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Towards a predictive model to assess the natural position of the Posidonia oceanica seagrass meadows upper limit Полный текст
2014
Vacchi, Matteo | Montefalcone, Monica | Schiaffino, Chiara F. | Parravicini, Valeriano | Bianchi, Carlo Nike | Morri, Carla | Ferrari, Marco
The upper portion of the meadows of the protected Mediterranean seagrass Posidonia oceanica occurs in the region of the seafloor mostly affected by surf-related effects. Evaluation of its status is part of monitoring programs, but proper conclusions are difficult to draw due to the lack of definite reference conditions. Comparing the position of the meadow upper limit with the beach morphodynamics (i.e. the distinctive type of beach produced by topography and wave climate) provided evidence that the natural landwards extension of meadows can be predicted. An innovative model was therefore developed in order to locate the region of the seafloor where the meadow upper limit should lie in natural conditions (i.e. those governed only by hydrodynamics, in absence of significant anthropogenic impact). This predictive model was validated in additional sites, which showed perfect agreement between predictions and observations. This makes the model a valuable tool for coastal management.
Показать больше [+] Меньше [-]History of human activity in coastal southern Brazil from sediment Полный текст
2014
Niencheski, L.F. | Moore, W.S. | Windom, H.L.
This study reports results of analysis of sediment cores collected from the Patos Lagoon estuary. This estuary receives materials from land runoff into Patos and Mirim lagoons and from exchange with the adjacent South Atlantic Ocean through a narrow inlet. Sediment from these sources is mostly natural, but additional contributions associated with source/activities related to the port of Rio Grande. The aim of this study was to estimate rates of accumulation of the sediments and to assess the significance of metal inputs from these activities relative to natural inputs. Our results indicate an average sedimentation rate of 0.3cm/yr and that the transport of suspended solids from offshore sources into the estuary was enhanced after the deepening of the channel and construction of the breakwaters (in the early 1900). Results for metal accumulation in these sediments suggest that there have been only minor enrichments which can be attributed to anthropogenic sources.
Показать больше [+] Меньше [-]Effect of glyphosate-based herbicide on early life stages of Java medaka (Oryzias javanicus): A potential tropical test fish Полный текст
2014
Yusof, Shahrizad | Ismail, Ahmad | Alias, Mohamad Shafiq
Glyphosate is globally a widely used herbicide, yet there is little information on their toxicity to marine fishes. Java medaka, a small tropical fish native to coastal areas in several Southeast Asian countries, is viewed as a suitable candidate for toxicity test and thus was used for this study. Java medaka adults were cultured in the laboratory and the fertilized eggs of the F2 generation were exposed to different concentrations of glyphosate-based herbicide (100, 200, 300, 400 and 500ppm) until they hatched. The survival and hatching rates of the embryos, changes in the heart rate and morphological impairments were recorded. Generally, survival and hatching percentage decreased as glyphosate concentration increased. Absence of pectoral fin(s) and cornea, permanently bent tail, irregular shaped abdomen, and cell disruption in the fin, head and abdomen are among the common teratogenic effects observed. Furthermore, risk factor also increased with the increased in glyphosate concentrations.
Показать больше [+] Меньше [-]Suspended microplastics in the surface water of the Yangtze Estuary System, China: First observations on occurrence, distribution Полный текст
2014
Zhao, Shiye | Zhu, Lixin | Wang, Teng | Li, Daoji
Levels of microplastics (MPs) in China are completely unknown. This study characterizes suspended MPs quantitatively and qualitatively for the Yangtze Estuary and East China Sea. MPs were extracted via a floatation method. MPs were counted and categorized according to shape and size under a stereomicroscope. The MP densities were 4137.3±2461.5 and 0.167±0.138n/m3, respectively, in the estuarine and the sea samples. Plastic abundances varied significantly in the estuary. Higher densities in three sea trawls confirmed that rivers were the important sources of MP to the marine environment. Plastic particles (>5mm) were observed with a maximum size of 12.46mm, but MPs (0.5–5mm) constituted more than 90% by number of items. The most frequent geometries were fibres, followed by granules and films. Plastic spherules occurred sparsely. Transparent and coloured plastics comprised the majority of the particles. This study provides clues in understanding the fate and potential sources of MPs.
Показать больше [+] Меньше [-]A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins Полный текст
2014
Alves, Tiago M. | Kokinou, Eleni | Zodiatis, George
This study combines bathymetric, geomorphological, geological data and oil spill predictions to model the impact of oil spills in two accident scenarios from offshore Crete, Eastern Mediterranean. The aim is to present a new three-step method of use by emergency teams and local authorities in the assessment of shoreline and offshore susceptibility to oil spills. The three-step method comprises: (1) real-time analyses of bathymetric, geomorphological, geological and oceanographic data; (2) oil dispersion simulations under known wind and sea current conditions; and (3) the compilation of final hazard maps based on information from (1) and (2) and on shoreline susceptibility data. The results in this paper show that zones of high to very-high susceptibility around the island of Crete are related to: (a) offshore bathymetric features, including the presence of offshore scarps and seamounts; (b) shoreline geology, and (c) the presence near the shore of sedimentary basins filled with unconsolidated deposits of high permeability. Oil spills, under particular weather and oceanographic conditions, may quickly spread and reach the shoreline 5–96h after the initial accident. As a corollary of this work, we present the South Aegean region around Crete as a valid case-study for confined marine basins, narrow seaways, or interior seas around island groups.
Показать больше [+] Меньше [-]Tracing the recently increasing anthropogenic Pb inputs into the East China Sea shelf sediments using Pb isotopic analysis Полный текст
2014
Wang, Deli | Zhao, Zhiqi | Dai, Minhan
This study examined the Pb content and Pb isotopic composition in a sediment core taken from the East China Sea (ECS) shelf, and it was observed that since 2003 the increasing anthropogenic Pb inputs have impacted as far as the ECS shelf sediments. The ECS shelf sediments were generally characterized with low bulk Pb contents (12.5–15.0μg/g) and relatively lithogenic Pb isotopic signatures (both HCl-leached and residual fractions). However, elevated Pb records along with lighter Pb isotopic signals have occurred in the post-2003 sediments, as a result of a small but increasing anthropogenic Pb contribution from the heavily human perturbed coastal sediments due to the sharply increasing coal consumption in mainland China since 2003.
Показать больше [+] Меньше [-]Organohalogen contaminants and total mercury in forage fish preyed upon by thick-billed murres in northern Hudson Bay Полный текст
2014
Braune, Birgit M. | Gaston, Anthony J. | Elliott, Kyle H. | Provencher, Jennifer F. | Woo, Kerry J. | Chambellant, Magaly | Ferguson, Steven H. | Letcher, Robert J.
Twelve marine fish species collected from a thick-billed murre (Uria lomvia) breeding colony in northern Hudson Bay in the Canadian Arctic during 2007–2009 were analyzed for legacy organochlorines (e.g. PCBs, DDT), polybrominated diphenyl ethers (PBDEs), perfluorinated carboxylates (PFCAs) and sulfonates (PFSAs), and total mercury (Hg). No one species of prey fish had the highest levels across all contaminant groups analyzed. For the two pelagic fish species sampled, concentrations of the major organochlorine groups (e.g. Σ21PCB, ΣDDT, ΣCHL, ΣCBz), ΣPBDE, ΣPFCA and Hg were consistently higher in Arctic cod (Boreogadus saida) than in capelin (Mallotus villosus). Biomagnification factors from whole fish to thick-billed murre liver across all species were generally higher for Σ21PCB and ΣDDT. ΣPBDE did not biomagnify.
Показать больше [+] Меньше [-]Contrasting recovery of shallow and deep water seagrass communities following climate associated losses in tropical north Queensland, Australia Полный текст
2014
Rasheed, Michael A. | McKenna, Skye A. | Carter, Alexandra B. | Coles, Robert G.
Tropical seagrass decline and recovery from severe storm impacts was assessed via quarterly measurements of seagrass biomass, species composition and experimental investigations of recovery in north Queensland. Shallow and deep seagrass meadows suffered major declines. Significant recovery in the two years following loss only occurred at deeper sites. Halophila spp. in deep water areas had a high capacity for recovery through the availability of seed banks. In contrast, the shallow species did not recover quickly from experimental disturbance, had poor seed reserves and relied on asexual propagation. The potential for shallow species to recover rapidly from widespread losses was limited as seed banks were limited or non-existent. Understanding inter- and intra-specific differences in seagrass recovery and how this interacts with location is critical to predict the consequences of climate events to tropical seagrasses. This is especially important as more frequent severe storms are predicted as a consequence of climate change.
Показать больше [+] Меньше [-]A review of the association between air pollutant exposure and allergic diseases in children Полный текст
2014
Lee, Jae Young | Lee, Seung–Bok | Bae, Gwi–Nam
We reviewed the results of previous studies that investigated the association between allergic symptoms in children and exposure to the major air pollutants, here identified as nitrogen dioxide (NO2), ozone (O3), particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), sulfur dioxide (SO2), soot, and carbon monoxide (CO), in terms of the odds ratios reported. We also reviewed a common procedure used in previous studies for building a whole study design based on application of an observational research method and various analysis models. Most previous studies reported odds ratios above unity and found a positive association between allergic symptoms and exposure to major air pollutants. When the strength of the associations between exposure to air pollutants and allergic disease in children were compared by normalization of the odds ratios, exposure to PM2.5 was found to have the strongest association, followed by NO2, while exposure to PM10 was found to have the weakest association.
Показать больше [+] Меньше [-]Use of passive samplers for improving oil toxicity and spill effects assessment Полный текст
2014
Letinski, Daniel | Parkerton, Thomas | Redman, Aaron | Manning, Ryan | Bragin, Gail | Febbo, Eric | Palandro, David | Nedwed, Tim
Methods that quantify dissolved hydrocarbons are needed to link oil exposures to toxicity. Solid phase microextraction (SPME) fibers can serve this purpose. If fibers are equilibrated with oiled water, dissolved hydrocarbons partition to and are concentrated on the fiber. The absorbed concentration (Cpolymer) can be quantified by thermal desorption using GC/FID. Further, given that the site of toxic action is hypothesized as biota lipid and partitioning of hydrocarbons to lipid and fibers is well correlated, Cpolymer is hypothesized to be a surrogate for toxicity prediction. To test this method, toxicity data for physically and chemically dispersed oils were generated for shrimp, Americamysis bahia, and compared to test exposures characterized by Cpolymer. Results indicated that Cpolymer reliably predicted toxicity across oils and dispersions. To illustrate field application, SPME results are reported for oil spills at the Ohmsett facility. SPME fibers provide a practical tool to improve characterization of oil exposures and predict effects in future lab and field studies.
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