خيارات البحث
النتائج 1611 - 1620 من 3,991
Selective responses of benthic foraminifera to thermal pollution
2016
Titelboim, Danna | Almogi-Labin, Ahuva | Herut, Barak | Kucera, M. (Michal) | Schmidt, Christiane | Hyams-Kaphzan, Orit | Ovadia, Ofer | Abramovich, Sigal
Persistent thermohaline pollution at a site along the northern coast of Israel, due to power and desalination plants, is used as a natural laboratory to evaluate the effects of rising temperature and salinity levels on benthic foraminifera living in shallow hard-bottom habitats. Biomonitoring of the disturbed area and a control station shows that elevated temperature is a more significant stressor compared to salinity, thus causing a decrease in abundance and richness.Critical temperature thresholds were observed at 30 and 35°C, the latter representing the most thermally tolerant species in the studied area Pararotalia calcariformata, which is the only symbiont-bearing species observed within the core of the heated area.Common species of the shallow hard-bottom habitats including several Lessepsian invaders are almost absent in the most exposed site indicating that excess warming will likely impede the survival of these species that currently benefit from the ongoing warming of the Eastern Mediterranean.
اظهر المزيد [+] اقل [-]Electrochemical disinfection of simulated ballast water on PbO2/graphite felt electrode
2016
Chen, Shuiping | Hu, Weidong | Hong, Jianxun | Sandoe, Steve
A novel PbO2/graphite felt electrode was constructed by electrochemical deposition of PbO2 on graphite felt and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) analysis. The prepared electrode is a viable technology for inactivation of Escherichia coli, Enterococcus faecalis, and Artemia salina as indicator organisms in simulated ballast water treatment, which meets the International Maritime Organization (IMO) Regulation D-2. The effects of contact time and current density on inactivation were investigated. An increase in current density generally had a beneficial effect on the inactivation of the three species. E.faecalis and A.salina were more resistant to electrochemical disinfection than E. coli. The complete disinfection of E.coli was achieved in <8min at an applied current density of 253A/m2. Complete inactivation of E. faecalis and A.salina was achieved at the same current density after 60 and 40min of contact time, respectively. A. salina inactivation follows first-order kinetics.
اظهر المزيد [+] اقل [-]Variation in characteristics of air concentrations of NH3, NO2 and O3 induced by applications of urea in soils of plastic greenhouses in suburban China
2016
Jiang, Zhaohui | Zeng, Qingru | Pi, Hejie | Tie, Baiqing
Few studies have been carried out so far for measuring concentrations of NH3, NO2 and O3 in plastic greenhouses. In this study, NH3, NO2 and O3 concentrations were measured with passive sampler technology in a plastic greenhouse located in the Changsha suburb in southern China over a one and a half month period (November 30, 2008 to January 11, 2009). Soil in the greenhouse was subjected to four treatment (T) types (no N fertilizer T1, common urea T2, coated urea T3 and common urea with nitrification inhibitor dicyandiamide (DCD) T4. The average concentrations (μg/m3) of NH3, NO2 and O3 in descending order was: T4 (31.66) > T2 (25.93) > T3 (23.52) > T1 (7.96), T2 (10.99) > T3 (8.16) > T4 (7.48) > T1 (5.20), T2 (75.05) > T3 (64.20) > T4 (63.85) > T1 (49.02), respectively. This implied that photochemical reactions took place and that harmful gases accumulated after application of N fertilizer in the plastic greenhouse. DCD inhibited the conversion of ammonium to nitrate, increased NH3 volatilization and decreased NO2 level. The coated urea decreased the emissions of NH3 and increased nitrogen use efficiency. We found significant positive correlations (p < 0.01) between temperature and both NH3 and NO2 levels. Correlations between soil pH and both NH3 and NO2 concentrations were also significant (p < 0.01). The O3 average concentration from March 31, 2009 to April 10, 2009 in the higher latitude of the Yinchuan suburb in northern China was two times greater than that in the Changsha suburb in southern China. The O3 daily concentrations in the Yinchuan suburb exceeded 160 μg/m3 (i.e., China's Grade I standard), and the maximal value 214.83 μg/m3 exceeded 200 μg/m3 (i.e., China's Grade III standard).
اظهر المزيد [+] اقل [-]A study of oxidative stress induced by two polybrominated diphenyl ethers in the rotifer Brachionus plicatilis
2016
Zhang, Jing | Wang, You | Sun, Kai-Ming | Fang, Kuan | Tang, Xuexi
Polybrominated diphenyl ethers (PBDEs) are widely dispersed persistent organic pollutants in the marine ecosystem. However, their toxic mechanisms in marine organisms, especially invertebrates, remain poorly understood. Two common congeners of PBDEs, tetrabrominated diphenyl ether-47 (BDE-47) and decabrominated diphenyl ether-209 (BDE-209), were investigated. Their toxic mechanisms, with a focus on oxidative stress, were examined in rotifer Brachionus plicatilis. Overproduction of reactive oxygen species (ROS) was induced by two PBDEs. The expression of superoxide dismutase (SOD) mRNA was increased, suggesting SOD play a main role in ROS-scavenging. The intercellular concentrations of calcium ([Ca2+]in) and the expression of calmodulin (CaM) mRNA were increased. This indicates the calcium ion (Ca2+) signaling channel is involved in PBDEs stress. Further analysis showed that the reproductive system might be the target site for toxicity of PBDEs. Moreover, high value of detection indexes in BDE-47 experimental groups suggested BDE-47 might cause higher oxidative damage than BDE-209 in rotifers.
اظهر المزيد [+] اقل [-]Can gelatinous zooplankton influence the fate of crude oil in marine environments?
2016
Gemmell, Brad J. | Bacosa, Hernando P. | Liu, Zhanfei | Buskey, Edward J.
Gelatinous zooplankton are known for their capacity to excrete copious amounts of mucus that can be utilized by other organisms. The release of mucus is exacerbated by stressful conditions. Despite the recognized importance of cnidarian mucus to production and material flux in marine ecosystems, the role of gelatinous zooplankton in influencing the fate of oil spills is unknown. In this study we used laboratory experiments to observe the influence of mucus from the moon jellyfish (Aurelia aurita) on the aggregation and degradation of crude oil. The results show that jellyfish swimming in a dispersed solution of oil droplets produced copious amounts of mucus and the mucus aggregates that were shed by the animals contained 26 times more oil than the surrounding water. Incubation experiments showed that hydrocarbon degrading bacteria cell densities more than doubled in the presence of mucus and after 14days, resulted in a significant increase in oil degradation. These results suggest that jellyfish can aggregate dispersed oil droplets and embed them within a matrix that favors hydrocarbon degrading bacteria. While this study lends support to the hypothesis that the presence of gelatinous zooplankton can impact oil spills large scale mesocosm studies will be needed to fully quantify the influence on a natural system.
اظهر المزيد [+] اقل [-]Detection and risk assessment of diarrheagenic E. coli in recreational beaches of Brazil
2016
Rodrigues, Vanessa F.V. | Rivera, Irma N.G. | Lim, Keah-Ying | Jiang, Sunny C.
Marine beaches are important recreational and economic resources in Brazil, but the beaches' water quality is negatively impacted by the discharge of domestic sewage effluent. The occurrence of diarrheagenic Escherichia coli among the E. coli isolated from three Brazilian marine beaches was investigated. Multiplex and single step PCR were used to screen 99 E. coli isolates for ten target toxin genes. Six toxin genes, stx1, eae, estp, esth, astA, and bfpA, were identified in 1% to 35% of the isolates. A quantitative microbial risk assessment (QMRA) of human exposure to diarrheagenic E. coli during marine recreation was carried out. The results indicated that the diarrheagenic E. coli risk is well below the U.S. EPA's recommended daily recreational risk benchmark. However, the overall recreational health risk due to all pathogens in the water could be much higher and exceeded the U.S. EPA's benchmark.
اظهر المزيد [+] اقل [-]Magnetic properties of air suspended particles in thirty eight cities from south India
2016
Gargiulo, José D. | Kumar, R Senthil | Chaparro, Marcos A.E. | Chaparro, Mauro A.E. | Natal, Marcela | Rajkumar, P.
Air pollution is a basic problem nowadays and it requires special concern. In India, the air pollution is a growing problem because of the enhanced anthropogenic activities such as burning fossil fuels involving industrial processes and motor vehicles. We study airborne dust particles collected at the height of 7 m in roadside and land area from thirty-eight cities in the state of Tamil Nadu. The collection involves a total of 111 samples concerning vehicular, industrial and residential areas, and allows us to assess the spatial distribution of magnetic particles produced and emitted on a short period of time (about one month). Magnetic properties of these air suspended particles were determined by techniques of environmental magnetism, revealing the presence of magnetite and hematite. We found the overall average of mass-specific magnetic susceptibility χ of 589.0 × 10−8 m3 kg−1 and saturation of remanent magnetization SIRM of 68.1 × 10−3 A m2 kg−1; as well as χ and SIRM values higher than 900.0 × 10−8 m3 kg−1 and 700.0 × 10−3 A m2 kg−1, respectively, corresponding to the most impacted zones in industrial/vehicular areas and in cities located in the central/eastern region respectively (e.g.: Hosur, Krishnagiri, Salem, Dharapuram, Ranipet, Ayanavaram, Cuddalore and Chidambaram). We analyzed the relationship between magnetic parameters, between areas and possible grouping of cities using multivariate statistical analysis. The SEM-EDS observations and grain size estimations reveal the presence of trace elements (Sb, Zn, Co, Ni, As and V) and fine particles (1–5 μm) that can be inhaled and therefore are dangerous to human health.
اظهر المزيد [+] اقل [-]Is existing legislation fit-for-purpose to achieve Good Environmental Status in European seas?
2016
Boyes, Suzanne J. | Elliott, Michael | Murillas-Maza, Arantza | Papadopoulou, Nadia | Uyarra, Maria C.
Recent additions to marine environmental legislation are usually designed to fill gaps in protection and management, build on existing practices or correct deficiencies in previous instruments. Article 13 of the European Marine Strategy Framework Directive (MSFD) requires Member States to develop a Programme of Measures (PoM) by 2015, to meet the objective of Good Environmental Status (GES) for their waters by 2020. This review explores key maritime-related policies with the aim to identify the opportunities and threats that they pose for the achievement of GES. It specifically examines how Member States have relied on and will integrate existing legislation and policies to implement their PoM and the potential opportunities and difficulties associated with this. Using case studies of three Member States, other external impediments to achieving GES are discussed including uses and users of the marine environment who are not governed by the MSFD, and gives recommendations for overcoming barriers.
اظهر المزيد [+] اقل [-]Fate, behaviour and weathering of priority HNS in the marine environment: An online tool
2016
Cunha, Isabel | Silva, Helena Oliveira da | Neuparth, Teresa | Torres, Tiago | Santos, Miguel Machado
Literature data and data obtained with modelling tools were compiled to derive the physicochemical behaviour of 24 priority Hazardous and Noxious Substances (HNS), as a proxy to improve environmental, public health and political issues in relation to HNS spills. Parameters that rule the HNS behaviour in water and those that determine their distribution and persistence in the environment, such as fugacity, physicochemical degradation, biodegradation, bioaccumulation/biotransformation and aquatic toxicity, were selected. Data systematized and produced in the frame of the Arcopol Platform project was made available through a public database (http://www.ciimar.up.pt/hns/substances.php). This tool is expected to assist stakeholders involved in HNS spills preparedness and response, policy makers and legislators, as well as to contribute to a current picture of the scientific knowledge on the fate, behaviour, weathering and toxicity of priority HNS, being essential to support future improvements in maritime safety and coastal pollution response before, during and after spill incidents.
اظهر المزيد [+] اقل [-]Ophthalmic effects of petroleum dispersant exposure on common murres (Uria aalge): An experimental study
2016
Fiorello, Christine V. | Freeman, Kate | Elias, Becky A. | Whitmer, Emily | Ziccardi, Michael H.
The safety of chemical dispersants used during oil spill responses is largely unknown in birds. We captured common murres in Monterey Bay, CA and exposed them to Corexit EC9500a, crude oil, or a combination in artificial seawater. We performed ophthalmic examinations and measured intraocular pressures and tear production before and after exposure. Loglinear analysis found that exposure to oil or dispersant was related to the development of conjunctivitis and corneal ulcers. Odds ratios for birds exposed to oil or dispersant were positive and significant for the development of conjunctivitis, while odds ratios for the development of corneal ulcers were positive and significant only for birds exposed to a high concentration of oil. Ocular exposure to dispersants and petroleum in seabirds may cause conjunctivitis and may play a role in the development of corneal ulcers. These results have implications for policymakers who develop protocols for the use of dispersants during marine oil spills.
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