The Fukushima Nuclear Power Plant accident and exposures in the environment

The Great East Japan Earthquake has occurred on March 11, 2011, in the Tohoku District of Japan. Due to the earthquake, big tsunamis were induced, and they rushed to the Fukushima Nuclear Power Stations, causing severe accidents. Radioactive materials including I-131, Cs-137 and so on were emitted from the plant to the environment. The Japanese government, Fukushima prefectural government and other local governments have struggled against the accidents. The restricted area and deliberate evacuation area are set by the government, and the residents are evacuated. The dose rates in and around Fukushima Prefecture have been monitored by the governments and other involved organizations. Fukushima government has started the health management survey for all residents in Fukushima Prefecture including the questions on their activities for the estimations of their external doses.     

Degradation characteristics of a dibenzofuran-degrader Terrabacter sp. strain DBF63 toward chlorinated dioxins in soil

Nonylphenols (NPs) are the primary stable metabolites of alkylphenol polyethoxylates (APEs), a family of compounds widely used in industry and in some domestic products. As NPs accumulate in sediments in aquatic environments, the risk to benthic organisms needs to be assessed. In this study 4NP-spiked sediments were tested on larvae of the dipteran Chironomus riparius. First instar larvae obtained from populations at three different sources were used. To spike the sediments, an equilibration procedure between water and sediment was adopted to avoid the use of solvents. Lower 10-d LC50 values were determined for two populations of C. riparius from clean environments (315-465 and 315-350 microg g(-1) d.w., respectively) than those of a strain deriving from a population collected in a polluted river (600-680 microg g(-1) d.w.). Larval growth always decreased with increasing 4NP concentration but without any defined trend. The results of this study suggest that tolerance to the toxicant can be developed in populations of polluted environments and that testing procedures should be standardised.     

Processing and Characterization of Recycled Polypropylene and Acrylonitrile Butadiene Rubber Blends

In this paper investigation on thermoplastic elastomers (TPE) and thermoplastic vulcanizates (TPV) derived from waste polypropylene (WPP) of Municipal Solid Waste (MSW) and acrylonitrile-butadiene rubber (NBR) are reported. The WPP was segregated, cleaned, dried and melt processed with NBR at 180 °C in a Brabender Plasticorder at different blend ratios. TPV was prepared by dynamic vulcanization of the TPE with conventional sulfur accelerator curing system. The mechanical properties measured were found to decrease with increase in NBR proportion in the blend; however the dynamic vulcanization of the nitrile rubber phase enhanced the strength properties of the corresponding TPE. The crystallinity of the WPP reduced with increase in NBR ratio. The dynamic modulus decreased with nitrile rubber content in the TPE. Interestingly, the storage modulus of the TPV at higher rubber content enhanced significantly and damping characteristics increased sharply. The rheology studies reveal that the damping of the blend has been reduced with the addition of high storage modulus rubber at melt processing conditions and hence increased viscosity. The amorphous rubber content with higher storage modulus imparts higher viscosity for the polypropylene (PP) matrix at the processing temperature. The SEM study reveals that the dynamic vulcanization of the rubber phase in the blend caused a smoother and finer surface morphology.     

Feminization of genetic males by a symbiotic bacterium in a butterfly,Eurema hecabe (Lepidoptera: Pieridae)

Wolbachia are symbiotic bacteria found in many arthropods and filarian nematodes. They often manipulate the reproduction of host arthropods. In the present study, female-biased sex-ratio distortion in the butterfly Eurema hecabe was investigated. Breeding experiments showed that this distorted sex ratio is maternally inherited. When treated with tetracycline, adult females of the thelygenic line produced male progeny only. After PCR using Wolbachia-specific primers for the ftsZ gene a positive result was seen in the thelygenic females, but not in male progeny from tetracycline-treated females, or individuals from a Tokyo population with normal sex ratio and reproduction. Cytological observations showed that thelygenic females lack the sex chromatin body (W chromosome). The results strongly suggest that the sex-ratio distortion in E. hecabe is due to feminization of genetic males by Wolbachia.     

Resurrection of the iron and phosphorus resource in steel-making slag

 This research focused on the treatment of steel-making slags to recycle and recover iron and phosphorus. The carbothermal reduction behavior of both synthesized and factory steel-making slag in microwave irradiation was investigated. The slags were mixed with graphite powder and heated to a temperature higher than 1873 K to precipitate a lump of Fe–C alloy with a diameter of 2–8 mm. The larger the carbon equivalent (C_eq, defined in the text), the higher the fractional reduction of iron and phosphorus. An increase in the SiO₂ content of slag led to a considerable improvement in the reduction for both iron and phosphorus because of the improvement in the fluidity of the slags and an increase in the activity coefficient of P₂O₅ in the slags. The extraction behavior of phosphorus from Fe–P–C_satd alloy was also investigated at 1473 K by carbonate flux treatment. For all the experiments with a processing time longer than 10 min, the phosphorus in the fluxes could be concentrated to more than 9% (w/w) showing that it could be used as a phosphorus resource. Compared with K₂CO₃ flux treatment, that using Na₂CO₃ was more effective for the extraction of phosphorus, and this was attributed to the lower evaporation of Na₂CO₃. Finally, a recycling scheme for steel-making slag is proposed. Received: March 16, 2001 / Accepted: November 12, 2001     

Small queens and big-headed workers in a monomorphic ponerine ant

Evolution of caste is a central issue in the biology of social insects. Comparative studies on their morphology so far suggest the following three patterns: (1) a positive correlation between queen–worker size dimorphism and the divergence in reproductive ability between castes, (2) a negative correlation among workers between morphological diversity and reproductive ability, and (3) a positive correlation between queen–worker body shape difference and the diversity in worker morphology. We conducted morphological comparisons between castes in Pachycondyla luteipes, workers of which are monomorphic and lack their reproductive ability. Although the size distribution broadly overlapped, mean head width, head length, and scape length were significantly different between queens and workers. Conversely, in eye length, petiole width, and Weber’s length, the size differences were reversed. The allometries (head length/head width, scape length/head width, and Weber’s length/head width) were also significantly different between queens and workers. Morphological examinations showed that the body shape was different between queens and workers, and the head part of workers was disproportionately larger than that of queens. This pattern of queen–worker dimorphism is novel in ants with monomorphic workers and a clear exception to the last pattern. This study suggests that it is possible that the loss of individual-level selection, the lack of reproductive ability, influences morphological modification in ants.     

Poor efficacy of herbicides in biochar-amended soils as affected by their chemistry and mode of action

We evaluated wheat straw biochar produced at 450 °C for its ability to influence bioavailability and persistence of two commonly used herbicides (atrazine and trifluralin) with different modes of action (photosynthesis versus root tip mitosis inhibitors) in two contrasting soils. The biochar was added to soils at 0%, 0.5% and 1.0% (w/w) and the herbicides were applied to those soil-biochar mixes at nil, half, full, two times, and four times, the recommended dosage (H₄). Annual ryegrass (Lolium rigidum) was grown in biochar amended soils for 1 month. Biochar had a positive impact on ryegrass survival rate and above-ground biomass at most of the application rates, and particularly at H₄. Within any given biochar treatment, increasing herbicide application decreased the survival rate and fresh weight of above-ground biomass. Biomass production across the biochar treatment gradient significantly differed (p < 0.01) and was more pronounced in the case of atrazine than trifluralin. For example, the dose-response analysis showed that in the presence of 1% biochar in soil, the value of GR₅₀ (i.e. the dose required to reduce weed biomass by 50%) for atrazine increased by 3.5 times, whereas it increased only by a factor of 1.6 in the case of trifluralin. The combination of the chemical properties and the mode of action governed the extent of biochar-induced reduction in bioavailability of herbicides. The greater biomass of ryegrass in the soil containing the highest biochar (despite having the highest herbicide residues) demonstrates decreased bioavailability of the chemicals caused by the wheat straw biochar. This work clearly demonstrates decreased efficacy of herbicides in biochar amended soils. The role played by herbicide chemistry and mode of action will have major implications in choosing the appropriate application rates for biochar amended soils.     

Ozonation as an efficient pretreatment method to alleviate reverse osmosis membrane fouling caused by complexes of humic acid and calcium ion

Humic acids (HA) didn’t cause obvious reverse osmosis (RO) membrane fouling in 45 h. Osmotic pressure (NaCl) affected slightly the RO membrane fouling behavior of HA. Ca²⁺ promoted aggregation of HA molecules and thus aggravated RO membrane fouling. Ozonation eliminated the effect of Ca²⁺ on the RO membrane fouling behavior of HA. The change of the structure of HA was related to its membrane fouling behavior. Humic acid has been considered as one of the most significant sources in feed water causing organic fouling of reverse osmosis (RO) membranes, but the relationship between the fouling behavior of humic acid and the change of its molecular structure has not been well developed yet. In this study, the RO membrane fouling behavior of humic acid was studied systematically with ozonation as a pretreatment method to control RO membrane fouling. Furthermore, the effect of ozone on the structure of humic acid was also explored to reveal the mechanisms. Humic acid alone (10–90 mg/L, in deionized water) was found not to cause obvious RO membrane fouling in 45-h operation. However, the presence of Ca²⁺ aggravated significantly the RO membrane fouling caused by humic acid, with significant flux reduction and denser fouling layer on RO membrane, as it was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). However, after the pretreatment by ozone, the influence of Ca²⁺ was almost eliminated. Further analysis revealed that the addition of Ca²⁺ increased the particle size of humic acid solution significantly, while ozonation reduced the SUVA₂₅₄, particle size and molecular weight of the complexes of humic acid and Ca²⁺ (HA-Ca²⁺ complexes). According to these results and literature, the bridge effect of Ca²⁺ aggregating humic acid molecules and the cleavage effect of ozone breaking HA-Ca²⁺ complexes were summarized. The change of the structure of humic acid under the effect of Ca²⁺ and ozone is closely related to the change of its membrane fouling behavior.     

Geology-dependent impacts of forest conversion on stream fish diversity

Forest conversion is one of the greatest global threats to biodiversity, and land-use change and subsequent biodiversity declines sometimes occur over a variety of underlying geologies. However, how forest conversion and underlying geology interact to alter biodiversity is underappreciated, although spatial variability in geology is considered an integral part of sustaining ecosystems. We aimed to examine the effects of forest conversion to farmland, the underlying geology, and their interaction on the stream fishes’ diversity, evenness, and abundance in northeastern Japan. We disentangled complex pathways between abiotic and biotic factors with structural equation modeling. Species diversity of stream fishes was indirectly shaped by the interaction of land use and underlying geology. Diversity declined due to nutrient enrichment associated with farmlands, which was mainly the result of changes in evenness rather than by changes in species richness. This impact was strongest in streams with volcanic geology with coarse substrates probably because of the differential responses of abundant stream fishes to nutrient enrichment (i.e., dominance) and the high dependency of these fishes on large streambed materials during their life cycles. Our findings suggest that remediation of deforested or degraded forest landscapes would be more efficient if the interaction between land use and underlying geology was considered. For example, the negative impacts of farmland on evenness were larger in streams with volcanic geology than in other stream types, suggesting that riparian forest restoration along such streams would efficiently provide restoration benefits to stream fishes. Our results also suggest that land clearing around such streams should be avoided to conserve species evenness of stream fishes.