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A model for performance of sulfite oxidation of ammonia-based flue gas desulfurization system
2015
Jia, Yong | Yin, Liguo | Xu, Yalin | Ding, Xilou | Sheng, Guanghong
A mathematical model was developed to simulate the oxidation of total sulfite in the holding tank of ammonia-based flue gas desulfurization (FGD) system. The model could provide predictions of the oxidation ratio of total sulfite at different operating condition such as pH, concentration of total sulfur, air flow and residence time. The calculation results of an ammonia-based FGD system for 2 × 150 MW boilers by this model were compared to that of corresponding measured values. The comparison results show that the simulated oxidation ratio of total sulfite agrees well with the measured data. The difference between calculated values and measured data is below 4.2%. This model appears to be beneficial for optimizing design and operation of total sulfite oxidation of an ammonia-based FGD system.
显示更多 [+] 显示较少 [-]Thermophilic biotrickling filtration of gas–phase trimethylamine
2015
Wei, Zaishan | Huang, Qianru | Ye, Qihong | Chen, Zhouyang | Li, Baoren | Wang, Jianbin
The objectives of this work were to investigate trimethylamine (TMA) removal by thermophilic biotrickling filtration (TBTF) and to examine the microbial community developed at 56 °C. TMA removal efficiency in the TBTF system was up to 99.9%. At a bed contact time of 25.8s, the elimination capacity at 56 °C in the TBTF was 375.2g TMAm−3 h−1, which was higher than that of mesophilic biotrickling filtration. TBTF was able to quickly recover from a normal temperature shutdown period of a month. The thermophilic bacterial communities in the TBTF which were assessed by polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE), play the dominant role in the thermophilic biological processes of metabolism, ammoxidation, nitrification, denitrification and carbon oxidation. These results show that TBTF is achievable and open new possibilities for applying biotrickling filtration to hot odorous gas streams from sewage sludge drying.
显示更多 [+] 显示较少 [-]Accurate assessment of the impact of salmon farming on benthic sediment enrichment using foraminiferal metabarcoding
2015
Pochon, X. | Wood, S.A. | Keeley, N.B. | Lejzerowicz, F. | Esling, P. | Drew, J. | Pawlowski, J.
Assessing the environmental impact of salmon farms on benthic systems is traditionally undertaken using biotic indices derived from microscopic analyses of macrobenthic infaunal (MI) communities. In this study, we tested the applicability of using foraminiferal-specific high-throughput sequencing (HTS) metabarcoding for monitoring these habitats. Sediment samples and physico-chemical data were collected along an enrichment gradient radiating out from three Chinook salmon (Oncorhynchus tshawytscha) farms in New Zealand. HTS of environmental DNA and RNA (eDNA/eRNA) resulted in 1,875,300 sequences that clustered into 349 Operational Taxonomic Units. Strong correlations were observed among various biotic indices calculated from MI data and normalized fourth-root transformed HTS data. Correlations were stronger using eRNA compared to eDNA data. Quantile regression spline analyses identified 12 key foraminiferal taxa that have potential to be used as bioindicator species. This study demonstrates the huge potential for using this method for biomonitoring of fish-farming and other marine industrial activities.
显示更多 [+] 显示较少 [-]Impact of industrial pollution on recent dinoflagellate cysts in Izmir Bay (Eastern Aegean)
2015
Aydın, Hilâl | Yürür, Emine Erdem | Uzar, Serdar | Küçüksezgin, Filiz
The spatial distribution of dinoflagellate cysts was studied to understand the impact of industrial pollution on the surface sediment of Izmir Bay, Turkey. Forty two dinoflagellate cyst morphotypes belonging to 12 genera were identified and qualified at 12 sampling points. The cyst of Gymnodinium nolleri dominated the bay and had the highest abundance in most of the stations, following Spiniferites bulloideus and Lingulodinium machaerophorum. The highest cyst concentration was recorded in the inner part of the bay. Cyst concentration ranged between 384 and 9944cystg−1 dry weight of sediment in the sampling area. Sediment metal concentrations were determined. Heavy metal levels in Izmir Inner Bay were higher than the Middle and Outer Bay. L. machaerophorum, Dubridinium caperatum and Polykrikos kofoidii showed significant positive correlation with some metals (Cd, Pb, Cu, Zn) and organic carbon content. However, there was no significant correlation between dinoflagellate cyst abundance and sediment type.
显示更多 [+] 显示较少 [-]Assessment of oil slick hazard and risk at vulnerable coastal sites
2015
Melaku Canu, Donata | Solidoro, Cosimo | Bandelj, Vinko | Quattrocchi, Giovanni | Sorgente, Roberto | Olita, Antonio | Fazioli, Leopoldo | Cucco, Andrea
This work gives an assessment of the hazard faced by Sicily coasts regarding potential offshore surface oil spill events and provides a risk assessment for Sites of Community Importance (SCI) and Special Protection Areas (SPA). A lagrangian module, coupled with a high resolution finite element three dimensional hydrodynamic model, was used to track the ensemble of a large number of surface trajectories followed by particles released over 6 selected areas located inside the Sicily Channel. The analysis was carried out under multiple scenarios of meteorological conditions. Oil evaporation, oil weathering, and shore stranding are also considered. Seasonal hazard maps for different stranding times and seasonal risk maps were then produced for the whole Sicilian coastline. The results highlight that depending on the meteo-marine conditions, particles can reach different areas of the Sicily coast, including its northern side, and illustrate how impacts can be greatly reduced through prompt implementation of mitigation strategies.
显示更多 [+] 显示较少 [-]The development of a dense urban air pollution monitoring network
2015
Taheri Shahraiyni, Hamid | Sodoudi, Sahar | Kerschbaumer, Andreas | Cubasch, U.
The importance of air pollution monitoring networks in urban areas is well known because of their miscellaneous applications. At the beginning of the 1990s, Berlin had more than 40 particulate matter monitoring stations, whereas, by 2013, there were only 12 stations. In this study, a new and free–of–charge methodology for the densifying of the PM10 monitoring network of Berlin is presented. It endeavors to find the non–linear relationship between the hourly PM10 concentration of the still–operating PM10 monitoring stations and the shut–down stations by using the Artificial Neural Network (ANN), and, consequently, the results of the shut–down stations were simulated and re–constructed. However, input–variables selection is a pre–requisite for any ANN simulation, and hence a new fuzzy–heuristic input selection has been developed and joined to the ANN for the simulation. The hourly PM10 concentrations of the 20 shut–down stations were simulated and re–constructed. The mean error, bias and absolute error of the simulations were 27.7%, –0.03 (μg/m3), and 7.4 (μg/m3), respectively. Then, the simulated hourly PM10 concentration data were converted to a daily scale and the performance of ANN models which were developed for the simulation of the daily PM10 data were evaluated (correlation coefficient >0.94). These appropriate results imply the ability of the developed input selection technique to make the appropriate selection of the input variables, and it can be introduced as a new input variable selection for the ANN. In addition, a dense PM10 monitoring network was developed by the combination of both the re–constructed (20 stations) and the current (12 stations) stations. This dense monitoring network was applied in order to determine a reliable mean annual PM10 concentration in the different areas in Berlin in 2012.
显示更多 [+] 显示较少 [-]Meteorological driven changes on air quality over Portugal: a KZ filter application
2015
Sá, Elisa | Tchepel, Oxana | Carvalho, Anabela | Borrego, C.
The Kolmogorov–Zurbenko (KZ) filter method is a tool to improve air quality management, since it determines meteorological effects on air quality concentrations and separates out those effects in order to examine underlying trends. Air quality in Portugal is exceeding the legislated particulate matter (PM10), nitrogen oxides (NO2) and ozone (O3) levels; accordingly, measures to reduce pollutant emissions have been designed. The primary objective of this work is to investigate the influence of meteorology on O3, NO2 and PM10 levels and the long-term air quality trends. Air quality and meteorological datasets were explored for the period 2002–2012 through the decomposition of time-series using the Kolmogorov–Zurbenko (KZ) filter. To determine the best meteorological predictors for the air quality data, a stepwise regression analysis of the filtered time-series was applied. The KZ filter application revealed that the short-term component has the highest contribution to the total variance of the original air quality data (≈64%–PM10; ≈52%–O3; ≈54%–NO2) followed by the seasonal component. The long-term component exhibits the influence of the emission control regulations implemented in each study region. The statistical analysis of the air quality and the meteorological data indicated that O3 has a statistically significant relationship with temperature in most of the components. The results also indicate that emission control strategies are primary regulators for NO2 and PM10 levels. Therefore, to establish an accurate strategy to improve air quality further, it will be essential to include meteorological effects. This study highlights that the KZ filter is a useful tool to support the design and implementation of adequate air quality strategies and for the investigation of the interactions between the emissions, the meteorological conditions and the air quality levels, to improve air quality management in these two urban areas.
显示更多 [+] 显示较少 [-]The amount and accumulation rate of plastic debris on marshes and beaches on the Georgia coast
2015
Lee, Richard F. | Sanders, Dorothea P.
The amount and accumulation rate of plastic debris at 20 sites along the Georgia coast were prepared using data reported by a number of volunteer organizations. The amount of plastic debris at highly visited barrier island beaches and estuarine marshes ranged from 300 to >1000kg. Relatively large amount of plastics (180–500kg) were found on less visited barrier island beaches, i.e. Blackbeard, Ossabaw and Cumberland Islands. A follow up monthly or quarterly collection study was carried out on two of the sites, a barrier beach and estuarine marsh, to determine accumulation rate in 8000m2 areas. Accumulation rates ranged from 0.18 to 1.28kg/30days–8000m2 on the barrier island beach and from 0.6 to 1.61kg/30days–8000m2 at the estuarine marsh site. The major type of plastics, e.g. bottles, food wrappers, plastic fragments, was highly variable at different seasons and sites. The authors recommend consideration of a standardization in reporting plastic debris, with respect to quantitation of debris and sample area.
显示更多 [+] 显示较少 [-]Mapping elements distribution in carapace of Caretta caretta: A strategy for biomonitoring contamination in sea turtles?
2015
Mattei, D. | Veschetti, E. | D’Ilio, S. | Blasi, M.F.
This study analyzed the carapace distribution of Ca, Cd, Cr, Cu, Mg, Mn, Pb, Sb, U, V and Zn by GF-AAS and ICP-AES in one specimen of Caretta caretta from Mediterranean Sea. Calcium, Mg, Mn, Pb, U, Zn were mainly distributed in the central area while Cd, Cr, Cu, Sb, V in lateral areas. Cadmium, Cr, Mg, Mn, Sb, U and V were different between lateral areas.The different distribution may be related to several exposures during lifetime and/or the shell ossification during growth. Carapace may be a suitable matrix for metal biomonitoring, however, further studies are required to confirm these findings.
显示更多 [+] 显示较少 [-]Stable isotope variations in benthic primary producers along the Bosphorus (Turkey): A preliminary study
2015
Calizza, Edoardo | Aktan, Yelda | Costantini, Maria Letizia | Rossi, Loreto
The Bosphorus Strait is a dynamic and complex system. Recent evidences showed nitrogen and heavy metal concentrations to follow opposite patterns across the Strait, suggesting a complex spatial organisation of the anthropogenic disturbance in this system. Here, we provide isotopic information on the origin and transportation of dissolved nitrogen along the Bosphorus. C and N isotopic and elemental analyses were performed on specimens of Ulva lactuca and associated epiphytes sampled in five locations across the Strait. Variations in C and N isotopic signatures were observed in U. lactuca, pointing to a decrease in the availability of anthropogenic organic dissolved nitrogen along a north-south direction. Conversely, epiphytes did not show isotopic or elemental patterns across the Strait. These results suggest that preliminary stable isotope surveys in extended costal systems basing on U. lactuca can represent a valuable tool to focus meaningful targets and hypotheses for pollution studies in the Mediterranean region.
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