خيارات البحث
النتائج 1071 - 1080 من 3,197
Potential oil spill risk from shipping and the implications for management in the Caribbean Sea
2015
Singh, Asha | Asmath, Hamish | Chee, Candice Leung | Darsan, Junior
The semi enclosed Caribbean Sea is ranked as having one of the most intense maritime traffic in the world. These maritime activities have led to significant oil pollution. Simultaneously, this sea supports many critical habitats functioning as a Large Marine Ecosystem (LME). While the impacts of oil pollution are recognised, a number of management challenges remain. This study applies spatial modelling to identify critical areas potentially at risk from oil spills in the form of a potential oil spill risk (POSR) model. The model indicates that approximately 83% of the sea could be potentially impacted by oil spills due to shipping. The results from this study collectively support a management framework for minimising ship generated oil pollution in the Caribbean Sea. Among the recommended components are a common policy, surveillance and monitoring controls, standards, monitoring programmes, data collection and greater rates of convention ratifications.
اظهر المزيد [+] اقل [-]Metabarcoding approach for nonindigenous species surveillance in marine coastal waters
2015
Zaiko, Anastasija | Samuiloviene, Aurelija | Ardura, Alba | García Vázquez, Eva
In this study, high-throughput sequencing (HTS) metabarcoding was applied for the surveillance of plankton communities within the southeastern (SE) Baltic Sea coastal zone. These results were compared with those from routine monitoring survey and morphological analyses. Four of five nonindigenous species found in the samples were identified exclusively by metabarcoding. All of them are considered as invasive in the Baltic Sea with reported impact on the ecosystem and biodiversity. This study indicates that, despite some current limitations, HTS metabarcoding can provide information on the presence of exotic species and advantageously complement conventional approaches, only requiring the same monitoring effort as before. Even in the currently immature status of HTS, this combination of HTS metabarcoding and observational records is recommended in the early detection of marine pests and delivery of the environmental status metrics of nonindigenous species.
اظهر المزيد [+] اقل [-]Screening for contaminant hotspots in the marine environment of Kuwait using ecotoxicological and chemical screening techniques
2015
Smith, A.J. | McGowan, T. | Devlin, M.J. | Massoud, M.S. | Al-Enezi, M. | Al-Zaidan, A.S. | Al-Sarawi, H.A. | Lyons, B.P.
Kuwait is a country with low rainfall and highly concentrated industrial and domestic effluents entering its coastal waters. These can be both treated and untreated. In this study we sampled a series of coastal and open-sea sites and used a variety of analyses to identify those sites requiring the most attention. We used a high throughput GC–MS screen to look for over 1000 chemicals in the samples. Estrogen and androgen screens assessed the potential to disrupt endocrine activity. An oyster embryo development screen was used to assess biological effect potential.The chemical screen identified sites which had high numbers of identified industrial and domestic chemicals. The oyster screen showed that these sites had also caused high levels of developmental abnormalities with 100% of embryos affected at some sites. The yeast screen showed that estrogenic chemicals were present in outfalls at 2–3ng/l E2 equivalent, and detectable even in some open water sites.
اظهر المزيد [+] اقل [-]Assessing trace element contamination in Fildes Peninsula (King George Island) and Ardley Island, Antarctic
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 [-]Release of heavy metals from sediment bed under wave-induced liquefaction
2015
Sun, Zhenhong | Xu, Guohui | Hao, Ting | Huang, Zhe | Fang, Hongru | Wang, Gang
Sediments in lakes and coasts can release metals into water via static diffusion and especially resuspension. The resuspension under sediment liquefaction may severely affect the concentrations of metals in water. In this study, flume experiments were carried out twice to study the release of two metal combinations (Zn and Pb; Zn and Cu), respectively. Each experiment included three phases: consolidation; non-liquefaction and liquefaction. Results showed that total Zn concentration at liquefaction phase increased by a maximum rate of 26 compared with the consolidation phase. The concentration of particulate Zn at liquefaction phase increased by a maximum rate of 8.30 compared with the non-liquefaction phase. The average concentration of dissolved Zn at the liquefaction phase increased up to 0.24 times from the consolidation phase. Total Zn concentration at the non-liquefaction phase increased by several times compared with the consolidation phase. Metals were homogeneously distributed in the liquefaction layer through wave actions.
اظهر المزيد [+] اقل [-]Effects of aquaculture fallowing on the recovery of macrofauna communities
2015
Zhulay, Irina | Reiss, Katrin | Reiss, Henning
The fallowing period is a management measure in aquaculture where the production is paused for a few months to reduce the impact on the benthic environment. We studied the effects of different fallowing periods on the recovery of macrofauna at two salmon farms in Norway. The macrofauna at the farm stations were characterised by high abundances of opportunistic taxa (e.g. Capitella spp.), low diversity and significantly different community structure compared to reference sites. The fallowing initiated macrofauna recovery at both farm stations, indicated by a decline of dominant opportunistic taxa after 2months. Significant changes in taxa composition occurred only after 6months, although indications of disturbance were still evident. Surprisingly, no corresponding spatial or temporal differences were found in the sediment parameters such as redox, TOC and pH. The results suggest that macrofauna is a more sensitive indicator and that the seasonal timing of fallowing may affect recovery dynamics.
اظهر المزيد [+] اقل [-]GC–MS analysis of two types of mixed oils, a comparison of composition and weathering patterns
2015
Ho, S.J. | Wang, C.Y. | Luo, Y.M.
In order to compare the effects of weathering on two types of mixed oil, simulated weathering experiments were performed. The first sample was a mixture of two fresh oils and the second sample was a mixture of one fresh oil and another oil sample that had undergone a serious weathering process. Comparative studies evaluated decay rates and changes in diagnostic ratios of some fingerprinting biomarkers. Results showed that the mixing process affected the weathering rate of some compounds in the oils and also that certain diagnostic ratios are more suitable for estimating mixing proportions. A Pr/n-C17 versus Ph/n-C18 plot can be used to identify the end-numbers of mixed oils and the (C13+C14)/(C25+C26) ratio is a useful diagnostic ratio to detect the degree of weathering. Finally, hopane, sterane, and alkylated PAH fingerprints were found to give useful insights about the sources of the mixed oils.
اظهر المزيد [+] اقل [-]Are red mullet efficient as bio-indicators of mercury contamination? A case study from the French Mediterranean
2015
Cresson, P. | Bouchoucha, M. | Miralles, F. | Elleboode, R. | Mahé, K. | Marusczak, N. | Thebault, H. | Cossa, D.
Mercury (Hg) is one of the main chemicals currently altering Mediterranean ecosystems. Red mullet (Mullus barbatus and M. surmuletus) have been widely used as quantitative bio-indicators of chemical contamination. In this study, we reassess the ability of these species to be used as efficient bio-indicators of Hg contamination by monitoring during 18months Hg concentrations in muscle tissue of mullet sampled from 5 French Mediterranean coastal areas. Mean concentrations ranged between 0.23 and 0.78μgg−1 dry mass for both species. Values were consistent with expected contamination patterns of all sites except Corsica. Results confirmed that red mullets are efficient bio-indicators of Hg contamination. Nevertheless, the observed variability in Hg concentrations calls for caution regarding the period and the sample size. Attention should be paid to environmental and biologic specificities of each studied site, as they can alter the bioaccumulation of Hg, and lead to inferences about environmental Hg concentrations.
اظهر المزيد [+] اقل [-]Forensic investigation of aliphatic hydrocarbons in the sediments from selected mangrove ecosystems in the west coast of Peninsular Malaysia
2015
Vaezzadeh, Vahab | Zakaria, Mohamad Pauzi | Shau-Hwai, Aileen Tan | Ibrahim, Zelina Zaiton | Mustafa, Shuhaimi | Abootalebi-Jahromi, Fatemeh | Masood, Najat | Magam, Sami Mohsen | Alkhadher, Sadeq Abdullah Abdo
Peninsular Malaysia has gone through fast development during recent decades resulting in the release of large amounts of petroleum and its products into the environment. Aliphatic hydrocarbons are one of the major components of petroleum. Surface sediment samples were collected from five rivers along the west coast of Peninsular Malaysia and analyzed for aliphatic hydrocarbons. The total concentrations of C10 to C36 n-alkanes ranged from 27,945 to 254,463ng·g−1dry weight (dw). Evaluation of various n-alkane indices such as carbon preference index (CPI; 0.35 to 3.10) and average chain length (ACL; 26.74 to 29.23) of C25 to C33 n-alkanes indicated a predominance of petrogenic source n-alkanes in the lower parts of the Rivers, while biogenic origin n-alkanes from vascular plants are more predominant in the upper parts, especially in less polluted areas. Petrogenic sources of n-alkanes are predominantly heavy and degraded oil versus fresh oil inputs.
اظهر المزيد [+] اقل [-]Glyphosate and AMPA in the estuaries of the Baltic Sea method optimization and field study
2015
Skeff, Wael | Neumann, Christine | Schulz-Bull, Detlef E.
Water samples from ten German Baltic estuaries were collected in 2012 in order to study the presence of the herbicide glyphosate, its primary metabolite AMPA and their potential transport to the marine environment. For the analyses an LC–MS/MS based analytical method after derivatization with FMOC-Cl was optimized and validated for marine water samples. All investigated estuarine stations were contaminated with AMPA and nine of them also with glyphosate. Concentration ranges observed were 28 to 1690ng/L and 45 to 4156ng/L for glyphosate and AMPA, respectively with strong spatial and temporal fluctuations. Both contaminants were found at inbound sampling sites in the stream Muehlenfliess and concentrations decreased along the salinity gradient to the estuaries of the Baltic Sea. The data obtained in this study clearly depict the transport of glyphosate and AMPA to the Baltic Sea. Hence, detailed fate and risk assessment for both contaminants in marine environments are required.
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