Distribution of 90Sr in coastal seawater, sediments and organisms off two atomic power stations in Korea

We have measured 90Sr activities in the marine environment (seawater, sediments and organisms) off the two Korean atomic power stations at Gori and Weolseong. The marine sampling sites were chosen in the vicinity of the power stations to investigate the dispersion of any local 90Sr sources. The 90Sr activities in seawater ranged from 1.3 to 1.9 mBq/l (mean: 1.4, n = 16) and 0.9 to 1.5 mBq/l (mean: 1.3, n = 29) at the Gori and Weolseong sites, respectively. These activities are comparable with those reported for the remote open ocean, suggesting that the 90Sr at these sites originated primarily from global fallout, which occurred during the 1960s, rather than from any local sources. The 90Sr activities in marine sediments ranged from 116 to 1,277 mBq/kg (mean: 565, n = 12) and from 304 to 1,799 mBq/kg (mean 933, n = 6) at the Gori and Weolseong sites, respectively. The horizontal distribution of 90Sr in surface sediments appears to be affected by grain size as well as local sedimentation rate. The enrichment of 90Sr in fish (5.5 +/- 2.6 mBq/kg, n = 5) and shellfish (7.1 +/- 1.2 mBq/kg, n = 2) was much lower than that in seaweed (57 +/- 33 mBq/kg, n = 5).     

生物炭与土壤调理剂对滨海荒芜重盐碱地的改良效应

以土壤改良剂对荒芜重盐碱地生物改良和开发利用为研究目标,在华北低平原区滨海荒芜重盐碱地开展了施用生物炭（B）和调理剂（C）种植先锋作物油葵的大田试验.生物炭用量设2个水平（0和1.25 kg ·m^-2）调理剂施用量设3个水平,分别为0、0.83和1.66 kg ·m^-2,共6个处理.油葵收获后按照每30 cm一层采至90 cm搜集土样.结果表明,施用生物炭提高0~30 cm和60~90 cm土层含盐量,而土壤调理剂则显著降低0~30 cm土壤含盐量.没有发现生物炭或调理剂对土壤pH有显著影响.生物炭处理显著抑制土壤硝化作用,导致0~90 cm土层NO₃^--N含量显著下降,NH₄⁺-N含量提高,对有机质（SOM）含量没有显著影响.施用土壤调理剂提高0~30 cm土壤SOM含量,调理剂施用量为1.66 kg ·m^-2时0~90 cm土层的NO₃^--N含量显著增加.单施生物炭与调理剂或者二者组合均显著增加0~90 cm土壤NH₄⁺-N含量、有效磷（Olsen-P）含量和有效钾（K_ex）含量,但生物炭对这3种养分含量的提升效果更显著,土壤调理剂则在增加0~30 cm土壤有机质和降盐方面更有效.施用高量调理剂促进土壤硝化作用,而施用生物炭恰恰起到硝化抑制剂的作用,因此,将生物炭与土壤调理剂结合施用,是滨海荒芜重盐碱地防止NO₃^--N淋失、减少环境污染、增肥降盐并保障耐盐先锋作物高肥低盐生长环境的有效措施.     

Effects on nano zero-valent iron reactivity of interactions between hardness, alkalinity, and natural organic matter in reverse osmosis concentrate

Nanoscale zero-valent iron （NZVI） is considered to have potential to reduce nitrate in the concentrate generated by high pressure membrane processes aimed at water reuse. However, it is necessary to verify the effect of the matrix components in the concentrates on NZVI reactivity. In this study, the influence of hardness, alkalinity, and organic matter on NZVI reactivity was evaluated by the response surface method （RSM）. Hardness （Ca/＋） had a positive effect on NZVI reactivity by accelerating iron corrosion. In contrast, alkalinity （bicarbonate; HCO3） and organic matter （humic acid; HA） had negative effects on NZVI reactivity due to morphological change to carbonate green rust, and to competitive adsorption of HA, respectively. The validity of the statistical prediction model derived from RSM was confirmed by an additional confirmation experiment, and the experimental result was within the 95% confidential interval. Therefore, it can be indicated that the RSM model produced results that were statistically significant.     

Determination of the mechanism of photoinduced toxicity of selected metal oxide nanoparticles (ZnO, CuO, Co3O4 and TiO2) to E. coli bacteria

Cytotoxicity of selected metal oxide nanoparticles(MNPs)(ZnO,CuO,Co 3 O 4 and TiO 2)was investigated in Escherichia coli both under light and dark conditions.Cytotoxicity experiments were conducted with spread plate counting and the LC 50 values were calculated.We determined the mechanism of toxicity via measurements of oxidative stress,reduced glutathione,lipid peroxidation,and metal ions.The overall ranking of the LC 50 values was in the order of ZnO < CuO < Co 3 O 4 < TiO 2 under dark condition and ZnO < CuO < TiO 2 < Co 3 O 4 under light condition.ZnO MNPs were the most toxic among the tested nanoparticles.Our results indicate depletion of reduced glutathione level and elevation of malondialdehyde level correlated with the increase in oxidative stress.Released metal ions were found to have partial effect on the toxicity of MNPs to E.coli.In summary,the dynamic interactions of multiple mechanisms lead to the toxicity of the tested MNPs to E.coli.     

Silica-quaternary ammonium “Fixed-Quat” nanofilm coated fiberglass mesh for water disinfection and harmful algal blooms control

Intensification of pollution loading worldwide has promoted an escalation of different types of disease-causing microorganisms, such as harmful algal blooms(HABs), instigating detrimental impacts on the quality of receiving surface waters. Formation of unwanted disinfection by-products(DBPs) resulting from conventional disinfection technologies reveals the need for the development of new sustainable alternatives. Quaternary Ammonium Compounds(QACs) are cationic surfactants widely known for their effective biocidal properties at the ppm level. In this study, a novel silica-based antimicrobial nanofilm was developed using a composite of silica-modified QAC(Fixed-Quat) and applied to a fiberglass mesh as an active surface via sol–gel technique. The synthesized Fixed-Quat nanocoating was found to be effective against E. coli with an inactivation rate of 1.3 × 10~(-3) log reduction/cm min. The Fixed-Quat coated fiberglass mesh also demonstrated successful control of Microcystis aeruginosa with more than 99% inactivation after 10 hr of exposure.The developed antimicrobial mesh was also evaluated with wild-type microalgal species collected in a water body experiencing HABs, obtaining a 97% removal efficiency. Overall,the silica-functionalized Fixed-Quat nanocoating showed promising antimicrobial properties for water disinfection and HABs control, while decreasing concerns related to DBPs formation and the possible release of toxic nanomaterials into the environment.     

Molecular approaches for the detection and monitoring of microbial communities in bioaerosols: A review

Bioaerosols significantly affect atmospheric processes while they undergo long-range vertical and horizontal transport and influence atmospheric chemistry and physics and climate change. Accumulating evidence suggests that exposure to bioaerosols may cause adverse health effects, including severe disease. Studies of bioaerosols have primarily focused on their chemical composition and largely neglected their biological composition and the negative effects of biological composition on ecosystems and human health. Here, current molecular methods for the identification, quantification, and distribution of bioaerosol agents are reviewed. Modern developments in environmental microbiology technology would be favorable in elucidation of microbial temporal and spatial distribution in the atmosphere at high resolution. In addition, these provide additional supports for growing evidence that microbial diversity or composition in the bioaerosol is an indispensable environmental aspect linking with public health.     

Barnacle suspension-feeding in variable flow

Suspension-feeding behavior of the adult barnacleSemibalanus balanoides (L.), collected at Woods Hole, USA, in 1987 and 1988, was studied in variable conditions of unidirectional and oscillating water flow. Barnacles growing on rocks were placed in a laboratory flume and exposed to precise patterns of water flow created with a specially designed electronic-circuit controlling a motor-driven propeller submersed in the flume. Laser darkfield and brightfield illumination were used to video-record the movement of suspended particles and dye in the flume and barnacle activity. When water was accelerated unidirectionally past feeding barnacles, they consistently changed feeding behavior from actively sweeping their thoracic appendages (cirri) through the water in slow-flow to passively holding cirri into the current in faster flow. The mean water velocity at which this behavioral switch occurred was 3.10 cm s^–1. In slow-flow, each active sweep of the cirri created a feeding vortex that caused suspended particles to swirl into the capture zone of the following sweep. Barnacles in simulated wave-action conditions (oscillatory flow) fed passively, and orientated extended cirri to flow direction. Cirri were rapidly reoriented with the same frequency at which flow direction reversed. Slow-motion analysis of one barnacle feeding in oscillating flow (0.65 Hz) indicated that reversal of the orientation of the cirri began 0.19 s before the water itself started to reverse direction. In additional experiments, barnacles were exposed to a repetitive pattern of accelerating-decelerating flow. During each flow cycle, barnacles switched from active to passive feeding as water accelerated. Repeated exposure of an individual to the same flow-cycle caused a consistent decrease in the water-velocity threshold at which the behavioral switch occurred.     

Isolation,identification, Pb(Ⅱ) biosorption isotherms and kinetics of a lead adsorbing Penicillium sp. MRF-1 from South Korean mine soil

A heavy metal contaminated soil sample collected from a mine in Chonnam Province of South Korea was found to be a source of heavy metal adsorbing biosorbents. Chemical analyses showed high contents of lead (Pb) at 357 mg/kg and cyanide (CN) at 14.6 mg/kg in the soil. The experimental results showed that Penicillium sp. MRF-1 was the best lead resistant fungus among the four individual metal tolerant fungal species isolated from the soil. Molecular characterization of Penicillium sp. MRF-1 was determined using ITS regions sequences. E ects of pH, temperature and contact time on adsorption of Pb(II) by Penicillium sp. MRF-1 were studied. Favorable conditions for maximum biosportion were found at pH 4 with 3 hr contact time. Biosorption of Pb(II) gradually increased with increasing temperature. E cient performance of the biosorbent was described using Langmuir and Freundlich isotherms. Adsorption kinetics was studied using pseudo first-order and pseudo second-order models. Biosorbent Penicillium sp. MRF-1 showed the maximum desorption in alkali conditions. Consistent adsorption/desorption potential of the biosorbent in repetitive cycles validated the e cacy of it in large scale. SEM studies given notes on surface modification of fungal biomass under metal stress and FT-IR results showed the presence of amino groups in the surface structure of the biosorbent. In conclusion, the new biosorbent Penicillium sp. MRF-1 may potentially be used as an inexpensive, easily cultivatable material for the removal of lead from aqueous solution.     

地下水铀污染的原位微生物还原与固定:在美国能源部田纳西橡树岭放射物污染现场的试验

总结了美国斯坦福大学和橡树岭国家实验室等在美国能源部田纳西州橡树岭综合试验基地进行的铀污染原位微生物修复阶段性试验结果.本试验利用微生物以乙醇为电子供体还原地下水和沉积物中的六价铀为不溶解的四价铀,使之原位固定化.随后通过加入溶解氧和硝酸盐来试验微生物还原后的地下水层中还原固定态铀的稳定性.通过预处理和长期间隔注入乙醇...