细化搜索
结果 501-510 的 1,506
Grounded or submerged bulk carrier: The potential for leaching of coal trace elements to seawater
2012
Lucas, Steven Andrew | Planner, John
This study investigates the potential for leaching of coal trace elements to seawater from a grounded bulk carrier. The coal type and ecological scenario was based on the grounding of the “Shen Neng” (April 2010) at Douglas Shoal located within the Great Barrier Reef (Queensland, Australia). The area is of high ecological value and the Queensland Water Quality Guidelines (2009) provided threshold limits to interpret potential impacts. Coal contains many trace elements that are of major and moderate concern to human health and the environment although many of these concerns are only realised when coal is combusted. However, “unburnt” coal contains trace elements that may be leached to natural waterways and few studies have investigated the potential ecological impact of such an occurrence. For example, coal maritime transport has increased by almost 35% over the last five reported years (Jaffrennou et al., 2007) and as a result there is an increased inherent risk of bulk carrier accidents. Upon grounding or becoming submerged, coal within a bulk carrier may become saturated with seawater and potentially leach trace elements to the environment and impact on water quality and ecological resilience. The worst case scenario is the breakup of a bulk carrier and dispersal of cargo to the seafloor.
显示更多 [+] 显示较少 [-]Creating a GIS-based model of marine debris “hot spots” to improve efficiency of a lobster trap debris removal program
2012
Martens, Justin | Huntington, Brittany E.
Debris removal programs are combatting the accumulation of derelict fishing gear and other debris in marine habitats. We analyzed 5years of lobster trap debris removal data in Biscayne National Park, Florida to assess removal efficiency and develop spatially-explicit mapping tools to guide future removals. We generated and validated debris “hot spots” maps that combined remotely-sensed data (i.e. benthic habitat type and bathymetry) with 862 locations of previous debris collection. Our hot spot models spatially depict regions of likely debris accumulation, reducing the search area by 95% (from 332km² to 18km²) and encompassing 100% of the validation sites. Our analyses indicate removal contractors using sub-surface towed divers enhanced debris recovery. Additionally, the quantity of debris removed did not decrease with increased efforts, suggesting that debris supply in situ exceeds removal efforts. We conclude with the importance of coupling analysis of ongoing debris removal programs with GIS technology to improve removal efforts.
显示更多 [+] 显示较少 [-]Seasonal and spatial heterogeneity of recent sea surface temperature trends in the Caribbean Sea and southeast Gulf of Mexico
2012
Chollett, Iliana | Muller-Karger, Frank E. | Heron, Scott F. | Skirving, William | Mumby, P. J. (Peter J.)
Recent changes in ocean temperature have impacted marine ecosystem function globally. Nevertheless, the responses have depended upon the rate of change of temperature and the season when the changes occur, which are spatially variable. A rigorous statistical analysis of sea surface temperature observations over 25years was used to examine spatial variability in overall and seasonal temperature trends within the wider Caribbean. The basin has experienced high spatial variability in rates of change of temperature. Most of the warming has been due to increases in summer rather than winter temperatures. However, warming was faster in winter in the Loop Current area and the south-eastern Caribbean, where the annual temperature ranges have contracted. Waters off Florida, Cuba and the Bahamas had a tendency towards cooling in winter, increasing the amplitude of annual temperature ranges. These detailed patterns can be used to elucidate ecological responses to climatic change in the region.
显示更多 [+] 显示较少 [-]A historical review and bibliometric analysis of research on estuary pollution
2012
Sun, Jinshui | Wang, Ming-Huang | Ho, Yuh-Shan
A bibliometric method based on Science Citation Index-Expanded published by the Thomson Reuters was used to quantitatively assess the global estuary pollution research from 1991 to 2010. The main results were as follows: there had been a notable growth trend in publication outputs. Marine Pollution Bulletin was the most active journal. Environmental sciences were top popular subject categories. USA produced the most single, internationally collaborative, first authored and corresponding authored articles. The Chinese Academy of Sciences was the most productive institute for the total articles. Sediment was the most active research topic, which ranked 1st in article title, article abstract, author keyword, and KeyWords Plus analysis, respectively. Heavy metals received stable focus on a high degree in the field of estuary pollution research. Mostly refractory organic compounds (e.g. PAHs) became more active. Biomarkers and bioaccumulation both were active issues. Eutrophication of estuarine waters receives increasing concern in estuary pollution research.
显示更多 [+] 显示较少 [-]Molecular and biochemical biomarkers responses in the mussel Mytilus edulis collected from Southern Brazil coast
2012
Rola, Regina Coimbra | Monteiro, Maurício da Costa | Reis, Sérgio Renan da Silva | Sandrini, Juliana Zomer
Marine ecosystems are typically subjected to a variety of stressors containing complex xenobiotics mixtures. This study aims to evaluate the responses of molecular and biochemical biomarkers in the mussel Mytilus edulis providing data for environmental monitoring programs development in Southern Brazil. Mussels were collected at a polluted site, near Patos Lagoon outfall, and at a control site. Gills, muscle and mantle samples were used for biomarker determinations. Mussels collected at the polluted site significantly increased superoxide dismutase (SOD) and glutathione S-transferase (GST) activities and decreased catalase (CAT) activity. Moreover, an increase in sod1, gstπ and hsp70 mRNA expression was observed. Overall, biochemical and molecular biomarkers responses were observed, but these responses varied depending on the analyzed tissue. These results indicate possible contaminants effects on organisms and the need for effective environmental monitoring programs in this ecosystem.
显示更多 [+] 显示较少 [-]Concentration and fractionation of trace metals in surface sediments of intertidal Bohai Bay, China
2012
Gao, Xuelu | Li, Peimiao
Surface sediments from intertidal Bohai Bay were sampled for the geochemical and environmental assessment of six trace metals (Cd, Cr, Cu, Ni, Pb and Zn). Results indicate that sediment grain size plays an important role in controlling the distribution and fractionation of them. Metal concentrations in clayey silt sediments are all clearly higher than in sand and silty sand ones. Cd and Pb in clayey silt sediments are more mobile than in sand and silty sand ones. Two sediment quality guidelines and two geochemical normalization methods (index of geoaccumulation and enrichment factor) were used to judge the potential risk and accumulation of metals. According to the mean probable effects level quotient, the combination of studied metals may have a 21% probability of being toxic. The sediments with high fraction of clay and silt have been contaminated by trace metals to various degrees, among which Cr contributes the most to contamination.
显示更多 [+] 显示较少 [-]Environmental factors responsible for the incidence of antibiotic resistance genes in pristine Crassostrea virginica reefs
2012
Barkovskii, Andrei L. | Thomas, Michael | Hurley, Dorset | Teems, Clifford
The occurrence of tetracycline resistance (TRG) and integrase (INT) genes were monitored in Crassostrea virginica oyster reefs of three pristine creeks (SINERR, Georgia, USA). Their profiles revealed 85% similarity with the TRG/INT profiles observed in the adjacent to the SINERR and contaminated Altamaha River estuary (Barkovskii et al., 2010). The TRG/INT spectra and incidence frequencies corresponded to the source of oceanic input and to run-offs from creeks’ watersheds. The highest incidence frequencies and concentrations were observed in oysters. TRG/INT incidences correlated positively (Spearman Rank=0.88), and negatively correlated (−0.63 to −0.79) with creek salinity, conductivity, dissolved solids, and temperature. Coliform incidence positively correlated with temperature, and not with the TRG/INT incidence. The Altamaha River estuary was the primary TRG/INT source for the reefs with contributions from creek’s watersheds. TRG/INT were carried by non-coliforms with a preference for low-to-temperate thermohaline environments coupled with bioaccumulation by oysters.
显示更多 [+] 显示较少 [-]Multi-scale distribution and dynamics of bivalve larvae in a deep atoll lagoon (Ahe, French Polynesia)
2012
Thomas, Y. | Garen, P. | Bennett, A. | Le Pennec, M. | Clavier, J.
Bivalve larvae and hydrographic parameters were sampled over a range of spatio-temporal scales in a deep atoll lagoon. Bivalve larvae abundances were very high throughout the year: 18,550m⁻³ in average. Larvae were (i) concentrated at mid-depth with nocturnal ascent and diurnal descent, (ii) heterogeneously dispersed at the lagoon scale, (iii) subject to day-to-day variation in abundance and (iv) transferred between different parts of the lagoon providing evidence of intra-lagoonal connectivity. The primacy of physical factors was seen on large spatial scale with the diluting effect of water renewal and transfers by hydrodynamics. On smaller spatial scale, the primacy of biological processes was recognised, with larval swimming activity leading to dial vertical migration correlated with food concentration. Variations in larval abundance were driven by bivalve reproductive activity correlated with meteorological conditions (i.e. windy periods). Finally, relationship between bivalve larvae patterns and pearl oyster (Pinctada margaritifera) settlement structuring is discussed.
显示更多 [+] 显示较少 [-]Metazooplankton communities in the Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia): Spatiotemporal variations and trophic relationships
2012
Pagano, Marc | Sagarra, Pascual-boi | Champalbert, Gisele | Bouvy, Marc | Dupuy, Christine | Thomas, Yoann | Charpy, Loic
Metazooplankton abundance, biomass (<80 mu m, 200-500 mu m and >500 mu m) and community structure in the Ahe atoll were studied together with their relationships with environmental factors (temperature, salinity, wind) and trophic factors (phytoplankton, bacteria, heterotrophic nanoflagellates (HNF) and ciliates) during three periods in 2008-2009. Meroplankton, mainly bivalve and gastropod larvae, was dominant. Holoplankton was dominated by copepods, the main species being Oithona spp., Paracalanus parvus, Clausocalanus spp., Corycaeus spp., Acartia fossae and Undinula vulgaris. The results suggest a clear wind influence on the structure and horizontal distribution of the zooplankton communities. The metazooplankton appeared to be controlled mainly by food resources, suggesting a bottom-up control. The low nanophytoplankton biomass in contrast to the high abundance of picophytoplankton, HNF and nano-particle grazers (mainly Oithona spp., Paracalanus and bivalve larvae) highlighted the importance of the microbial loop in the food web. (C) 2012 Elsevier Ltd. All rights reserved.
显示更多 [+] 显示较少 [-]Differential biomagnification of PCB, PBDE, Hg and Radiocesium in the food web of the European hake from the NW Mediterranean
2012
Harmelin-vivien, Mireille | Bodiguel, Xavier | Charmasson, Sabine | Loizeau, Veronique | Mellon, Capucine | Tronczynski, Jacek | Cossa, Daniel
Consumption of marine organisms represents one of the main exposure sources of contaminants for human populations. To obtain a global view of the contamination in commercial fish in the NW Mediterranean Sea, we analysed four types of priority contaminants (PCBs, PBDEs, Hg and Cs-137) in the European hake, Merluccius merluccius, from the Gulf of Lions in relation with organism's trophic level (delta N-15). All contaminants presented a significant increase in concentration in hake muscle with trophic level. However, obvious differences between contaminants were evidenced. Biomagnification factors (BMF and FWMF) along the hake food web were higher for Hg and CB-153 than for BDE-47 and Cs-137, and increase in contaminant concentration with trophic level occurred at different rates depending on contaminants. Such differences of biomagnification patterns can be related to physico-chemical properties of the different contaminants. (C) 2012 Elsevier Ltd. All rights reserved.
显示更多 [+] 显示较少 [-]