خيارات البحث
النتائج 1791 - 1800 من 4,307
Combined membrane photocatalytic ozonation and wet absorption of elemental mercury النص الكامل
2017
Huang, Z.S. | Wei, Z.S. | He, Y.M. | Pei, J.L. | Xiao, X.L. | Tang, M.R. | Yu, S.
Membrane photocatalytic ozonization coupled with wet absorption offers potential for elemental mercury (Hg0) removal. This study reports on a novel FeTiO2-coated polyvinylidene fluoride (PVDF) wet photocatalytic membrane reactor (WPCMR) for mercury removal in flue gas. Hg0 removal efficiency in the WPCMR reached up to 93.3%. Ozone could enhance mercury oxidation in WPCMR. Wet absorption helps to increases mercury removal efficiency. FeTiO2 catalyst was synthesized by sol-gel method and characterized by XRD, FTIR, UV–Vis, XPS and SEM. XPS analysis confirmed Hg0 oxidation to divalent mercury (Hg (II)). Elemental mercury was oxidized to mercuric oxide followed by wet absorption in the presence of OH free radical and ozone. Wet photocatalytic membrane reactor and photocatalytic membrane reactor (PCMR) of elemental mercury reaction with the FeTiO2/PVDF catalyst all follow Langmuir-Hinshelwood kinetics.
اظهر المزيد [+] اقل [-]The impact of wastewater treatment effluent on microbial biomasses and diversities in coastal sediment microcosms of Hangzhou Bay النص الكامل
2017
Tao, Yile | Dai, Tianjiao | Huang, Bei | Wen, Donghui
Disposal of wastewater treatment plant (WWTP) effluent into sea, a typical anthropogenic disturbance, may influence many environmental factors and change the coastal microbial community structure. In this study, by setting up coastal sediment microcosms perturbed by WWTP effluent, the changes of microbial community structure under different degree of disturbances were investigated. Quantitative PCR (qPCR) and terminal restriction fragment length polymorphism (T-RFLP) were used to analyzed the biomass and biodiversity. High throughput sequencing analysis was used to identify the classification of the microorganisms. Our study suggested that low ratio of WWTP effluent may stimulate dominant species, which increase the biomass but decrease the biodiversity; while high ratio of WWTP effluent may depress all species, which decrease the biomass but increase the biodiversity. In other words, the impact was dose-dependent. The changes of microbial community structure may provide a metric for water environmental assessment and pollution control.
اظهر المزيد [+] اقل [-]Comparing different methods for fast screening of microbiological quality of beach sand aimed at rapid-response remediation النص الكامل
2017
Testolin, Renan C. | Almeida, Tito C.M. | Polette, Marcus | Branco, Joaquim O. | Fischer, Larissa L. | Niero, Guilherme | Poyer-Radetski, Gabriel | Silva, Valéria C. | Somensi, Cleder A. | Corrêa, Albertina X.R. | Corrêa, Rogério | Rörig, Leonardo R. | Itokazu, Ana Gabriela | Férard, Jean-François | Cotelle, Sylvie | Radetski, Claudemir M.
There is scientific evidence that beach sands are a significant contributor to the pathogen load to which visitors are exposed. To develop beach quality guidelines all beach zones must be included in microbiological evaluations, but monitoring methods for beach sand quality are relatively longstanding, expensive, laborious and require moderate laboratory infrastructure. This paper aimed to evaluate the microorganism activity in different beach zones applying and comparing a classical method of membrane filtration (MF) with two colorimetric screening methods based on fluorescein (FDA) and tetrazolium (TTC) salt biotransformation to evaluate a new rapid and low-cost method for beach sand microbiological contamination assessments. The colorimetric results can help beach managers to evaluate rapidly and at low cost the microbiological quality of different beach zones in order to decide whether remedial actions need to be adopted to prevent exposure of the public to microbes due to beach sand and/or water contamination.
اظهر المزيد [+] اقل [-]Distribution, sources and contamination assessment of heavy metals in surface sediments of the South Yellow Sea and northern part of the East China Sea النص الكامل
2017
Lu, Jian | Li, Anchun | Huang, Peng
Surface sediment samples collected from the South Yellow Sea and northern part of the East China Sea during spring and autumn, respectively, were analyzed for grain size, aluminum, and heavy metals (Cr, Ni, Cu, Zn, and Pb) to evaluate heavy metal levels and the contamination status. The results showed that all of the heavy metal concentrations met the standard criteria of the Chinese National Standard Criteria for Marine Sediment Quality. Both the EFs and a multivariate analysis (PCA) indicated that Cr, Ni, Cu, and Zn were mainly from natural contributions, while Pb was influenced by anthropogenic inputs, especially during autumn. The geoaccumulation index of Pb near the mouth of the Yangtze River suggested that the pollution degree in autumn was heavier than that in spring, which might be caused by the greater river discharge in summer and more heavy metal adsorption with finer grain sizes.
اظهر المزيد [+] اقل [-]Concentrations of metallic elements in kidney, liver, and lung tissue of Indo-Pacific bottlenose dolphin Tursiops aduncus from coastal waters of Zanzibar, Tanzania النص الكامل
2017
Mapunda, Edgar C. | Othman, Othman C. | Akwilapo, Leonard D. | Bouwman, Hindrik | Mwevura, Haji
Concentrations of metallic elements in kidney, liver and lung tissues of Indo-Pacific bottlenose dolphins Tursiops aduncus from coastal waters of Zanzibar were determined using inductively coupled plasma – optical emission spectroscopy. Cadmium, chromium, copper, and zinc were quantifiable in all tissues at concentration ranges of 0.10–150, 0.08–3.2, 1.1–88 and 14–210μg/g dry mass, respectively. Copper and zinc was significantly higher in liver, and females had significantly higher Cd in liver, and chromium in lung. Generally, T. aduncus dolphins from coastal waters around Zanzibar carry low concentrations of metals compared with dolphins from other areas. Cadmium increased significantly with age in kidney and lung. Copper decreased significantly with age in liver, probably due to foetal metallothionein. This study supplied baseline data against which future trends in marine mammals in the Indian Ocean, the world's third largest, can be assessed.
اظهر المزيد [+] اقل [-]Effects of rainfall on oil droplet size and the dispersion of spilled oil with application to Douglas Channel, British Columbia, Canada النص الكامل
2017
Wu, Yongsheng | Hannah, Charles G. | Thupaki, Pramod | Mo, Ruping | Law, Brent
Raindrops falling on the sea surface produce turbulence. The present study examined the influence of rain-induced turbulence on oil droplet size and dispersion of oil spills in Douglas Channel in British Columbia, Canada using hourly atmospheric data in 2011–2013. We examined three types of oils: a light oil (Cold Lake Diluent - CLD), and two heavy oils (Cold Lake Blend - CLB and Access Western Blend - AWB). We found that the turbulent energy dissipation rate produced by rainfalls is comparable to what is produced by wind-induced wave breaking in our study area. With the use of chemical dispersants, our results indicate that a heavy rainfall (rain rate>20mmh−1) can produce the maximum droplet size of 300μm for light oil and 1000μm for heavy oils, and it can disperse the light oil with fraction of 22–45% and the heavy oils of 8–13%, respectively. Heavy rainfalls could be a factor for the fate of oil spills in Douglas Channel, especially for a spill of light oil and the use of chemical dispersants.
اظهر المزيد [+] اقل [-]Nowhere safe? Exploring the influence of urbanization across mainland and insular seashores in continental Portugal and the Azorean Archipelago النص الكامل
2017
Bertocci, Iacopo | Arenas, Francisco | Cacabelos, Eva | Martins, Gustavo M. | Seabra, Maria I. | Álvaro, Nuno V. | Fernandes, Joana N. | Gaião, Raquel | Mamede, Nuno | Mulas, Martina | Neto, Ana I.
Differences in the structure and functioning of intensively urbanized vs. less human-affected systems are reported, but such evidence is available for a much larger extent in terrestrial than in marine systems. We examined the hypotheses that (i) urbanization was associated to different patterns of variation of intertidal assemblages between urban and extra-urban environments; (ii) such patterns were consistent across mainland and insular systems, spatial scales from 10scm to 100skm, and a three months period. Several trends emerged: (i) a more homogeneous distribution of most algal groups in the urban compared to the extra-urban condition and the opposite pattern of most invertebrates; (ii) smaller/larger variances of most organisms where these were, respectively, less/more abundant; (iii) largest variability of most response variables at small scale; (iv) no facilitation of invasive species by urbanization and larger cover of canopy-forming algae in the insular extra-urban condition. Present findings confirm the acknowledged notion that future management strategies will require to include representative assemblages and their relevant scales of variation associated to urbanization gradients on both the mainland and the islands.
اظهر المزيد [+] اقل [-]Comparison of organochlorine and PAHs residues in terns eggs from two natural protected areas in the Gulf of Mexico النص الكامل
2017
Vallarino, Adriana | Rendon von Osten, Jaime
Persistent organic pollutants (POPs) are dispersed all over the world while polycyclic aromatic hydrocarbons (PAHs) are released into the environment from pyrogenic and petrogenic sources and are not very mobile or persistent. The aim of this study was to identify POPs and PAHs from eggs of Least and Sooty Terns nesting in two protected marine areas with different anthropogenic impacts in the southern Gulf of Mexico. ΣHCHs were higher in Terminos in 2010 and higher in Alacranes in 2011. ΣDienes and ΣDDTs were higher in 2011 in both study sites. ΣEndosulfan was higher in Terminos than in Alacranes in both years. ΣDienes, ΣDDT and ΣHeptachlor were the highest in both species both years. Acenaphtylene and Fluoranthene were higher in Terminos while Pyrene was higher in Alacranes. No differences were present within species between years. In 2011 PAHs in eggs could have reflected the BP oil spill input.
اظهر المزيد [+] اقل [-]Coastal debris survey in a Remote Island of the Chilean Northern Patagonia النص الكامل
2017
Perez-Venegas, D. | Pavés, H. | Pulgar, J. | Ahrendt, C. | Seguel, M. | Galbán-Malagón, C.J.
Global marine litter pollution is increasing dramatically, and oceanic islands are one of the most vulnerable ecosystems due to their high debris accumulation rate compared to continental sites. Remote areas, such as inhabited islands, represent a perfect study case to track marine debris sources, due to the assumed low rates of local production of debris. Guafo Island is one of the largest islands of the Chilean Northern Patagonia and is considered a remote zone. The accessible coast of Guafo Island was monitored during four austral summers revealing higher levels of marine debris accumulation than continental Chile. Plastic was the most abundant type of debris constituting 50% of the total litter monitored. Our results suggest that most of the plastic identified is likely to be related to local fisheries activities. Mitigation measures including collaboration among fishing communities and scientists could contribute to reduce the coastal debris pollution in remote areas.
اظهر المزيد [+] اقل [-]Potential bioavailability assessment, source apportionment and ecological risk of heavy metals in the sediment of Brisbane River estuary, Australia النص الكامل
2017
Duodu, Godfred Odame | Goonetilleke, Ashantha | Ayoko, G. A. (Godwin A.)
A weak acid extraction was used to mobilize the loosely bound metals in estuary sediment samples. More than 30% of Ag, As, Ca, Cd, Co, Cu, Hg, Mn Ni, Pb and Zn were leached from the sediment showing that these metals are significantly present in the bioavailable form. PCA/APCS identified three sources of the metals, namely: lithogenic accounting for 72%, shipping related contributing 15% and traffic related representing 13% of the total load. Application of pollution index (PI) and modified pollution index (MPI) revealed that the sediment range from unpolluted to heavily polluted while ecological risk index (RI) classifies the sediment as posing low ecological risk modified ecological risk index (MRI) suggests considerable to very high ecological risk. To provide holistic insights into the ecological risks posed by metals, enrichment factor, MPI and MRI are recommended for the assessment of sediment in complex environments such as estuaries.
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