خيارات البحث
النتائج 1451 - 1460 من 4,021
Effects of temperature and nutrients on changes in genetic diversity of bacterioplankton communities in a semi-closed bay, South Korea
2016
Kim, Hyun Jung | Jung, Seung Won | Lim, Dhong-Il | Jang, Min-Chul | Lee, Taek-Kyun | Shin, Kyoungsoon | Ki, Jang-seu
Bacterioplankton communities in a semi-closed bay (Jangmok Bay, South Korea) were analysed using a 16S rDNA multiplex 454 pyrosequencing approach. Diversity and operational taxonomic units of bacterioplankton communities in the Jangmok Bay are highest in cold water seasons and lowest in warm water ones. During cold seasons, α-proteobacteria respond rapidly to pulses of the concentration of inorganic nutrients, while γ-proteobacteria during warm water seasons are the most active type of bacterioplankton resent in the prevailing conditions, which include high dissolved organic carbon, chemical oxygen demand and primary production. Cyanobacteria, a minor group constituting 4.58% of the total bacterioplankton, are more abundant at low temperature. Flavobacteria are more abundant in nutrient-rich conditions and the abundance of this group also demonstrated a delayed decline following summer phytoplankton blooms. The pronounced seasonal oscillations in phosphorus concentration and temperature exert strong selection pressure on bacterioplankton communities.
اظهر المزيد [+] اقل [-]Young of the year bluefish (Pomatomus saltatrix) as a bioindicator of estuarine health: Establishing a new baseline for persistent organic pollutants after Hurricane Sandy for selected estuaries in New Jersey and New York
2016
Smalling, Kelly L. | Deshpande, Ashok D. | Blazer, Vicki S. | Dockum, Bruce W. | Timmons, DeMond | Sharack, Beth L. | Baker, Ronald J. | Samson, Jennifer | Reilly, Timothy J.
Atlantic coastal bays of the US are essential habitat for young of year bluefish (Pomatomus saltatrix). Their residence in these estuaries during critical life stages, high lipid content, and piscivory make bluefish an ideal bioindicator species for evaluating estuarine health. Individual whole fish from four estuaries impacted by Hurricane Sandy were collected in August 2013, analyzed for a suite of persistent organic pollutants (POPs) including polychlorinated biphenyls, polybrominated diphenyl ethers and organochlorine pesticides and evaluated using health metrics. Concentrations in whole bluefish differed by estuary; however, concentrations for many POPs decreased or were similar to those observed prior to the hurricane. Prevalence of the ectoparasitic gill isopod (Lironeca ovalis) varied by estuary and no relationships between contaminants and lesions were observed. Bluefish should be considered for monitoring programs and, if sampled frequently, could be an effective bioindicator of incremental and episodic changes in contaminants within aquatic food webs.
اظهر المزيد [+] اقل [-]Large amounts of marine debris found in sperm whales stranded along the North Sea coast in early 2016
2016
Unger, Bianca | Rebolledo, Elisa L Bravo | Deaville, Rob | Gröne, Andrea | IJsseldijk, Lonneke L. | Leopold, Mardik F. | Siebert, Ursula | Spitz, Jérôme | Wohlsein, Peter | Herr, Helena
30 sperm whales (Physeter macrocephalus) stranded along the coasts of the North Sea between January and February 2016. The gastro-intestinal tracts of 22 of the carcasses were investigated. Marine debris including netting, ropes, foils, packaging material and a part of a car were found in nine of the 22 individuals. Here we provide details about the findings and consequences for the animals. While none of the items was responsible for the death of the animal, the findings demonstrate the high level of exposure to marine debris and associated risks for large predators, such as the sperm whale.
اظهر المزيد [+] اقل [-]Abnormally high phytoplankton biomass near the lagoon mouth in the Huangyan Atoll, South China Sea
2016
Ke, Zhixin | Liu, Huajian | Wang, Junxing | Liu, Jiaxing | Tan, Yehui
Nutrient concentration and phytoplankton biomass were investigated in Huangyan Atoll in May 2015. The concentrations of nutrients were very low, and dissolved inorganic nitrogen was composed mainly of ammonia. Nitrogen likely was the primary limiting factor for phytoplankton growth. The spatial variation of phytoplankton biomass was significant among the lagoon, reef flats, and outer reef slopes. Extremely high chlorophyll a concentration and micro-phytoplankton abundance were found in the region near the lagoon mouth. This high phytoplankton biomass might be due to nutrient input from fishing vessels and phytoplankton aggregation driven by the southwestern wind. Our results indicate that phytoplankton biomass could be a reliable indicator of habitat differences in this coral reef ecosystem, and micro-phytoplankton seems to be more sensitive to nutrient input than pico-phytoplankton.
اظهر المزيد [+] اقل [-]Microplastics elutriation from sandy sediments: A granulometric approach
2016
Kedzierski, Mikaël | Le Tilly, Véronique | Bourseau, Patrick | Bellegou, Hervé | César, Guy | Sire, Olivier | Bruzaud, Stéphane
Although relatively easy to extract in the marine environment, microplastics are very difficult to recover when they are trapped in sediments. The elutriation column is one of the best tools currently available for extracting plastics from sediment, but with a high sand recovery yield. This study aims to address the following questions: (i) is it possible to use a sedimentological approach to limit the sand recovery? (ii) does the extraction velocity of the sand and plastic particles vary according to density and granulometry? (iii) what is the relative recovery efficiency obtained for dense polymer particles mixed with marine sand? Based on a new granulometric classification, different plastic particle-size fractions are defined. Their extraction velocities are experimentally determined on particles of sediment and different plastics (PA, PVC). The particle recovery experiments indicate that it is possible to extract >90% of dense plastic particles in cases of negligible sand recovery.
اظهر المزيد [+] اقل [-]Spatial variations in annual cycles of body-size spectra of planktonic ciliates and their environmental drivers in marine ecosystems
2016
Xu, Henglong | Jiang, Yong | Xu, Guangjian
Body-size spectra has proved to be a useful taxon-free resolution to summarize a community structure for bioassessment. The spatial variations in annual cycles of body-size spectra of planktonic ciliates and their environmental drivers were studied based on an annual dataset. Samples were biweekly collected at five stations in a bay of the Yellow Sea, northern China during a 1-year cycle. Based on a multivariate approach, the second-stage analysis, it was shown that the annual cycles of the body-size spectra were significantly different among five sampling stations. Correlation analysis demonstrated that the spatial variations in the body-size spectra were significantly related to changes of environmental conditions, especially dissolved nitrogen, alone or in combination with salinity and dissolve oxygen. Based on results, it is suggested that the nutrients may be the environmental drivers to shape the spatial variations in annual cycles of planktonic ciliates in terms of body-size spectra in marine ecosystems.
اظهر المزيد [+] اقل [-]Investigation of fungal volatile organic compounds in hospital air
2016
Pantoja, Lydia Dayanne Maia | do Nascimento, Ronaldo Ferreira | de Araújo Nunes, Ana Barbara
Fungal growth within the structure of buildings or in ventilation filters generates “hidden contamination”, which cannot be detected only through visual inspection. At the beginning of development, the fungi release fungal volatile organic compounds (FVOCs) into the atmosphere, which can originate from metabolic pathways or from the enzymatic degradation of materials. This study analyzed the air quality of a public referral hospital in Fortaleza, Ceará, Brazil in terms of FVOCs, to establish ways to improve methods of monitoring and control of specific sectors in the hospital. For that, we created and validated a protocol for detection of FVOCs, using GC/MS, while fungal samples were identified by analysis of macro and micromorphology. In total, 48 samples (60.5% positive) were analyzed for FVOCs; 7 were detected in at least one of the sectors analyzed, with 2-heptanone (179.5 μg/m3) and 2-methyl-1-propanol (121.5 μg/m3) as the most abundant. With respect to fungal findings, 24 samples were analyzed, with a high number of colony-forming units per cubic meter (CFU/m3) observed in all sectors. The airborne fungal spectrum revealed the existence of 19 genera, composed predominantly by hyaline filamentous deuteromycetes. Analysis with periodic monitoring is still needed to allow improvement in the data quality. Also, further discussion on the subject in the academic and legislative environment is needed to contribute to the systematic study of aerobiology.
اظهر المزيد [+] اقل [-]Ultrasound-assisted extraction combined with reverse phase-dispersive liquid-liquid micro extraction as a new approach for preconcentration and spectrophotometric determination of total phenol in marine sediments of Chabahar Bay
2016
Ziyaadini, Morteza | Zahedi, Mir Mahdi | Khosravinia, Saeid
In this study, Reverse phase dispersive liquid–liquid micro extraction (RP-DLLME) technique have been successfully developed to preconcentrate trace amount of phenol from sediment samples as a prior step to its derivatization with 4-aminoantipyrine and enhanced determination by UV–Vis spectrophotometry after primary ultrasonic extraction. In this procedure, 50μL 0.7M NaOH solution was chosen as extraction solvent and other factors including pH, extraction time, concentration of 4-aminoantipyrine, type and volume of dispersive solvents were optimized. Under selected conditions, the limit of detection, the linearity range, relative standard deviation and enrichment factor of method were obtained 15μg·kg−1, 50–1800μg·kg−1, 4.8% (n=10) and 33, respectively. Finally, using the high sensitivity, low organic solvent consumption and waste generation method, total phenol content in marine sediments from several locations in Chabahar Bay (southeast Iran) was estimated at 55.8–73.2μg·kg−1.
اظهر المزيد [+] اقل [-]Enhanced biodegradation of pyrene and indeno(1,2,3-cd)pyrene using bacteria immobilized in cinder beads in estuarine wetlands
2016
Huang, Ru-ying | Tian, Wei-jun | Liu, Qing | Yu, Hui-bo | Jin, Xin | Zhao, Yang-guo | Zhou, Yu-hang | Feng, Gong
Two strains (Pseudomonas taiwanensis PYR1 and Acinetobacter baumannii INP1) were isolated from PAH-contaminated Liaohe estuarine wetland using enrichment. The cells of PYR1 and INP1 were immobilized in cinder beads for pyrene and indeno(1,2,3-cd)pyrene biodegradation in wetland. Biodegradation of pyrene and indeno(1,2,3-cd)pyrene in soils from wetland was carried out in pots using free cells as well as those immobilized in cinder beads to ascertain the role of bioaugmentation. Supported by the cinder beads, the immobilized cells degraded 70.7% and 80.9% of pyrene and indeno(1,2,3-cd)pyrene respectively after 30days. While the free cells degraded only 58.2% and 55.3%. Additionally, microbial analysis with high-throughput sequencing revealed the changes of microbial communities in soil without and with cinder beads immobilized with strains. The result indicated that Gammaproteobacteria were dominant PAH-degrading groups during bioaugmentation. This effective approach can be used to treat other PAH-contaminated wetlands by immobilizing different species of bacteria in cinder beads.
اظهر المزيد [+] اقل [-]A multidisciplinary approach for the characterization of the coastal marine ecosystems of Monte Di Procida (Campania, Italy)
2016
Mangoni, Olga | Aiello, G. (Giuseppe) | Balbi, Simona | Barra, Diana | Bolinesi, Francesco | Donadio, Carlo | Ferrara, Luciano | Guida, Marco | Parisi, Roberta | Pennetta, Micla | Trifuoggi, Marco | Arienzo, Michele
A multidisciplinary survey was carried out on the quality of water and sediments of a coastal protected marine area, embedded between the inputs from Bagnoli steel plant to the south and a sewage plant, Volturno River and Regi Lagni channel to the north. The study integrated chemical-sedimentological data with biological and ecotoxicological analyses to assess anthropogenic pressures and natural variability. Data reveal marked differences in anthropogenic pollution between southeastern and northwestern zone, with the north affected by both inorganic and organic flows and the south influenced by levels of As, Pb and Zn in the sediments above law limits, deriving from inputs of the Bagnoli brownfield site. Meiobenthic data revealed at south higher relative abundance of sensitive species to pollution and environmental stress to the south, i.e. Lobatula lobatula and Rosalina bradyi, whereas to the north relative abundance of stress tolerant Quinqueloculina lata, Quinqueloculina pygmaea and Cribroelphidium cuvilleri were determined.
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