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Результаты 1341-1350 из 3,991
Natural mitigation factor adjustment for re-suspended particulate matter emissions inventory for Bogotá, Colombia
2016
Pérez, María Paula | Henderson, Barron H. | Nedbor-Gross, Robert | Pachón, Jorge E.
This work improves atmospheric emissions of particulate matter in Bogotá Colombia, and provides a tool applying this technique around the world. Bogotá's air pollution is largely impacted by particulate matter, and specifically by re-suspended particulate matter (RPM). RPM sources include paved and unpaved roads, agricultural tilling, construction activities, mining and quarrying. RPM emissions are frequently estimated using annual emission factors, time-varying vehicle traffic activity, a time/space invariant meteorological scaling factor, and a time/space invariant correction factor. This work updates the meteorological factors to be hour-specific, and replacing the correction factor with land use-specific local deposition factors. These techniques are codified in a flexible Python tool based on EPA's AP42 methods and the broader emission literature.Meteorology inhibits RPM emission directly via precipitation scavenging and indirectly by accumulation of road surface moisture. The effects of precipitation and surface moisture are parameterized as mitigation factors differently for paved and unpaved roads due to their porosity and drainage characteristics.These estimates of hourly mitigation factors (on average for paved roads: 0.86 and for unpaved roads: 0.61) agree well with annual factors previously used (paved: 0.90; unpaved: 0.60), however hourly factors have clear diurnal patterns that reduce emissions more significantly latter in the day for paved roads (00–12: 0.95; 12–24: 0.78), and to a lesser extent for unpaved roads (00–12: 0.64; 12–24: 0.58).Emissions are also significantly reduced by vehicle induced turbulence and local deposition. The transportable fraction (0.59 ± 0.22), parameterized based on land use, significantly reduced emissions and correlates with unpaved roads (r = 0.30) more so than with paved roads (r = 0.02). These fractions were used to construct a new inventory, which might improve air pollution predictions compared to the raw inventory, as well as new efforts to simulate exposure fields in Bogotá and our understanding of local particulate sources and sinks.
Показать больше [+] Меньше [-]Research on carbon emissions embodied in trade between China and South Korea
2016
Yang, Yu | Fei-fan, Chen
With the signature of the free trade agreement, trade ties will develop rapidly between China and South Korea. Based on input–output model, this paper calculates and decomposes the embodied carbon emissions in the trade between China and South Korea from 2000 to 2010, analyses the reasons and gives some future advices. This paper suggests that the embodied carbon emissions surplus is not caused by trade surplus. It further points out that textile and leather industries, chemical manufacturing industries and metal manufacturing industries are three main sectors contributing to imported and exported embodied carbon emissions. In addition, the trade diversion between China and South Korea helps a lot in reducing the global carbon emissions and eases the pressure of carbon emissions in China. This paper also proposes that China should learn advanced technologies from South Korea and reduce carbon-intensive energy consumption in the future.
Показать больше [+] Меньше [-]Identifications and seasonal variations of sources of polycyclic aromatic hydrocarbons (PAHs) in the Yangtze River Estuary, China
2016
Yu, Wenwen | Liu, Ruimin | Xu, Fei | Men, Comg | Shen, Zhenyao
In this study, positive matrix factorization models (PMFx) were used to analyze the sources of sedimentary PAHs in Yangtze River Estuary (YRE) using 120 data samples from 30 sites collected over four seasons. Three sources were defined for the PAHs: coal and gasoline combustion was the dominant source, accounting for approximately 50%; coke plant emissions and wood or grass combustion each contributed approximately 25%. The coal tar origin was the major source in summer; wood or grass combustion dominated in autumn; coal combustion was the primary source of PAHs in spring and winter. More than 90% of the coke plant emissions were from summer, while pollutants from wood or grass combustion were discharged primarily in autumn. These three sources distributed in different primary regions, the spatial patterns of coal combustion presented an increasing trend in the seaward direction.
Показать больше [+] Меньше [-]Trace metal contamination in surface sediments of intertidal zone from Qinhuangdao, China, revealed by geochemical and magnetic approaches: Distribution, sources, and health risk assessment
2016
Zhu, Zongmin | Xue, Junhui | Deng, Yuzhen | Chen, Lin | Liu, Jiangfeng
Based on geochemical and magnetic approaches, the distribution, sources, and health risk of trace metals in surface sediments from a seashore tourist city were investigated. A significant correlation was found between magnetic susceptibility (χ) and trace metals, which suggested that levels of trace metals in the sediments can be effectively depicted by the magnetic approach. The spatial distribution of χ and trace metals matched well with the city layout with relatively higher values being found in the port and busy tourist areas. This result, together with enrichment factors (EFs) and Tomlinson pollution load index (PLI) of metals, suggested that the influence of human activities on the coastal environment was noticeable. Principal component analysis (PCA) indicated that trace metals in the sediments were derived from both anthropogenic and natural sources. Noncarcinogenic risk assessment showed that there was no potential health risk of exposure to metals by means of ingestion or inhalation.
Показать больше [+] Меньше [-]Bioavailable metals in tourist beaches of Richards Bay, Kwazulu-Natal, South Africa
2016
Vetrimurugan, E. | Jonathan, M.P. | Roy, Priyadarsi D. | Shruti, V.C. | Ndwandwe, O.M.
Acid Leachable Trace Metal (ALTMs) concentrations in tourist beaches of Richards Bay, Kwazulu-Natal, South Africa were assessed. 53 surface sediment samples were collected from five different beaches (Kwambonambi Long Beach; Nhlabane Beach; Five Mile Beach; Alkanstrand Beach and Port Durnford Beach). The results of ALTMs (Fe, Mn, Cr, Cu, Ni, Co, Pb, Cd, Zn, As, Hg) suggest that they are enriched naturally and with some local industrial sources for (avg. in μgg−1) Fe (3530–7219), Mn (46–107.11), Cd (0.43–1.00) and Zn (48–103.98). Statistical results indicate that metal concentrations were from natural origin attributed to leaching, weathering process and industrial sources. Comparative studies of metal concentrations with sediment quality guidelines and ecotoxicological values indicate that there is no adverse biological effect. Enrichment factor and geoaccumulation indices results indicate moderate enhancement of Fe (Igeo class 1 in FMB), Cd (EF>50; Igeo classes 2–4) and Zn (Igeo classes 1 & 2).
Показать больше [+] Меньше [-]Communication masking in marine mammals: A review and research strategy
2016
Erbe, Christine | Reichmuth, Colleen | Cunningham, Kane | Lucke, Klaus | Dooling, Robert
Underwater noise, whether of natural or anthropogenic origin, has the ability to interfere with the way in which marine mammals receive acoustic signals (i.e., for communication, social interaction, foraging, navigation, etc.). This phenomenon, termed auditory masking, has been well studied in humans and terrestrial vertebrates (in particular birds), but less so in marine mammals. Anthropogenic underwater noise seems to be increasing in parts of the world's oceans and concerns about associated bioacoustic effects, including masking, are growing. In this article, we review our understanding of masking in marine mammals, summarise data on marine mammal hearing as they relate to masking (including audiograms, critical ratios, critical bandwidths, and auditory integration times), discuss masking release processes of receivers (including comodulation masking release and spatial release from masking) and anti-masking strategies of signalers (e.g. Lombard effect), and set a research framework for improved assessment of potential masking in marine mammals.
Показать больше [+] Меньше [-]The usage of visual indicators in regulatory monitoring at hard-bottom finfish aquaculture sites in Newfoundland (Canada)
2016
Hamoutene, Dounia | Salvo, Flora | Donnet, Sebastien | Dufour, Suzanne C.
Finfish aquaculture can be installed over hard and patchy substrates where grab sampling is challenging and use of video can be an appropriate tool to document benthic changes. Video monitoring can show visual indicators of enrichment, namely flocculent matter, Beggiatoa-like mats, and opportunistic polychaete complexes (OPC). We examined factors influencing presence of indicators using 52 video monitoring reports collected in Newfoundland, Canada. The main driving factor was distance to cage, with indicators showing a higher probability of occurrence within 10m from cages due to low current velocities. Indicators were less prevalent on sites dominated by hard substrates while OPC in particular were restricted to depths >35m. Beggiatoa-like bacteria covered a larger surface than the two other indicators; however, our results suggest the necessity of amalgamating information related to all the indicators (including bare stations that could indicate anoxia) to establish a more accurate evaluation of aquaculture impact.
Показать больше [+] Меньше [-]On some physical and dynamical properties of microplastic particles in marine environment
2016
Chubarenko, I. | Bagaev, A. | Zobkov, M. | Esiukova, E.
Simplified physical models and geometrical considerations reveal general physical and dynamical properties of microplastic particles (0.5–5mm) of different density, shape and size in marine environment. Windage of extremely light foamed particles, surface area and fouling rate of slightly positively buoyant microplastic spheres, films and fibres and settling velocities of negatively buoyant particles are analysed. For the Baltic Sea dimensions and under the considered idealised external conditions, (i) only one day is required for a foamed polystyrene particle to cross the sea (ca. 250km); (ii) polyethylene fibres should spend about 6–8months in the euphotic zone before sinking due to bio-fouling, whilst spherical particles can be retained on the surface up to 10–15years; (iii) for heavy microplastic particles, the time of settling through the water column in the central Gotland basin (ca. 250m) is less than 18h. Proper physical setting of the problem of microplastics transport and developing of physically-based parameterisations are seen as applications.
Показать больше [+] Меньше [-]Origins of suspended particulate matter based on sterol distribution in low salinity water mass observed in the offshore East China Sea
2016
Kim, Moonkoo | Jung, Jee-hyun | Jin, Yongnu | Han, Gi Myeong | Lee, Taehee | Hong, Sang Hee | Yim, Un Hyuk | Shim, Won Joon | Choi, Dong-Lim | Kannan, Narayanan
The molecular composition and distribution of sterols were investigated in the East China Sea to identify the origins of suspended particulate matter (SPM) in offshore waters influenced by Changjiang River Diluted Water (CRDW). Total sterol concentrations ranged from 3200 to 31,900pgL−1 and 663 to 5690pgL−1 in the particulate and dissolved phases, respectively. Marine sterols dominated representing 71% and 66% in the particulate and dissolved phases, respectively. Typical sewage markers, such as coprostanol, were usually absent at ~250km offshore. However, sterols from allochthonous terrestrial plants were still detected at these sites. A negative relationship was observed between salinity and concentrations of terrestrial sterols in SPM, suggesting that significant amounts of terrestrial particulate matter traveled long distance offshore in the East China Sea, and the Changjiang River Diluted Water (CRDW) was an effective carrier of land-derived particulate organic matter to the offshore East China Sea.
Показать больше [+] Меньше [-]Coral Sr/Ca-based sea surface temperature and air temperature variability from the inshore and offshore corals in the Seribu Islands, Indonesia
2016
Cahyarini, Sri Yudawati | Zinke, Jens | Troelstra, Simon | Suharsono, | Aldrian, Edvin | Hoeksema, B.W.
The ability of massive Porites corals to faithfully record temperature is assessed. Porites corals from Kepulauan Seribu were sampled from one inshore and one offshore site and analyzed for their Sr/Ca variation. The results show that Sr/Ca of the offshore coral tracked SST, while Sr/Ca variation of the inshore coral tracked ambient air temperature. In particular, the inshore SST variation is related to air temperature anomalies of the urban center of Jakarta. The latter we relate to air—sea interactions modifying inshore SST associated with the land-sea breeze mechanism and/or monsoonal circulation. The correlation pattern of monthly coral Sr/Ca with the Niño3.4 index and SEIO-SST reveals that corals in the Seribu islands region respond differently to remote forcing. An opposite response is observed for inshore and offshore corals in response to El Niño onset, yet similar to El Niño mature phase (December to February). SEIO SSTs co-vary strongly with SST and air temperature variability across the Seribu island reef complex. The results of this study clearly indicate that locations of coral proxy record in Indonesia need to be chosen carefully in order to identify the seasonal climate response to local and remote climate and anthropogenic forcing.
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