خيارات البحث
النتائج 1251 - 1260 من 4,042
Synthetic fibers in atmospheric fallout: A source of microplastics in the environment? النص الكامل
2016
Dris, Rachid | Gasperi, Johnny | Saad, Mohamed | Mirande, Cécile | Tassin, Bruno
Sources, pathways and reservoirs of microplastics, plastic particles smaller than 5mm, remain poorly documented in an urban context. While some studies pointed out wastewater treatment plants as a potential pathway of microplastics, none have focused on the atmospheric compartment. In this work, the atmospheric fallout of microplastics was investigated in two different urban and sub-urban sites. Microplastics were collected continuously with a stainless steel funnel. Samples were then filtered and observed with a stereomicroscope. Fibers accounted for almost all the microplastics collected. An atmospheric fallout between 2 and 355particles/m2/day was highlighted. Registered fluxes were systematically higher at the urban than at the sub-urban site. Chemical characterization allowed to estimate at 29% the proportion of these fibers being all synthetic (made with petrochemicals), or a mixture of natural and synthetic material. Extrapolation using weight and volume estimates of the collected fibers, allowed a rough estimation showing that between 3 and 10 tons of fibers are deposited by atmospheric fallout at the scale of the Parisian agglomeration every year (2500km2). These results could serve the scientific community working on the different sources of microplastic in both continental and marine environments.
اظهر المزيد [+] اقل [-]Polycyclic aromatic hydrocarbons in surface sediments and marine organisms from the Daya Bay, South China النص الكامل
2016
Sun, Run-Xia | Lin, Qin | Ke, Chang-Liang | Du, Fei-Yan | Gu, Yang-Guang | Fanhuolaoren, | Luo, Xiao-Jun | Mai, Bi-Xian
Polycyclic aromatic hydrocarbons (PAHs) were investigated in the marine ecosystem of the Daya Bay, South China. The PAH concentrations ranged from 340 to 710ng/g dry weight in the sediments and from 110 to 520ng/g wet weight in marine organisms, respectively. The dominant compounds were three- and four-ring PAHs in the sediments (53%–89%) and two- and three-ring PAHs in the marine species (67%–94%), respectively. PAHs mainly originated from both pyrolytic and petrogenic sources. Comparison with the effects-based sediment quality guideline values suggested that the ecological risk caused by the total PAHs was relatively low (less than 25% incidence of adverse effects) in the sedimentary environment. The median cancer risk level via seafood consumption (1.6×10−5 for urban residents and 1.2×10−5 for rural residents, respectively) was slightly higher than the maximum admissible level (10−5) set by US EPA, but lower than the priority risk level (10−4).
اظهر المزيد [+] اقل [-]Is the way an oil spill response is reported in the media important for the final perception of the clean-up? النص الكامل
2016
Chilvers, B.L. | Finlayson, G. | Ashwell, D. | Low, S.I. | Morgan, K.J. | Pearson, H.E.
This research investigates the media coverage during the C/V Rena grounding in New Zealand (NZ), in 2011, to analyze if information reported in printed media is important for the final perception of the overall oil spill response. We took all articles available from NZ's largest circulated newspaper and the regional newspaper closest to the incident and analyzed the themes within each article; the article's tone (positive, neutral or negative); the time of the report relative to incident events and any differences between the regional and national papers. This analysis indicates that oil spills are reported and perceived as inherently negative incidents. However, along with coordinating an effective spill response, fast, factual and frequent media releases and increased effect in media liaison in areas of response with high public intrinsic value such as oiled wildlife response can significantly influence tone of media coverage and likely overall public perception.
اظهر المزيد [+] اقل [-]Decadal increase in the number of recreational users is concentrated in no-take marine reserves النص الكامل
2016
Gonson, Charles | Pelletier, Dominique | Gamp, Elodie | Preuss, Bastien | Jollit, Isabelle | Ferraris, Jocelyne
Decadal increase in the number of recreational users is concentrated in no-take marine reserves النص الكامل
2016
Gonson, Charles | Pelletier, Dominique | Gamp, Elodie | Preuss, Bastien | Jollit, Isabelle | Ferraris, Jocelyne
In coastal areas, demographic increase is likely to result in greater numbers of recreational users, with potential consequences on marine biodiversity. These effects may also occur within Marine Protected Areas (MPAs), which are popular with recreational users. Our analysis builds on data collected over a ten-year period during three year-round surveys to appraise changes in recreational boating activities in coral ecosystems. Results show that the number of boaters has greatly increased, particularly so within MPAs during weekends and the warm season, when peaks in boat numbers have become more frequent. We also observed that the number of anchored boats has increased over the period. These changes may be resulting in biophysical impacts that could be detrimental to conservation objectives in MPAs. This steady increase over time may cause changes in the spatial and temporal distribution of users and in their practices, thus highlighting the importance of monitoring recreational activities.
اظهر المزيد [+] اقل [-]Decadal increase in the number of recreational users is concentrated in no-take marine reserves النص الكامل
2016
Gonson, Charles | Pelletier, Dominique | Gamp, Elodie | Preuss, Bastien | Jollit, Isabelle | Ferraris, Jocelyne
In coastal areas, demographic increase is likely to result in greater numbers of recreational users, with potential consequences on marine biodiversity. These effects may also occur within Marine Protected Areas (MPAs), which are popular with recreational users. Our analysis builds on data collected over a ten-year period during three year-round surveys to appraise changes in recreational boating activities in coral ecosystems. Results show that the number of boaters has greatly increased, particularly so within MPAs during weekends and the warm season, when peaks in boat numbers have become more frequent. We also observed that the number of anchored boats has increased over the period. These changes may be resulting in biophysical impacts that could be detrimental to conservation objectives in MPAs. This steady increase over time may cause changes in the spatial and temporal distribution of users and in their practices, thus highlighting the importance of monitoring recreational activities.
اظهر المزيد [+] اقل [-]The biodegradation of crude oil in the deep ocean النص الكامل
2016
Prince, Roger C. | Nash, Gordon W. | Hill, Stephen J.
Oil biodegradation at a simulated depth of 1500m was studied in a high-pressure apparatus at 5°C, using natural seawater with its indigenous microbes, and 3ppm of an oil with dispersant added at a dispersant:oil ratio of 1:15. Biodegradation of the detectable hydrocarbons was prompt and extensive (>70% in 35days), although slower by about a third than under otherwise identical conditions equivalent to the surface. The apparent half-life of biodegradation of the total detectable hydrocarbons at 15MPa was 16days (compared to 13days at atmospheric pressure), although some compounds, such as the four-ring aromatic chrysene, were degraded rather more slowly.
اظهر المزيد [+] اقل [-]Purification and characterization of biosurfactant produced by Bacillus licheniformis Y-1 and its application in remediation of petroleum contaminated soil النص الكامل
2016
Liu, Boqun | Liu, Jinpeng | Ju, Meiting | Li, Xiaojing | Yu, Qilin
In our previous research, a petroleum degrading bacteria strain Bacillus licheniformis Y-1 was obtained in Dagang Oilfield which had the capability of producing biosurfactant. This biosurfactant was isolated and purified in this work. The biosurfactant produced by strain Y-1 had the capability to decrease the surface tension of water from 74.66 to 27.26mN/m, with the critical micelle concentration (CMC) of 40mg/L. The biosurfactant performed not only excellent stabilities against pH, temperature and salinity, but also great emulsifying activities to different kinds of oil, especially the crude oil. According to the results of FT-IR spectrum and 1H NMR spectrum detection, the surfactant was determined to be a cyclic lipopeptide. Furthermore, through the addition of surfactant, the effect of petroleum contaminated soil remediation by fungi got a significant improvement.
اظهر المزيد [+] اقل [-]Determination of microcystin-LR in clams (Tapes decussatus) of two Sardinian coastal ponds (Italy) النص الكامل
2016
Sedda, Tiziana | Baralla, Elena | Varoni, Maria Vittoria | Pasciu, Valeria | Lorenzoni, Giuseppa | Demontis, Maria Piera
The presence of microcystin-LR (MC-LR) was monitored in Tapes decussatus harvested in two Sardinian ponds (Cabras and Tortolì, Italy) in spring and summer. After solid phase extraction, samples were analyzed using a screening enzyme-linked immunosorbent assay (ELISA) followed by a liquid chromatographic coupled to tandem mass spectrometer (LC–MS/MS) analysis. Results obtained through the ELISA test showed the presence of microcystins with a maximum concentration in August for Cabras pond (0.55ng/g) and in September for Tortolì pond (0.85ng/g). The LC–MS/MS analysis did not confirm the presence of MC-LR suggesting that results obtained with the ELISA technique could be due to the presence of other microcystins. According to the tolerable daily intake suggested by the World Health Organization, these results hint that clams harvested in these ponds are safe for human health. These data can contribute to enrich the knowledge about the healthiness of Sardinian ponds and of their products.
اظهر المزيد [+] اقل [-]Landsat 8-based inversion methods for aerosol optical depths in the Beijing area النص الكامل
2016
Ou, Yang | Chen, Fantao | Zhao, Wenji | Yan, Xing | Zhang, Qianzhong
As an essential component of the Earth-atmosphere system, aerosols have important impacts on the atmospheric environment and human health. Based on the data sourced from Landsat 8 satellite images, the goal of this paper is to retrieve aerosol optical depth (AOD) in the Beijing area by means of the MODIS Dark Target (DT) Method and the visible near-infrared (VNIR) atmospheric correction method (ACM), of which the accuracy is verified by observation data from AERONET. Furthermore, analysis was conducted to assess the effects of the two specific inversion methods on AOD values and AOD distribution characteristics in Beijing. The results indicate the following: 1) both the DT method and the VNIR method can be used successfully in the inversion of AOD in Beijing with Landsat 8 satellite data, while the DT method generates a slightly higher accuracy than that of the VNIR method, in which the root mean squared error (RMSE) values are 0.195 and 0.282, respectively; 2) AOD distribution in Beijing is presented with significant regional features, in which the areas with high AOD values were mainly concentrated in six districts (Dongcheng, Xicheng, Chaoyang, Fengtai, Haidian, and Shijingshan) and their surrounding areas. In addition, the AOD values are relatively low in the southwestern and northern regions of Beijing, which was mainly due to minor impacts of human activity and transportation.
اظهر المزيد [+] اقل [-]A reduced form model for ozone based on two decades of CMAQ simulations for the continental United States النص الكامل
2016
Porter, P Steven | Rao, S.T. | Hogrefe, Christian | Mathur, Rohit
A Reduced Form Model (RFM) is a mathematical relationship between the inputs and outputs of an air quality model, permitting estimation of additional modeling without costly new regional-scale simulations. A 21-year Community Multiscale Air Quality (CMAQ) simulation for the continental United States provided the basis for the RFM developed in this study. Predictors included the principal component scores (PCS) of emissions and meteorological variables, while the predictand was the monthly mean of daily maximum 8-h CMAQ ozone for the ozone season at each model grid. The PCS form an orthogonal basis for RFM inputs. A few PCS incorporate most of the variability of emissions and meteorology, thereby reducing the dimensionality of the source-receptor problem. Stochastic kriging was used to estimate the model.The RFM was used to separate the effects of emissions and meteorology on ozone concentrations. By running the RFM with emissions constant (ozone dependent on meteorology), or constant meteorology (ozone dependent on emissions). Years with ozone-conducive meteorology were identified, and meteorological variables best explaining meteorology-dependent ozone were identified. Meteorology accounted for 19%–55% of ozone variability in the eastern US, and 39%–92% in the western US. Temporal trends estimated for original CMAQ ozone data and emission-dependent ozone were mostly negative, but the confidence intervals for emission-dependent ozone are much narrower. Emission-driven changes in monthly mean ozone levels for the period 2000–2010 ranged from 6.4 to 10.9 ppb for the eastern US and from 1.4 to 2.5 ppb for the western US.
اظهر المزيد [+] اقل [-]Difference analysis of the relationship between household per capita income, per capita expenditure and per capita CO2 emissions in China: 1997–2014 النص الكامل
2016
Dong, Yiman | Zhao, Tao
Driven by the buoyancy of economy and continuous improvement of people's living standards, residential sector has gradually become the second largest CO2 emissions source in China. Reducing the fast rising rate of CO2 emissions in this sector is essential for realizing the target of carbon emission mitigation in China. The researches on the driving factors of residential CO2 emissions have attracted scholars' attention recently, yet few studies can interpret the causality relationship between household per capita income-expenditure-CO2 emissions at national and regional levels. Based on econometric techniques and a panel data set, this paper presents an investigation of the causality relationship, which combines household per capita income, per capita expenditure and per capita CO2 emissions (hereafter referred to as PI, PE, and CE, respectively) on a national level and within three regions (namely, eastern, central, and western regions of China) from 1997 to 2014. Urban and rural areas are considered as well. The empirical results manifest a varied causality relationship in different regions. For example, PI and PE correspond to CE in eastern rural area, but this phenomenon does not occur in central rural area. In addition, urban and rural differences are displayed. There is no causality between PI and PE in western urban area, while a bidirectional causal relationship emerges in PI and PE for western rural area. Finally, this study proposes some policy implications to decrease the increase rate of household CO2 emissions in China.
اظهر المزيد [+] اقل [-]