خيارات البحث
النتائج 2141 - 2150 من 5,151
Corporate social responsibility in marine plastic debris governance النص الكامل
2018
Landon-Lane, Micah
This paper explores the governance characteristics of marine plastic debris, some of the factors underpinning its severity, and examines the possibility of harnessing corporate social responsibility (CSR) to manage plastic use within the contextual attitudes of a contemporary global society. It argues that international and domestic law alone are insufficient to resolve the “wicked problem” of marine plastic debris, and investigates the potential of the private sector, through the philosophy of CSR, to assist in reducing the amount and impacts of marine plastic debris. To illustrate how CSR could minimise marine plastic pollution, an industry-targeted code of conduct was developed. Applying CSR would be most effective if implemented in conjunction with facilitating governance frameworks, such as supportive governmental regulation and non-governmental partnerships. This study maintains that management policies must be inclusive of all stakeholders if they are to match the scale and severity of the marine plastic debris issue.
اظهر المزيد [+] اقل [-]Magnesium Oxide-Based Absorbents for CO2 Capture at Medium Temperature النص الكامل
2018
Yang, Xinfang | Zhao, Lifeng | Li, Xueyao | Xiao, Yunhan
MgO-based absorbent has been recognized as a promising CO₂ absorbent at intermediate temperature, though the carbonation performance of pure MgO is poor. Researchers have been devoted to optimize the CO₂ absorption ability via introducing alkali metal carbonates or nitrates. In this paper, the absorption performance of MgO-based absorbents promoted by alkali metal carbonates or modified by alkali metal nitrates has been summarized, and the affecting mechanism has been concluded. Alkali metal nitrates are essential for high absorption ability, and alkali metal carbonates facilitate high-temperature carbonation. Effects of fuel gas conditions and absorbent pelletization are also mentioned for practical applications. H₂O can accelerate the carbonation rate effectively, but the influencing mechanism of H₂O and the CO₂ absorption stability in presence of H₂O was not clearly reported. Further investigations on pelletized MgO-based absorbents modified by alkali metal salts considering regeneration conditions of high CO₂ concentration are proposed based on the recent research findings.
اظهر المزيد [+] اقل [-]20th century increase in body size of a hypoxia-tolerant bivalve documented by sediment cores from the northern Adriatic Sea (Gulf of Trieste) النص الكامل
2018
Fuksi, Tomáš | Tomašových, Adam | Gallmetzer, Ivo | Haselmair, Alexandra | Zuschin, Martin
An increase in the frequency of hypoxia, mucilages, and sediment pollution occurred in the 20th century in the Adriatic Sea. To assess the effects of these impacts on bivalves, we evaluate temporal changes in size structure of the opportunistic bivalve Corbula gibba in four sediment cores that cover the past ~500 years in the northern, eutrophic part and ~10,000 years in the southern, mesotrophic part of the Gulf of Trieste. Assemblages exhibit a stable size structure during the highstand phase but shift to bimodal distributions and show a significant increase in the 95th percentile size during the 20th century. This increase in size by 2–3 mm is larger than the northward size increase associated with the transition from mesotrophic to eutrophic habitats. It coincides with increasing concentrations of total organic carbon and nitrogen, and can be related to enhanced food supply and by the tolerance of C. gibba to hypoxia.
اظهر المزيد [+] اقل [-]Effects of sub-seabed CO2 leakage: Short- and medium-term responses of benthic macrofaunal assemblages النص الكامل
2018
Amaro, T. | Bertocci, I. | Queiros, A.M. | Rastelli, E. | Borgersen, G. | Brkljacic, M. | Nunes, J. | Sorensen, K. | Danovaro, R. | Widdicombe, S.
The continued rise in atmospheric carbon dioxide (CO2) levels is driving climate change and temperature shifts at a global scale. CO2 Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO2 emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO2 from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO2 leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO2 leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO2 concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO2), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO2 leakage on macrofaunal assemblages occurs almost exclusively at the higher CO2 concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible context-dependency of the present findings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies.
اظهر المزيد [+] اقل [-]Historical trends of anthropogenic metals in sediments of Jiaozhou Bay over the last century النص الكامل
2018
Kang, Xuming | Song, Jinming | Yuan, Huamao | Li, Xuegang | Li, Ning | Duan, Liqin
Reconstructing heavy metal historical trends are essential for better understanding anthropogenic impact on marine ecosystems. In this work, the ecological risk and sources of Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb in Jiaozhou Bay were studied and the anthropogenic metal emissions was also quantified. The ecological risk was mainly caused by Cd, As and Cu, which presented an increasing trend with increased anthropogenic activities since the 1950s. The statistical analysis show that Cr, Mn, Ni, Cu and Zn were primarily from natural sources. Cadmium and Mn might originate from both natural and anthropogenic sources. Arsenic and Pb were sourced from agricultural activities and atmospheric precipitation, respectively. The anthropogenic flux of Cr, Mn, Ni, Cu, Zn, As, Cd and Pb were 138, 586, 63, 66, 161, 35, 0.31 and 44 mg/m2/a since the 1950s. Over 40.0% of Cu and As were quantified from anthropogenic emissions since the 1950s.
اظهر المزيد [+] اقل [-]Marine debris ingestion of green sea turtles, Chelonia mydas, (Linnaeus, 1758) from the eastern coast of the United Arab Emirates النص الكامل
2018
Yaghmour, Fadi | Al Bousi, Marwa | Whittington-Jones, Brendan | Pereira, John | García-Nuñez, Soledad | Budd, Jane
The deleterious effects of marine debris ingestion on marine turtles are well documented in literature globally. In this study, the qualitative and quantitative aspects of marine debris ingested by 14 stranded green sea turtles Chelonia mydas, (Linnaeus, 1758) along the eastern coast of the United Arab Emirates were investigated. The numeric and gravimetric proportions of debris in the esophagus, stomach and intestines were documented following classification of color, presumed sources and Marine Strategy Framework Directive categories and sub-categories. The results show that 85.7% of the specimens examined consumed marine debris. On average, specimens consumed 61.9 ± 17.2 items of 1.0 ± 0.3 g mass. Plastics, particularly white, and transparent thread-like and sheet-like plastics, were the predominant debris ingested. The results reflect a potentially high level of interaction between green sea turtles and anthropogenic marine debris along the Gulf of Oman coast of the UAE.
اظهر المزيد [+] اقل [-]The combined effects of elevated pCO2 and food availability on Tigriopus japonicus Mori larval development, reproduction, and superoxide dismutase activity النص الكامل
2018
Li, Fei | Shi, Jiahui | Cheung, S.G. | Shin, P.K.S. | Liu, Xiaoshou | Sun, Yan | Mu, Fanghong
Previous studies have shown that ocean acidification has little effect on adult Tigriopus japonicus copepods, and mainly impairs the early development and reproduction of females. This study investigated the possible interactive effect between CO2-induced seawater acidification and food availability on larval development and reproductive output in T. japonicus. Copepods were exposed to either pH8.1 or pH7.3 under different food concentrations (0.5×104–80.0×104cells/mL). Both the development of nauplii and copepodites was delayed at pH7.3 with a greater effect at lower food concentrations. The reproductive output followed a bell-shaped curve with the highest reproductive output at food concentrations between 30×104 and 40×104cells/mL. As an indicator of oxidative stress, the activity of superoxide dismutase increased at lower pH, with a greater increase at lower food concentrations. Therefore, the effect of elevated pCO2 on T. japonicus was food dependent.
اظهر المزيد [+] اقل [-]Amino acids as indicators to elucidate organic matter degradation profile in the Cochin estuarine sediments, Southwest coast of India النص الكامل
2018
Salas, P.M. | Sujatha, C.H. | Ratheesh Kumar, C.S. | Cheriyan, Eldhose
Surface sediments from three zones (fresh water, estuarine, and riverine/industrial zones) of the Cochin estuary, Southwest coast of India, were seasonally analyzed to understand the nature and degradation status of organic matter. Amino acid-based indices such as total hydrolyzable amino acids (THAAs), percentage contributions of amino acid carbon to total organic carbon (THAA-C%) and those of amino acid nitrogen to total nitrogen (THAA-N%), and degradation index (DI) were calculated. Elevated levels of amino acids in the sediments of the estuary were attributed to river runoff, autochthonous production, allochthonous inputs, and industrial and domestic effluent discharges. Higher levels of THAA-C%, THAA-N%, THAA, and positive DI found in most of the stations suggest the fresh deposition of organic matter. Multivariate statistical analyses revealed that the dispersal pattern of amino acids depends on the sediment texture, organic matter, redox state, and microbial processes in the study region.
اظهر المزيد [+] اقل [-]Seawater quality assessment and identification of pollution sources along the central coastal area of Gabes Gulf (SE Tunisia): Evidence of industrial impact and implications for marine environment protection النص الكامل
2018
El Zrelli, Radhouan | Rabaoui, Lotfi | Ben Alaya, Mohsen | Daghbouj, Nabil | Castet, Sylvie | Besson, Philippe | Michel, Sylvain | Bejaoui, Nejla | Courjault-Radé, Pierre
Temperature, pH and trace elements (F, P, Cr, Cu, Zn, Cd, and Pb) contents were determined in 16 stations as well as in 2 industrial and 2 domestic discharge sources, in the central coastal area of the Gulf of Gabes. Compared to the northern and southern areas of the study area, the highest contents of contaminants were reached in the central area which hosts the coastal industrial complex. The seawater in this central area was also found to be acid and of higher temperature. Based on the Water Pollution Index results, an increasing degradation gradient of the seawater quality was revealed from northern and/or southern stations to central ones, categorized as ‘strongly to seriously affected’. Phosphogypsum wastes dumped by the Tunisian Chemical Group (GCT) seem to have continuously degraded the seawater quality in the study area. A rapid intervention is needed to stop the effects on the marine environment.
اظهر المزيد [+] اقل [-]Spectroscopic analyses and genotoxicity of dioxins in the aquatic environment of Alexandria النص الكامل
2018
Abdel-Gawad, Fagr Kh | Osman, Osama | Bassem, Samah M. | Nassar, Hossam F. | Temraz, Tarek A. | Elhaes, Hanan | Ibrahim, Medhat
Dioxins have global concerns because of the bioaccumulation tendency and persistency in the environment. Water, seabream Pagrus auratus and seabass Dicentrarchus labrax samples were collected from Abu Qir, Alexandria to evaluate the concentration of dioxin. Fourier Transform Infrared Spectrometer (FTIR) and molecular modeling was applied for elucidating the molecular structure of fish samples. Furthermore, HPLC with UV detection was used to determine the concentration of dioxins (2,8-dichloro dibenzo-p-dioxin). RT-PCR assay was conducted to verify the expression of some immune genes in the fish species as a result of water pollution. The average detected concentrations varied from 0.2 to 1.3μg/l. Gene expression revealed that MHC class 1 and C3 were highly upregulated in liver and muscle of seabass and seabream while T2BP was highly regulated in seabass liver and seabream muscle and seabass muscle for transferrin, FTIR and molecular modeling indicate that dioxin finds its way to fish protein.
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