Daleykang8552

In order to elucidate the radiocesium transport behaviors in natural environment, we systematically investigated sediments from the highly contaminated rivers of Ukedo and Odaka around the Fukushima Daiichi Nuclear Power Plant. We focused on determining the key factors controlling the radiocesium sorption and fixation, such as variations in the particle size, clay mineralogy, and organic matter (OM). The distribution patterns of the 137Cs concentration and particle size fractions were found to be similar for the two rivers, indicating that both clay and silt fractions contributed almost equally to the Cs sorption. The clay mineralogical composition evaluated using X-ray diffraction analysis showed that the relative contents of micaceous minerals were higher in the Ukedo River samples, whereas the relative contents of smectite and kaolinite were higher in the Odaka River samples. This implies that the sediments in both rivers were likely at different weathering stages due to the different geological settings in both catchments. The effects of OM on the sediment properties were also investigated by comparing the cation exchange capacity (CEC) and the radiocesium interception potential (RIP) of the two samples both with and without OM present. The CEC values were controlled by both the clay minerals and OM, and the RIP values increased significantly in the absence of OM. Such trends were correlated to the total organic carbon values, which may be used to understand the direct and indirect roles of OM in the sorption and fixation of Cs. These key differences in river sediment were attributed to the differences in the geological settings and weathering stages. These properties may contribute to the different sorption and fixation behaviors of radiocesium. In the second part paper, we further examined these behaviors and identified key factors by investigating their relationship to the sediment properties of both rivers. The design, preparation process, binding abilities, morphological characteristic and prospective field of application of dummy-template magnetic molecularly imprinted polymer (DMMIP) for preliminary recognition of the selected low-mass polybrominated diphenyl ethers (PBDE-47 and PBDE-99) from aquatic environment were investigated. The surface of iron oxide (Fe3O4) nanopowder (50-100 nm particles size) was modified with tetraethoxysilane and next prepared Fe3O4@SiO2 particles were dispersed in anhydrous toluene functionalized by (3-aminopropyl)triethoxysilane. check details Finally, MIPs' thin film layer on the surface of Fe3O4@SiO2@NH2 was formed in acetonitrile as a solvent solution, using ethylene glycol dimethacrylate as the cross-linker, building monomer, 1,1'-Azobis(cyclohexanecarbonitrile) as the radical initiator, methacrylic acid as a functional monomer and 4,4'-Dihydroxydiphenyl ether as the dummy template molecule as a structural analogue of low-mass PBDEs. To characterize the chemical structure of prepared DMMIPed for targeted recognition of low-mass PBDEs in aquatic solutions. A mechanistic understanding of perfluorooctanoic acid (PFOA) toxicity to plants is essential for future risk assessment of PFOA in agricultural soil. In this study, soil-grown cucumber (Cucumis sativus) was exposed to 0, 0.2, and 5 mg/kg of PFOA for 60 days. At harvest, contaminant accumulation, cucumber biomass, photosynthesis profiles and metabolites were measured. Results showed that PFOA depressed cucumber biomass and accumulated highest in leaves. Photosynthesis analysis revealed that PFOA at both doses reduced the chlorophyll contents and net photosynthesis rate of cucumber leaves. Gas chromatography-mass spectrometry-based non-targeted metabolomics revealed that PFOA induced metabolic reprogramming in cucumber leaves, including up-regulation of phenols (at 0.2 and 5 mg/kg) and down-regulation of amino acids (at 5 mg/kg), indicating disrupted nitrogen and carbon metabolism. Results revealed how PFOA represses plant growth by down-regulating photosynthetic pigments and disturbing the metabolism of carbohydroxides, phenols and amino acids. These findings provide valuable information for understanding the molecular mechanisms involved in plant responses to PFOA-induced stress. Toxic metal(loid) pollution in sulphide mineralized area has been increasingly concerned. In the present study, the pollution characteristics and the health risk of Hg, As, Tl and other metal(loid)s in soils under different land use, from a rural area impacted by Tl-Hg-rich sulphide mineralization, were assessed using statistical analysis, enrichment factor (EF), potential ecological risk index (RI) and health risk assessment model. The results showed that Tl, Hg and As were highly enriched in the mine area due to the historic sporadic mining activities, and Tl, Hg and Sb were enriched in the peripheral area. Hg and Tl pollution in soils of the mine area impacted by past mining activities posed high ecological risk. High contents and enrichment of Tl and Hg in forest/grass land had a greater impact on the ecological risk in the mine area; whereas Tl and Hg in the grain land and vegetable land dominated the soil ecological risk in the peripheral area. Human health risk assessment indicated that children are more sensitive and vulnerable to toxic metal(loid)s in soils than the adults. Hg, Tl and As have potential non-carcinogenic risk to local children and adults. The HQ levels for different exposure pathways of toxic metal(loid)s were in the order of ingestion > dermal contact > air inhalation for Tl and As, and dermal contract > ingestion > air inhalation for Hg. For carcinogenic risk, all the mean CR values of ingestion in the mine area were higher than 10-4, indicating seriously potential risk. The descending order of ILCR via different pathways was the same as the HQ, for which ingestion was predominant, followed by dermal and air inhalation. The findings may help provide basic knowledge and guidelines for toxic metal(loid) pollution remediation in similar sulphide mineralized areas. In this work, we investigated the impact of iron nanoparticle, including magnetite nanoparticles (Fe3O4 NPs) and nanoscale zero-valent iron (nZVI), on the anaerobic digestion (AD) performance. Moreover, the evolutions of antibiotic resistance genes (ARGs), class 1 integrons-integrase (intI1) and potential hosts of ARGs were also investigated. The optimal addition of Fe3O4 NPs and nZVI to promote methane production was 0.5 g/L and 1 g/L, which led to 22.07% and 23.02% increase in methane yield, respectively. The degradation rate of organic matter was also enhanced with the addition of Fe3O4 NPs or nZVI. The results of high-throughput sequencing showed that the reactors with iron NPs exhibited significant differences in microbial community structure, compared to the reactors with the non‑iron NPs. Iron NPs have caused the relative abundance of the dominant bacteria (Proteobacteria, Firmicutes and Actinobacteria) generally decreased, while the dominant archaea (Euryarchaeota) increased in AD sludge. Quantitative PCR results revealed that iron NPs accelerated the reductions in total absolute abundance of ARGs, especially a beta-lactamase resistance encoded gene (blaOXA). Network analysis displayed that the attenuation of ARGs was mainly attributed to the decline of potential hosts (Proteobacteria, Firmicutes and Actinobacteria). Meanwhile, environmental factors (such as pH, soluble chemical oxygen demand and heavy metals) were also strongly correlated with ARGs. V.The transformation and transport of Sb are significantly influenced by strong oxides (e.g. MnO2) in the natural environment. Furthermore, Fe(II) can coexist with Sb(III) and MnO2 in waters contaminated by acidic mine drainage. However, role of Fe(II) in Sb(III) oxidation and adsorption by MnO2 remains unclear. Therefore, in the present study, the effects of Fe(II) on the oxidation and adsorption of Sb(III) by MnO2 under acidic conditions (pH 3) and the mechanism thereof were comprehensively investigated. The results of kinetic experiments showed that, in the presence of soluble Fe(II), Sb(III) oxidation is inhibited, but adsorption is promoted. Further characterization confirmed that Fe(III) compounds are formed around MnO2 particles and that these inhibit Sb(III) oxidation. However, two different Fe(III) compounds are formed around MnO2 particles depending on how the Fe(II) is introduced into the experimental system. In the simultaneous oxidation system, poorly crystallized or amorphous FeSb precipitates are formed (probably FeSbO4) around MnO2 particles, while in the Fe(II) pretreated oxidation system, schwertmannite is formed. Thus, the present study revealed that Fe(II) is critical to Sb(III) oxidation and adsorption by MnO2 and that the mechanism of its action is depend upon how it is introduced into the reaction system. This information is of relevance to predicting the fate of Sb. Temperature is an important abiotic variable that greatly influences the performance of aquatic ectotherms, especially under current anthropogenic global warming and thermal discharges. The aim of the present study was to evaluate thermal stress (20 °C vs 28 °C) in Daphnia magna over 21 d, focusing on the linkage among molecular and biochemical biomarker responses. Thermal stress significantly increased the levels of reactive oxygen species (ROS) and lipid peroxidation, especially in the 3-d short-term exposure treatment. This change in the ROS level was also correlated with mitochondrial membrane damage. These findings suggest that oxidative stress is the major pathway for thermally-induced toxicity of D. magna. Additionally, the expression levels of genes related to hypoxia (Hb), development (Vtg1), and sex determination (Dsx1-α, Dsx1-β, and Dsx2) were greatly increased by elevated temperature in a time-dependent manner. The cellular energy allocation was markedly decreased at the elevated temperature in the 3-d exposure treatment, mainly due to carbohydrates consumption for survival (oxidative stress defense). The present study showed that linking multiples biomarker responses are crucial for understanding the underlying mechanism of thermal stress on D. magna. Erhai Lake in the Yunnan-Guizhou Plateau, a typical subtropical deep lake, experienced long-time input of nutrients and pollutants, which provides beneficial conditions for evolution and spread of resistance genes. In this study, the profile of bacterial community, antibiotic and metal resistance genes in sediments of Erhai Lake were analyzed via high-thought sequencing of 16S rRNA and metagenomic DNA. Proteobacteria, Firmicutes, Nitrospirae, and Bacteroidetes were found to be the main composition of the bacterial community. Multidrug-, bacitracin-, macrolide-lincosamide-streptogramin (MLS)- and tetracycline resistance genes were the primary antibiotic resistance gene (ARG) types with high relative abundance, whereas Multi-metal-, and arsenic- resistance genes were the primary metal resistance gene (MRG) types. The effects of nitrogen and phosphorus on the abundance of ARGs and MRGs depended on the different types. Some specific ARG (fosmidomycin resistance genes) and MRG types (multi-metal resistance genes) also showed significant geographic distribution.