than 98.9% of PCDD/Fs in the soil was successfully removed in a laboratory-scale experiment. Some pretreatment of the soil sample, such as drying, pre-granulation and addition of limestone was found to make the removal efficiency better. Although, some fundamentals on the behavior of PCDD/Fs, e.g., decomposition/vaporization ratios and formation of other compounds cannot be certainly identified yet, the present results clearly show a way to remediate the contaminated soils and solid wastes.     

Development of a dynamic transfer model of (14)C from the atmosphere to rice plants

A dynamic compartment model was investigated to describe ¹⁴C accumulation in rice plants exposed to atmospheric ¹⁴C with temporally changing concentrations. In the model, rice plants were regarded to consist of three compartments: the ear and the mobile and immobile carbon pools of the shoot. Photosynthetically fixed carbon moves into the ear and the mobile carbon pool, and these two compartments release a part of this carbon into the atmosphere by respiration. Carbon accumulated in the mobile carbon pool is redistributed to the ear, while carbon transferred into the immobile carbon pool from the mobile one is accumulated there until harvest. The model was examined by cultivation experiments using the stable isotope, ¹³C, in which the ratios of carbon photosynthetically fixed at nine times during plant growth to the total carbon at the time of harvest were determined. The model estimates of the ratios were in relatively good agreement with the experimental observations, which implies that the newly developed compartment model is applicable to estimate properly the radiation dose to the neighboring population due to an accidental release of ¹⁴C from nuclear facilities.     

Measurement of natural radioactive nuclide concentrations in various metal ores used as industrial raw materials in Japan and estimation of dose received by workers handling them

Natural resources such as ores and rocks contain natural radioactive nuclides at various concentrations. If these resources contain high concentrations of natural radioactive nuclides, workers handling them might be exposed to significant levels of radiation. Therefore, it is important to investigate the radioactive activity in these resources. In this study, concentrations of radioactive nuclides in Th, Zr, Ti, Mo, Mn, Al, W, Zn, V, and Cr ores used as industrial raw materials in Japan were investigated. The concentrations of ²³⁸U and ²³²Th were determined by inductively coupled plasma mass spectrometry (ICP-MS), while those of ²²⁶Ra, ²²⁸Ra, and ⁴⁰K were determined by gamma-ray spectrum. We found the concentrations of ²³⁸U series, ²³²Th series, and ⁴⁰K in Ti, Mo, Mn, Al, W, Zn, V, and Cr ores to be lower than the critical values defined by regulatory requirements as described in the International Atomic Energy Agency (IAEA) Safety Guide. The doses received by workers handling these materials were estimated by using methods for dose assessment given in a report by the European Commission. In transport, indoor storage, and outdoor storage scenarios, an effective dose due to the use of Th ore was above 4.3 × 10⁻² Sv y⁻¹, which was higher than that of the other ores. The maximum value of effective doses for other ores was estimated to be about 4.5 × 10⁻⁴ Sv y⁻¹, which was lower than intervention exemption levels (1.0 × 10⁻³ Sv y⁻¹) given in International Commission of Radiological Protection (ICRP) Publication 82.     

Assays of dioxins and dioxin-like compounds in actually contaminated soils using transgenic tobacco plants carrying a recombinant mouse aryl hydrocarbon receptor-mediated β-glucuronidase reporter gene expression system

The transgenic tobacco plant XD4V-26 carrying the recombinant mouse aryl hydrocarbon receptor XD4V-mediated β-glucuronidase (GUS) reporter gene expression system was used for assay of dioxins and dioxin-like compounds consisting of polychlorodibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls (Co-PCBs) in actually contaminated soils. The transgenic tobacco plant XD4V-26 showed a significant dose-dependent induced GUS activity when cultured on MS medium containing PCB126 [toxic equivalency factor (TEF) = 0.1]. In contrast, PCB169 and PCB180, which have 0.03 of TEF and unassigned TEF values, respectively, did not significantly induce GUS activity under the same conditions as with PCB126. When the tobacco plants were cultivated for up to 5 weeks on actually contaminated soils with dioxins and dioxin-like compounds collected from the periphery of an incinerator used for disposal of life and industrial wastes, GUS activity in the leaves was dose-dependently increased. The plants clearly detected 360 pg-TEQ g(-1) of dioxins and dioxin-like compounds in this assay. There was a positive correlation between GUS activity and TEQ value of dioxins and dioxin-like compounds in the plants. This assay does not require any extraction and purification processes for the actually contaminated soil samples.     

Utilizing the Cyberforest live sound system with social media to remotely conduct woodland bird censuses in Central Japan

We have developed a system that streams and archives live sound from remote areas across Japan via an unmanned automatic camera. The system was used to carry out pilot bird censuses in woodland; this allowed us to examine the use of live sound transmission and the role of social media as a mediator in remote scientific monitoring. The system has been streaming sounds 8 h per day for more than five years. We demonstrated that: (1) the transmission of live sound from a remote woodland could be used effectively to monitor birds in a remote location; (2) the simultaneous involvement of several participants via Internet Relay Chat to listen to live sound transmissions could enhance the accuracy of census data collection; and (3) interactions through Twitter allowed members of the public to engage or help with the remote monitoring of birds and experience inaccessible nature through the use of novel technologies.     

Traditional Farming Landscapes for Sustainable Living in Scandinavia and Japan: Global Revival Through the Satoyama Initiative

Traditional, pre-industrial farming was adapted to the natural environment—topography, geology, hydrology, climate, and biota. Traditional land use systems are still to be traced in Scandinavia as an “infield/outland landscape”, and in Japan as a “Satoyama landscape.” There are obvious similarities and differences in land use—the main difference being that pasturing of cattle and sheep has been less important in Japan. These land use systems can be traced back to early sedentary settlements 1500–2500 years ago. In both regions, traditional management almost ceased in the mid-twentieth century leading to afforestation and decreased biological diversity. Today, there is in Japan a growing movement for landscape restoration and promotion of a sustainable living countryside based on local agrarian and forestry production, local energy, tourism, etc. With this background, the so-called Satoyama Initiative has been organized and introduced as a global socio-ecological project with ecosystem services for human well-being.     

Assays of dioxins and dioxin-like compounds in actually contaminated soils using transgenic tobacco plants carrying a recombinant mouse aryl hydrocarbon receptor-mediated β-glucuronidase reporter gene expression system

The transgenic tobacco plant XD4V-26 carrying the recombinant mouse aryl hydrocarbon receptor XD4V-mediated β-glucuronidase (GUS) reporter gene expression system was used for assay of dioxins and dioxin-like compounds consisting of polychlorinated dibenzeno-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls (Co-PCBs) in actually contaminated soils. The transgenic tobacco plant XD4V-26 showed a significant dose-dependent induced GUS activity when cultured on MS medium containing PCB126 [toxic equivalency factor (TEF) = 0.1]. In contrast, PCB169 and PCB180, which have 0.03 of TEF and unassigned TEF values, respectively, did not significantly induce GUS activity under the same conditions as with PCB126. When the tobacco plants were cultivated for up to 5 weeks on actually contaminated soils with dioxins and dioxin-like compounds collected from the periphery of an incinerator used for disposal of residential and industrial wastes, GUS activity in the leaves was dose-dependently increased. The plants clearly detected 360 pg-TEQ g^?1 of dioxins and dioxin-like compounds in this assay. There was a positive correlation between GUS activity and TEQ value of dioxins and dioxin-like compounds in the plants. This assay does not require any extraction and purification processes for the actually contaminated soil samples.     

Uptake and distribution of iodine in rice plants

Rice (Oryza sativa L.) plants were cultivated in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, straw, and root. The contents of iodine in these components and the soil were determined by inductively coupled plasma-mass spectrometry and radiochemical neutron activation analysis, respectively. Iodine content varied by more than three orders of magnitude among the plant components. Mean concentration of iodine in the entire plants was 20 mg kg(-1) dry weight, and the concentration of iodine in the surface soil (0-20 cm depth) was 48 mg kg(-1). The highest concentration of iodine (53 mg kg(-1) dry weight) was measured in root and the lowest concentration (0.034 mg kg(-1) dry weight) in polished rice. While the edible component (polished rice) accounted for 32% of the total dry weight, it contained only 0.055% of iodine found in the entire rice plants. Atmospheric gaseous iodine (5.9 ng m(-3)) was estimated to contribute <0.2% of the total iodine content in the biomass of rice plants; therefore nearly all of the iodine in the rice plants was a result of the uptake of iodine from the soil. The content of iodine in the aboveground part of rice plants was 16 mg kg(-1) dry weight and the percentage of iodine transferred per cropping from the soil into the aboveground biomass corresponded to 0.27% (20 mg m(-2)) of the upper soil layer content.     

The effects of pH on fluoxetine in Japanese medaka (Oryzias latipes): acute toxicity in fish larvae and bioaccumulation in juvenile fish

Recent detection of fluoxetine in the aquatic environment and fish suggests a possibly high accumulation of fluoxetine; however, no report is available on the bioaccumulation of fluoxetine in aquatic organisms. Since bioaccumulation of fluoxetine was probably dependent on pH near the pK(a) value of 10.1, experiments were conducted approximately at pH 7, 8, and 9. Distribution coefficients between 1-octanol and water (D(ow)), and those between synthetic membrane vesicles (liposomes) and water (D(lip-wat)) were determined at pH 7, 8, and 9. The D(ow) and D(lip-wat) values increased significantly with increasing pH. Acute toxicity tests were performed using Japanese medaka (Oryzias latipes) prior to the bioaccumulation test, and 96-h LC(50) values were 5.5, 1.3, and 0.20mgl(-1) at pH 7, 8, and 9, respectively. In the bioaccumulation test, concentrations of fluoxetine and its major metabolite, norfluoxetine, in the fish body and liver were measured. The bioconcentration factors (BCF) of fluoxetine for Japanese medaka were 8.8, 3.0x10, and 2.6x10(2) in the body and 3.3x10(2), 5.8x10(2), and 3.1x10(3) in the liver at pH 7, 8, and 9, respectively. The BCF values were lower at pH 7 and higher at pH 9 mainly because of the increase in nonionized species with significantly higher hydrophobicity than the ionized species at pH values closer to pK(a). A similar trend was obtained for the concentration of norfluoxetine in the fish but the pseudo-BCF values (the ratio of the norfluoxetine concentration in the fish and the fluoxetine concentration in test water) were higher than the BCF value of fluoxetine at all pH conditions.