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النتائج 791 - 800 من 3,240
Spatial–temporal analysis of marine debris on beaches of Niterói, RJ, Brazil: Itaipu and Itacoatiara النص الكامل
2015
Silva, Melanie Lopes da | Araújo, Fábio Vieira de | Castro, Rebeca Oliveira | Sales, Alessandro Souza
In many areas of the world, studies of marine debris are conducted with an emphasis on analyzing their composition, quantification and distribution on sandy beaches. However, in Brazil, studies are still restricted to some areas of the coast, and the quantities and the spatial and temporal patterns are unknown. To enhance the marine debris information in these areas, we selected the Itaipu and Itacoatiara beaches in Niterói, RJ, to collect, quantify and qualify the solid residues present in their sands. We collected 12 samples and recorded 118.39kg of residues in Itaipu and 62.94kg in Itacoatiara. At both beaches, the largest portion of debris was located on the upper part of the beach. Several debris items were related to food and drink consumption on the beaches, which indicated the contribution of beach users to pollution. Most of the debris was plastic. The greatest amount of debris was found at Itaipu in January and February and at Itacoatiara in January and March, months related to both the holiday season and abundant rainfall. The results demonstrated the necessity to implement an Environmental Education project for these areas to reduce its degradation.
اظهر المزيد [+] اقل [-]Sharks and people: Insight into the global practices of tourism operators and their attitudes to Shark behaviour النص الكامل
2015
Richards, Kirsty | O’Leary, Bethan C. | Roberts, Callum M. | Ormond, Rupert | Gore, Mauvis | Hawkins, Julie P.
Shark tourism is a popular but controversial activity. We obtained insights into this industry via a global e-mailed questionnaire completed by 45 diving/snorkelling operators who advertised shark experiences (shark operators) and 49 who did not (non-shark operators). 42% of shark operators used an attractant to lure sharks and 93% stated they had a formal code of conduct which 86% enforced “very strictly”. While sharks were reported to normally ignore people, 9 operators had experienced troublesome behaviour from them. Whilst our research corroborates previous studies indicating minimal risk to humans from most shark encounters, a precautionary approach to provisioning is required to avoid potential ecological and societal effects of shark tourism. Codes of conduct should always stipulate acceptable diver behaviour and appropriate diver numbers and shark operators should have a moral responsibility to educate their customers about the need for shark conservation.
اظهر المزيد [+] اقل [-]Spatial and temporal distribution and risk assessment of polycyclic aromatic hydrocarbons in surface seawater from the Haikou Bay, China النص الكامل
2015
Li, Yuhu | Li, Ping | Ma, Wandong | Song, Qingqing | Zhou, Hailong | Han, Qian | Diao, Xiaoping
Spatial and temporal distributions of 14 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface waters of Haikou Bay, China from October 2013 to September 2014. The total PAHs concentrations ranged from 420.2 to 2539.1ngL−1 with the average value of 1016.3±455.8ngL−1, which were predominated by low molecular weight PAHs (2- and 3-ring PAHs). Moreover, PAHs displayed spatial and temporal variations in the concentration and composition pattern. Source analysis based on isomer ratios indicated that the PAHs mostly originated from petroleum and combustion processes. An eco-toxicological risk assessment showed that the potential risk of individual PAHs had reached moderate to high levels and the total concentrations of PAHs had also reached a relatively high level compared with previous studies. This study offers important information on the pollution levels of 14 PAHs in the surface waters of Haikou Bay and recommends that prevention and control of PAHs pollution should be implemented in the region.
اظهر المزيد [+] اقل [-]Response of a seagrass fish assemblage to improved wastewater treatment النص الكامل
2015
Ourgaud, M. | Ruitton, S. | Bell, J.D. | Letourneur, Y. | Harmelin, J.G. | Harmelin-Vivien, M.L.
We compared the structure of a seagrass fish assemblage near a sewage outlet before and after improvements to wastewater treatment. To determine whether responses by the fish assemblage were due to changes in water quality or to other factors, comparisons were made with the structure of a fish assemblage from a nearby site unaffected by sewage effluent. Total species richness, density and biomass of fish, decreased at both sites over the 30-year period. An increase in mean trophic level near the sewage outlet following improvements in water quality indicated that wastewater treatment had another important effect. This result is consistent with the reductions in food webs supporting pelagic and benthic fishes that typically accompany decreases in nutrient inputs. Although improvements to wastewater treatment explained much of the variation in the structure of the fish assemblage at PC, our results also suggest that fishing and climate change, at both sites.
اظهر المزيد [+] اقل [-]Source apportionment analysis of airborne VOCs using positive matrix factorization in industrial and urban areas in Thailand النص الكامل
2015
Saeaw, Neungrothai | Thepanondh, Sarawut
Airborne volatile organic compounds (VOCs) concentration data from monitoring stations in industrial and urban (Bangkok) area of Thailand were analyzed using Positive Matrix Factorization (PMF) to identify and elaborate on their source profiles. Analyzed data were obtained from those measured from January 2009 to December 2013 in the study area. The PMF was performed to estimate the contribution of specific source types to ambient concentrations. The most suitable number of factors for a dataset in this study was found to be eleven factors for compositions and characteristics of VOCs. Emission sources of VOCs in industrial area were classified into three to five groups based on their contribution. In industrial area, 42 to 57% of total VOC concentrations were contributed from mobile sources. Contribution to total VOCs concentration from industrial processes and household chemical usage were about 15 to 44% and 3 to 10%, respectively. Moreover, some species of VOCs particularly the ozone depleting substances such as Freon 11, Freon 114 and carbon tetrachloride were found as background concentration in ambient air. As for Bangkok, it was found that most of total VOC concentrations were contributed from mobile source emissions.
اظهر المزيد [+] اقل [-]Long-term hydrodynamic modeling of the Arabian Gulf النص الكامل
2015
Elhakeem, Abubaker | Elshorbagy, Walid | Bleninger, Tobias
A 3-D prognostic baroclinic hydrodynamic model of the Arabian Gulf (AG) was developed using Delft3D-FLOW. The model was forced with long-term time averaged climatological data over the computational domain and long-term salinity and temperature boundary conditions applied at its tidal open boundary. The model simulation results were thoroughly validated against measured tides from 5 stations and measured currents at 4 locations in the central and southern parts. Water salinity and temperature were validated in space and time using observations spanning over 73years from 1923 to 1996 for the AG, the Strait of Hormuz and the Gulf of Oman. The bottom flow of the AG basin at the vicinity of the Strait of Hormuz was also validated against the available measurements. Seasonal evaporation and surface density spatial distribution maps were produced and compared with available records. The developed model setup successfully generated the AG seasonal stratification and hydrographic conditions.
اظهر المزيد [+] اقل [-]The amount and accumulation rate of plastic debris on marshes and beaches on the Georgia coast النص الكامل
2015
Lee, Richard F. | Sanders, Dorothea P.
The amount and accumulation rate of plastic debris at 20 sites along the Georgia coast were prepared using data reported by a number of volunteer organizations. The amount of plastic debris at highly visited barrier island beaches and estuarine marshes ranged from 300 to >1000kg. Relatively large amount of plastics (180–500kg) were found on less visited barrier island beaches, i.e. Blackbeard, Ossabaw and Cumberland Islands. A follow up monthly or quarterly collection study was carried out on two of the sites, a barrier beach and estuarine marsh, to determine accumulation rate in 8000m2 areas. Accumulation rates ranged from 0.18 to 1.28kg/30days–8000m2 on the barrier island beach and from 0.6 to 1.61kg/30days–8000m2 at the estuarine marsh site. The major type of plastics, e.g. bottles, food wrappers, plastic fragments, was highly variable at different seasons and sites. The authors recommend consideration of a standardization in reporting plastic debris, with respect to quantitation of debris and sample area.
اظهر المزيد [+] اقل [-]Background values for evaluation of heavy metal contamination in sediments in the Parnaíba River Delta estuary, NE/Brazil النص الكامل
2015
de Paula Filho, Francisco José | Marins, Rozane Valente | Lacerda, Luiz Drude de | Aguiar, José Edvar | Peres, Tiago Farias
This study establishes regional background levels and upper thresholds (geochemical baseline) for Zn, Cu, Pb, Cr, Mn, and Fe from surface samples and profiles taken in 16 sedimentary environments of the Parnaíba River Delta estuary, NE–Brazil. Three approaches were applied to evaluate metal contamination: normalization to Fe, statistical analysis and sediment quality guidelines or environmental assessment criteria (TEL–PEL). Metal concentrations in sediments ranged from 2.4 to 31mgZnkg−1, 1.5 to 48mgCukg−1, 1.3 to 28mgPbkg−1, 1.5 to 38mgCrkg−1; 145 to 1,356mgMnkg−1, and 0.3% to 2.5% for Fe. All metals showed positive correlations with the <0.63μm sediment fraction, indicating a significant association with rich lithogenic sources of iron oxide–hydroxides. Results suggest a low probability of adverse effects to the local aquatic biota. The background values of the area were lower than those reported for other areas of the northeastern coast of Brazil.
اظهر المزيد [+] اقل [-]Assessing trace element contamination in Fildes Peninsula (King George Island) and Ardley Island, Antarctic النص الكامل
2015
Amaro, Eduardo | Padeiro, Ana | Mão de Ferro, André | Mota, Ana Maria | Leppe, Marcelo | Verkulich, Sergey | Hughes, Kevin A. | Peter, H. U. (Hans-Ulrich) | Canário, João
King George Island, situated in the South Shetland Islands archipelago, is one of the most visited sites in Antarctica. This has contributed to a high density of scientific stations and shelters in the region, especially in Fildes Peninsula. In order to evaluate the natural and anthropogenic sources of trace elements (As, Cd, Cu, Zn, Pb and Hg) soil and moss samples were collected from different sites in January 2013. In general, the results revealed homogeneous concentrations (μgg−1) for each element in the majority of collected samples (As: 3.8±1.4; Cd: 0.4±0.9; Cu: 34±4; Zn: 115±13; Pb: 20±5; Hg; 0.011±0.009). However, some samples in specific areas of Fildes Bay showed the existence of local anthropogenic activities that have contributed to the enrichment of contaminants in soils and moss samples that correlated to one another (e.g. Pb: 1101μgg−1).Human presence is linked to examples of contamination and environmental perturbation, making essential the implementation of this type of study in order to understand and protect unique places in Antarctica.
اظهر المزيد [+] اقل [-]Responses of benthic foraminifera to the 2011 oil spill in the Bohai Sea, PR China النص الكامل
2015
Lei, Yan Li | Li, Tie Gang | Bi, Hongsheng | Cui, Wen Lin | Song, Wen Peng | Li, Ji Ye | Li, Cheng Chun
The 2011 oil spill in the Bohai Sea was the largest spill event in China. Nine sediment cores were taken near the spill site and environmental factors including Polycyclic Aromatic Hydrocarbon (PAHs), oils, sulfides, organic carbon were measured 6months later. Benthic foraminifera were separated into >150μm (large) and 63–150μm (small) size fractions for 2-cm depth interval of each sediment core. Statistical analyses suggested that the species composition of living foraminifera was impacted by oils, PAHs and sulfides. Large foraminifera were more sensitive to the oils than the small. Abnormal specimens were positively correlated with oils or PAHs. Small forms, however, tended to have high reproduction and mortality. Pollution-resistant and opportunistic taxa were identified to calculate a Foraminiferal Index of Environmental Impacts (FIEI). The FIEI increased from low to high oil-polluted station and from deep layer to surface sediment reflects the impact of oil pollution in this area.
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