خيارات البحث
النتائج 1351 - 1360 من 1,552
Mycoremediation—a prospective environmental friendly technique of bioseparation and dewatering of domestic wastewater sludge النص الكامل
2012
Molla, Abul Hossain | Fakhru’l-Razi, Ahmadun
INTRODUCTION: Environmental safe and friendly management and disposal of wastewater sludge is a problem of every treatment plant throughout the world. Bioseparation and dewaterability of raw domestic wastewater sludge were evaluated for proper management and disposal by mycoremediation, i.e., using prior grown 2% (v/v) spore suspension of filamentous fungal (Mucor hiemalis Wehmer) broth inoculation, which were grown in 2% (w/v) solution of malt extract and wheat flour for 48–60 h in orbital shaker. DISCUSSION: Within 2–3 days of treatment application, encouraging results were achieved in total dry solids (TDS), total suspended solid (TSS), turbidity, chemical oxygen demand (COD), specific resistance to filtration (SRF), and pH due to fungal treatment in recognition of bioseparation and dewaterability of wastewater sludge compared to control. The significant reduction of TDS was remarked at fungal biomass (FB) in wheat flour (WF) treatment. The removal of TSS, turbidity, COD, and SRF were observed 96.0%, 99.4%, 92.6%, and 97.6%, respectively, in supernatant at 5 days by FB in WF. The SRF measuring the dewaterability was decreased with maximum (0.26 × 10−12 mg/kg) equivalent to 95.5% at 2 days in FB in WF also. FB in WF broth is a potential, environmental friendly, comparatively low-cost biological technique which might play the significant role for bioremediation and bioseparation of domestic wastewater sludge. The present technique may bring a dynamic change in treatment of wastewater in future.
اظهر المزيد [+] اقل [-]Personal monitoring of exposure to particulate matter with a high temporal resolution النص الكامل
2012
Broich, Anna V. | Gerharz, Lydia E. | Klemm, Otto
BACKGROUND: Continuous monitoring of air quality is implemented by government institutions at fixed ambient sites. However, the correlation between fixed site measurements and exposure of individual persons to air contaminants is likely to be weak. MATERIALS AND METHODS: We measured particulate matter both outdoors and indoors by following the spatial movement of individuals. Sixteen test persons took part and carried a measurement backpack for a 24-h period. The backpack was comprised of a Grimm Aerosol Spectrometer model 1.109, a GPS device, and a video camera for tracking of human behavior. The spectrometer provided information about particle numbers and mass in 32-size classes with a high temporal resolution of 6 s. RESULTS: The personal exposure of individuals during 24 h could significantly exceed the outdoor particulate matter (PM)₁₀ concentrations measured at the fixed sites. The average 24-h exposure of all test persons for PM₁₀ varied from 27 to 322 μg m⁻³. Environmental tobacco smoke and cooking emissions were among the main indoor sources for PM. The amount of particulate matter a test person was exposed to was highly dependent on the spatial behavior and the surrounding microenvironment conditions. DISCUSSION: Large-scale experiments including personal measurements might help to improve modeling approaches to approximate the actual exposure on a statistically sound basis.
اظهر المزيد [+] اقل [-]Organochlorine pesticides and polychlorinated biphenyls in air and soil across Azerbaijan النص الكامل
2012
Aliyeva, Gulchohra | Kurkova, Romana | Hovorkova, Ivana | Klánová, Jana | Halsall, Crispin
Concentrations of selected organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are reported in air and surface soil in an extensive spatial survey across Azerbaijan, a country bordering the Caspian Sea with a history of OCP production and extensive use. Polyurethane foam disc passive air samplers (PAS) were deployed during October–November 2008 with soil samples collected in July 2009. Levels of Σ7PCB in ambient air were generally low (mean of 0.046 ng m−3, n = 13) and comparable to concentrations reported in countries within Eastern Europe and similar to or lower than concentrations reported in urban air in the UK and other western countries. Surprisingly, PCB concentrations in rural/background soil fell below the method detection limits at most sites, although concentrations were 0.209 and 0.071 ng Σ7PCB g−1 dry weight (dw) for two urban sites, again comparable to PCB levels measured at background sites in Europe. Levels of α-HCH, β-HCH, γ-HCH and p,p′-DDT/E were elevated in ambient air across Azerbaijan in comparison to PAS-derived concentrations reported elsewhere, with concentrations of α-HCH in air ranging from 0.085 to 2.699 ng m−3 and p,p′-DDE, 0.037–2.290 ng m−3. High concentrations of OCPs occurred at several of the urban sites and at sites in proximity to old pesticide storage facilities with concentrations in soil >0.1 μg g−1 dw for p,p′-DDE and p,p′-DDT at several sites. The ratio of p,p′-DDT/p,p′-DDE was close to unity in the soil at these sites, but elsewhere, the ratio was <1, indicating a weathered DDT pattern, which was also reflected in the air at all sites. A fugacity approach revealed the strong likelihood of net soil-to-air transfer at the majority of sites for all OCPs. The calculated annual fluxes or loading to the atmosphere from a rural/agricultural area (representing land as vineyards and cotton cultivation) were estimated to be on the order of ≈10–100 kg year−1 for the HCH isomers (including the β -isomer) and p,p′-DDE. The high levels of OCPs in soils, particularly in the vicinity of obsolete-pesticide storage facilities and at select urban sites are of concern and warrant regular monitoring activities and the development of containment or mitigation strategies.
اظهر المزيد [+] اقل [-]Comparison of methods for evaluation of activity of photocatalytic films النص الكامل
2012
Simonsen, Morten E. | Sørensen, Martin B. | Søgaard, Erik G.
OBJECTIVE: This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase. METHOD: The photocatalytic TiO2 coatings included in this investigation ranged from thin commercially available coatings (ActivTM and BioCleanTM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol–gel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably. RESULTS: The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably. CONCLUSION: The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.
اظهر المزيد [+] اقل [-]Microbial structure and chemical components of aerosols caused by rotating brushes in a wastewater treatment plant النص الكامل
2012
Han, Yunping | Li, Lin | Liu, Junxin | Zhang, Mengzhu
PURPOSE: Bacterial community structure and the chemical components in aerosols caused by rotating brushes in an Orbal oxidation ditch were assessed in a Beijing municipal wastewater treatment plant. METHODS: Air samples were collected at different distances from the aerosol-generating rotating brushes. Molecular culture-independent methods were used to characterize the community structure of the airborne bacteria in each sample regardless of cell culturability. A clone library of 16S rDNA directly amplified from air DNA of each sample was constructed and sequenced to analyze the community composition and diversity. Insoluble particles and water-soluble ions emitted with microorganisms in aerosols were analysis by a scanning electron microscope together with energy dispersive X-ray spectroscopy and ion chromatogram analyzer. RESULTS: In total, most of the identified bacteria were Proteobacteria. The majority of sequences near the rotating brushes (the main source of the bioaerosols) were Proteobacteria (62.97 %) with β-(18.52 %) and γ-(44.45 %) subgroups and Bacteroidetes (29.63 %). Complex patterns were observed for each sampling location, suggesting a highly diverse community structure, comparable to that found in water in the Orbal oxidation ditch. Accompany with microorganisms, 46.36 μg/m3 of SO 4 2− , 29.35 μg/m3 of Cl−, 21.51 μg/m3 of NO 3 − , 19.76 μg/m3 of NH 4 + , 11.42 μg/m3 of PO 4 3− , 6.18 μg/m3 of NO 2 − , and elements of Mg, Cl, K, Na, Fe, S, and P were detected from the air near the aerosols source. CONCLUSIONS: Differences in the structure of the bacterial communities and chemical components in the aerosols observed between sampling sites indicated important site-related variability. The composition of microorganisms in water was one of the most important sources of bacterial communities in bioaerosols. Chemical components in bioaerosols may provide a media for airborne microorganism attachment, as well as a suitable microenvironment for their growth and survival in the air. This study will be benefit for the formulation of pollution standards, especially for aerosols, that take into account plant workers’ health.
اظهر المزيد [+] اقل [-]Molecular cloning and expression of novel metallothionein (MT) gene in the polychaete Perinereis nuntia exposed to metals النص الكامل
2012
Won, Eun-Ji | Rhee, Jae-Sung | Ra, Kongtae | Kim, Kyung-Tae | Au, Doris W. T. | Shin, Kyung-Hoon | Lee, Jae-seong
To report a novel metallothionein (MT) gene and evaluate its potency as a biomarker, we clone this MT gene and measured the expression levels in the metal-exposed polychaete Perinereis nuntia. Accumulated metal contents and metallothionein-like proteins (MTLPs), which have been recognized as potential biomarkers, were compared with the relative mRNA expressions of the MT gene of P. nuntia (Pn-MT). In addition, the metal-binding affinity was estimated by recombinant Pn-MT protein. Pn-MT having high cysteine residues with three metal response elements in the promoter region closely clusters with those of other invertebrates. The accumulation patterns of metals were dependent on the exposure times in lead (Pb), cadmium (Cd), and copper (Cu) exposure. Particularly, both MTLP levels and relative mRNA expressions of MT were increased with accumulated metal contents and exposure time in P. nuntia exposed to Pb and Cd. There was no significant modulation of the Pn-MT gene in polychaetes exposed to Zn and As. However, the metal-binding ability of the recombinant Pn-MT protein provides a clear evidence for a high affinity of MT to several metal elements. These results suggest that Pn-MT would play an important role in the detoxification and/or sequestration of specific metals (e.g., Pb and Cd) in P. nuntia and have potential as a molecular biomarker in the monitoring of the marine environment using a polychaete.
اظهر المزيد [+] اقل [-]Effect of Pb toxicity on leaf growth, antioxidant enzyme activities, and photosynthesis in cuttings and seedlings of Jatropha curcas L النص الكامل
2012
Shu, Xiao | Yin, LiYan | Zhang, QuanFa | Wang, Weibo
BACKGROUND: Cuttings and seedlings of Jatropha curcas L. were exposed to different regimes of lead (Pb) stress as Pb(NO3)2 at 0 (CK), 0.5, 1, 2, 3, and 4 mM kg−1 soil. OBJECTIVES: The effect of Pb treatment on the root length, tolerance index, photosynthetic pigments, photosynthetic activity, lipid peroxidation, and antioxidant enzyme was studied in a greenhouse pot experiment. RESULTS: The results showed that root lengths and tolerance index decreased with increase of Pb concentration, but tolerance index of cuttings was always lower than those of the seedlings. For cuttings, Pb treatment had a stimulating effect on chlorophyll content, carotenoid content, and superoxide dismutase (SOD) activity at low concentration and an inhibitory effect at higher concentration. For seedlings, SOD activity increased with increasing Pb concentration. In both seedlings and cuttings, Pb caused inhibition of leaf growth and photosynthesis, and induced the membrane damage which was more obvious in the cuttings. In comparison with the control, the dynamic tendency of catalase and perxidase activities in the leaves of Pb-stressed plants all ascended, and then declined. DISCUSSION: The increase in enzyme activities demonstrated that seedlings were more tolerant to Pb stress than cuttings. These results also indicate that the antioxidant system may play an important role in eliminating or alleviating the toxicity of Pb in J. curcas seedlings and cuttings. The accumulation of Pb increased in a concentration-dependent manner; however, its translocation from root to shoot was low. The cuttings accumulated significantly higher Pb in roots than seedlings.
اظهر المزيد [+] اقل [-]Characterization of particulate polycyclic aromatic hydrocarbons in the east of France urban areas النص الكامل
2012
Delhomme, Olivier | Millet, Maurice
BACKGROUND: Air samples collected on three different urban sites in East of France (Strasbourg, Besançon, and Spicheren), from April 2006 to January 2007, were characterized to measure the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the particulate phase (PM10) and to examine their seasonal variation, diurnal variations, and emission sources. RESULTS: The average concentrations of ΣPAHs were 12.6, 9.5, and 8.9 ng m−3 for the Strasbourg, Besançon, and Spicheren sites, respectively. Strong seasonal variations of individual PAH concentrations were found at the three sampling sites, with higher levels in the winter that gradually decreased to the lowest levels in the summer. The diurnal variations of PAH concentrations in summer presented highest concentrations during the morning (04:00–10:00) and the evening (16:00–22:00) times, indicating the important contribution from vehicle emissions, in the three sampling sites. Furthermore, the ratio of BaP/BeP suggests that the photochemical degradation of PAHs can suppress their concentrations in the midday/afternoon (10:00–16:00), time interval of highest global irradiance. In winter, concentrations of PAH were highest during the evening (16:00–22:00) time, suggesting that domestic heating can potentially be an important source for particulate PAH, for the three sampling sites. CONCLUSION: Diagnostic ratios were used to identify potential sources of PAHs. Results showed that vehicle emissions may be the major source of PAHs, especially in summer, with a prevalent contribution of diesel engines rather than gasoline engines at the three sites studied, independently of the seasons.
اظهر المزيد [+] اقل [-]Investigation of environmental contamination of mono-isopropylnaphthalene, di-isopropylnaphthalene and tri-isopropylnaphthalene in Hyogo in Japan النص الكامل
2012
Suzuki, Motoharu | Matsumura, Chisato | Nakano, Takeshi | Imaishi, Hiromasa
Di-isopropylnaphthalene (DIPN) has highly persistent and bioaccumulative properties, and a large amount of DIPN is used as a PCB substitute in Japan. However, DIPN in the environment has not been thoroughly investigated. In addition, mono-isopropylnaphthalene (MIPN) and tri-isopropylnaphthalene (TIPN), which are the homologues of DIPN, have similar properties to DIPN. In this study, simultaneous analytical methods for MIPN, DIPN, and TIPN for air, environmental water, sediment, and biological samples were developed, and the resultant contamination caused by each in the environment was investigated. DIPN was detected at 1.1 ± 0.38 ng/m3 in air and between < 1.9 and 9.8 ng/L in river water, but MIPN and TIPN were not. In Lateolabrax japonicas (Japanese sea perch), TIPN was detected from only females at between 0.65 and 1.4 ng/g-wet. DIPN was detected from all perches at between 1.2 and 3.4 ng/g-wet. DIPN and TIPN isomer fingerprints in females were different from those in the reference standard stock solution ones. In sediments, MIPN, DIPN, and TIPN were detected at between < 0.16 and 8.6 ng/g-dry, between < 1.1 and 4400 ng/g-dry, and between < 0.83 and 500 ng/g-dry, respectively. The contamination trend of DIPN in the sediments was similar to that of PCBs.
اظهر المزيد [+] اقل [-]Biodegradability and ecotoxicitiy of tramadol, ranitidine, and their photoderivatives in the aquatic environment النص الكامل
2012
Bergheim, Marlies | Gieré, Reto | Kümmerer, Klaus
PURPOSE: This study was designed to assess the fate and the overall potential impacts of the widely prescribed drugs ranitidine and tramadol after their introduction into the aquatic environment. METHODS: The probability to detect these two drugs in the aquatic environment was studied by analyzing their abiotic and biotic degradation properties. For this purpose, samples were irradiated with different light sources, and three widely used biodegradability tests from the OECD series, the closed bottle test (OECD 301 D), the manometric respirometry test (OECD 301 F) and the Zahn–Wellens test (OECD 302 B), were conducted. The ecotoxicity of the photolytically formed transformation products was assessed by performing the bacterial growth inhibition test (EN ISO 10712). Furthermore, quantitative structure–activity relationship analysis and a risk analysis based on the calculation of the predicted environmental concentrations have also been conducted to assess the environmental risk potential of the transformation products. The possible formation of stable products by microbial or photolytical transformation has been investigated with DOC and LC-MS analytics. RESULTS: In the present study, neither ranitidine, nor tramadol, nor their photoderivatives were found to be readily or inherently biodegradable according to test guidelines. The photolytic transformation was faster under a UV lamp compared to the reaction under an Xe lamp with a spectrum that mimics sunlight. No chronic toxicity against bacteria was found for ranitidine or its photolytic decomposition products, but a low toxicity was detected for the resulting mixture of the photolytic transformation products of tramadol. CONCLUSIONS: The study demonstrates that transformation products may have a higher environmental risk potential than the respective parent compounds.
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