خيارات البحث
النتائج 1531 - 1540 من 4,308
Elucidation of seasonal variations of physicochemical and biological parameters with statistical analysis methods in Puducherry coastal waters النص الكامل
2017
Bharathi, M.D. | Sivaji Patra, | Sundaramoorthy, S. | Madeswaran, P. | Sundaramanickam, A.
The present investigation aimed to study the effect of monsoonal and anthropogenic influences on the water quality parameters of Puducherry coastal waters. Surface water sampling was performed at three fixed stations in four distinct seasons during 2011. Physical water quality parameters such as salinity and TSM showed strong seasonal and spatial variability. Evaporation and monsoonal runoff seem to be the major controlling forces for these parameters in the coastal waters. Seasonal distribution of the parameters showed a random pattern for nitrate and a well-defined pattern for silicate. Chl-a was minimum during monsoon when high TSM was encountered in the system. Moreover, factors that regulated the phytoplankton biomass varied with seasons. Moreover, TSM was strongly correlated with silicate. The relationship between Chl-a and nutrients were more consistent throughout the year, and much weaker correlations were noticed between Chl-a and TSM. Cluster analysis depicted the existence of a marked seasonal heterogeneity.
اظهر المزيد [+] اقل [-]Assessment of sediment pollution by metals. A case study from Cienfuegos Bay, Cuba النص الكامل
2017
Peña-Icart, Mirella | Mendiguchía, Carolina | Villanueva-Tagle, Margarita | Bolaños-Alvarez, Yoelvis | Alonso-Hernandez, Carlos | Moreno, Carlos | Pomares-Alfonso, Mario Simeón
Sediments were grouped in three zones of the bay: two in the northern basin with higher metal contamination; and another in the southern basin, where lithogenic metals were predominant. Sediment pollution classification made using Index of geoaccumulation and Enrichment factor was consistent, indicating higher accumulation of Cd and Pb in the northern basin. The negative influence of activities linked to petrol was predicted by V/Ni and V/(Ni+V) ratios. Cd and Pb did not represent a potential risk; while Cu and Ni could be risky for biota in most sediment, according to Screening Quick Reference Tables (SQuiRTs). Comparison of bioavailable fraction of metals with references in SQuiRTs corroborated the low potential damage on the biota due to As, Cd, Pb, Cr, Zn; and a higher potential damage due to Cu; while an attenuation of the risk due to Ni predicted by SQuiRTs could be expected.
اظهر المزيد [+] اقل [-]Navigational threats by derelict fishing gear to navy ships in the Korean seas النص الكامل
2017
Hong, Sunwook | Lee, Jongmyoung | Lim, Sehan
This study assessed the impact of derelict fishing gear (DFG) on navigation. The Republic of Korea's navy (ROKN) recorded every case of approximately 170 naval ships associated with propeller entanglement by DFG from January 2010 to December 2015. The frequency of cases was 2.3 per ship and 397.7 (±37.5) per year. The amount of DFG disentangled was 0.025tons per ship and 10.0 (±1.7) tons per year. The frequency temporally decreased whereas the amount increased over these six years. To disentangle propellers, 3.1 divers were needed on average per case. Propeller entanglement occurred in all local seas and some of these areas showed increases over time. Our study highlights that the impact of DFG on navigational threats has been persistent and ubiquitous and can potentially be reduced by preventing DFG in fishing areas, with a focus on improved management by fishermen and government and with more efficient retrieval of DFG.
اظهر المزيد [+] اقل [-]The impacts of the Samarco mine tailing spill on the Rio Doce estuary, Eastern Brazil النص الكامل
2017
Gomes, Luiz Eduardo de Oliveira | Correa, Lucas Barreto | Sá, Fabian | Neto, Renato Rodrigues | Bernardino, Angelo Fraga
Over 50 million cubic meters of mining tailings were released in the Rio Doce basin after the collapse of the Fundão dam (Samarco) in November 2015. Predicting significant impacts on the Rio Doce estuary, we sampled sediments to investigate short-term impacts on the benthic assemblages and trace metal accumulation on estuarine sediments. With the arrival of the tailing plumes in the estuary, we detected a predominance of clay particles and increased trace metal concentrations of up to 5 times in some areas. The rapid sedimentation after the impact also impacted estuarine macrofaunal assemblages through loss surface-dwelling taxa. As expected, the impacts on benthic assemblages observed up to 3days after the arrival of tailings were not clearly associated with trace metal concentrations, but long-term effects need to be studied. We recommend that the high spatial variability within the estuary be considered in future impact assessment studies.
اظهر المزيد [+] اقل [-]Polycyclic aromatic hydrocarbons (PAHs) at the Gulf of Kutch, Gujarat, India: Occurrence, source apportionment, and toxicity of PAHs as an emerging issue النص الكامل
2017
Rajpara, Rahul K. | Dudhagara, Dushyant R. | Bhatt, Jwalant K. | Gosai, Haren B. | Dave, Bharti P.
The present study extrapolates the assessment and characterization of a barely studied region, the Gulf of Kutch, (near Jamnagar), Gujarat, India, in terms of PAH exposure, adverse effects caused by them, and various toxicological indices showing the catastrophic effects of their elevated concentrations. ΣPAH concentration in the site ranged from 118,280 to 1,099,410ngg−1 dw, with a predominance of 2–3-ring PAHs (79.09%) as compared to 4–5- and 6-ring PAHs (20.91%). The concentrations of carcinogenic PAHs were found to be between 8120 and 160,000ngg−1 dw, with a mean of 63,810ngg−1 dw, which is much higher than normal acceptable values. The toxic equivalent quotient for 6CPAHs ranged from 150.47 to 26,330ngg−1 BaPeq, encompassing 50.63% of ΣPAH toxicity. This toxicological profile of the present study site would be of paramount importance as it offers fresh information regarding the load of legacy pollutants such as PAHs and the inputs and methods to cope with their extremely high concentrations in less explored marine habitats.
اظهر المزيد [+] اقل [-]An ecotoxicological approach to evaluate the effects of tourism impacts in the Marine Protected Area of La Maddalena (Sardinia, Italy) النص الكامل
2017
Moschino, V. | Schintu, M. | Marrucci, A. | Marras, B. | Nesto, N. | Da Ros, L.
In the Marine Protected Area of La Maddalena Archipelago, environmental protection rules and safeguard measures for nautical activities have helped in reducing anthropogenic pressure; however, tourism related activities remain particularly significant in summer. With the aim of evaluating their impacts, the biomarker approach using transplanted Mytilus galloprovincialis as sentinel organisms coupled with POCIS deployment was applied. Mussels, translocated to four marine areas differently impacted by tourism activities, were sampled before, during and after the tourist season. Moreover, endocrine disruptors in passive samplers POCIS and the cellular toxicity of whole POCIS extracts on mussel haemocytes were evaluated to integrate ecotoxicological information. Lysosomal biomarkers, condition index and mortality rate, as well as metals in tissues suggested an alteration of the health status of mussels transplanted to the most impacted sites. The cellular toxicity of POCIS extracts was pointed out, notwithstanding the concentrations of the examined compounds were always below the detection limits.
اظهر المزيد [+] اقل [-]Cluster analysis of aerosol properties retrieved from a sky-radiometer over a coastal site: Thiruvananthapuram, India النص الكامل
2017
Sateesh, M. | Soni, V.K. | Raju, P.V.S. | Mor, Vikram
The present work analysed the characteristics of aerosol optical, physical properties over Thiruvananthapuram, a coastal site in southern part of India using Sky-radiometer (Model POM-02, Prede Co. Ltd, Japan) for a period 2011–2015. The lowest value of AOD was found during winter season which was followed by monsoon season. The highest value of AOD was found in pre-monsoon. The Angstrom Exponent which characterizes the size of the aerosols, decreases from January to June and increases from June to December months. The monthly back trajectory analysis using HYSPLIT describes the source of air masses for the station. The fine mode particles are dominant during winter season, which may be associated with the anthropogenic emissions and long range transport. A gradual increase in the coarse mode aerosol load was found from pre-monsoon season to the monsoon season, because of the large air mass coming from the ocean. A decrease in coarse mode aerosol was found during the post-monsoon period, due to the preferential washout of coarse mode particles during monsoon season. The result showed the dominance of mixed type aerosols during all seasons. The C1 cluster originating from Bay of Bengal contributed 29.8% of ensemble of trajectories, C2 cluster from Arabian Sea 31.9%, C3 cluster from the Indian Ocean (Northern hemisphere) 18.0%, and C4 cluster Indian Ocean (Southern hemisphere) 20.3%.
اظهر المزيد [+] اقل [-]Seasonal changes of polycyclic aromatic hydrocarbons in response to hydrology and anthropogenic activities in the Pearl River estuary, China النص الكامل
2017
Liu, Feng | Niu, Lixia | Chen, Hui | Li, Ping | Tian, Feng | Yang, Qingshu
The behaviours of PAHs (containing 2–6 aromatic rings) in the Pearl River estuary were examined each month in 2011. This study was designed to investigate the abundance of 16 priority PAHs and their response to the seasonal dynamics of anthropogenic activities and hydrological cycles. Monthly mean concentrations of ∑16PAHs in water and suspended particulate matter (SPM) were 88.31ng/L and 252.31ng/L respectively, with higher concentrations in the wet season (April to September). Heavy precipitation in the wet season resulted in relatively increased PAH input via riverine discharges and atmospheric deposition. Seasonal variations in suspended sediment concentration (SSC), temperature and salinity have considerably affected the PAH phase association. Higher SSC in the wet season contributed to higher concentration of the PAHs in SPM, and higher temperature and lower salinity facilitated desorption from SPM. The PAH sources were largely attributed to vehicular emissions, coal combustion and coke ovens.
اظهر المزيد [+] اقل [-]Shallow rocky nursery habitat for fish: Spatial variability of juvenile fishes among this poorly protected essential habitat النص الكامل
2017
Chemineé, Adrien | Rider, Mary | Lenfant, Philippe | Zawadzki, Audrey | Mercière, Alexandre | Crec'hriou, Romain | Mercader, Manon | Saragoni, Gilles | Neveu, Reda | Ternon, Quentin | Pastor, Jérémy
Coastal nursery habitats are essential for the renewal of adult fish populations. We quantified the availability of a coastal nursery habitat (shallow heterogeneous rocky bottoms) and the spatial variability of its juvenile fish populations along 250km of the Catalan coastline (France and Spain). Nurseries were present in 27% of the coastline, but only 2% of them benefited from strict protection status. For nine taxa characteristic of this habitat, total juvenile densities varied significantly between nursery sites along the coastline, with the highest densities being found on the northern sites. Recruitment level (i.e. a proxy of nursery value) was not explained by protection level, but it was moderately and positively correlated with an anthropization index. Patterns of spatial variations were taxa-specific. Exceptional observations of four juveniles of the protected grouper Epinephelus marginatus were recorded. Our data on habitat availability and recruitment levels provides important informations which help to focus MPA management efforts.
اظهر المزيد [+] اقل [-]Acute toxicity of organic antifouling biocides to phytoplankton Nitzschia pungens and zooplankton Artemia larvae النص الكامل
2017
Jung, S.M. | Bae, J.S. | Kang, S.G. | Son, J.S. | Jeon, J.H. | Lee, H.J. | Jeon, J.Y. | Sidharthan, M. | Ryu, SH | Shin, H.W.
The toxicity of the antifouling biocides Irgarol 1051, Diuron, Chlorothalonil, Dichlofluanid, Sea-nine 211, Copper pyrithione, Zinc pyrithione, Ziram and Zineb were evaluated on Nitzschia pungens and Artemia larvae. Results showed that EC50 for Irgarol 1051 was 0.586μgl−1 was the strongest effect on N. pungens following by Copper pyrithione (4.908μgl−1), Ziram (5.421μgl−1), Zinc pyrithione (5.513μgl−1), Diuron (6.640μgl−1), Zineb (232.249μgl−1), Sea-nine 211(267.368μgl−1), Chlorothalonil (360.963μgl−1) and Dichlofluanid (377.010μgl−1) in 96h. In Artemia larvae, the biocides were evaluated the LC50 for larval survivals at 48h. Sea-nine 211 and Copper pyrithione were 0.318 and 0.319mgl−1. Chlorothalonil, Zinc pyrithione and Ziram were 2.683, 3.147 and 4.778mgl−1. Irgarol 1051, Diuron, Zineb and Dichlofluanid were 9.734, 30.573, 41.170 and 154.944mgl−1. These results provide baseline data concerning the toxicity of antifouling biocides against marine environment.
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