خيارات البحث
النتائج 841 - 850 من 4,895
Insights into potential consequences of fusion hypothetical accident, lessons learnt from the former fission accidents
2019
Nie, Baojie | Ni, Muyi | Liu, Jinchao | Zhu, Zhilin | Zhu, Zuolong | Li, Fengchen
From previous catastrophic fission nuclear accidents, such as the Chernobyl and Fukushima accidents, researchers learnt the lessons that external hazard beyond design basis or human errors could result in severe accidents and multi-failure of the confinements although they were considered as very-low-probability events and not requested to be paid much attention to according to the current nuclear safety regulations. Fusion energy is always regarded as a safe and clean energy. However, massive quantity of radioactivity still exists in the fusion reactor and is possible to be released into the environment. The environmental pollution and potential public consequences due to severe accidents of fusion reactor remain largely unexplored. In this contribution, we intended to investigate the hypothetical accident to envelop the worst but probable consequences of fusion reactor, and compare with historic Chernobyl and Fukushima accidents under assumed environmental conditions. It was demonstrated that, the radiation consequences of a hypothetical fusion accident would be much less severe than fission accidents, e.g. an INES 7 accident could not appear in a fusion reactor, as in the Chernobyl and Fukushima nuclear accidents. However, it would still be disastrous and the publics close to site might be exposed to “potentially lethal” radiation dose.
اظهر المزيد [+] اقل [-]Vertical distribution of 129I and radiocesium in forest soil collected near the Fukushima Daiichi Nuclear Power Plant boundary
2019
Yang, Guosheng | Hu, Jun | Tsukada, Hirofumi | Tazoe, Hirofumi | Shao, Yang | Yamada, Masatoshi
Three soil core samples were collected from a forest located about 1.1 km south of the Fukushima Daiichi Nuclear Power Plant (FDNPP) boundary in 2017, and the vertical profiles of 129I from the FDNPP accident were determined by the combination of TMAH (tetramethyl ammonium hydroxide) extraction and ICP-MS/MS analysis. The humus layer above the soil layer was heavily contaminated with 134Cs (1983–5985 Bq g−1) and 137Cs (1947–5902 Bq g−1) (decay-corrected to March 11, 2011). The 129I activity concentrations decreased sharply with the soil depth, from 1894 to 34.1, from 9384 to 78.9, and from 2536 to 51.3 mBq kg−1, for the three sites. Downward migration of 129I was slightly faster than the one of 134Cs. In addition, the cumulative 129I inventories were observed to be 43.4 ± 1.0, 71.7 ± 1.8, and 56.5 ± 1.8 Bq m−2, respectively. Subsequently, the cumulative 131I inventories were estimated to be 1.76 ± 0.06, 2.90 ± 0.11, and 2.28 ± 0.10 GBq m−2 (decay-corrected to March 11, 2011), respectively. Finally, the total atmospheric deposition of 129I on the land of Japan due to the FDNPP accident was estimated to be around 1.09–1.71 kg (7.11–11.2 GBq).
اظهر المزيد [+] اقل [-]A review on removing antibiotics and antibiotic resistance genes from wastewater by constructed wetlands: Performance and microbial response
2019
Liu, Xiaohui | Guo, Xiaochun | Liu, Ying | Lu, Shaoyong | Xi, Beidou | Zhang, Jian | Wang, Zhi | Bi, Bin
Pollution caused by antibiotics has been highlighted in recent decades as a worldwide environmental and health concern. Compared to traditional physical, chemical and biological treatments, constructed wetlands (CWs) have been suggested to be a cost-efficient and ecological technology for the remediation of various kinds of contaminated waters. In this review, 39 antibiotics removal-related studies conducted on 106 treatment systems from China, Spain, Canada, Portugal, etc. were summarized. Overall, the removal efficiency of CWs for antibiotics showed good performance (average value = over 50%), especially vertical flow constructed wetlands (VFCWs) (average value = 80.44%). The removal efficiencies of sulfonamide and macrolide antibiotics were lower than those of tetracycline and quinolone antibiotics. In addition, the relationship between the removal efficiency of antibiotics and chemical oxygen demand (COD), total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and ammonia nitrogen (NH₃-N) concentrations showed an inverted U-shaped curve with turning points of 300 mg L⁻¹, 57.4 mg L⁻¹, 40 mg L⁻¹, 3.2 mg L⁻¹ and 48 mg L⁻¹, respectively. The coexistence of antibiotics with nitrogen and phosphorus slightly reduced the removal efficiency of nitrogen and phosphorus in CWs. The removal effect of horizontal subsurface flow constructed wetlands for antibiotic resistance genes (ARGs) had better performance (over 50%) than that of vertical wetlands, especially for sulfonamide resistance genes. Microorganisms are highly sensitive to antibiotics. In fact, microorganisms are one of the main responsible for antibiotic removal. Moreover, due to the selective pressure induced by antibiotics and drug-resistant gene transfer from resistant bacteria to other sensitive strains through their own genetic transfer elements, decreased microbial diversity and increased resistance in sewage have been consistently reported. This review promotes further research on the removal mechanism of antibiotics and ARGs in CWs.
اظهر المزيد [+] اقل [-]Metal pollution in surface sediments from Rodrigo de Freitas Lagoon (Rio de Janeiro, Brazil): Toxic effects on marine organisms
2019
Vezzone, Mariana | Cesar, Ricardo | Moledo de Souza Abessa, Denis | Serrano, Aline | Lourenço, Rodrigo | Castilhos, Zuleica | Rodrigues, Ana Paula | Perina, Fernando Cesar | Polivanov, Helena
The Rodrigo de Freitas Lagoon (RFL - Rio de Janeiro, RJ, Brazil) is a highly polluted and eutrophic lacustrine system, which has been often used for the practice of aquatic sports, including during the 2016 Summer Olympic Games. This study proposes the evaluation of metal concentrations in surface sediments from the RFL before and after urban interventions performed for the 2016 Olympics, as well as their toxicity to the benthic amphipod Tiburonella viscana and embryos of the sea-urchin Echinometra lucunter. Metal concentrations determined in 2017 were significantly higher than those obtained in 2015 (especially Cu, Cd and Ni), suggesting that the interventions performed to fulfill the requirements of the Olympics increased metal contents in sediments. The sediments from the northern sector of the RFL were muddier, more organically enriched, exhibited higher metal concentrations and were more toxic to T. viscana when compared to the sediments collected in the southern sector. This fact is particularly important since the practice of sports, including during the 2016 Olympics, has been preferably performed in the northern sector. Metal distribution was strongly correlated with organic matter and mud contents. The toxicity to E. lucunter embryos was high for both northern and southern sediments; most of the samples led to 100% lack or abnormal embryonic development. The integration of physical, chemical and ecotoxicological data indicates that the mortality to T. viscana was correlated with metal contents, whereas the toxicity to E. lucunter was apparently related to the release of ammonia from the sediment to water column. Finally, high metal concentrations and the toxicity to aquatic organisms evidence the ecological risks to the biota from RFL.
اظهر المزيد [+] اقل [-]Exposure to ultrafine particulate matter induces NF-κβ mediated epigenetic modifications
2019
Bhargava, Arpit | Shukla, Anushi | Bunkar, Neha | Shandilya, Ruchita | Lodhi, Lalit | Kumari, Roshani | Gupta, Pushpendra Kumar | Rahman, Akhlaqur | Chaudhury, Koel | Tiwari, Rajnarayan | Goryacheva, Irina Yu. | Mishra, Pradyumna Kumar
Exposure to ultrafine particulate matter (PM0.1) is positively associated with the etiology of different acute and chronic disorders; however, the in-depth biological imprints that link these submicron particles with the disturbances in the epigenomic machinery are not well defined. Earlier, we showed that exposure to these particles causes significant disturbances in the mitochondrial machinery and triggers PI-3-kinase mediated DNA damage responses. In the present study, we aimed to further understand the epigenomic insights of the ultrafine PM exposure. The higher levels of intracellular reactive oxygen species and depleted Nrf-2 in ultrafine PM exposed cells reconfirmed its potential to induce oxidative stress. Importantly, the observed increase in the levels of NF-κβ and associated cytokines among exposed cells suggested the activation of NF-κβ mediated inflammatory loop which potentially serves as a platform for initiating epigenetic insinuations. This fact was strongly supported by the altered miRNA expression profile of the ultrafine PM exposed cells. These NF-κβ induced miRNA alterations were also found to be associated with other epigenetic targets as the exposed cells showed higher expression levels of DNA methyltransferases which positively corresponded with the global changes in DNA methylation levels. Upon further analysis, significant alterations in histone code were also reported in ultrafine PM exposed cells. Conclusively our results suggested that NF-κβ acts as an inflammatory switch that possesses the potential to induce genome-wide epigenetic modification upon ultrafine PM exposure.
اظهر المزيد [+] اقل [-]Artificial illumination near rivers may alter bat-insect trophic interactions
2019
Russo, Danilo | Cosentino, Francesca | Festa, Francesca | De Benedetta, Flavia | Pejic, Branka | Cerretti, Pierfilippo | Ancillotto, Leonardo
Artificial illumination at night represents an increasingly concerning threat to ecosystems worldwide, altering persistence, behaviour, physiology and fitness of many organisms and their mutual interactions, in the long-term affecting ecosystem functioning. Bats are very sensitive to artificial light at night because they are obligate nocturnal and feed on insects which are often also responsive to lights. Here we tested the effects of LED lighting on prey-predator interactions at riverine ecosystems, using bats and their insect prey as models, and compared bat and insect reactions in terms of bat activity and prey insect abundance and diversity, respectively, on artificially lit vs. unlit nights. Artificial light influenced both insect and bat assemblages in taxon-specific directions: insect abundances increased at lit sites, particularly due to an increase in small dipterans near the light source. Composition of insect assemblages also differed significantly between lit and unlit sites. Total bat activity declined at lit sites, but this change was mainly due to the response of the most abundant species, Myotis daubentonii, while opportunistic species showed no reaction or even an opposite pattern (Pipistrellus kuhlii). We show that artificial lighting along rivers may affect trophic interactions between bats and insects, resulting in a profound alteration of community structure and dynamics.
اظهر المزيد [+] اقل [-]Long-term aquaria study suggests species-specific responses of two cold-water corals to macro-and microplastics exposure
2019
Mouchi, Vincent | Chapron, Leila | Peru, Erwan | Pruski, Audrey M. | Meistertzheim, Anne-Leila | Vétion, Gilles | Galand, Pierre E. | Lartaud, Franck
Plastic pollution has been identified as a major threat for coastal marine life and ecosystems. Here, we test if the feeding behaviour and growth rate of the two most common cold-water coral species, Lophelia pertusa and Madrepora oculata, are affected by micro- or macroplastic exposures. Low-density polyethylene microplastics impair prey capture and growth rates of L. pertusa after five months of exposure. Macroplastic films, mimicking plastic bags trapped on deep-sea reefs, had however a limited impact on L. pertusa growth. This was due to an avoidance behaviour illustrated by the formation of skeletal ‘caps’ that changed the polyp orientation and allowed its access to food supply. On the contrary, M. oculata growth and feeding were not affected by plastic exposure. Such a species-specific response has the potential to induce a severe change in coral community composition and the associated biodiversity in deep-sea environments.
اظهر المزيد [+] اقل [-]Comparison of long-term stability under natural ageing between cement solidified and chelator-stabilised MSWI fly ash
2019
Du, Bing | Li, Jiantao | Fang, Wen | Liu, Jianguo
Cement-solidification and chelator-stabilisation of municipal solid waste incineration fly ash (MSWI-FA) are two main treatment techniques to immobilise heavy metals. Differences in the long-term stabilities of those two methods of heavy-metal immobilisation were explored to aid in determining the better MSWI-FA treatment. However, few comparative studies have been conducted on 6-year-old cement-solidified FA (Ce-6-FA) and chelator-stabilised FA (Ch-6-FA). In this study, we compared the physicochemical and heavy metal leaching characteristics of Ce-6-FA and Ch-6-FA. The chemical speciation of heavy metals was modelled using geochemical software to assess long-term stability. The results showed weaker long-term stability in Pb immobilisation under the chelating system. The leaching concentrations of target heavy metals, acetic acid leaching tests, acid neutralising capacity, and pH-dependent leaching results indicated that Ce-6-FA had higher long-term stability than Ch-6-FA. A column experiment indicated that the cumulative release rates of Pb in Ce-6-FA and Ch-6-FA were 2.49% and 4.72%, respectively. The phase-controlled leaching of Pb in Ce-6-FA mainly occurred through Pb2(OH)3Cl and chloropyromorphite (Pb5(PO4)3Cl), whereas that in Ch-6-FA mainly occurred through Pb5(PO4)3Cl. The decomposition of heavy metal chelates in Ch-6-FA and salt generation in this process led to the release of Pb via the inorganic complex.
اظهر المزيد [+] اقل [-]Short-term exposure to ambient ozone and inflammatory biomarkers in cross-sectional studies of children and adolescents: Results of the GINIplus and LISA birth cohorts
2019
Zhao, Tianyu | Markevych, Iana | Standl, Marie | Schikowski, Tamara | Berdel, Dietrich | Koletzko, Sibylle | Jörres, Rudolf A. | Nowak, Dennis | Heinrich, Joachim
While exposure to ambient particulate matter (PM) and nitrogen dioxide (NO₂) is thought to be associated with diseases via inflammatory response, the association between exposure to ozone, an oxidative pollutant, and inflammation has been less investigated.We analyzed associations between short-term exposure to ozone and three inflammatory biomarkers among children and adolescents.These cross-sectional analyses were based on two follow-ups of the GINIplus and LISA German birth cohorts. We included 1330 10-year-old and 1591 15-year-old participants. Fractional exhaled nitric oxide (FeNO) and high-sensitivity C-reactive protein (hs-CRP) were available for both age groups while interleukin (IL)-6 was measured at 10 years only. Maximum 8-h averages of ozone and daily average concentrations of NO₂ and PM with an aerodynamic diameter <10 μm (PM₁₀) were adopted from two background monitoring stations 0 (same day), 1, 2, 3, 5, 7, 10 and 14 days prior to the FeNO measurement or blood sampling. To assess associations, we utilized linear regression models for FeNO, and logistic regressions for IL-6 and hs-CRP, adjusting for potential covariates and co-pollutants NO₂ and PM₁₀.We found that short-term ozone exposure was robustly associated with higher FeNO in adolescents at age 15, but not at age 10. No consistent associations were observed between ozone and IL-6 in children aged 10 years. The relationship between hs-CRP levels and ozone was J-shaped. Relatively low ozone concentrations (e.g., <120 μg/m³) were associated with reduced hs-CRP levels, while high concentrations (e.g., ≥120 μg/m³) tended to be associated with elevated levels for both 10- and 15-year-old participants.Our study demonstrates significant associations between short-term ozone exposure and FeNO at 15 years of age and a J-shaped relationship between ozone and hs-CRP. The finding indicates that high ozone exposure may favor inflammatory responses in adolescents, especially regarding airway inflammation.
اظهر المزيد [+] اقل [-]Electrokinetic remediation of contaminants of emergent concern in clay soil: Effect of operating parameters
2019
Guedes, Paula | Lopes, Vanda | Couto, Nazaré | Mateus, Eduardo P. | Pereira, Cristina Silva | Ribeiro, Alexandra B.
The potential of electrokinetic (EK) remediation to remove from soils one particular group of contaminants - contaminants of emergent concern (CECs), remains largely overlooked. The present study aimed to evaluate the efficiency of the EK process for the remediation of an agricultural clay soil containing CECs. The soil was spiked with four CECs - sulfamethoxazole, ibuprofen, triclosan and caffeine - and their status (i.e. residual amounts and spatial distribution) evaluated at the seventh day of EK treatment at a defined current intensity, directionality and duration of void period. The characterization of the soil physicochemical properties was also undertaken. The results showed similar degradation trends in all applied EK strategies, which were suchlike to that of the natural attenuation (biotic control): sulfamethoxazole > ibuprofen ≥ triclosan ≥ caffeine. The removal of the CECs was higher under a 10 mA constant current application than in the natural attenuation (up to 2.8 times higher; from 13 to 85%). Caffeine was the exception with its best removal efficiency being achieved when the ON/OFF switch mode with a void period duration of 12 h was used (36%). The use of electro-polarization reversal mode did not favour the remediation. The soil pH variations resulting from EK application were determinant for triclosan remediation, which increased with soil pH increase. The only EK condition that promoted the removal of all CECs was the ON/OFF switch mode of 12 h (removals between 36 and 72%), in which only minor physicochemical disturbances of the soil were observed. This is in accordance with a potential application of EK in-situ. The last is reinforced by the low estimated electrical cost of the best EK technology - 2.33 €/m³ for the 7 days. Overall the EK remediation processes are a promising technology to stimulate in situ the removal of CECs from agricultural soils.
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