خيارات البحث
النتائج 1441 - 1450 من 4,307
Assessment and source identification of pollution risk for touristic ports: Heavy metals and polycyclic aromatic hydrocarbons in sediments of 4 marinas of the Apulia region (Italy) النص الكامل
2017
Mali, Matilda | Dell'Anna, Maria Michela | Mastrorilli, Piero | Damiani, Leonardo | Piccinni, Alberto Ferruccio
The Apulia region in Italy has the longest Adriatic coastline; thus, maritime tourism is the driving force for its economic development. Pollution risk for four representative touristic ports of the region was assessed by determining the concentrations of 10 metals, 16 polycyclic aromatic hydrocarbons (PAHs) congeners, and the main nutrients. The cumulative mean Effects Range–Median quotient (mERMq) was used to assess the hazard degree, while the distribution patterns and content ratios of different PAH sediment concentrations were investigated to identify the pollution sources. Principal component analyses indicated an anomalous pollution trend for one of the small touristic ports assessed; this trend emerged from contamination by heavy metals and PAHs to a larger extent than expected, considering the main activity in this port, especially in its inner basin. The reason of this anomaly is thought to be the hydrodynamic and/or other stress factors.
اظهر المزيد [+] اقل [-]A possible CO2 leakage event: Can the marine microbial community be recovered? النص الكامل
2017
Borrero-Santiago, A.R. | Bautista-Chamizo, E. | DelValls, T.Á | Riba, I.
Bacterial communities have been studied to a much lesser degree than macrofauna in the case of a CO2 release. The resistance capacity of marine bacteria is well known, but their possible responses and their ability to recover after a CO2 release has not been investigated. Therefore, this work evaluated the responses of a marine bacterial community after 96h of CO2 exposure under diverse pH treatments (7.8 as control without CO2, 7.0, 6.5, and 6.0) and 24h after CO2 exposure. Results showed that the respiration activity and the diversity of the community were affected in all pH treatments. However, after 24h without CO2 enrichment, the respiration activity and diversity increased, showing a partial recovery. Consequently, bacterial responses have the potential to be used as a monitoring tool for risk assessment related to carbon capture and storage techniques or in any similar CO2 enrichment situations.
اظهر المزيد [+] اقل [-]Thermal stress exposure, bleaching response, and mortality in the threatened coral Acropora palmata النص الكامل
2017
Williams, D.E. | Miller, M.W. | Bright, A.J. | Pausch, R.E. | Valdivia, A.
Demographic data for Elkhorn coral, Acropora palmata, and in situ water temperature data from seven upper Florida Keys (USA) reefs revealed three warm thermal stress events between 2010 and 2016. During a mild bleaching event in 2011, up to 59% of colonies bleached, but no mortality resulted. In both 2014 and 2015, severe and unprecedented bleaching was observed with up to 100% of colonies bleached. A. palmata live tissue cover declined by one-third following the 2014–2015 events. Colony mortality of mildly- and non-bleached colonies did not differ but increased significantly with more severe bleaching. Increased bleaching prevalence corresponded to maximum daily average water temperatures above 31.3°C. However, the cumulative days with daily average exceeding 31.0°C provided a better predictor of bleaching response. The bleaching response of surviving colonies in 2015 was not consistent with acclimatization as most individual colonies bleached at least as badly as in 2014.
اظهر المزيد [+] اقل [-]Performance and bacterial community structure of a 10-years old constructed mangrove wetland النص الكامل
2017
Tian, Tingting | Tam, Nora F.Y. | Zan, Qijie | Cheung, S.G. | Shin, Paul K.S. | Wong, Y.S. | Zhang, Li | Chen, Zhanghe
Constructed mangrove wetland has been used for wastewater treatment but its long-term performance has not been reported. One-year monitoring of a 10-years old horizontal subsurface-flow constructed mangrove wetland consisting of three belts, two with mangrove plants and one without, revealed that the system maintained high and stable removal percentages of organic matter and nutrients, and planted belts performed better than unplanted control. Substrates in belts planted with Aegiceras corniculatum or Kandelia obovata had higher abundance of ammonifiers, nitrifiers and denitrifiers but lower total heterotrophic bacteria than unplanted substrate. Denaturing gradient gel electrophoresis showed that microbial diversity in planted substrate was significantly lower than that in unplanted one. The bacteria in substrates, irrespective to belts, were phylogenetically related to Proteobacteria (most dominant), Acidobacteria, Firmicutes, Nitrospirae, Gemmatimonadetes, Chloroflexi and Cyanobacteria. The steady performance of this 10-year old constructed mangrove wetland was affected by the abundance and diversity of bacterial community in substrate.
اظهر المزيد [+] اقل [-]Spatial and temporal analysis of the risks posed by total petroleum hydrocarbon and trace element contaminants in coastal waters of Kuwait النص الكامل
2017
Nicolaus, E.E.M. | Wright, S.R. | Barry, J. | Bolam, T.P.C. | Ghareeb, K. | Ghaloom, M. | Al-Kanderi, N. | Harley, B.F.M. | Le Quesne, W.J.F. | Devlin, M.J. | Lyons, B.P.
Nine trace elements including As, Cd, Cu, Fe, Hg, Ni, Pb, V and Zn, and total petroleum hydrocarbons were analysed from water samples collected from 23 stations since 1984 from Kuwaiti coastal waters. Here it was investigated whether concentrations of these determinants are at levels above Kuwaiti and internationally established assessment criteria (AC). The results indicate that Cu and Cd had the most Kuwaiti AC breaches over time. Comparing the data of the last sampled year to the least stringent international AC, then Cu and Cd showed breaches at all stations. The trends for trace metals are significantly downwards, especially for Cd and Hg. No determinant measured showed a significant upward trend, indicating that water pollution for these contaminants is not a worsening situation. However, further sampling should be carried out to confirm these findings, especially at shoreline locations, where routine monitoring ceased in 2011 to investigate any recent changes.
اظهر المزيد [+] اقل [-]In situ elemental characterisation of marine microplastics by portable XRF النص الكامل
2017
Turner, Andrew
The performance of a portable x-ray fluorescence spectrometer configured in a test stand and coupled to a laptop has been evaluated for the determination of various elements (including Br, Cd, Cl, Cr, Cu, Fe, Pb and Zn) in beached microplastics. Under laboratory conditions, analysis of samples that covered the 3-mm x-ray beam returned concentrations that, on average, were within 20% of concentrations determined by ICP following acid digestion. Analysis of progressively smaller offcuts (to <1mm) resulted in corresponding concentrations that were comparable to those determined in original samples but errors and detection limits that progressively increased. When the configuration was deployed in situ with two operators, up to 35 microplastics counted for 60s each could be processed per hour. Advantages of immediate measurements include the development of an iterative study strategy, rapid compliance-evaluation, and identification of specific materials for further characterisation or study in the laboratory.
اظهر المزيد [+] اقل [-]Bacterial community structure in the intertidal biofilm along the Yangtze Estuary, China النص الكامل
2017
Guo, Xing-pan | Niu, Zuo-shun | Lu, Da-pei | Feng, Jing-nan | Chen, Yu-ru | Tou, Fei-yun | Liu, Min | Yang, Yi
In this study, the 16S rRNA-based Illumina MiSeq sequencing was used to investigate the bacterial community structure and composition of intertidal biofilm taken along the Yangtze Estuary. The results showed that 680,721 valid sequences of seven samples were assigned to 147,239 operational taxonomic units, which belonged to 49 phyla, 246 family and 314 genera. Compared to other studies on water and sediments in the study area, biofilms showed highest index of bacterial diversity and abundances. At different taxonomic levels, both dominant taxa and their abundances varied among the seven samples, with Proteobacteria as the dominant phylum in general. Principal component analysis and cluster analysis revealed that bacterial communities at WSK differed from those at other sampling sites. Salinity, dissolved oxygen, pH and nutrients were the vital environmental factors to influence the bacterial community structure of biofilms. These results may provide a new insight into the microbial ecology in estuarine environments.
اظهر المزيد [+] اقل [-]A short note on a present-day benthic recovery status in the formerly heavily polluted Idefjord (Sweden/Norway) النص الكامل
2017
Polovodova Asteman, Irina | Nordberg, Kjell
Idefjord (Skagerrak, North Sea) has had a long pollution history due to a heavy exposure to effluents from sawmills and pulp and paper industry, which had a detrimental effect on fjord life. Earlier we presented a paper on the pollution history and benthic recovery in the fjord by studying sediment geochemistry (TOC and heavy metals) and benthic foraminifera in the sediment cores taken in the inner and the outer Idefjord. At that stage the foraminiferal (~benthic recovery) record was limited to years 2000 (inner fjord) and 2002 (outer fjord), in contrast to pollutant data reaching all the way up to 2014. In this short note we extend the foraminiferal record to year 2014 and fill the gap in the benthic recovery in the inner and the outer fjord over the last 12years. The results show that both inner and outer fjord inlets currently undergo a steady benthic recovery reflected in comeback of transitional and pre-pollution benthic foraminiferal species after 2000–2002 and towards 2014. The recovery is also supported by increasing faunal diversity, low dominance and since 2000–2002 re-appearance of calcareous foraminiferal species (Bulimina marginata, Elphidium spp., Epistominella vitrea, Hyalinea balthica and Lagena spp), which all disappeared during the period of maximum effluent discharges. At the same time, detection of opportunistic newcomers (e.g. Stainforthia fusiformis) and persisting absence of some transitional species such as Ammoscalaria tenuimargo suggests a recolonization by foraminiferal population with a different species composition as compared to the original pre-pollution community either due to changed environmental conditions or/and increased competition.
اظهر المزيد [+] اقل [-]Dramatic increase in mud distribution across a large sub-tropical embayment, Moreton Bay, Australia النص الكامل
2017
Lockington, James R. | Albert, Simon | Fisher, Paul L. | Gibbes, Badin R. | Maxwell, Paul S. | Grinham, Alistair R.
Major flood events can dramatically alter the coastal sediment environment. This study established the current sediment distribution in a large sub-tropical embayment, Moreton Bay, Australia, and examined the effect of three recent floods on modifying this distribution. In 2015, surface sediment samples were collected from 223 sites across the study area and analysed for particle size distribution with the resultant sediment distribution mapped. In addition, sampling of flood waters during two major events in 2011 and 2013 was undertaken and particle size distribution of suspended sediment was determined. Data was compared to the result of an earlier large-scale survey completed in 1970, with three large flood events occurring between the two surveys. The sediment environment has undergone a dramatic change with muddy sediments now covering an estimated area of over 860km2, more the double the area found in 1970. Mud is now the dominant sediment type within Moreton Bay.
اظهر المزيد [+] اقل [-]Fighting Nemo: Effect of 17α-ethinylestradiol (EE2) on aggressive behavior and social hierarchy of the false clown anemonefish Amphiprion ocellaris النص الكامل
2017
Chen, Te-Hao | Hsieh, Chun-Yu
Aggressive behavior is crucial for maintaining social hierarchy in anemonefish. Endocrine disrupting chemicals such as EE2 may affect fish social hierarchy via disrupting their aggression. In this study, we aimed to characterize the effects of 17α-ethinylestradiol (EE2) on aggressive behavior and social hierarchy in the false clown anemonefish (Amphiprion ocellaris). In the laboratory experiment, juvenile anemonefish were randomly distributed to separated tanks to form small colonies of three individuals and were fed with EE2-dosed diet (100ng/g food) or a control diet for 90d. Through the experiment, each tank was videotaped and behavioral indicators of social status, including aggressive behavior, submissive response, and shelter utilization, were quantitatively analyzed from the videos. The EE2 exposure caused a higher frequency of intra-colonial aggressive interactions and a less stable social hierarchy. Our findings demonstrate the importance of examining the effects of endocrine disrupting chemicals on the social behavior of coral reef fish.
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