خيارات البحث
النتائج 1321 - 1330 من 4,029
Effect of enhanced reactive nitrogen availability on plant-sediment mediated degradation of polycyclic aromatic hydrocarbons in contaminated mangrove sediment
2016
Jiang, Shan | Lu, Haoliang | Zhang, Qiong | Liu, Jingchun | Yan, Chongling
As land–ocean interaction zones, mangrove systems receive substantial polycyclic aromatic hydrocarbons (PAHs) from sewage and combustion of fossil fuel. In this study, we investigated the relationship between dissolved inorganic nitrogen (DIN) availability and degradation rate of phenanthrene, a typical PAH compound, in mangrove plant-sediment systems, using Avicennia marina as a model plant. After 50day incubation, phenanthrene removal ratios in sediments ranged from 53.8% to 97.2%. In non-rhizosphere sediment, increasing DIN accessibility increased microbial biomass and total microbial activity, while enhancements in population size of phenanthrene degradation bacteria (PDB) and phenanthrene degradation rates were insignificant. In contrast, the presence of excessive DIN in rhizosphere sediment resulted in a significantly large number of PDB, leading to a rapid dissipation rate of phenanthrene. The differences in degradation rates and abundances of degrader in sediment may be explained by the enhanced root activity due to the elevation in DIN accessibility.
اظهر المزيد [+] اقل [-]Loss and self-restoration of macrobenthic diversity in reclamation habitats of estuarine islands in Yangtze Estuary, China
2016
Lv, Weiwei | Liu, Zhiquan | Yang, Yang | Huang, Youhui | Fan, Bin | Jiang, Qichen | Zhao, Yunlong
In this study, macrobenthic diversity data were collected from intertidal habitats of island wetlands in Yangtze Estuary before and after reclamation. Three survey regions based on habitat features were investigated: protected region, normal region, and self-restored region. The pattern of diversity variation showed a sharp decrease in reclamation sites and an obvious increase in vegetated sites of the self-restored region before and after reclamation. A declining trend in habitat health was observed in reclamation sites, but the degree of perturbation was relatively weaker in protected region than in normal region. The vegetated site showed a better self-restoration of biodiversity than the bald site. These results suggest that reclamation may have a negative influence on biodiversity and habitat health status in the intertidal wetland. Also, there is a possibility of self-restoration in tidal flats disturbed by reclamation and the resistance effect in nature reserve may reduce the disturbances resulting from reclamation.
اظهر المزيد [+] اقل [-]The effects of urbanization and household-related factors on residential direct CO2 emissions in Shanxi, China from 1995 to 2014: A decomposition analysis
2016
Zang, Xueling | Zhao, Tao | Wang, Juan | Guo, Fang.
Multiple household-related driving factors of residential direct carbon emissions (RDCE) in China at regional level have not yet been sufficiently addressed or quantified. In this paper, a logarithmic mean Divisia index (LMDI) decomposition analysis was employed to examine the factors (e.g., the number of households, per capita household income, household size, urbanization, energy intensity, energy structure and emission coefficient) impacting the changes in RDCE in Shanxi province of China from 1995 to 2014. The results showed that the increase in RDCE mainly attributed to the growing per capita household income and the increasing number of households. Additionally, the expansion of urbanization also contributed marginally to the increase in emissions. However, the shrinking household size was a main inhibitory factor and the decline in energy intensity was also responsible for the diminishing emissions. Based on the results, four emission reduction measures and strategies were identified: (i) using market economic mechanism to regulate household consumption behaviors towards environment protection and low carbon development, as well as encouraging the use of energy-efficiency domestic appliances and less energy-intensive lifestyles; (ii) setting strict divorce processes to lower divorce rates and encouraging people to live with their children and parents; (iii) realizing green transformation development of urbanization; (iv) promoting a shift to renewable and clean energy in people's daily life and power generation, e.g., wind, solar, hydro, nuclear and biogas.
اظهر المزيد [+] اقل [-]Biodegradation potentiality of psychrophilic bacterial strain Oleispira antarctica RB-8T
2016
Gentile, G. | Bonsignore, M. | Santisi, S. | Catalfamo, M. | Giuliano, L. | Genovese, L. | Yakimov, M.M. | Denaro, R. | Genovese, M. | Cappello, S.
The present study is focused on assessing the growth and hydrocarbon-degrading capability of the psychrophilic strain Oleispira antarctica RB-8T. This study considered six hydrocarbon mixtures that were tested for 22days at two different cultivation temperatures (4 and 15°C). During the incubation period, six sub-aliquots of each culture at different times were processed for total bacterial abundance and GC–FID (gas chromatography–flame ionization detection) hydrocarbon analysis.Results from DNA extraction and DAPI (4′,6-diamidino-2-phenylindole) staining showed a linear increase during the first 18days of the experiment in almost all the substrates used; both techniques showed a good match, but the difference in values obtained was approximately one order of magnitude. GC–FID results revealed a substantial hydrocarbon degradation rate in almost all hydrocarbon sources and in particular at 15°C rather than 4°C (for commercial oil engine, oily waste, fuel jet, and crude oil). A more efficient degradation was observed in cultures grown with diesel and bilge water at 4°C.
اظهر المزيد [+] اقل [-]Heavy metals in river and coast sediments of the Jakarta Bay region (Indonesia) — Geogenic versus anthropogenic sources
2016
Sindern, Sven | Tremöhlen, Martin | Dsikowitzky, Larissa | Gronen, Lars | Schwarzbauer, Jan | Siregar, Tuti Hartati | Ariyani, Farida | Irianto, Hari Eko
Sediment geochemistry of the Jakarta region, a densely populated tropical coast, is studied — with particular focus on rivers discharging to Jakarta Bay. Weathering volcanics in the river catchment area control the composition of major elements, As, Cr and in part Cu. In contrast, Zn, Ni, Pb and partly Cu are affected by anthropogenic sources, mainly in central Jakarta City. The data reflect a high variability of local emission sources, among which metal processing industries, fertilizers or untreated animal waste may be important. In particular, the role of street dusts is emphasized. Locally, heavy metals reach levels considered to have adverse biological effects. River discharge leads to anthropogenic enrichment of heavy metals in the coastal sediments. Element data also show geogenic effects on the composition of the coastal sediments, such as mixing of detrital silicates with biogenic carbonates as well as suspended particulate matter from the ocean.
اظهر المزيد [+] اقل [-]Assessment of bioavailable hydrocarbons in Pribilof Island rock sandpiper fall staging areas and overwintering habitat
2016
Nesvacil, Kelly | Carls, Mark | Holland, Larry | Wright, Sadie
At present, significant adverse hydrocarbon influence on the Pribilof Island rock sandpiper (Calidris ptilocnemis ptilocnemis) is unlikely. Almost the entire population overwinters in Cook Inlet and breeds on four Bering Sea islands. Passive samplers deployed several times in a three year period and corresponding sediment and soft tissue samples on St. Paul Island and in Cook Inlet generally accumulated small quantities of polycyclic aromatic hydrocarbons (PAHs). Composition was consistent with oil in <15% of the passive samplers and rarely in soft tissue. Total PAH concentrations in corresponding sediment were very low (<42ng/g dry weight); composition was consistent with oil in 39% of these samples and biomarker composition confirmed this on St. Paul Island. However, composition was dominated by normal alkanes from natural sources.
اظهر المزيد [+] اقل [-]The exposure of pedestrians, drivers and road transport passengers to nitrogen dioxide
2016
Żak, Magdalena | Melaniuk-Wolny, Edyta | Widziewicz, Kamila
People travelling by road transport are exposed to high levels of nitrogen oxides (NOx), that are considered to be one of the primary pollutants from motor vehicles. This study examines the exposure of drivers, passengers and pedestrians to NO2 during different trip scenarios: travelling by private or public means of transport, along the major commuter routes in one of the biggest Polish agglomerations - Silesia Agglomeration, and other important communication routes in Poland, as well as during walks in both city centers and residential areas. The NO2 samples were collected in cars, trucks and buses interiors, as well as in the ambient air by passive samplers and next NO2 concentrations were analyzed by means of the spectrophotometric technique. The obtained results indicate that travelling by cars through city centers is associated with the exposure to NO2 concentrations of about 15% higher than in the case of travelling suburban routes; 33% greater than travelling by bus in urban traffic; more than app. 60% higher than in the case of travelling by bus in suburban traffic or by foot in city centers and up to 80% higher than moving on foot near little-used roads. The exposure profile of six groups of road users exposed to NO2 was therefore determined in this study. The obtained results could be used by policy makers to minimize the exposure to transportation-related pollutants concentrations and for planning far-reaching changes in the field of urban road transport.
اظهر المزيد [+] اقل [-]Regional variability in bed-sediment concentrations of wastewater compounds, hormones and PAHs for portions of coastal New York and New Jersey impacted by hurricane Sandy
2016
Phillips, Patrick J. | Gibson, Catherine A. | Fisher, Shawn C. | Fisher, Irene J. | Reilly, Timothy J. | Smalling, Kelly L. | Romanok, Kristin M. | Foreman, William T. | ReVello, Rhiannon C. | Focazio, Michael J. | Jones, Daniel K.
Bed sediment samples from 79 coastal New York and New Jersey, USA sites were analyzed for 75 compounds including wastewater associated contaminants, PAHs, and other organic compounds to assess the post-Hurricane Sandy distribution of organic contaminants among six regions. These results provide the first assessment of wastewater compounds, hormones, and PAHs in bed sediment for this region. Concentrations of most wastewater contaminants and PAHs were highest in the most developed region (Upper Harbor/Newark Bay, UHNB) and reflected the wastewater inputs to this area. Although the lack of pre-Hurricane Sandy data for most of these compounds make it impossible to assess the effect of the storm on wastewater contaminant concentrations, PAH concentrations in the UHNB region reflect pre-Hurricane Sandy conditions in this region. Lower hormone concentrations than predicted by the total organic carbon relation occurred in UHNB samples, suggesting that hormones are being degraded in the UHNB region.
اظهر المزيد [+] اقل [-]Underwater soundscape of marine protected areas in the south Brazilian coast
2016
Sánchez-Gendriz, I. | Padovese, L.R.
The Laje de Santos Marine State Park (LSMSP) and Xixová-Japuí State Park (XJSP) are two protected areas (PA), close to the Santos Bay in the south Brazilian coast. The region encompasses both important biodiversity and anthropogenic activities. This study aims to serve as a first reference survey of the underwater soundscape of these PAs. Additionally it evaluates the presence of the anthropogenic and biological sound in these areas. One month of continuous recorded underwater sound, at selected locations in XJSP and LSMSP, is used in this study. The data were characterized by its spectral content and by the temporal evolution of Sound Pressure Levels (SPL). Both locations showed sound events with daily periodicities, mainly related with boats and fish chorus.
اظهر المزيد [+] اقل [-]Anthropogenic influences on aerosols at Ny-Ålesund in the summer Arctic
2016
Zhan, Jianqiong | Li, Wei | Chen, Liqi | Lin, Qi | Gao, Yuan
The Arctic atmosphere has been disturbed by human activities. To improve the understanding of anthropogenic influences, major ionic species and carbonaceous components were measured at Ny-Ålesund in July 2012. The results suggested that Na+ and Cl− are the dominant water soluble inorganic species, accounting for 57 ± 17% of the mass of measured ionic species, and 61% of the variance in organic carbon can be explained by oceanic emissions. Aerosols in this area were found to be altered by secondary production involving oxides of sulfur, nitrogen and ammonia from anthropogenic activities, resulting in relative high concentrations of secondary inorganic aerosols (SIA) (such as non-sea salt (nss)-SO42−, NO3− and NH4+), with a mean concentration of 158 ng m−3. SIAs were featured by a mean [NH4+]/[nss-SO42−] ratio of 0.57 and a neutralization ratio (NR) of 0.074, indicating a deficit of NH4+. Thus, the production of particulate NH4 NO3 was strongly limited and SIAs were likely to remain in more acidic forms, NH4HSO4 or H2SO4 rather than as (NH4)2SO4. Chloride depletion of 11%–22% occurred in the samples with high concentrations of excess acidic species (defined as [nss-SO42− + NO3− − NH4+]) and high sea salts. The formation of SIAs and chloride depletion appeared to produce acidic aerosols with a mean pH of 4.51 and high free [H] concentrations of 3.06 ± 0.75 nmol m−3 in aerosols, accounting for 77% of the total [H] concentration. This implies that anthropogenic species could be engaged efficiently in modifying of the properties of aerosols at Ny-Ålesund.
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