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Comparison of methods for evaluation of activity of photocatalytic films
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.
Показать больше [+] Меньше [-]Organochlorine pesticides and polychlorinated biphenyls in air and soil across Azerbaijan
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.
Показать больше [+] Меньше [-]Multivariate analysis of mineral constituents of edible Parasol Mushroom (Macrolepiota procera) and soils beneath fruiting bodies collected from Northern Poland
2012
Gucia, Magdalena | Jarzyńska, Grażyna | Rafał, Elżbieta | Roszak, Magdalena | Kojta, Anna K. | Osiej, Irena | Falandysz, Jerzy
Caps and stipes of 141 fruiting bodies of Parasol Mushroom (Macrolepiota procera) and surface layer of soils collected from 11 spatially distant and background (pristine) areas in Northern Poland were analyzed for Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr, and Zn by inductively coupled plasma optical emission spectroscopy and cold vapor atomic absorption spectroscopy. In terms of bioconcentration and bioexclusion concept, K, Ag, Cu, Rb, and P were highly bioconcentrated in caps, and their bioconcentration factor values varied for the 11 sites between 120 and 500—67–420, 70–220, 10–170, and 45–100, respectively. Cd, Zn, Mg, and Na showed bioconcentration factors (BCFs) between 3.3 and 36, 3.7–15, 0.92–6.3, and 1.4–44 while Al, Ba, Ca, Co, Cr, Mn, Ni, Pb, and Sr were excluded (BCF < 1). The Parasol Mushroom is a species harvested in the wild, and its caps are of unique taste and can contain a spectrum of essential and hazardous mineral compounds accumulated at elevated concentrations, even if collected at the background (pristine) areas. These elevated mineral concentrations of the caps are due to the efficient bioconcentration potential of the species (K, Ag, Cu, Rb, P, Cd, Zn, Mg, and Na) and abundance in the soil substrates (Al, Ca, Fe, Mn). The estimated intake rates of Cd, Hg, and Pb contained in Parasol Mushroom’s caps show a cause for concern associated with these metals resulting from the consumption of between 300- and 500-g caps daily, on a frequent basis in the mushrooming season.
Показать больше [+] Меньше [-]VOC amounts in ambient areas of a high-technology science park in Taiwan: their reciprocal correlations and impact on inhabitants
2012
Liu, Hsin-Wang | Wu, Bei-Zen | Nian, Hung-Chi | Chen, Hsing-Jung | Lo, Jiunn-Guang | Chiu, Kong-Hwa
INTRODUCTION: This study presents bihourly, seasonal, and yearly concentration changes in volatile organic compounds (VOCs) in the inlet and effluent water of the wastewater treatment plant (WWTP) of a high-technology science park (HTIP) in Taiwan, with the VOC amounts at different sites correlated geologically. MATERIALS AND METHODS: This research adopted a combination of two systems, solid-phase microextraction with a gas chromatography/flame ionization detector and an assembly of purge and trap coupled with gas chromatography/mass spectrometry, to monitor polar and nonpolar VOCs in wastewater. This paper investigated the total VOCs, acetone, isopropyl alcohol (IPA), and dimethylsulfide (DMS) concentrations in real water samples collected in the ambient area of the HTIP. RESULTS AND DISCUSSION: The major contents of VOCs measured in the effluent of the WWTP in the HTIP and the surrounding river region were DMS (14–176 ppb), acetone (5–95 ppb), and IPA (15–316 ppb). In comparison with the total VOCs in the inlet wastewater of the WWTP, no corresponding relationship for total VOC concentration in the wastewater was observed between the inlet water and effluent water of the WWTP. CONCLUSIONS: The peak VOC concentrations appeared in the third season, and the correlation of different VOC amounts reflects the production situation of the factories. In addition, VOC concentrations at different sites indicate that the Ke-Ya River is seemingly an effective channel for transporting wastewater to its final destination. The data are good indications for the management of environmental pollution near the HTIP.
Показать больше [+] Меньше [-]The occurrence and environmental effect of persistent organic pollutants (POPs) in Taurus Mountains soils
2012
Turgut, Cafer | Atatanir, Levent | Mazmanci, Birgül | Mazmanci, Mehmet Ali | Henkelmann, Bernhard | Schramm, Karl-Werner
PURPOSE: Persistent organic pollutants (POPs) are of global concern due to their ubiquitous presence and toxicity. The occurence of polychlorinated dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs), co-planar biphenyls (PCBs), hexachlorocyclohexanes (HCH), dichlorodiphenyltrichloroethanes (DDT), and organochlorine pesticides (OCPs) in forest soil collected from Taurus mountains may have adverse effects on the environment and health. The aim of the study was to investigate the outcome and distribution of POPs in the environment and the possible grasshopper effect along an altitude transect from sea level up to nearly 2,000 m a.s.l at a spatial distance of about 60 km in the southeastern Turkish Mediterranean Sea. METHODS: The samples were collected at a height of 121, 408, 981, 1,225, 1,373, 1,639, and 1,881 m above sea level from Taurus Mountains, Turkey. The results were confirmed using high-resolution gas chromatography–high-resolution mass spectrometry. RESULTS: The levels of the PCDD in forest soil from Taurus Mountains varied from nearly 4 to 12 pg g−1 dry weight (dw). PCDF concentrations ranged from 2 to 7 pg g−1 dw. Considerably high DDT levels detected in five stations indicated (3,223–24,564 pg g−1) its extensive local application or atmospheric transport. PCB levels were determined between 80 and 288 pg g−1 dw. HCH concentrations ranged from 141 to 1,513 pg g−1 dw. The other OCP was between 102 and 731 pg g−1. CONCLUSION: Although the use of POPs has been banned, our results show that they could still be found in Turkey. Their presence may be attributed to the degradation of pesticides which are newly banned and, as well as to the atmospheric migration and deposition. The lattitude of sampling sites, the chemical, and physical parameters of soil have observed no effect on the fate of POPs in the environment.
Показать больше [+] Меньше [-]Transition metal-modified zinc oxides for UV and visible light photocatalysis
2012
Bloh, J. Z. | Dillert, R. | Bahnemann, D. W.
In order to use photocatalysis with solar light, finding more active and especially visible light active photocatalysts is a very important challenge. Also, studies of these photocatalysts should employ a standardized test procedure so that their results can be accurately compared and evaluated with one another. A systematic study of transition metal-modified zinc oxide was conducted to determine whether they are suitable as visible light photocatalysts. The photocatalytic activity of ZnO modified with eight different transition metals (Cu, Co, Fe, Mn, Ni, Ru, Ti, Zr) in three different concentrations (0.01, 0.1, and 1 at.%) was investigated under irradiation with UV as well as with visible light. The employed activity test is the gas-phase degradation of acetaldehyde as described by the ISO standard 22197-2. The results suggest that the UV activity can be improved with almost any modification element and that there exists an optimal modification ratio at about 0.1 at.%. Additionally, Mn- and Ru-modified ZnO display visible light activity. Especially the Ru-modified ZnO is highly active and surpasses the visible light activity of all studied titania standards. These findings suggest that modified zinc oxides may be a viable alternative to titanium dioxide-based catalysts for visible light photocatalysis. Eventually, possible underlying mechanisms are proposed and discussed.
Показать больше [+] Меньше [-]Sampling and analytical methods for assessing the levels of organic pollutants in the atmosphere: PAH, phthalates and psychotropic substances: a short review
2012
Cecinato, Angelo | Balducci, Catia | Mastroianni, Daniele | Perilli, Mattia
This short review presents the procedures used to monitor PAHs, phthalates and psychotropic substances in the air, and the results of some measurements made in Italy and abroad. Organic contaminants are characterized by a variety of physical and chemical properties, including aggregation phase, concentration level, and life time. This variety widens the spectrum of procedures developed to assess their occurrence in the environment and biota, but prevents the complete speciation of the “organic fraction” of air, waters and particulates, and attention is paid to a few substances. The progress in health sciences stimulates the concern on contaminants and the development of new instrumental apparatuses and methods; new chemicals are continuously identified or recognized as capable of injuring the environment and organisms. Persistent organic pollutants and persistent biologically active toxicants are subject to regulation and extensively measured by means of standard procedures. For instance, polycyclic aromatic hydrocarbons, polychlorobiphenyls and polychlorodibenzodioxins are recovered from air through phase partition, thermal desorption or solvent extraction, then separated and detected through GC–MS or HPLC–MS procedures. By contrast, dedicated methods must be still optimized to monitor candidates or possible candidates as emerging organic pollutants, e.g. phthalates, flame retardants and perfluoroalkanes. Also, psychotropic substances appear of potential concern. Legal and illicit substances are commonly detected in the urban air besides waste and surface waters. If nicotine, caffeine and cocaine will result to enough persistence in the air, their monitoring will become an important issue of global chemical watching in the next future.
Показать больше [+] Меньше [-]Performance evaluation of a tailor-made passive sampler for monitoring of tropospheric ozone
2012
Özden, Özlem | Döğeroğlu, Tuncay
INTRODUCTION: This study presents the performance evaluation of a tailor-made passive sampler developed for the monitoring of tropospheric ozone. METHODS: The performance of the passive sampler was tested in the field conditions in terms of accuracy, precision, blank values, detection limit, effects of some parameters such as sampling site characteristics and sampling period on the field blanks, self-consistency, experimental and theoretical uptake rates, shelf life and comparison with commercial passive samplers. RESULTS: There was an agreement (R 2 = 0.84) between the responses of passive sampler and the continuous automatic analyser. The accuracy of the sampler, expressed as percent relative error, was obtained lower than 15%. Method precision in terms of coefficient of variance for three simultaneously applied passive samplers was 12%. Sampler detection limit was 2.42 μg m−3 for an exposure period of 1 week, and the sampler can be stored safely for a period of up to 8 weeks before exposure. Satisfactory self-consistency results showed that extended periods gave the same integrated response as a series of short-term samplers run side by side. The uptake rate of ozone was found to be 10.21 mL min−1 in a very good agreement with the theoretical uptake rate (10.32 mL min−1). The results of the comparison study conducted against a commercially available diffusion tube (Gradko diffusion tube) showed a good linear relationship (R 2 = 0.93) between two passive samplers. CONCLUSIONS: The sampler seems suitable to be used in large-scale measurements of ozone where no data are available or the number of existing automated monitors is not sufficient.
Показать больше [+] Меньше [-]Microbial structure and chemical components of aerosols caused by rotating brushes in a wastewater treatment plant
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.
Показать больше [+] Меньше [-]Impacts of urbanization on surface sediment quality: evidence from polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) contaminations in the Grand Canal of China
2012
Hong, Youwei | Yu, Shen | Yu, Guangbin | Liu, Yi | Li, Guilin | Wang, Min
INTRODUCTION: Organic pollutants, especially synthetic organic compounds, can indicate paces of anthropogenic activities. Effects of urbanization on polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) distributions in surface sediment were conducted in urban sections of the Grand Canal, China, consisting of a four-level urbanization gradient. MATERIALS AND METHODS: The four-level urbanization gradients include three countryside towns, two small-size cities, three medium-size cities, and a large-size city. Diagnostic ratio analysis and factor analysis–multiple linear regression model were used for source apportionment of PAHs. Sediment quality guidelines (SQGs) of USA and Canada were employed to assess ecological risks of PAHs and PCBs in surface sediments of the Canal. RESULTS AND DISCUSSION: Ranges of PAH and PCB concentrations in surface sediments were 0.66–22 mg/kg and 0.5–93 μg/kg, respectively. Coal-related sources were primary PAH sources and followed by vehicular emission. Total concentration, composition, and source apportionment of PAHs exhibited urbanization gradient effects. Total PCB concentrations increased with the urbanization gradient, while total PAHs concentration in surface sediments presented an inverted U Kuznets curve with the urbanization gradient. Elevated concentrations of both PAHs and PCBs ranged at effect range low levels or interim SQG, assessed by USA and Canadian SQGs. CONCLUSIONS: PAHs and PCBs in surface sediments of the Grand Canal showed urbanization gradient effects and low ecological risks.
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