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Результаты 1051-1060 из 4,307
Boat anchoring pressure on coastal seabed: Quantification and bias estimation using AIS data Полный текст
2017
Deter, Julie | Lozupone, Xavier | Inacio, Adrien | Boissery, Pierre | Holon, Florian
Global shipping is economically important, but has many adverse environmental effects. Anchoring contributes greatly to this adverse impact, as it is responsible for mechanical disturbance of highly sensitive marine habitats. Recovery of these ecosystems is limited by slow regrowth. Anchoring pressure on coastal seabed habitats was estimated using AIS (Automatic Identification System) data along 1800km of Mediterranean coastline between 2010 and 2015. A comparison with field observations showed that these results were most consistent for large boats (>50m). An analysis of AIS data coupled with a seabed map showed that around 30% of the habitats between 0 and −80m exhibited anchoring pressure. Posidonia oceanica seagrass beds were the most impacted habitat in terms of duration. This methodology efficiently estimates spatial and temporal anchoring pressure principally due to large boats and should interest managers of marine protected areas as much as coastline managers.
Показать больше [+] Меньше [-]Molecular characterization of ABC transporters in marine ciliate, Euplotes crassus: Identification and response to cadmium and benzo[a]pyrene Полный текст
2017
Kim, Hokyun | Yim, Bora | Kim, Jisoo | Kim, Haeyeon | Lee, Young-Mi
ATP-binding cassette (ABC) transporters participate in transporting various substances, including xenobiotics, in or out of cells. However, their genetic information and function in ciliates remain still unclear. In this study, we sequenced and characterized two ABC transporter genes (EcABCB and EcABCC), and investigated the effect of cadmium (Cd) and benzo[a]pyrene (B[a]P) on their function and gene expression, using efflux assay and real-time reverse transcription-polymerase chain reaction (qRT-PCR), respectively, in the marine ciliate, Euplotes crassus. Sequencing analysis and efflux assay showed that EcABCB and EcABCC are typical ABC transporters, possessing conserved function. Exposure to Cd (≥5mg/L) and B[a]P (≥50.5μg/L) enhanced accumulation of a substrate. A significant increase in the expression of EcABCB and EcABC mRNA was observed at lower concentration in response to Cd and B[a]P. Our findings indicate that Cd and B[a]P could inhibit the efflux function of ABC transporters, leading to cellular toxicity in the ciliate.
Показать больше [+] Меньше [-]Magnetic assessment and pollution status of beach sediments from Kerala coast (southwestern India) Полный текст
2017
Chaparro, Marcos A.E. | Suresh, G. | Chaparro, Mauro A.E. | Ramasamy, V. | Sundarrajan, M.
Natural and anthropogenic activities along the coastal region of densely populated Kerala may introduce hazardous components into the coastal environment. The present study aimed to investigate the sources and impacts of hazardous components in beach sediments by environmental magnetism methods as additional tools. Magnetic parameters (such as mass-specific magnetic susceptibility χ=−1.2–154.4×10−8m3kg−1) and ratios that describe the magnetic properties of minerals such as Fe-oxides, indicate variable concentration of mixtures of magnetite and hematite (magnetite/hematite). The direct significant relationships between the variables indicate that higher concentration magnetic parameters are associated with higher radionuclides and metal contents. Magnetic properties and multivariate statistical analyses evidence the presence of contrasting groups defined only using a reduced number of magnetic variables. One of these groups, the central area of the Kerala coastline, showed the highest magnetic concentrations of mixtures of magnetite/hematite and higher values (up to 6.7) of pollution load index because of extensive anthropogenic activities.
Показать больше [+] Меньше [-]Effects of anthropogenic surfactants on the conversion of marine dissolved organic carbon and microgels Полный текст
2017
Shiu, Ruei-Feng | Lee, Chon-Lin
The possible impact of three types of anthropogenic surfactants on the ability of marine dissolved organic carbon (DOC) to form self-assembled microgels was evaluated. The behavior of existing native microgels was also examined in the presence of surfactants. These results reveal that the release of surfactants even at low concentrations into the aquatic environment could effectively hinder the self-assembly of DOC polymers. The extent of the size reduction had the following order: anionic, cationic, and non-ionic. Furthermore, charged surfactants can disrupt existing native microgels, converting large assemblies into smaller particles. One possible mechanisms is that surfactants are able to enhance the stability of DOC polymers and disrupt aggregates due to their surface charges and protein-denaturing activities. These findings suggest that the ecological system is altered by anthropogenic surfactants, and provide useful information for ecological assessments of different types of surfactants and raise warnings about surfactant applications.
Показать больше [+] Меньше [-]Chemical analysis of particulate products of aged 1,3,5-trimethylbenzene secondary organic aerosol in the presence of ammonia Полный текст
2017
Huang, Mingqiang | Xu, Jun | Cai, Shunyou | Liu, Xingqiang | Hu, Changjin | Gu, Xuejun | Zhao, Weixiong | Fang, Li | Zhang, Weijun
Ammonia (NH3) gas-aging of secondary organic aerosol (SOA) results in the formation of organonitrogen compound is an important class of brown carbon. The particulate products of aged 1,3,5-trimethylbenzene (135-TMB) SOA in the presence of NH3 were measured by UV–Vis spectrophotometer, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and aerosol laser time-of-flight mass spectrometer (ALTOFMS) in present study. Experimental results indicated that NH3 has significant promotion effect on 135-TMB SOA formation. Organic ammonium salts, such as ammonium methyl glyoxylate, ammonium 3,5-dimethylbenzoate, which are formed from NH3 reactions with gaseous organic acids were detected as the principal particulate products of NH3-aged 135-TMB SOA. 4-methyl-imidazole-2-acetaldehyde, 4-methyl- 1H-imidazole and other imidazole products via the heterogeneous reactions between NH3 and dialdehydes of 135-TMB SOA were newly measured. The formation of imidazole products suggests that some ambient particles contained organonitrogen compounds may be come from this mechanism. The results of this study may provide valuable information for discussing SOA aging mechanisms and new route for NH3 deposition.
Показать больше [+] Меньше [-]Characterizing light attenuation within Northwest Florida Estuaries: Implications for RESTORE Act water quality monitoring Полный текст
2017
Conmy, Robyn N. | Schaeffer, Blake A. | Schubauer-Berigan, Joseph | Aukamp, Jessica | Duffy, Allyn | Lehrter, John C. | Greene, Richard M.
Water Quality (WQ) condition is based on ecosystem stressor indicators (e.g. water clarity) which are biogeochemically important and critical when considering the Deepwater Horizon oil spill restoration efforts under the 2012 RESTORE Act. Nearly all of the proposed RESTORE projects list restoring WC as a goal, but 90% neglect water clarity. Here, dynamics of optical constituents impacting clarity are presented from a 2009–2011 study within Pensacola, Choctawhatchee, St. Andrew and St. Joseph estuaries (targeted RESTORE sites) in Northwest Florida. Phytoplankton were the smallest contribution to total absorption (at-wPAR) at 412nm (5–11%), whereas colored dissolved organic matter was the largest (61–79%). Estuarine at-wPAR was significantly related to light attenuation (KdPAR), where individual contributors to clarity and the influence of climatic events were discerned. Provided are conversion equations demonstrating interoperability of clarity indicators between traditional State-measured WQ measures (e.g. secchi disc), optical constituents, and even satellite remote sensing for obtaining baseline assessments.
Показать больше [+] Меньше [-]Tungsten Contamination of Soils and Sediments: Current State of Science Полный текст
2017
Datta, Saugata | Vero, Sara E. | Hettiarachchi, Ganga M. | Johannesson, Karen
Tungsten (W) is commonly employed as a non-toxic alternative to lead in a broad variety of industrial and military applications. However, correlations between environmental contamination through soil, water and airborne pathways, and biological effects such as epithelial damage, bioaccumulation, and trophic mobility, have led to its classification as an “emerging contaminant.” Of particular concern are recent clusters of childhood leukemia and lung cancer in the vicinity of tungsten mines and processing facilities. High environmental tungsten availability has also been associated with altered thyroid function, cardiovascular disease, and prolonged elevation of concentrations in blood, breath, and urine. Tungsten’s use as a replacement for lead (Pb) in military munitions has resulted in leaching of tungsten into soil and into soft tissues in which bullet fragments are embedded. Despite these associations, no consensus has been reached regarding the mechanisms by which tungsten affects the human body. Particularly confounding are the issues of co-toxicity with other known contaminants such as arsenic, cobalt, and cadmium, and differences resulting from the various methods of ingestion. The present paper summarizes the current behavior of tungsten in the environment, its occurrence within the pedosphere, biosphere, and atmosphere, and discusses its potential effects on exposed biota (especially humans). In particular, knowledge gaps are identified regarding the biological mechanisms of tungsten-related disease, which urgently require further elucidation in order to develop appropriate policies and management practices for the use of this element.
Показать больше [+] Меньше [-]Benefits and shortcomings of non-destructive benthic imagery for monitoring hard-bottom habitats Полный текст
2017
Beisiegel, Kolja | Därr, Alexander | Gogina, Mayya | Zettler, Michael L.
Hard-bottom habitats with complex topography and fragile epibenthic communities are still not adequately considered in benthic monitoring programs, despite their potential ecological importance. While indicators of ecosystem health are defined by major EU directives, methods commonly used to measure them are deficient in quantification of biota on hard surfaces. We address the suitability of seafloor imaging for monitoring activities. We compared the ability of high-resolution imagery and physical sampling methods (grab, dredge, SCUBA-diving) to detect taxonomic and functional components of epibenthos. Results reveal that (1) with minimal habitat disturbance on large spatial scales, imagery provides valuable, cost-effective assessment of rocky reef habitat features and community structure, (2) despite poor taxonomic resolution, image-derived data for habitat-forming taxa might be sufficient to infer richness of small sessile and mobile fauna, (3) physical collections are necessary to develop a robust record of species richness, including species-level taxonomic identifications, and to establish a baseline.
Показать больше [+] Меньше [-]Green oysters occurring in an industrial harbor in Central Taiwan Полный текст
2017
Fang, Tien-Hsi | Dai, Shi-Yan
Green oysters were found within the Mailiao industrial harbor (MIH) located in Central Taiwan. The metal concentrations in seawater (dissolved and particulate phases), sediment and oyster samples collected within the MIH were analyzed to examine the green oysters. The dissolved and particulate metal concentrations ranged within 0.008–1.47μgl−1 and 0.97–799.2mgkg−1, respectively. The Cu concentration in seawater was dominated in the dissolved phase. In contrast, Cr, Pb and Zn in seawater were chiefly present in the particulate phase. The metal concentrations in sediment and oyster samples ranged within 0.02–148.4mgkg−1 and 0.18–1238mgkg−1 (dry W.), respectively. No anomalous values were found in the analyzed samples, except the Cu content in the oyster samples ranged within 274–1238mgkg−1. The relatively high bioconcentration factor of Cu in oyster and the longer exposure time induced the green oysters occurred within the MIH.
Показать больше [+] Меньше [-]Predator–prey interaction between muricid gastropods and mussels under ocean acidification Полный текст
2017
Xu, X. Y. | Yip, K.R. | Shin, P.K.S. | Cheung, S.G.
Predation of the muricid gastropod Thais clavigera on two-sized groups of the mussel Brachidontes variabilis was studied under three pCO2 levels, 380, 950, and 1250μatm. At 950μatm pCO2 level, the prey handling time decreased significantly and large-sized B. variabilis were preferred by T. clavigera. However, the prey consumption rate was independent of pCO2 levels, although the prey searching time increased significantly at elevated pCO2. These findings indicated that the predator–prey interaction between T. clavigera and B. variabilis was altered under ocean acidification, which will have a long-term impact on the population dynamics of the interacting species.
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