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结果 1101-1110 的 3,207
Stable isotope variations in benthic primary producers along the Bosphorus (Turkey): A preliminary study 全文
2015
Calizza, Edoardo | Aktan, Yelda | Costantini, Maria Letizia | Rossi, Loreto
The Bosphorus Strait is a dynamic and complex system. Recent evidences showed nitrogen and heavy metal concentrations to follow opposite patterns across the Strait, suggesting a complex spatial organisation of the anthropogenic disturbance in this system. Here, we provide isotopic information on the origin and transportation of dissolved nitrogen along the Bosphorus. C and N isotopic and elemental analyses were performed on specimens of Ulva lactuca and associated epiphytes sampled in five locations across the Strait. Variations in C and N isotopic signatures were observed in U. lactuca, pointing to a decrease in the availability of anthropogenic organic dissolved nitrogen along a north-south direction. Conversely, epiphytes did not show isotopic or elemental patterns across the Strait. These results suggest that preliminary stable isotope surveys in extended costal systems basing on U. lactuca can represent a valuable tool to focus meaningful targets and hypotheses for pollution studies in the Mediterranean region.
显示更多 [+] 显示较少 [-]Atmospheric particle number concentration and size distribution in a traffic–impacted area 全文
2015
Schneider, Ismael Luis | Teixeira, Elba Calesso | Silva Oliveira, Luis Felipe | Wiegand, Flavio
This study measured ambient particle number concentrations (PNC) and the particle number distributions (PND) in the urban area of Porto Alegre, Rio Grande do Sul, Brazil. The samples were analyzed using a NanoScan model 3910 from TSI (diameters between 10 and 420 nm) and were taken from sites with high density of vehicular traffic, including two roadsides, two traffic intersections, one street canyon and one urban background. Association of meteorological variables (temperature, relative humidity, solar radiation, wind direction, and wind speed) on nanoparticle concentrations was examined. The results indicated PNC averages between 4.85×104 cm–3 and 1.80×105 cm–3 for locations affected by vehicular traffic, wherein highest concentrations were observed at sites corresponding to traffic intersections. In addition, all sites studied showed a trimodal average PND, with the modes centered at ~14 nm, ~30 nm, and ~105 nm. PND was dominated by nucleation (44.9%) and Aitken (42.0%) modes being representative at the studied sites of the pollution originating from urban traffic, except at the urban background. Meteorological parameters and synoptic meteorological conditions contributed to the variation in the results between the sampled days in the same location.
显示更多 [+] 显示较少 [-]Jellyfish (Cyanea nozakii) decomposition and its potential influence on marine environments studied via simulation experiments 全文
2015
Qu, Chang-Feng | Song, Jin-Ming | Li, Ning | Li, Xue-Gang | Yuan, Hua-Mao | Duan, Li-Qin | Ma, Qing-Xia
A growing body of evidence suggests that the jellyfish population in Chinese seas is increasing, and decomposition of jellyfish strongly influences the marine ecosystem. This study investigated the change in water quality during Cyanea nozakii decomposition using simulation experiments. The results demonstrated that the amount of dissolved nutrients released by jellyfish was greater than the amount of particulate nutrients. NH4+ was predominant in the dissolved matter, whereas the particulate matter was dominated by organic nitrogen and inorganic phosphorus. The high N/P ratios demonstrated that jellyfish decomposition may result in high nitrogen loads. The inorganic nutrients released by C. nozakii decomposition were important for primary production. Jellyfish decomposition caused decreases in the pH and oxygen consumption associated with acidification and hypoxia or anoxia; however, sediments partially mitigated the changes in the pH and oxygen. These results imply that jellyfish decomposition can result in potentially detrimental effects on marine environments.
显示更多 [+] 显示较少 [-]Mapping elements distribution in carapace of Caretta caretta: A strategy for biomonitoring contamination in sea turtles? 全文
2015
Mattei, D. | Veschetti, E. | D’Ilio, S. | Blasi, M.F.
This study analyzed the carapace distribution of Ca, Cd, Cr, Cu, Mg, Mn, Pb, Sb, U, V and Zn by GF-AAS and ICP-AES in one specimen of Caretta caretta from Mediterranean Sea. Calcium, Mg, Mn, Pb, U, Zn were mainly distributed in the central area while Cd, Cr, Cu, Sb, V in lateral areas. Cadmium, Cr, Mg, Mn, Sb, U and V were different between lateral areas.The different distribution may be related to several exposures during lifetime and/or the shell ossification during growth. Carapace may be a suitable matrix for metal biomonitoring, however, further studies are required to confirm these findings.
显示更多 [+] 显示较少 [-]Major hydrogeochemical processes in an Acid Mine Drainage affected estuary 全文
2015
Asta, Maria P. | Calleja, Maria Ll | Pérez López, Rafael | Auqué, Luis F.
This study provides geochemical data with the aim of identifying and quantifying the main processes occurring in an Acid Mine Drainage (AMD) affected estuary. With that purpose, water samples of the Huelva estuary were collected during a tidal half-cycle and ion–ion plots and geochemical modeling were performed to obtain a general conceptual model. Modeling results indicated that the main processes responsible for the hydrochemical evolution of the waters are: (i) the mixing of acid fluvial water with alkaline ocean water; (ii) precipitation of Fe oxyhydroxysulfates (schwertmannite) and hydroxides (ferrihydrite); (iii) precipitation of Al hydroxysulfates (jurbanite) and hydroxides (amorphous Al(OH)3); (iv) dissolution of calcite; and (v) dissolution of gypsum. All these processes, thermodynamically feasible in the light of their calculated saturation states, were quantified by mass-balance calculations and validated by reaction-path calculations. In addition, sorption processes were deduced by the non-conservative behavior of some elements (e.g., Cu and Zn).
显示更多 [+] 显示较少 [-]Synthetic ultraviolet light filtering chemical contamination of coastal waters of Virgin Islands national park, St. John, U.S. Virgin Islands 全文
2015
Bargar, Timothy A. | Alvarez, David A. | Garrison, Virginia H.
Contamination of surface waters by synthetic ultraviolet light (UV) filtering chemicals is a concern for the Virgin Islands National Park (VINP). Discrete water samples were collected from VINP bays to determine UV filter chemical presence in the coastal waters. Spatial distribution and the potential for partitioning between subsurface waters and the sea surface microlayer (SML) were also examined. The UV filter chemicals 4-methylbenzylidene camphor, benzophenone-3, octinoxate, homosalate, and octocrylene were detected at concentrations up to 6073ng/L (benzophenone-3). Concentrations for benzophenone-3 and homosalate declined exponentially (r2=0.86 to 0.98) with distance from the beach. Limited data indicate that some UV filter chemicals may partition to the SML relative to the subsurface waters. Contamination of VINP coastal waters by UV filter chemicals may be a significant issue, but an improved understanding of the temporal and spatial variability of their concentrations would be necessary to better understand the risk they present.
显示更多 [+] 显示较少 [-]The Mediterranean non-indigenous ascidian Polyandrocarpa zorritensis: Microbiological accumulation capability and environmental implications 全文
2015
Stabili, Loredana | Licciano, Margherita | Longo, Caterina | Lezzi, Marco | Giangrande, Adriana
We investigated the bacterial accumulation and digestion capability of Polyandrocarpa zorritensis, a non-indigenous colonial ascidian originally described in Peru and later found in the Mediterranean. Microbiological analyses were carried out on homogenates from “unstarved” and “starved” ascidians and seawater from the same sampling site (Adriatic Sea, Italy). Culturable heterotrophic bacteria (22°C), total culturable bacteria (37°C) and vibrios abundances were determined on Marine Agar 2216, Plate Count Agar and TCBS Agar, respectively. Microbial pollution indicators were measured by the most probable number method. All the examined microbiological groups were accumulated by ascidians but differently digested. An interesting outcome is the capability of P. zorritensis to digest allochthonous microorganisms such as coliforms as well as culturable bacteria at 37°C, counteracting the effects of microbial pollution. Thus, the potential exploitation of these filter feeders to restore polluted seawater should be taken into consideration in the management of this alien species.
显示更多 [+] 显示较少 [-]POPs monitoring in Australia and New Zealand using plastic resin pellets, and International Pellet Watch as a tool for education and raising public awareness on plastic debris and POPs 全文
2015
Yeo, Bee Geok | Takada, Hideshige | Taylor, Heidi | Ito, Maki | Hosoda, Junki | Allinson, Mayumi | Connell, Sharnie | Greaves, Laura | McGrath, John
Persistent organic pollutants (i.e. PCBs, DDTs, and HCHs) were analyzed along Australia and New Zealand North Island coastlines. PCB concentrations were high in urban areas (107–294ng/g-pellet), with Sydney Harbour the most polluted. Hepta-chlorinated PCB was abundant, with ~30% in urban areas suggesting legacy pollution. DDT concentrations showed similar pattern except in rural agricultural sites, Taupo Bay and Ahipara, New Zealand (23 and 47ng/g-pellet). p,p′-DDE predominance at these 2 sites suggested historical input; they also had high HCH concentrations (17 and 29ng/g-pellet). The role of International Pellet Watch (IPW) in science communication was studied through feedbacks from IPW volunteers, case studies and examples. IPW data were categorized into understandable terms and tailored reports based on volunteers' backgrounds complemented with pollution maps. The effectiveness of IPW science communication has led to its use in awareness and education activities focusing on both POPs and plastic debris issues.
显示更多 [+] 显示较少 [-]Integrating dispersion modelling and lichen sampling to assess harmful heavy metal pollution around the Karabash copper smelter, Russian Federation 全文
2015
Pollard, Adam S. | Williamson, Ben J. | Taylor, Mark | Purvis, William O. | Goossens, Marc | Reis, Stefan | Aminov, Pavel | Udachin, Valery | Osborne, Nicholas J.
Cu smelting has had a severe impact on the environment around the town of Karabash, Russia. Dispersion modelling has been carried out to estimate atmospheric fallout of metals and metalloids (henceforth termed metals for brevity) from the copper smelter, calibrated and ground-truthed using metal concentrations in transplanted and naturally growing lichens.Lichens (Hypogymnia physodes) were transplanted in June 2011 from a relatively little impacted ‘reference site’ to stations in NE–SW and W–E transects centred on the smelter at Karabash. The transplants were removed during September 2011 and then analysed for As, Cu and Pb. The results were compared with deposition loads estimated using TAPM modelling which was carried out for particles of various sizes, and with simple chemistries, and with the smelter conceptualised as a continuously emitting point source.Variation in the ratio of lichen divided by modelled concentrations was lowest for Pb, ranging from 30.3 to 939.9 and 4.9–107.8 for PM2.5 and PM10, respectively, across eight sample points.The TAPM modelling is in agreement with previous studies that smelter emissions are the major source of environmental Pb deposition around Karabash. Further modelling will be required to determine whether the Pb in the lichens is largely sourced from current smelter airborne emissions or windblown soil particles containing historic additions of Pb.
显示更多 [+] 显示较少 [-]The NET effect of dispersants — a critical review of testing and modelling of surface oil dispersion 全文
2015
Zeinstra-Helfrich, Marieke | Koops, Wierd | Murk, Albertinka J.
Application of chemical dispersants or mechanical dispersion on surface oil is a trade-off between surface effects (impact of floating oil) and sub-surface effects (impact of suspended oil). Making an informed decision regarding such response, requires insight in the induced change in fate and transport of the oil.We aim to identify how natural, chemical and mechanical dispersion could be quantified in oil spill models. For each step in the dispersion process, we review available experimental data in order to identify overall trends and propose an algorithm or calculation method. Additionally, the conditions for successful mechanical and chemical dispersion are defined.Two commonly identified key parameters in surface oil dispersion are: oil properties (viscosity and presence of dispersants) and mixing energy (often wind speed). Strikingly, these parameters play a different role in several of the dispersion sub-processes. This may explain difficulties in simply relating overall dispersion effectiveness to the individual parameters.
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