خيارات البحث
النتائج 941 - 950 من 3,197
Characterization of spatial and temporal variability in hydrochemistry of Johor Straits, Malaysia
2015
Abdullah, Pauzi | Sharifah Mastura, | Jaafar, Othman | Mastura Mahmud, | Khalik, Wan Mohd Afiq Wan Mohd
Characterization of hydrochemistry changes in Johor Straits within 5years of monitoring works was successfully carried out. Water quality data sets (27 stations and 19 parameters) collected in this area were interpreted subject to multivariate statistical analysis. Cluster analysis grouped all the stations into four clusters ((Dlink/Dmax)×100<90) and two clusters ((Dlink/Dmax)×100<80) for site and period similarities. Principal component analysis rendered six significant components (eigenvalue>1) that explained 82.6% of the total variance of the data set. Classification matrix of discriminant analysis assigned 88.9–92.6% and 83.3–100% correctness in spatial and temporal variability, respectively. Times series analysis then confirmed that only four parameters were not significant over time change. Therefore, it is imperative that the environmental impact of reclamation and dredging works, municipal or industrial discharge, marine aquaculture and shipping activities in this area be effectively controlled and managed.
اظهر المزيد [+] اقل [-]Development of current and future pollutant emissions for Portugal
2015
Sa, Elisa | Ferreira, Joana | Carvalho, Anabela | Borrego, C.
Air pollutant emissions are a fundamental input for accurate air quality simulations. Therefore, a detailed estimation of current emissions should be performed, mainly for the activity sectors that have higher contributions to emission totals. In order to estimate air quality under climate change at regional scale, it is extremely important to provide the most accurate emission inventories based on the emission scenarios used as input for the global climate models. The Representative Concentration Pathways (RCPs) are the most recent developed emission scenarios. Emission inventories used in air quality simulations at regional scale for future periods should be based on these recent developments. In this sense, an Emission Projections under RCP scenarios (EmiPro–RCP) model was developed to assist the estimation of future emission inventories for GHG and common air pollutants. This paper describes the methodology developed under EmiPro–RCP model and presents the estimation of current and projected emissions for Portugal for CO, PM2.5, PM10, SOx, NOx, NMVOC and NH3, which will be used as input in air quality modeling systems. A comparison between the inventories was performed and the results indicated that all the RCPs scenarios predict a decrease in most of the air pollutant emissions until 2100, with the exception of NH3 that increases. The main decreases are found in the coastal zone of Portugal, mainly in Porto and Lisbon urban areas, while the NH3 increases are located not only in the coastal zone but also in the southern inland of Portugal.
اظهر المزيد [+] اقل [-]Sample port design for ballast water sampling: Refinement of guidance regarding the isokinetic diameter
2015
Wier, Timothy P. | Moser, Cameron S. | Grant, Jonathan F. | First, Matthew R. | Riley, Scott C. | Robbins-Wamsley, Stephanie H. | Drake, Lisa A.
By using an appropriate in-line sampling system, it is possible to obtain representative samples of ballast water from the main ballast line. An important parameter of the sampling port is its “isokinetic diameter” (DISO), which is the diameter calculated to determine the velocity of water in the sample port relative to the velocity of the water in the main ballast line. The guidance in the U.S. Environmental Technology Verification (ETV) program protocol suggests increasing the diameter from 1.0× DISO (in which velocity in the sample port is equivalent to velocity in the main line) to 1.5–2.0× DISO. In this manner, flow velocity is slowed—and mortality of organisms is theoretically minimized—as water enters the sample port. This report describes field and laboratory trials, as well as computational fluid dynamics modeling, to refine this guidance. From this work, a DISO of 1.0–2.0× (smaller diameter sample ports) is recommended.
اظهر المزيد [+] اقل [-]Organophosphorus flame retardants (PFRs) and plasticisers in harbour porpoises (Phocoena phocoena) stranded or bycaught in the UK during 2012
2015
Papachlimitzou, Alexandra | Barber, Jonathan L. | Losada, Sara | Bersuder, Philippe | Deaville, Rob | Brownlow, Andrew | Penrose, Rod | Jepson, Paul D. | Law, Robin J.
A suite of twenty organophosphorus flame retardant compounds have been determined in blubber and liver tissue of twenty harbour porpoises stranded or bycaught in the UK during 2012 in order to establish current levels of contamination. Fourteen of the twenty compounds were below the limits of quantification in all samples. Six could be quantified at maximum concentrations (in blubber) between 6.7 and 246μgkg−1 wet weight. These levels do not suggest a high level of concern regarding potential impacts and do not indicate that routine monitoring in UK porpoises is warranted at this time.
اظهر المزيد [+] اقل [-]Repeated rapid assessment surveys reveal contrasting trends in occupancy of marinas by non-indigenous species on opposite sides of the western English Channel
2015
Bishop, John D.D. | Wood, Christine A. | Lévêque, Laurent | Yunnie, Anna L.E. | Viard, Frédérique
Rapid assessment surveys of non-indigenous species (NIS) of sessile invertebrates were made at seven marinas in NW France and 10 marinas in SW England in 2010, and repeated in 2013. Fourteen NIS were recorded, 12 of which were seen on both coasts. Site occupancy differed between the opposite sides of the western English Channel. In Brittany, most species occurred at most sites in both 2010 and 2013. In 2010, site occupancy in Devon & Cornwall was distinctly lower; by 2013, the difference compared to Brittany had narrowed considerably, largely because of rapid colonisation of additional sites by species that were infrequent in 2010. Three more of the recent NIS are present in Devon & Cornwall but have still not become widespread. It is concluded that the recently introduced fouling animals studied here are longer established in NW France than in SW England, and have probably spread northwards across the Channel.
اظهر المزيد [+] اقل [-]Spatial–temporal variations and diversity of the bacterioplankton communities in the coastal waters of Kuwait
2015
Almutairi, Awatef
The dynamics and composition of the bacterial community in the coastal waters of Kuwait are poorly understood. In this study, the spatial–temporal variations in the bacterial composition in the surface water along the Kuwaiti coast was examined by 16S rRNA denaturing gradient gel electrophoresis (DGGE) fingerprinting and phylogeny analyses. The sampling sites were Kuwait Bay, Al-Sabbiya (north of the bay) and Al-Khairan (to the south). The bacterial composition was more variable in the summer for all sites. A cluster analysis of the DGGE fingerprint revealed two main clusters, indicating a temporal similarity between sites. Kuwait Bay and Al-Khairan were more similar to each other than to Al-Sabbiya. The bacterial community composition exhibited distinctive spatial variations, with more diversity at Al-Khairan and less diversity at Al-Sabbiya. At all sites, the dominant bacteria were Alphaproteobacteria, in particular Rhodobacteraceae, followed by Alteromonadaceae (Gammaproteobacteria) and Bacteroidetes.
اظهر المزيد [+] اقل [-]Environmental triggers for primary outbreaks of crown-of-thorns starfish on the Great Barrier Reef, Australia
2015
Wooldridge, Scott A. | Brodie, J. E. (Jon E.)
In this paper, we postulate a unique environmental triggering sequence for primary outbreaks of crown-of-thorns starfish (COTS, Acanthaster planci) on the central Great Barrier Reef (GBR, Australia). Notably, we extend the previous terrestrial runoff hypothesis, viz. nutrient-enriched terrestrial runoff→elevated phytoplankton ‘bloom’ concentrations→enhanced COTS larval survival, to include the additional importance of strong larvae retention around reefs or within reef groups (clusters) that share enhanced phytoplankton concentrations. For the central GBR, this scenario is shown to occur when El Niño-Southern Oscillation (ENSO) linked hydrodynamic conditions cause the ‘regional’ larval connectivity network to fragment into smaller ‘local’ reef clusters due to low ocean current velocities. As inter-annual variations in hydrodynamic circulation patterns are not amenable to direct management intervention, the ability to reduce the future frequency of COTS outbreaks on the central GBR is shown to be contingent on reducing terrestrial bioavailable nutrient loads ~20–40%.
اظهر المزيد [+] اقل [-]Evaluation for coastal reclamation feasibility using a comprehensive hydrodynamic framework: A case study in Haizhou Bay
2015
Feng, Lan | He, Jia | Ai, Junyong | Sun, Xiang | Bian, Fangyuan | Zhu, Xiaodong
Coastal reclamation (CR) is a prevailing approach to solve the contradiction between the land shortage and the growing demand of living space for human beings. In general, environmental impact assessment (EIA) focuses on evaluating the feasibility of individual coastal reclamation project (CRP). However, few studies have investigated the cumulative effect of multiple CRPs on surrounding environment. In this study, an integrated framework based on coastal hydrodynamics was established, and then applied to the feasibility evaluation of multiple CRPs for future coastal management in Haizhou Bay, China. The results indicated that three out of five reclamation projects were feasible and the remaining two were forbidden in the study area, whereas EIA approves of all the CRPs. It provides a scientific reference for effective management of coastal reclamation and future environmental impact researches when new CRPs are proposed.
اظهر المزيد [+] اقل [-]Biotransformation of petroleum hydrocarbons and microbial communities in seawater with oil dispersions and copepod feces
2015
Størdal, Ingvild Fladvad | Olsen, Anders Johny | Jenssen, Bjørn Munro | Netzer, Roman | Altin, Dag | Brakstad, Odd Gunnar
To determine biotransformation of components in crude oil dispersions in the presence of feces from marine copepods, dispersed oil was incubated alone, with the addition of clean or oil-containing feces. We hypothesized that the feces would contribute with nutrients to bacteria, and higher concentrations of oil-degrading bacteria, respectively. Presence of clean feces resulted in higher degradation of aromatic oil compounds, but lower degradation of n-alkanes. Presence of oil-containing feces resulted in higher degradation of n-alkanes. The effect of clean feces on aromatic compounds are suggested to be due to higher concentrations of nutrients in the seawater where aromatic degradation takes place, while the lower degradation of n-alkanes are suggested to be due to a preference by bacteria for feces over these compounds. Large aggregates were observed in oil dispersions with clean feces, which may cause sedimentation of un-weathered lipophilic oil compounds towards the seafloor if formed during oil spills.
اظهر المزيد [+] اقل [-]Optimization of biostimulant for bioremediation of contaminated coastal sediment by response surface methodology (RSM) and evaluation of microbial diversity by pyrosequencing
2015
Subha, Bakthavachallam | Song, Young Chae | Woo, Jung Hui
The present study aims to optimize the slow release biostimulant ball (BSB) for bioremediation of contaminated coastal sediment using response surface methodology (RSM). Different bacterial communities were evaluated using a pyrosequencing-based approach in contaminated coastal sediments. The effects of BSB size (1–5cm), distance (1–10cm) and time (1–4months) on changes in chemical oxygen demand (COD) and volatile solid (VS) reduction were determined. Maximum reductions of COD and VS, 89.7% and 78.8%, respectively, were observed at a 3cm ball size, 5.5cm distance and 4months; these values are the optimum conditions for effective treatment of contaminated coastal sediment. Most of the variance in COD and VS (0.9291 and 0.9369, respectively) was explained in our chosen models. BSB is a promising method for COD and VS reduction and enhancement of SRB diversity.
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