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Resultados 1361-1370 de 4,043
Biases and best approaches for assessing debris ingestion in sea turtles, with a case study in the Mediterranean Texto completo
2016
Casale, Paolo | Freggi, Daniela | Paduano, Valentina | Oliverio, Marco
In a sample of 567 loggerhead turtles (Caretta caretta) from the central Mediterranean, debris occurrence varied according to methods and turtle source, and was up to 80% in pelagic turtles. Frequencies of plastic types, size and color are also reported. These results and a critical review of 49 studies worldwide indicate that: (i) the detected occurrence of plastic (% turtles) is affected by several factors (e.g., necropsy/feces, ecological zone, type and date of finding, captivity period for feces collection), (ii) mixed dataset and opportunistic approaches provide results which are biased , not comparable, and ultimately of questionable value, (iii) only turtles assumed to have had a normal feeding behaviour at the time of capture or death should be considered, (iv) turtle foraging ecology and possible selectivity may undermine the use of turtles as indicator species for monitoring marine litter, as recently proposed for the Mediterranean.
Mostrar más [+] Menos [-]The phenomena of spreading ambient ozone at the west coast air basin of Taiwan Texto completo
2016
Liang, Chen-Jui | Xue, Yang-Shen | Liang, Jeng-Jong
The total air pollution model (TAPM, www.cmar.csiro.au/research/tapm) was used to explore the phenomena of spreading ambient ozone in the complex 196 km × 196 km terrain of the west coast air basin of Taiwan (including ocean area). The altitude in the air basin ranges from 0 m (sea level) to 3000+ m (high mountain). The data of 2010–2014 from 21 air-quality monitoring stations were used to ensure the accuracy of the simulation results in accordance with an average index of agreement (IOA) > 0.61. Four ozone-spreading phenomena were observed among the air basin: the north–south spreading on the offshore (N–S SOO), north–south spreading around the coast (N–S SAC), east–west spreading from the ocean (E–W SFO), and east–west spreading around the mountain front (E–W SAMF). The results indicate that when two prevailing flows meet and interact at their boundaries, they form a convergence zone. The convergence zone presents distinctive weather conditions and accumulates air pollutants. More than wind direction, the ozone concentration is dependent on the topography and surrounding conditions. The results clearly show that the ozone-spreading phenomena follow certain rules. The N–S SOO, N–S SAC, E–W SFO, and E–W SAMF phenomena are during the northeaster, fore-southwester, southwester, and fore-northeaster monsoon months, respectively. Wind fields are a major factor in the high concentration of ozone and ozone spreading, especially downdraft and onshore winds. The diversion of river valleys and the mountainous barrier between the basin/hill and mountains exert obvious influences on the local wind field, strongly affecting the ozone-spreading phenomena.
Mostrar más [+] Menos [-]Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea Texto completo
2016
Jamshidi, Siamak | Bastami, Kazem Darvish
In this study, the accumulation of metals, including Al, Fe, Zn, V, Ni, Cu, Cr, Cd, Co, As, and Pb, in sediments of Anzali wetland in the southwest region of the Caspian Sea was investigated. For this purpose, the sediments were collected from 17 sampling sites in Anzali wetland, Caspian Sea. The samples were then analyzed using inductively coupled plasma–optical emission spectrometry (ICP-OES). Pearson correlation coefficient showed significant and positive correlation between concentration of all metals (except As and Cd). Furthermore, the results implied that Al and Fe are probably responsible for the transportation of heavy metals into the sediments of Anzali wetland. According to mean effects range-median quotient (mean ERM quotient), the sediments from Anzali wetland had a 21% probability of toxicity.
Mostrar más [+] Menos [-]Impact of sea-land breezes on 210Pb in southern Iberian Peninsula – Feasibility study on using submicron-sized aerosol particles to analyze 210Pb hourly patterns Texto completo
2016
Hernández-Ceballos, M.A. | Sorribas, M. | San Miguel, E.G. | Cinelli Calvoli, Giovanni | Adame, J.A. | Bolívar, J.P.
This work addresses the impact of mesoscale circulations on 210Pb concentrations in southwestern Iberian Peninsula by analysing the 210Pb database at El Arenosillo station during 2004–2011 (128 periods with a time scale of 48 h).The analysis of surface winds during each one of these periods has revealed the positive impact of the two sea-land breeze patterns (pure and non-pure), previously identified in this region, on 210Pb activity concentrations. An average value of 0.80 ± 0.09 mBq m−3 was obtained for the pure pattern (34 periods), 0.54 ± 0.09 mBq m−3 for the non-pure pattern (23 periods) and 0.46 ± 0.04 mBq m−3 for the rest (71 periods).The analysis of one representative period of each sea-land breeze patterns is also presented. To perform this analysis we have used: hourly surface wind observations, surface wind fields simulated by the WRF mesoscale model and the hourly database of sub-micron-particle size range in the accumulation mode (NACC). The use of this type of particles to investigate the hourly temporal variability of 210Pb is based on the high correlation, obtained in the present work, between 210Pb activity and particles in the accumulation mode (R = 0.90).The analysis reveals that the highest concentrations of NACC, and hence, 210Pb, are obtained when the sampling area is under the influence of the pure breeze, due to it favours the accumulation of particles previously transported by Mediterranean flows along the Guadalquivir valley. In the case of the non-pure pattern, the increase in the concentration of particles is related to the arrival of background synoptic winds from the continental areas of western Iberian Peninsula. In the latest, the increment of NACC is faster and around 400 particles cm−3, while in the case of the pure pattern, it is progressive up to 1400 particles cm−3.
Mostrar más [+] Menos [-]Spatial variation of near-surface CO2 concentration during spring in Shanghai Texto completo
2016
Liu, Min | Zhu, Xiyang | Pan, Chen | Ma, Yukun | Zhang, Hao | Jia, Wenxiao | Xiang, Weining
Urban area plays an important role in global carbon cycle, yet few efforts have been made to investigate CO2 concentration and its spatial heterogeneity in cities. Using Shanghai, the commercial and financial center of mainland China, as a case study, this paper explored the spatial pattern and determinants of near-surface urban CO2 concentration during spring. A total number of 173 sample points were collected covering the whole urban area, to examine the atmospheric CO2 concentration across various land use types (transportation, commercial, agricultural, recreational, institutional, residential and industrial land use) and urbanization gradients (heavy, moderately heavy, medium, moderately low, and low urbanization). CO2 concentrations were measured at a height of 2 m above the ground during 9:00–11:00 am in April and May 2014. The results indicated that CO2 concentration for the region was 409.4 ± 20.8 parts per million (ppm), showing significant spatial heterogeneity. The daytime ambient CO2 concentration varied across land use types (p < 0.05), with the highest and lowest value appeared in transportation area (420.5 ± 33.3 ppm) and agricultural land (398.9 ± 16.2 ppm). Across the urban gradients of Shanghai, a significant decrease of CO2 concentration was observed as the distance from urban core increased. With the influence of both high residential density and activities in production, the highest CO2 concentration occurred in moderate urbanization area (423.9 ± 29.3 ppm), rather than the high urbanization area (417.2 ± 17.5 ppm). Further analysis indicated that the percent of impervious surface cover (ISA) was an important indicator to describe near surface CO2 concentration with a positive correlation, and the percent of vegetation coverage (Veg) had lower explanatory power with a negative correlation. When buffer distance of spatial scale was 2000 m, atmospheric CO2 concentration showed the highest correlation with impervious surface and vegetation coverage.
Mostrar más [+] Menos [-]Trace metals in a sediment core from the largest mariculture base of the eastern Guangdong coast, South China: Vertical distribution, speciation, and biological risk Texto completo
2016
Gu, Yang-Guang | Lin, Qin
A sediment core collected from Zhelin Bay, the biggest mariculture base of the eastern Guangdong Province, was analyzed for trace metal concentrations and chemical fractions. Average total concentrations (mg/kg) were 20.7±15.4 (Pb), 74.6±11.6 (Cr), 40.7±6.0 (Ni), 55.9±13.0 (Cu), and 169.0±11.9 (Zn), with the concentrations of Cr, Ni, Cu and Zn being significantly higher than their corresponding background values. We identified two vertical distribution patterns of the trace metals in the sediment core. In all sub-samples, Pb was mainly associated with the reducible fraction, whereas a major portion (62.2 to 95.2%) of Cr, Ni, Cu, and Zn was strongly associated with the residual fractions. Biological risk assessment based on the mean effects range-median quotient suggests that the Zhelin Bay sediment core has a 21% probability of being toxic.
Mostrar más [+] Menos [-]Oil residue contamination of continental shelf sediments of the Gulf of Mexico Texto completo
2016
Harding, V. | Camp, J. | Morgan, L.J. | Gryko, J.
We have investigated the distribution of a heavy oil residue in the coastal sediments of the Gulf of Mexico. The amount of the contamination was determined by high-temperature pyrolysis coupled with the Gas Chromatography–Mass Spectrometry (GCMS) of air-dried sediments. The pyrolysis products contain straight-chain saturated and unsaturated hydrocarbons, such as dodecane and 1-dodecene, resulting in a very characteristic pattern of double peaks in the GCMS. Hydrocarbons containing 8 to 23 carbon atoms were detected in the pyrolysis products. Using thermal pyrolysis we have found that the sediment samples collected along Texas, Louisiana, and Mississippi shores contain no detectable traces of oil residue, but most of the samples collected along Alabama and Florida shores contain ~200ppm of heavy oil residue.
Mostrar más [+] Menos [-]Water flux management and phytoplankton communities in a Mediterranean coastal lagoon. Part II: Mixotrophy of dinoflagellates as an adaptive strategy? Texto completo
2016
Cecchi, P. | Garrido, M. | Collos, Y. | Pasqualini, V.
Dinoflagellate proliferation is common in coastal waters, and trophic strategies are often advanced to explain the success of these organisms. The Biguglia lagoon is a Mediterranean brackish ecosystem where eutrophication has long been an issue, and where dominance of dinoflagellates has persisted for several years. Monthly monitoring of fluorescence-based properties of phytoplankton communities carried out in 2010 suggested that photosynthesis alone could not support the observed situation all year round. Contrasting food webs developed depending on the hydrological season, with a gradual shift from autotrophy to heterotrophy. Progressively, microphytoplankton assemblages became unequivocally dominated by a Prorocentrum minimum bloom, which exhibited very weak effective photosynthetic performance, whereas paradoxically its theoretical capacities remained fully operational. Different environmental hypotheses explaining this discrepancy were examined, but rejected. We conclude that P. minimum bloom persistence is sustained by mixotrophic strategies, with complex compromises between phototrophy and phagotrophy, as evidenced by fluorescence-based observations.
Mostrar más [+] Menos [-]Climate change impacts on marine water quality: The case study of the Northern Adriatic sea Texto completo
2016
Rizzi, J. | Torresan, S. | Critto, A. | Zabeo, A. | Brigolin, D. | Carniel, S. | Pastres, R. | Marcomini, A.
Climate change is posing additional pressures on coastal ecosystems due to variations in water biogeochemical and physico-chemical parameters (e.g., pH, salinity) leading to aquatic ecosystem degradation.With the main aim of analyzing the potential impacts of climate change on marine water quality, a Regional Risk Assessment methodology was developed and applied to coastal marine waters of the North Adriatic. It integrates the outputs of regional biogeochemical and physico-chemical models considering future climate change scenarios (i.e., years 2070 and 2100) with site-specific environmental and socio-economic indicators.Results showed that salinity and temperature will be the main drivers of changes, together with macronutrients, especially in the area of the Po’ river delta.The final outputs are exposure, susceptibility and risk maps supporting the communication of the potential consequences of climate change on water quality to decision makers and stakeholders and provide a basis for the definition of adaptation and management strategies.
Mostrar más [+] Menos [-]Assessing of surface-ozone concentration in Bucharest, Romania, using OML and satellite data Texto completo
2016
Grigoraş, Georgiana | Ştefan, Sabina | Rada, Constantin | Grigoraş, Cristinel
The aim of the paper is to assess the spatial distribution of surface-ozone concentrations for Bucharest urban agglomeration by running OML (“Operationelle Meteorologiske Luftkvalitetsmodeller” – Operational Meteorological Air Quality Model) dispersion model. Two data sets from 2009 were used to initialize the model for: (i) air quality data base of the National Network of Air Quality Monitoring (NNAQM); (ii) satellite data obtained from OMI (Ozone Monitoring Instrument) on board of AURA satellite. The potential of satellite data used in air quality assessment in lower troposphere, at local scale was also tested by comparison to data from air-quality monitoring stations. The intercomparison of simulated and measured data emphasized that satellite data can be used for assessment of air quality.
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