خيارات البحث
النتائج 1511 - 1520 من 4,241
Production of sorbent from paper industry solid waste for oil spill cleanup
2017
Demirel Bayık, G. | Altın, A.
The aim of the study is to select a cellulosic waste material from paper industry solid wastes and process it for sorbent production. Four different solid wastes were collected from a local paper production facility and rejects were selected due to its sorption capacity and processability. Oil sorption experiments were conducted according to the ASTM F 726-12 method. Effect of sorbent dosage, contact and dripping time, recovery of the oil, reusability of the sorbent and sorption from the water surface were also determined. Maximum oil sorption capacity was determined as 9.67, 12.92 and 12.84g/g for diesel oil, 0W30 and 10W30 motor oils respectively for the static test and 8.27, 10.45 and 11.69g/g for the dynamic test. An efficient and low-cost sorbent was produced from paper industry rejects that can be used on land and on water.
اظهر المزيد [+] اقل [-]Characteristics of mass concentration, chemical composition, source apportionment of PM2.5 and PM10 and health risk assessment in the emerging megacity in China
2017
Jiang, Nan | Yin, Shasha | Guo, Yue | Li, Jingyi | Kang, Panru | Zhang, Ruiqin | Tang, Xiaoyan
In this study, 228 daily Particulate matter (PM) filters (57 Quartz and 57 Teflon samples for both PM2.5 and PM10, respectively) were collected from an urban site in Zhengzhou in typical months from 2014 autumn to 2015 summer representing the four seasons. PM concentrations, water-soluble inorganic ions, organic carbon, elemental carbon, and elements were determined, and positive matrix factorization was used for source apportionments. Health risks of toxic elements in PM2.5 and PM10 were also evaluated. The annual mean values of PM2.5 and PM10 were higher than the standards in China, and the highest seasonal concentrations of PM2.5 and PM10 were in winter. Secondary inorganic aerosols (SIAs) were the major component, with the ratio of SIAs/PM highest in summer. The seasonal concentrations of SO42− were high in winter and summer. Crustal elements mainly existed in PM2.5–10; however, elements from anthropogenic sources (i.e., Zn, Pb, Cu, As, Cd, and Mo) were more abundant in fine particles than in the coarse fraction. The main pollution sources were dust, SIAs, coal combustion, vehicle and road dust, and industry, accounting for 10%, 26%, 25%, 20% and 15% in PM2.5 and 32%, 14%, 24%, 18% and 8% in PM10, respectively. Dust source has the highest contribution in PM10; however, SIAs source has the highest content in fine particles. The carcinogenic risks of As to children through the daily intake pathway in PM2.5 and PM10 exceeded the acceptable level. Noncarcinogenic risks of As and Cd in PM2.5 and PM10 to children via the daily intake pathway were significant. Moreover, the sum of noncarcinogenic risks in PM10 via inhalation exposure for local residents and that via dermal absorption for children were significant. The details of the pollution characteristics and the results of source apportionments and health risks assessment of PM2.5 and PM10 in this study can play an important role for the government to formulate reasonable and effective policy to mitigate the atmospheric pollution of PM. To our knowledge, this systematic study is the first to investigate the chemical characterizations, source apportionments, and health effects of PM2.5 and PM10 in Zhengzhou.
اظهر المزيد [+] اقل [-]Seasonal circulation assessments of the Northern Arabian/Persian Gulf
2017
Alosairi, Y. | Pokavanich, T.
Due to the continuous human activities linked to economic expansion in the Arabian Gulf area (also known as Persian Gulf), various activities have had an adverse impact on the coastal environment. Furthermore, reduction of precipitation and river flows has resulted in alterations to the hydro-environment regime at various levels. The current study uses a detailed numerical model that was validated with recent field measurements to determine the comprehensive seasonal circulations of the Northern Arabian/Persian Gulf (NAG). The seasons were studied individually using a three-dimensional setup and by considering the baroclinic effects and meteorological forcing. It was found that the NAG exhibits distinctive circulation characteristics each season. In winter, a dense water mass that forms near Kuwait flows toward the southeast near-bed, whereas relatively weak Indian Ocean Surface Waters (IOSW) flow along the Iranian coast and, to a lesser extent, oppose these currents. In spring, the southeast near bed circulations are weaker, while the IOSW is in highest conditions reaching the northern latitudes of the Gulf without being significantly diluted. In summer, a thermocline develops, particularly at the main axis of the NAG, and increases the chances of upwelling. The surface water during this season is significantly controlled by wind. Most distinctive, a non-uniform flow is evident at the offshore regions along the Arabian coast due to strong density gradients. In the fall, the circulations are relatively weaker compared to other seasons; however, cyclonic features are evident at the southeast of the estuary. Well-known counter clockwise circulations NAG are evident throughout the season, but at various strengths; summer is the most active season, while fall is the least active season. In a similar manner, the along shore current varied spatially and temporally throughout the seasons.
اظهر المزيد [+] اقل [-]Superstars: Assessing nutrient thresholds for enhanced larval success of Acanthaster planci, a review of the evidence
2017
Wolfe, Kennedy | Graba-Landry, Alexia | Dworjanyn, Symon A. | Byrne, Maria
Crown-of-thorns starfish, Acanthaster planci (COTS), predation is a major cause of coral reef decline, but the factors behind their population outbreaks remain unclear. Increased phytoplankton food resulting from eutrophication is suggested to enhance larval survival. We addressed the hypothesis that larval success is associated with particular chl-a levels in tightly controlled larval:algal conditions. We used chl-a conditions found on coral reefs (0.1–5.0μgchl-aL−1), including nominal threshold levels for disproportionate larval success (≥1.0μgchl-aL−1). High success to the juvenile occurred across an order of magnitude of chl-a concentrations (0.5–5.0μgchl-aL−1), suggesting there may not be a narrow value for optimal success. Oligotrophic conditions (0.1μgchl-aL−1) appeared to be a critical limit. With a review of the evidence, we suggest that opportunistic COTS larvae may be more resilient to low food levels than previously appreciated. Initiation of outbreak populations need not require eutrophic conditions.
اظهر المزيد [+] اقل [-]Fighting Nemo: Effect of 17α-ethinylestradiol (EE2) on aggressive behavior and social hierarchy of the false clown anemonefish Amphiprion ocellaris
2017
Chen, Te-Hao | Hsieh, Chun-Yu
Aggressive behavior is crucial for maintaining social hierarchy in anemonefish. Endocrine disrupting chemicals such as EE2 may affect fish social hierarchy via disrupting their aggression. In this study, we aimed to characterize the effects of 17α-ethinylestradiol (EE2) on aggressive behavior and social hierarchy in the false clown anemonefish (Amphiprion ocellaris). In the laboratory experiment, juvenile anemonefish were randomly distributed to separated tanks to form small colonies of three individuals and were fed with EE2-dosed diet (100ng/g food) or a control diet for 90d. Through the experiment, each tank was videotaped and behavioral indicators of social status, including aggressive behavior, submissive response, and shelter utilization, were quantitatively analyzed from the videos. The EE2 exposure caused a higher frequency of intra-colonial aggressive interactions and a less stable social hierarchy. Our findings demonstrate the importance of examining the effects of endocrine disrupting chemicals on the social behavior of coral reef fish.
اظهر المزيد [+] اقل [-]BTEX emissions from flex fuel motorcycles
2017
Macedo, Valéria C. | Daemme, Luiz C. | Penteado, Renato | da Motta, Heloísa N. | Corrêa, Sergio M.
Comparative studies were developed with regard to the criteria emissions of THC - total hydrocarbons, CO - carbon monoxide and NOx - nitrogen oxides, and BTEX (benzene, toluene, ethyl benzene and xylenes). Three four-stroke motorcycles were fuelled with E22 fuel (gasoline with 22% of ethanol). One flex fuel motorcycle was also fuelled with E100, 100% Hydrated Reference Ethanol, and with E61 (61% of ethanol). Criteria emissions were quantified using traditional measurement techniques based on the European Directive 97/24/EC (EURO protocol). To determine the BTEX emissions, gas chromatography coupled with mass spectrometry was employed. All motorcycles were equipped with a catalyst (TWC) used to reduce the amount of toxic emissions in the exhaust gases. To evaluate the performance of the catalyst, one motorcycle was tested with and without the device. One motorcycle was tested according to two different test protocols, namely, the ECE/TRANS/180 WMTC, also known as the Worldwide Motorcycle Test Cycle, and the EURO protocol. The main results were that toluene emissions were more prevalent than other aromatics. The tests with and without the catalyst showed that after the catalyst was employed the conversion efficiencies for benzene, toluene, ethyl benzene and xylene were 52.3%, 84.0%, 85.0%, and 86.0%, respectively. The results regarding the flex fuel motorcycle show that BTEX emissions decrease with an increase of ethanol in the mixture. Comparing the EURO and WMTC protocols, it was observed that the WMTC protocol generates lower emissions compared to the EURO protocol; however, NOx showed the opposite trend of BTEX.
اظهر المزيد [+] اقل [-]Effects of shipping on marine acoustic habitats in Canadian Arctic estimated via probabilistic modeling and mapping
2017
Aulanier, Florian | Simard, Yvan | Roy, Nathalie | Gervaise, Cédric | Bandet, Marion
Canadian Arctic and Subarctic regions experience a rapid decrease of sea ice accompanied with increasing shipping traffic. The resulting time-space changes in shipping noise are studied for four key regions of this pristine environment, for 2013 traffic conditions and a hypothetical tenfold traffic increase. A probabilistic modeling and mapping framework, called Ramdam, which integrates the intrinsic variability and uncertainties of shipping noise and its effects on marine habitats, is developed and applied. A substantial transformation of soundscapes is observed in areas where shipping noise changes from present occasional-transient contributor to a dominant noise source. Examination of impacts on low-frequency mammals within ecologically and biologically significant areas reveals that shipping noise has the potential to trigger behavioral responses and masking in the future, although no risk of temporary or permanent hearing threshold shifts is noted. Such probabilistic modeling and mapping is strategic in marine spatial planning of this emerging noise issues.
اظهر المزيد [+] اقل [-]Prioritizing Process in Action Plans: a Review of Approaches
2017
Licitra, Gaetano | Ascari, Elena | Fredianelli, Luca
PURPOSE OF THE REVIEW: The paper is focused on the prioritization process in noise action plans. The available indicators (noise scores) and methodologies for defining hotspots are analysed and discussed. Indicators and methodologies are classified in order to highlight their suitability for different specific aims. RECENT FINDINGS: The revised annex II of the European Directive 2002/49/EC fixed population exposure and modelling issues leading to different approaches in the prioritization process. Unfortunately, the indicators for rating areas are not commonly defined and a validated procedure is still not recognized at EU level. Furthermore, the importance of considering annoyance in the mitigation process arose, and this paper summarizes the pros and cons of their use for the purpose of prioritization process. A recent attempt to combine annoyance evaluations with limits compliance in noise score for the priority definition is presented. The paper classifies various priority indicators basing on their inclusion of compliance limits compliance, annoyance or both. Then, the methods for merging index values at dwelling for hotspot identification are classified according to their approaches, particularly between those using geometrical approaches, or needing reference administrative areas. The paper highlights the suitability of each method to specific sources, contexts and aims of the prioritization process. Merging methods resulted necessary whenever the epidemiological study is not the aim of the calculation; indeed, the mitigation measures could be planned for delimited and prioritized areas and not directly derived from building noise scores.
اظهر المزيد [+] اقل [-]Can benthic quality assessment be impaired by uncertain species sensitivities?
2017
Chuševė, Romualda | Daunys, Darius
This study tested robustness of mathematically defined species sensitivity with manipulation of disturbance gradient coverage by datasets on two different pressures and two depth zones of the central Baltic Sea. The results indicate large differences of sensitivity values for the same species when depth range changed. After addition of samples from impacted sites to the control datasets, estimated sensitivity values decreased for half of analysed species. Sensitivity of tolerant species appeared to be highly dependent on the coverage of disturbance gradient by the dataset, while sensitive species were highly robust to this effect. Although pressure type and coverage of disturbance gradient by the dataset was important, sensitivity changes were primarily linked to the altered environmental conditions. It is suggested that sensitivity values based on natural variability of pre-selected communities will better integrate the role of important environmental factors and increase robustness of discrimination between disturbed and undisturbed sites.
اظهر المزيد [+] اقل [-]The effects of sulfur amendments on the geochemistry of sulfur, phosphorus and iron in the mangrove plant (Kandelia obovata (S. L.)) rhizosphere
2017
Li, Jian | Junyi, Yu | Jingchun, Liu | Chongling, Yan | Haoliang, Lu | Spencer, Kate L.
P (phosphorus) and Fe (iron) are limiting elements and S (sulfur) is an important element of the biogeochemical cycle in the mangrove environment. To assess the effects of sulfur on the geochemical cycling of Fe and P at the sediment-plant interface, the speciation distributions of Fe, P and S in sediments were examined. The data showed that higher proportions of amorphous Fe, Fe-bound phosphate, chromium reducible sulfur and elemental sulfur were found in the rhizosphere, while more crystalline Fe, exchangeable phosphate and acid-volatile sulfide were determined in the non-rhizosphere. Sulfate application induced an increase in the Ex-P concentration, high P accumulation and high iron plaque deposition in the roots. In conclusion, sulfate applications had a significant influence on the geochemical cycling of Fe and P in the sediments. It significantly curtailed the Fe and P limit to plant growth and enhanced plant resistance to the rugged surroundings in mangrove.
اظهر المزيد [+] اقل [-]