Уточнить поиск
Результаты 2921-2930 из 4,043
Degradation of sunscreen agent p-aminobenzoic acid using a combination system of UV irradiation, persulphate and iron(II) Полный текст
2016
Xue, Yicen | Dong, Wenbo | Wang, Xiaoning | Bi, Wenlong | Zhai, Pingping | Li, Hongjing | Nie, Minghua
Increased usage and discharge of sunscreens have led to ecological safety crisis, and people are developing the advanced oxidation processes (AOPs) to treat them. The present study aimed to determine the degradation efficiency and mechanism of the sunscreen agent p-aminobenzoic acid (PABA) using the UV/Fe²⁺/persulphate (PS) method. A series of irradiation experiments were conducted to optimise the system conditions and to study the impacts of the natural anion. Free radicals and degradation products were identified in order to clarify the degradation mechanism. Initial PS and Fe²⁺ concentrations showed significant impacts on PABA degradation. Natural anions, such as Cl⁻, NO₃ ⁻, H₂PO₄ ⁻ and HCO₃ ⁻, impeded PABA degradation because of ion (Fe²⁺) capture, radical scavenging or pH effects. Hydroxyl (HO·) and sulphate (SO₄ ·⁻) radicals were two main radicals observed in the UV/Fe²⁺/PS system; of these, SO₄ ·⁻ showed greater effects on PABA degradation. Over 99 % of the available PABA was completely degraded into carbon dioxide (CO₂) and water (H₂O) by the UV/Fe²⁺/PS system, and the remaining PABA participated in complex radical reactions. By-products were identified by total ion chromatography and mass spectrometry. Our research provides a treatment process for PABA with high degradation efficiency and environmental safety and introduces a new strategy for sunscreen degradation.
Показать больше [+] Меньше [-]Evidence for the importance of litter as a co-substrate for MCPA dissipation in an agricultural soil Полный текст
2016
Barghūtī, ʻUmar al-Ṣāliḥ | Pagel, Holger | Enowashu, Esther | Devers, Marion | Martin-Laurent, Fabrice | Streck, Thilo | Kandeler, Ellen | Poll, Christian
Evidence for the importance of litter as a co-substrate for MCPA dissipation in an agricultural soil Полный текст
2016
Barghūtī, ʻUmar al-Ṣāliḥ | Pagel, Holger | Enowashu, Esther | Devers, Marion | Martin-Laurent, Fabrice | Streck, Thilo | Kandeler, Ellen | Poll, Christian
Environmental controls of 2-methyl-4-chlorophenoxyacetic acid (MCPA) degradation are poorly understood. We investigated whether microbial MCPA degraders are stimulated by (maize) litter and whether this process depends on concentrations of MCPA and litter. In a microcosm experiment, different amounts of litter (0, 10 and 20 g kg⁻¹) were added to soils exposed to three levels of the herbicide (0, 5 and 30 mg kg⁻¹). The treated soils were incubated at 20 °C for 6 weeks, and samples were taken after 1, 3 and 6 weeks of incubation. In soils with 5 mg kg⁻¹ MCPA, about 50 % of the MCPA was dissipated within 1 week of the incubation. Almost complete dissipation of the herbicide had occurred by the end of the incubation with no differences between the three litter amendments. At the higher concentration (30 mg kg⁻¹), MCPA endured longer in the soil, with only 31 % of the initial amount being removed at the end of the experiment in the absence of litter. Litter addition greatly increased the dissipation rate with 70 and 80 % of the herbicide being dissipated in the 10 and 20 g kg⁻¹ litter treatments, respectively. Signs of toxic effects of MCPA on soil bacteria were observed from related phospholipid fatty acid (PLFA) analyses, while fungi showed higher tolerance to the increased MCPA levels. The abundance of bacterial tfdA genes in soil increased with the co-occurrence of litter and high MCPA concentration, indicating the importance of substrate availability in fostering MCPA-degrading bacteria and thereby improving the potential for removal of MCPA in the environment.
Показать больше [+] Меньше [-]Evidence for the importance of litter as a co-substrate for MCPA dissipation in an agricultural soil Полный текст
2016
Saleh, Omar | Pagel, Holger | Enowashu, Esther | Devers, Marion | Martin-Laurent, Fabrice | Streck, Thilo | Kandeler, Ellen | Poll, Christian | Universität Hohenheim = University of Hohenheim | Birzeit University | Agroécologie [Dijon] ; Institut National de la Recherche Agronomique (INRA)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement | DFG Biogeochemical Interfaces [SPP1315, KA 1590/5-1]
International audience | Environmental controls of 2-methyl-4-chlorophenoxyacetic acid (MCPA) degradation are poorly understood. We investigated whether microbial MCPA degraders are stimulated by (maize) litter and whether this process depends on concentrations of MCPA and litter. In a microcosm experiment, different amounts of litter (0, 10 and 20 g kg(-1)) were added to soils exposed to three levels of the herbicide (0, 5 and 30 mg kg(-1)). The treated soils were incubated at 20 A degrees C for 6 weeks, and samples were taken after 1, 3 and 6 weeks of incubation. In soils with 5 mg kg(-1) MCPA, about 50 % of the MCPA was dissipated within 1 week of the incubation. Almost complete dissipation of the herbicide had occurred by the end of the incubation with no differences between the three litter amendments. At the higher concentration (30 mg kg(-1)), MCPA endured longer in the soil, with only 31 % of the initial amount being removed at the end of the experiment in the absence of litter. Litter addition greatly increased the dissipation rate with 70 and 80 % of the herbicide being dissipated in the 10 and 20 g kg(-1) litter treatments, respectively. Signs of toxic effects of MCPA on soil bacteria were observed from related phospholipid fatty acid (PLFA) analyses, while fungi showed higher tolerance to the increased MCPA levels. The abundance of bacterial tfdA genes in soil increased with the co-occurrence of litter and high MCPA concentration, indicating the importance of substrate availability in fostering MCPA-degrading bacteria and thereby improving the potential for removal of MCPA in the environment.
Показать больше [+] Меньше [-]Design of a toxicity biosensor based on Aliivibrio fischeri entrapped in a disposable card Полный текст
2016
Jouanneau, Sulivan | Durand-Thouand, Marie-José | Thouand, Gérald
The degradation of the marine environment is a subject of concern for the European authorities primarily because of its contamination by hydrocarbons. The traditional methods (ISO 11348 standard) of general toxicity assessment are unsuitable in a context of in situ monitoring, such as seaports or bathing zones. Consequently, to address this issue, bacterial biosensors appear to be pertinent tools. This article presents the design of an innovative bioluminescent biosensor dedicated to in situ toxicity monitoring. This biosensor is based on the entrapment of the wild marine bioluminescent bacterial strain Aliivibrio fischeri ATCC® 49387™ in an agarose matrix within a disposable card. A pre-study was needed to select the most biological parameters. In particular, the regenerating medium’s composition and the hydrogel concentration needed for the bacterial entrapment (mechanical resistance) were optimized. Based on these data, the ability of the bacterial reporter to assess the sample toxicity was demonstrated using naphthalene as a chemical model. The biosensor’s results show a lower sensitivity to naphthalene (EC₅₀ = 95 mg/L) compared with the results obtained using the reference method (EC₅₀ = 43 mg/L). With this architecture, the biosensor is an interesting compromise among low maintenance, ease of use, appropriate sensitivity, relatively low cost and the ability to control online toxicity.
Показать больше [+] Меньше [-]Iron and copper catalysis of PCDD/F formation Полный текст
2016
Liao, Junhong | Buekens, Alfons | Olie, Kees | Yang, Jie | Chen, Tong | Li, Xiaodong
The formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) was explored during de novo tests designed to compare the catalytic activity of copper (II) chloride (CuCl₂) with that of iron (III) oxide (Fe₂O₃) and to test some synergistic effect between these two catalytic compounds. Both copper chloride (CuCl₂) and iron oxide (Fe₂O₃) were earlier proposed as catalysts to explain the PCDD/F emissions from, e.g. municipal solid waste incineration (MSWI). In addition, haematite (Fe₂O₃) is the main iron ore and could be responsible for the typical iron ore sintering plant fingerprint. A total of nine model fly ash (MFA) samples were prepared by mixing and grinding of sodium chloride (NaCl), activated carbon and a powder matrix of silica (SiO₂) with the selected metal compound(s). The conditions of these de novo tests were 1 h in duration, 350 °C in a flow of synthetic combustion gas (10 vol.% oxygen in nitrogen). The effect of Fe–Cu catalyst concentration on yield and distribution pattern of PCDD/F was systematically explored; three strongly differing ratios of [Fe]:[Cu] were considered (1:1, 10:1 and 100:1) to study the potential interactions of Fe₂O₃ and CuCl₂ suggested earlier. The results show some slight rise of PCDD/F formed with raising iron concentration from 0 to 10.1 wt% (no Cu added; 0.1 wt% Cu), as well as strong surging of both amount and average chlorination level of PCDD/F when rising amounts of copper (0 to 1.1 wt%) are introduced. The resulting fingerprints are compared with those from sintering and from MSWI.
Показать больше [+] Меньше [-]An experimental study on usage of plastic oil and B20 algae biodiesel blend as substitute fuel to diesel engine Полный текст
2016
Ramesha, D. K. | Kumara, G Prema | Lalsaheb, | Mohammed, Aamir V. T. | Mohammad, Haseeb A. | Kasma, Mufteeb Ain
Usage of plastics has been ever increasing and now poses a tremendous threat to the environment. Millions of tons of plastics are produced annually worldwide, and the waste products have become a common feature at overflowing bins and landfills. The process of converting waste plastic into value-added fuels finds a feasible solution for recycling of plastics. Thus, two universal problems such as problems of waste plastic management and problems of fuel shortage are being tackled simultaneously. Converting waste plastics into fuel holds great promise for both the environmental and economic scenarios. In order to carry out the study on plastic wastes, the pyrolysis process was used. Pyrolysis runs without oxygen and in high temperature of about 250–300 °C. The fuel obtained from plastics is blended with B20 algae oil, which is a biodiesel obtained from microalgae. For conducting the various experiments, a 10-HP single-cylinder four-stroke direct-injection water-cooled diesel engine is employed. The engine is made to run at 1500 rpm and the load is varied gradually from 0 to 100 %. The performance, emission and combustion characteristics are observed. The BTE was observed to be higher with respect to diesel for plastic-biodiesel blend and biodiesel blend by 15.7 and 12.9 %, respectively, at full load. For plastic-biodiesel blend, the emission of UBHC and CO decreases with a slight increase in NO ₓ as compared to diesel. It reveals that fuel properties are comparable with petroleum products. Also, the process of converting plastic waste to fuel has now turned the problems into an opportunity to make wealth from waste.
Показать больше [+] Меньше [-]Microbial-based evaluation of foaming events in full-scale wastewater treatment plants by microscopy survey and quantitative image analysis Полный текст
2016
Leal, Cristiano | Amaral, António Luís | Costa, Maria de Lourdes
Activated sludge systems are prone to be affected by foaming occurrences causing the sludge to rise in the reactor and affecting the wastewater treatment plant (WWTP) performance. Nonetheless, there is currently a knowledge gap hindering the development of foaming events prediction tools that may be fulfilled by the quantitative monitoring of AS systems biota and sludge characteristics. As such, the present study focuses on the assessment of foaming events in full-scale WWTPs, by quantitative protozoa, metazoa, filamentous bacteria, and sludge characteristics analysis, further used to enlighten the inner relationships between these parameters. In the current study, a conventional activated sludge system (CAS) and an oxidation ditch (OD) were surveyed throughout a period of 2 and 3 months, respectively, regarding their biota and sludge characteristics. The biota community was monitored by microscopic observation, and a new filamentous bacteria index was developed to quantify their occurrence. Sludge characteristics (aggregated and filamentous biomass contents and aggregate size) were determined by quantitative image analysis (QIA). The obtained data was then processed by principal components analysis (PCA), cross-correlation analysis, and decision trees to assess the foaming occurrences, and enlighten the inner relationships. It was found that such events were best assessed by the combined use of the relative abundance of testate amoeba and nocardioform filamentous index, presenting a 92.9 % success rate for overall foaming events, and 87.5 and 100 %, respectively, for persistent and mild events.
Показать больше [+] Меньше [-]The effect of titanium dioxide nanoparticles on neuroinflammation response in rat brain Полный текст
2016
Grissa, Intissar | Guezguez, Sabrine | Ezzi, Lobna | Chakroun, Sana | Sallem, Amira | Kerkeni, Emna | Elghoul, Jaber | El Mir, Lassaad | Mehdi, Meriem | Cheikh, Hassen ben | Haouas, Zohra
Titanium dioxide nanoparticles (TiO₂ NPs) are widely used for their whiteness and opacity in several applications such as food colorants, drug additives, biomedical ceramic, and implanted biomaterials. Research on the neurobiological response to orally administered TiO₂ NPs is still limited. In our study, we investigate the effects of anatase TiO₂ NPs on the brain of Wistar rats after oral intake. After daily intragastric administration of anatase TiO₂ NPs (5–10 nm) at 0, 50, 100, and 200 mg/kg body weight (BW) for 60 days, the coefficient of the brain, acethylcholinesterase (AChE) activities, the level of interleukin 6 (IL-6), and the expression of glial fibrillary acidic protein (GFAP) were assessed to quantify the brain damage. The results showed that high-dose anatase TiO₂ NPs could induce a downregulated level of AChE activities and showed an increase in plasmatic IL-6 level as compared to the control group accompanied by a dose-dependent decrease inter-doses, associated to an increase in the cerebral IL-6 level as a response to a local inflammation in brain. Furthermore, we observed elevated levels of immunoreactivity to GFAP in rat cerebral cortex. We concluded that oral intake of anatase TiO₂ NPs can induce neuroinflammation and could be neurotoxic and hazardous to health.
Показать больше [+] Меньше [-]Influence of zinc nanoparticles on survival of worms Eisenia fetida and taxonomic diversity of the gut microflora Полный текст
2016
Yausheva, Еlena | Sizova, Еlena | Lebedev, Svyatoslav | Skalny, Anatoliy | Miroshnikov, Sergey | Plotnikov, Andrey | Khlopko, Yuri | Gogoleva, Natalia | Cherkasov, Sergey
The study was conducted to examine the effect of zinc nanoparticles on survival of worms Eisenia fetida and composition of the gut microflora. Analysis of the survival data has shown that the introduction of high doses of the nanoparticles causes death of worms in the second group with 35 % mortality rate and activates protective mechanisms realized as mucous film. DNA from the worm guts was extracted and 16S metagenomic sequencing was fulfilled using MiSeq (Illumina). Regarding the gut microflora of worms in the control group, high diversity of microorganisms (303 OTUs) was noted. Most of those belong to the taxa Firmicutes (51.9 % of the total high-quality united reads), Proteobacteria (24.1 % of the total), and Actinobacteria (13.3 % of the total), which were represented by numerous species of gen. Clostridium (C. saccharobutylicum, C. saccharoperbutylacetonicum, C. beijerinckii), gen. Pseudomonas (P. hydrogenovora, P. aeruginosa, and P. putida), gen. Bacillus (B. megaterium, B. silvestris), gen. Cellulomonas (B. megaterium, B. silvestris), and other numerically smaller genera. Adding of zinc nanoparticles to the substrate decreased the diversity of bacteria (78 OTUs) as well as percentage of bacteria belonging to the taxon Firmicutes (−41.6 %) and increased the proportion of Proteobacteria due to growth in abundance of gen. Verminephrobacter (+46 %) and gen. Ochrobactrum (+19.5 %).
Показать больше [+] Меньше [-]Temporal trends and risk assessment of polychlorinated biphenyls and heavy metals in a solid waste site in Taizhou, China Полный текст
2016
The solid wastes generated during the production of chemicals are important sources of polychlorinated biphenyls (PCBs) and heavy metals. However, few studies have been conducted regarding long-term monitoring of the risks and states of PCBs and heavy metal pollution from these sources. Herein, we reported the concentrations and risks posed by these pollutants at a chemical solid waste storage site in Taizhou, China, based on data collected before (in 2006) and after clearing the solid waste (in 2013). We examined the concentrations of 24 PCBs, including ten dioxin-like-PCB (DL-PCB) congeners (PCB77, 105, 114, 118, 123, 126, 156, 167, 169, and 189). Our data showed that the mean ∑₂₄PCB concentrations in the soil, water, and plant samples were 6902.90 ng/g, 1637.58 ng/L, and 33.95 ng/g, respectively, in 2013. Furthermore, Cr was the most prevalent contaminant. The hazard quotient (HQ) values showed that Pb posed the highest risk in the soil samples, followed by Hg. The results of the reporter gene assay showed that soil extracts from S1, S2, S3, S4, S5, S6, and S9 exhibited potential estrogenic activities. A comparison of the data showed that the PCB pollution in some sites of this area was still serious. The data provided here are fundamentally useful for policy makers to regulate this type of storage site.
Показать больше [+] Меньше [-]Terrestrial humic substances in Daliao River and its estuary: optical signatures and photoreactivity to UVA light Полный текст
2016
Fluorescent dissolved organic matter (FDOM) components were identified by Parallel Factor Analysis (PARAFAC) in surface water of Daliao River and its estuary with a focus on terrestrial humic substance-(HS)-like FDOM identified under two contrasting hydrological conditions. The hydrological conditions did not have noticeable effect on the spectral features of the terrestrial HS-like FDOM, but did affect the components’ intensities and photoreactivity: (1) the intensities of terrestrial HS-like components were higher in the normal flow period than in the high flow period, and (2) a spectrally similar terrestrial HS-like FDOM identified under the two contrasting hydrological conditions showed distinct photoreactivity to the same dose of UVA illumination. The findings indicated that terrestrial HS was generated at lower intensities at the terrestrial sources during the high flow period than during the normal flow period and that the transport of terrestrial HS material through the river-estuary system was affected dominantly by seawater dilution along the salinity gradient while fine-tuned by solar UVA illumination. This study exemplifies the effect of hydrological conditions on optical signatures of terrestrial HS-like FDOM and their photoreactivity towards UVA illumination, improving our understanding of the dynamics of terrestrial HS material in river-estuary systems in the framework of the currently proposed new conceptual model for terrestrial organic matter.
Показать больше [+] Меньше [-]