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Resultados 1431-1440 de 4,241
Characteristics of trace metals and phosphorus in seawaters offshore the Yangtze River
2017
Su, Han | Yang, Rujun | Zhang, Aibin | Li, Yan | Qu, Shenglu | Wang, Xuchen
This study presents the spatial distribution of total dissolved Cu, Zn, Co, and V during an autumn survey in the East China Sea (ECS). Dissolved Fe and its organic complexation were also investigated. The present study aimed to evaluate the relationship between Cu, Zn, Co, V, D-Fe and its organic ligands and total dissolved phosphate (TDP) in the coastal waters of the ECS. A correlation analysis shows that Cu, Zn and D-Fe were nutrient-like metals, whereas Co and V were non-nutrient-like metals. A multivariate statistical analysis showed that TDP was associated with D-Fe, Cu, Zn and Co, but was not associated with V. Furthermore, TDP was observed to be positively related with D-Fe, while negatively with Fe′, which indicated that the limitation of TDP decreased the uptake of Fe′. This paper improves our understanding of the association among trace metals, TDP and phytoplankton biomass in the ECS.
Mostrar más [+] Menos [-]Magnetic assessment and pollution status of beach sediments from Kerala coast (southwestern India)
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.
Mostrar más [+] Menos [-]Tungsten Contamination of Soils and Sediments: Current State of Science
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.
Mostrar más [+] Menos [-]Physicochemical characterization of Atlantic Canadian seafood processing plant effluent
2017
Jamieson, Bryan Lee | Gagnon, Graham A. | Gonçalves, Alex Augusto
The purpose of this study was to conduct a preliminary assessment of the potential impacts of Atlantic Canadian seafood processing effluents on the aquatic environment through physical-chemical characterization. Shellfish and finfish effluent samples were collected and characterized by biochemical oxygen demand (BOD5), chemical oxygen demand (COD), turbidity, total suspended solids (TSS), ammonia nitrogen (NH3-N), adsorbable organic halides (AOX), soluble BOD5 and soluble COD. Effluent concentration ranges were BOD5 (179 to 276mgL−1), COD (458 to 1717mgL−1), turbidity (28.8 to 88.3NTU), TSS (27.2 to 120.1mgL−1), NH3-N (1.5 to 12.9mgL−1) and AOX (3.2 and 0.4mgL−1) for flatfish and salmon processing effluents respectively, and cleanup shift AOX (3.5 and 0.5mgL−1). The characteristics of these effluents assessed have the potential to contaminate and degrade receiving water body environments. Improved performance may be possible with further treatment technology optimization on an effluent-specific basis.
Mostrar más [+] Menos [-]Characteristics of picoplankton abundances during a Thalassiosira diporocyclus bloom in the Taiwan Bank in late winter
2017
Jiang, Xin | Li, Jiajun | Ke, Zhixin | Xiang, Chenhui | Tan, Yehui | Huang, Liangmin
To understand the variations of picoplankton (Prochlorococcus, Synechococcus, picoeukaryotes, and heterotrophic bacteria) abundances during diatom bloom, the distribution of picoplankton in the Taiwan Bank, South China Sea was investigated using flow cytometry during a Thalassiosira diporocyclus bloom in March 2016. The results indicated an abrupt abundance decrease for Prochlorococcus, Synechococcus, and picoeukaryotes within the bloom area while the abundance of heterotrophic bacteria showed no significant difference between the bloom and non-bloom areas. We found two sub-groups of heterotrophic bacteria: high- and low-nucleic acid content (HNA and LNA) bacteria with HNA dominated in the bloom area whereas LNA dominated in the non-bloom area. Among the picoplankton components, HNA represented the highest (61.1%) carbon biomass in the bloom area while picoeukaryotes represented the highest (37.6%) in the non-bloom area. Our findings implied that heterotrophic bacteria, especially HNA, played an essential role during the diatom bloom.
Mostrar más [+] Menos [-]Associations between metal exposure and lesion formation in offshore Gulf of Mexico fishes collected after the Deepwater Horizon oil spill
2017
Granneman, Jennifer E. | Jones, David L. | Peebles, Ernst B.
The objectives of this study were to: (1) examine patterns of short- and long-term metal exposure within the otoliths of six offshore fish species in varying states of health, as indicated by the presence of external skin lesions, and (2) determine if there was a change in otolith metal concentrations concurrent with the Deepwater Horizon (DWH) oil spill. Otoliths collected from 2011 to 2013 in the Gulf of Mexico (GOM) were analyzed for a suite of trace metals known to be associated with DWH oil. We found that lesioned fish often had elevated levels of otolith 60Ni and 64Zn before, during, and after the DWH oil spill. In addition, metal exposure varied according to species-specific life history patterns. These findings indicate that lesioned individuals were exposed to a persistent source of trace-metals in the GoM prior to the oil spill.
Mostrar más [+] Menos [-]Recovery of marine Conus (Mollusca: Caenogastropoda) from imposex at Rottnest Island, Western Australia, over a quarter of a century
2017
Wells, Fred E. | Keesing, John K. | Brearley, Anne
Imposex is a reproductive abnormality in which female snails begin to transform to males, but do not become functional. It was caused by tributyltin (TBT) used as an antifoulant in boat paints. Imposex was first recorded marine snails (Conus) (Mollusca: Caenogastropoda) at Rottnest Island, Western Australia, in January 1991, where 88% of individuals at the west end were affected. Most were at moderate Stages 3 and 4 on a scale of 0 (no affect) to 6 (death). TBT was banned on boats <25m long in late 1991 in WA. In 1996, imposex had declined to 69% of females with Stages 3 and 4 still the most common. By 2007 only 35% of females exhibited imposex; Stage 3 was the highest level recorded. TBT was below detection limits. TBT was banned on vessels >25m in September 2013. In February 2017 only 4% of Conus had imposex, at Stage 1.
Mostrar más [+] Menos [-]Modelling and assessment of accidental oil release from damaged subsea pipelines
2017
Li, Xinhong | Chen, Guoming | Zhu, Hongwei
This paper develops a 3D, transient, mathematical model to estimate the oil release rate and simulate the oil dispersion behavior. The Euler-Euler method is used to estimate the subsea oil release rate, while the Eulerian-Lagrangian method is employed to track the migration trajectory of oil droplets. This model accounts for the quantitative effect of backpressure and hole size on oil release rate, and the influence of oil release rate, oil density, current speed, water depth and leakage position on oil migration is also investigated in this paper. Eventually, the results, e.g. transient release rate of oil, the rise time of oil and dispersion distance are determined by above-mentioned model, and the oil release and dispersion behavior under different scenarios is revealed. Essentially, the assessment results could provide a useful guidance for detection of leakage positon and placement of oil containment boom.
Mostrar más [+] Menos [-]Assessing marine environmental status through microphytobenthos assemblages colonizing the Autonomous Reef Monitoring Structures (ARMS) and their potential in coastal marine restoration
2017
Pennesi, Chiara | Danovaro, Roberto
Microphytobenthos is potentially highly sensitive to environmental alterations, but has been rarely utilized in monitoring studies. Here we investigated the use of microphytobenthos colonizing Autonomous Reef Monitoring Structures (ARMS) to assess the marine environmental quality. We analysed microphytobenthic assemblages in terms of abundance, biomass and species composition on ARMS deployed in northern Adriatic Sea along a gradient of increasing impacts. We show that microphytobenthic variables changed significantly across sites, with lowest abundance and biodiversity in the highly impacted site. Moreover, the specific analysis of Diatoms revealed that genera like Entomoneis and Cylindrotheca could be used as indicators of nutrient enriched and stressed conditions. We provide evidence that the analysis of microphytobenthos colonizing artificial substrates could be used as a tool for detecting altered environmental characteristics. We also show that the ARMS, recreating hot spots of microphytobenthic biodiversity, and protect them from grazing, could be potentially utilized to restore degraded hard substrates. Our result indicates that microphytobenthos can be easily incorporated in future monitoring and restoration programmes to assess and improve marine environmental health.
Mostrar más [+] Menos [-]Effect of nutrient pollution on dinoflagellate cyst assemblages across estuaries of the NW Atlantic
2017
Price, Andrea M. | Coffin, Michael R.S. | Pospelova, Vera | Latimer, James S. | Chmura, Gail L.
We analyzed surface sediments from 23 northeast USA estuaries, from Maine to Delaware, and nine estuaries from Prince Edward Island (PEI, Canada), to determine how dinoflagellate cyst assemblages varied with nutrient loading. Overall the abundance of cysts of heterotrophic dinoflagellates correlates with modeled nitrogen loading, but there were also regional signals. On PEI cysts of Gymnodinium microreticulatum characterized estuaries with high nitrogen loading while the sediments of eutrophic Boston Harbor were characterized by high abundances of Spiniferites spp. In Delaware Bay and the Delaware Inland Bays Polysphaeridium zoharyi correlated with higher temperatures and nutrient loading. This is the first study to document the dinoflagellate cyst eutrophication signal at such a large geographic scale in estuaries, thus confirming their value as indicators of water quality change and anthropogenic impact.
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