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The usefulness of transplantation studies in monitoring of metals in the marine environment: South African experience Полный текст
2014
Greenfield, R. | Brink, K. | Degger, N. | Wepener, V.
Due to their close proximity to the point sources of pollution, estuaries and harbours are exposed to metals. Mussels are used worldwide to monitor marine pollution due to their ability to take up contaminants and the ease of transplantation. Mussels were collected from two reference sites and transplanted in Richards Bay Harbour (2006 and 2010) and in three harbours. Transplanted and resident mussels were removed after 6weeks exposure and metal concentrations were analysed using ICP-MS techniques. Transplanted mussels had higher metal concentrations than the resident mussels. This was attributed to regulation of metals by the resident mussels. Metal regulation was greater in mussels that are continuously submerged as opposed to those that undergo tidal influences. For monitoring it is essential that the reference population for transplantation is considered carefully as upwelling events in the pristine reference location results in significant increases in metal bioaccumulation.
Показать больше [+] Меньше [-]Diving associated coral breakage in Hong Kong: Differential susceptibility to damage Полный текст
2014
We conducted the first quantitative assessment of coral breakage along a gradient of diving activities in Hong Kong, the most densely populated city in southern China. A survey of six 1×25m transects at seven sites revealed a total of 81 broken corals, among which 44% were branching, 44% plate-like and 12% massive. There were 3–19 broken colonies per site. At most study sites, the percentage of broken corals exceeded the recommended no-action threshold of 4%, suggesting that management intervention is justified. There was a significant positive correlation between the number of broken coral colonies and the number of divers visiting the site. The branching Acropora and the plate-like Montipora suffered from much higher frequency of damage than their relative abundance, raising the concern that the cumulative impact of such differential susceptibility to breakage may affect coral community composition.
Показать больше [+] Меньше [-]Metal pollution status in Zhelin Bay surface sediments inferred from a sequential extraction technique, South China Sea Полный текст
2014
Surface sediments collected from Zhelin Bay, the largest mariculture base of eastern Guangdong Province, were analyzed for total metal concentrations and chemical speciation. The results demonstrated that the average total concentration (mg/kg) ranges were 36.7–65.8 (Pb), 53.8–98.8 (Cr), 39.0–87.1 (Ni), 50.9–144.5 (Cu), and 175.0–251.2 (Zn), which were clearly higher with respect to their corresponding benchmark values. The predominant speciation of Pb was reducible and comprised a residual fraction, whereas a major portion (57.6–95.4%) of Cr, Ni, Cu, and Zn was strongly associated with the residual fractions. Taking as a whole, surface sediments of Zhelin Bay had a 21% probability of toxicity based on the mean effects range–median quotient.
Показать больше [+] Меньше [-]The mass concentration and optical properties of black carbon aerosols over a semi–arid region in the northwest of China Полный текст
2014
Black Carbon (BC) is the predominant absorption component of atmospheric aerosols, and it is believed to be the second largest contributor to global warming. Calculating its radiative forcing requires observational data regarding its physical, chemical and optical properties, so observation is the foundation of this research. The Semi–Arid Climate and Environment Observatory of Lanzhou University aims to improve our understanding in this regard by capturing direct evidence of the impact of human activity on the semi–arid climate over the Loess Plateau of Northwestern China. In this paper, the period from November 2010 to February 2011, which is within the heating period, was selected in order to study the optical properties of BC, such as its depolarization ratio, extinction coefficient, optical depth, Ångström exponent and effective radius. The average BC concentration was 2 334±1 546ng/m3 during the observation. The diurnal evolution of BC concentration had two maximums, which appeared at 10:00 and 20:00 (local time), and two minimums, which appeared at 03:00 and 16:00. The average Aerosol Optical Depth (AOD) during the observation was 0.26±0.2, the aerosols existed mostly between the surface of the Earth and a height of 3km, and the extinction coefficient decreased with height. The average of the depolarization ratio between the surface of the Earth and a height of 3km, the Ångström exponent (α440/870nm) and the effective radius of black carbon aerosols were 0.24, 0.86±0.30 and 0.54±0.17μm, respectively. The maximum distribution frequency of α440/870nm was 27%, with a range of 1.0 to 1.2. The maximum distribution frequency of the effective radius was 28%, with a range of 0.4μm to 0.5μm.
Показать больше [+] Меньше [-]Sources and preservation of sedimentary organic matter in the Southern Bohai Sea and the Yellow Sea: Evidence from lipid biomarkers Полный текст
2014
Lin, Tian | Wang, Lifang | Chen, Yingjun | Tian, Chongguo | Pan, Xiaohui | Tang, Jianhui | Li, Jun
The region of Southern Bohai Sea (SBS) and Yellow Sea (YS) represents one of the best examples of large river-dominated ocean margins. The transport and accumulation of sediments played a primary role in distribution of the lipids in the region and could lead to a preferential accumulation of these more refractory land-based lipids. The spatial distribution of total organic carbon (TOC) matched with the lipid distributions over the shelf, and high TOC presented in the central YS, but TOC burial fluxes decreased from 110ton/km2/yr of SBS to 25–32ton/km2/yr of YS. Good correlations were observed between terrestrial n-alkanes and TOC in the sediments of SBS and northern YS, but they were poor for southern YS, meanwhile higher ratios of nC27+nC29+nC31/nC15+nC17+nC19 (12±6) were observed in SBS, and lower in YS (2.2±1.0), suggesting the Yellow River discharge was an important source of terrestrial organic matter to the shelf.
Показать больше [+] Меньше [-]Polycyclic aromatic hydrocarbons in pine needles (Pinus halepensis) along a spatial gradient between a traffic intensive urban area (Barcelona) and a nearby natural park Полный текст
2014
van Drooge, Barend L. | Garriga, Guillem | Grimalt, Joan O.
Polycyclic aromatic hydrocarbons (PAHs) are emitted into the atmosphere from combustion of fuels, such as emissions from traffic in urban areas, which on their terms can be important sources for the translocation of these toxic compounds to the surrounding region. Pine needles can be used as time–integrated passive air–samplers for PAHs. Pine needles were collected between 2009 and 2011 along a spatial gradient (5km) from urban background sites towards sites situated in a natural park (Collserola) within the metropolitan area of Barcelona. City samples showed PAH levels that were two times higher than the levels in the natural park. A seasonal trend was reflected by the substantially higher PAH levels in pine needles collected in the colder sampling period than those collected in the warmer period. The observed trend can be explained in terms of source emission strength, dilution and photo–chemical degradation, while also gas–pine needles partitioning may have played an important role. The city is the major source area for the translocation of PAHs towards the nearby natural park.
Показать больше [+] Меньше [-]Time–series analysis of surface ozone and nitrogen oxides concentrations in an urban area at Brazil Полный текст
2014
Agudelo–Castaneda, Dayana Milena | Teixeira, Elba Calesso | Norte Pereira, Felipe
The purpose of the present work was to study the concentration variations in O3, NO, NO2, NOX over a 4–year period (2006–2009), using the Kolmogorov–Zurbenko filter. Data were decomposed into seasonal and trend components. Seasonal component of the time–series analysis (2006–2009) of NO and NOx in Canoas and Esteio showed values above average during the cold seasons, while O3 showed an opposite pattern. The trend component was marked by the decrease of NO2 at Canoas and the increase of NO at Esteio, thus revealing their variation (NO and NOX) due to local emissions. Furthermore, evaluations of the mean daily concentrations of NO, NOX, NO2, O3, PM10 and CO, and correlations of these pollutants with meteorological parameters (ambient temperature, wind velocity, solar radiation and relative humidity) allowed the confirmation of the influence of mobile sources in the study area.
Показать больше [+] Меньше [-]Modeling and experimental analysis of packed column for SO2 emission control process Полный текст
2014
Maheswari, Chenniappan | Krishnamurthy, Kasilingam | Parameshwaran, Rathinasamy
Sulfur dioxide (SO2) emissions from chemical process plants are increasing at an alarming rate. It is necessary to implement the best methodology to reduce the SO2 emissions. This paper presents physical modeling, computational fluid dynamics (CFD) analysis, and experimental analysis of a packed column used for flue gas desulfurization (FGD) process to reduce SO2 emission at a greater extent. The packed column parameters such as liquid/gas (L/G) ratio, diameter, packed height and total height were determined using physical modeling with two–film gas–liquid absorption theory. Simulation model of the packed column is developed by GAMBIT 2.2.30 and analysis is carried out by FLUENT 6.2.16. In CFD analysis, hydrogen peroxide (H2O2) (with different concentrations) was used as an absorbent. CFD simulation result ensures that when H2O2 is used as a reactant, better removal efficiency is obtained. Based on the physical modeling and CFD analysis, a lab scale packed column was developed. Experimental result showed that 95% SO2 removal efficiency is achieved for 0.1M H2O2 as a reactant. Experimental results agreed excellently with the developed CFD model and can be used for designing industrial packed columns.
Показать больше [+] Меньше [-]Oil droplet interaction with suspended sediment in the seawater column: Influence of physical parameters and chemical dispersants Полный текст
2014
Sørensen, Lisbet | Melbye, Alf G. | Booth, Andy M.
Oil droplet interaction with suspended sediment in the seawater column: Influence of physical parameters and chemical dispersants Полный текст
2014
Sørensen, Lisbet | Melbye, Alf G. | Booth, Andy M.
The interaction of dispersed oil droplets with large diameter suspended particulate materials (SPM) has been little studied. In the current study, particle size, oil characteristics and chemical dispersant significantly influence the adsorption of oil droplets to SPM in seawater. Sediments with a smaller particulate size (clay) approaching that of the oil droplets (2–20μm) adsorbed more oil per gram than sediments with large particle size (sand). Heavier, more polar oils with a high asphaltene content adsorbed more efficiently to SPM than lighter, less polar oils. A decrease in the smaller, more water soluble oil components in the sediment adsorbed oil was observed for all oil types. Addition of chemical dispersant decreased the adsorption of oil droplets to suspended carbonate sand in an exponential-like manner. No change in the relative distribution of compounds adsorbed to the sediment was observed, indicating dispersants do not alter the dissolution of compounds from oil droplets.
Показать больше [+] Меньше [-]Oil droplet interaction with suspended sediment in the seawater column: Influence of physical parameters and chemical dispersants Полный текст
2014
Sørensen, Lisbet | Melbye, Alf Glein | Booth, Andy
The interaction of dispersed oil droplets with large diameter suspended particulate materials (SPM) has been little studied. In the current study, particle size, oil characteristics and chemical dispersant significantly influence the adsorption of oil droplets to SPM in seawater. Sediments with a smaller particulate size (clay) approaching that of the oil droplets (2–20 lm) adsorbed more oil per gram than sediments with large particle size (sand). Heavier, more polar oils with a high asphaltene content adsorbed more efficiently to SPM than lighter, less polar oils. A decrease in the smaller, more water soluble oil components in the sediment adsorbed oil was observed for all oil types. Addition of chemical dispersant decreased the adsorption of oil droplets to suspended carbonate sand in an exponential-like manner. No change in the relative distribution of compounds adsorbed to the sediment was observed, indicating dispersants do not alter the dissolution of compounds from oil droplets. | acceptedVersion
Показать больше [+] Меньше [-]Mercury in the food chain of the Lagoon of Venice, Italy Полный текст
2014
Sediments and biota samples were collected in a restricted area of the Lagoon of Venice and analysed for total mercury, monomethyl mercury (MMHg), and nitrogen and carbon isotopes. Results were used to examine mercury biomagnification in a complex food chain. Sedimentary organic matter (SOM) proved to be a major source of nutrients and mercury to primary consumers. Contrary to inorganic mercury, MMHg was strongly biomagnified along the food chain, although the lognormal relationship between MMHg and δ15N was less constrained than generally reported from lakes or coastal marine ecosystems. The relationship improved when logMMHg concentrations were plotted against trophic positions derived from baseline δ15N estimate for primary consumers. From the regression slope a mean MMHg trophic magnification factor of 10 was obtained. Filter-feeding benthic bivalves accumulated more MMHg than other primary consumers and were probably important in MMHg transfer from sediments to higher levels of the food chain.
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