scholarly journals Dynamics of microalgal communities in the water-column/sediment interface of the inner shelf off Parana State, Southern Brazil

2004 ◽  
Vol 52 (3-4) ◽  
pp. 183-194 ◽  
Author(s):  
Ricardo Luiz Queiroz ◽  
Frederico Pereira Brandini ◽  
Franciane Maria Pellizzari
Keyword(s):  
Water Column ◽  
Cyanobacterial Bloom ◽  
Interface Layer ◽  
Benthic Diatoms ◽  
Southern Brazil ◽  
Planktonic Diatoms ◽  
Cell Densities ◽  
Sediment Interface ◽  
Microalgal Community

The composition and biomass of the microalgal community at the water-column/sediment interface on the continental shelf off Parana State (Brazil) were studied every 2 months during 1999. Samples for cell identification and determination of chlorophyll a were taken from the interface layer and at discrete depths up to 4 m above the sediment. Results showed a community mainly formed by benthic and planktonic diatoms >30 µm, benthic diatoms <30 µm and cyanobacteria. Cell densities were generally higher at the interface layer. Resuspension and sedimentation events seemed to be a paramount factor regulating the composition and biomass of these communities, and affected differently cells of different size classes. Cells >30 µm, which accounted for most of the pigment biomass, were resuspended from the interface after turbulent periods, and may take advantage of calm periods to stay and grow at the interface. Small benthic diatoms were more susceptible to wind-induced turbulence occurring in higher densities in the water column just above the water-sediment interface. A cyanobacterial bloom (Trichodesmiun) was observed at these bottom layers in the spring-summer periods.

Determination of methane yield of cellulose using different experimental setups

2014 ◽  
Vol 70 (4) ◽  
pp. 599-604 ◽  
Author(s):  
Bing Wang ◽  
Ivo Achu Nges ◽  
Mihaela Nistor ◽  
Jing Liu
Keyword(s):  
Water Column ◽  
Test System ◽  
Methane Yield ◽  
Biochemical Methane Potential ◽  
Methane Potential ◽  
Bmp Test ◽  
Potential Test

In this work, biochemical methane potential (BMP) tests with cellulose as a model substrate were performed with the aid of three manually operated or conventional experimental setups (based on manometer, water column and gas bag) and one automated apparatus specially designed for analysis of BMP. The methane yields were 340 ± 18, 354 ± 13, 345 ± 15 and 366 ± 5 ml CH4/g VS obtained from experimental setups with manometer, water column, gas bag, and automatic methane potential test system, which corresponded to a biodegradability of 82, 85, 83 and 88% respectively. The results demonstrated that the methane yields of cellulose obtained from conventional and automatic experimental setups were comparable; however, the methane yield obtained from the automated apparatus showed greater precision. Moreover, conventional setups for the BMP test were more time- and labour-intensive compared with the automated apparatus.

scholarly journals Determination of penicillin resistance in Streptococcus pneumoniae isolates from southern Brazil by PCR

2006 ◽  
Vol 10 (2) ◽  
pp. 110-115 ◽  
Author(s):  
Eduardo Walker Zettler ◽  
Rosane Machado Scheibe ◽  
Cícero A.G. Dias ◽  
Patrícia Santafé ◽  
Diógenes Santiago Santos ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Penicillin Resistance ◽  
Southern Brazil

scholarly journals ESTIMATION OF PHOSPHORUS AND NITROGEN RELEASED BY THE BREEDING OF OREOCHROMIS NILOTICUS IN CAGES IN THE TOHO AND TODOUGBA LAGOONS(SOUTHER BENIN) BETWEEN 2017 AND 2020

2021 ◽  
Vol 9 (11) ◽  
pp. 422-430
Author(s):  
Achoh Mardochee Ephraim ◽  
◽  
Agadjihouede Hyppolite ◽  
Gangbe Luc ◽  
Aizonou Romaric ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Oreochromis Niloticus ◽  
Nutrient Release ◽  
Laboratory Analysis ◽  
The Other ◽  
Production Data ◽  
Nitrogen Concentrations ◽  
High Production

The present study aim to estimate the ratio of aquaculture in the phosphorus and nitrogen concentrations determined in the Toho - Todougba lagoons. For this purpose, the two lagoons were subdivided into 7 stations for the determination of phosphorus and nitrogen concentrations in the water column. Production data from 2017 to 2019 were collected from the Direction of the Ficheries Production and from the literature. Data for 2020 were collected directly from fish farmers. Annual tilapia production was estimated by year and the amounts of phosphorus and nitrogen released from aquaculture are deduced based on the ratio of Montanhini Neto & Ostrensky (2013). The concentration of each of these nutrients was estimated by station and compared to the concentration determined by laboratory analysis of the water. This methodology shows that the amount of phosphorus and nitrogen released to the environment varies from 0.49 mg/L to 0.18 mg/L for phosphorus and from 1.53 mg/L to 0.58 mg/L for nitrogen. The lowest values are obtained in 2020 and differ significantly from the other years (p <0.05). The quantity of phosphorus discharged is higher at the high production stations (Tonon 0.20 mg/L and Lokohoue 0.11 mg/L). Some of this is stored in the sediment. The nitrogen generated by aquaculture is significantly lower than the average determined in water (p <0.05). However, the concentration determined is still related to the amount of organic matter released due to aquaculture. Although aquaculture is not the only source of nutrient release to water, strategies for aquaculture with less nutrient release should be determined.

scholarly journals The perforation of the frustules of planktonic diatoms Pseudosolenia calcar-avis and Proboscia alata (Bacillariophyceae)

2019 ◽  
Vol 2 ◽  
pp. 19-26
Author(s):  
Lyakh A.M.
Keyword(s):  
Surface Area ◽  
Geometric Modeling ◽  
Direct Determination ◽  
Entire Surface ◽  
Planktonic Diatoms ◽  
Centric Diatoms ◽  
Flow Through ◽  
Material Energy ◽  
The Relationship

Physiological and biophysical characteristics of microalgae should strongly depend on the surface area of the cover of organisms, as all the material-energy streams flow through the surface. However, to determine the relationship between the intensity of the flow of substances with the physiology of unicellular, it is necessary to take into account only the area of perforations, since the rest of the shell is impermeable for substances. The direct determination of the area of perforations on the entire surface of the microalgae is very difficult. Therefore, the indirect method of estimating the perforation area using geometric modeling of the perforation distribution (texture) on the surface was used in this study. The object of the research is two types of marine plankton diatoms with large cylindrical frustules. It was assumed that the frustules are covered with a regular triangular texture of the areola. This texture can be divided into regular hexagons, which allows us to estimate the number of areolas as the ratio of the surface area of the frustules to the area of one hexagon. The model takes into account that each areola is covered with a silicon plate perforated by a smaller pore. The multiplication of the number of areolas on the area of a given pore gives the value of the total area of perforations. Calculations showed that the perforation of the frustules of Proboscia alata was 4%, and Pseudosolenia calcar-avis – 6%. These are the first estimates of the perforation of the entire surface of the diatom frustules. The acquired data confirms the hypothesis that frustules of the most centric diatoms are covered by pores by about 5%, and the other surface is impervious to material flows.

DETERMINATION OF THE WOOD DRYING CURVE FOR FIVE SPECIES OF EUCALYPTUS CULTIVATED IN SOUTHERN BRAZIL.

2020 ◽  
pp. 315-323
Author(s):  
Huan Pablo de Souza ◽  
José Mateus Wisniewski Gonsalves ◽  
Claudiney do Couto Guimarães ◽  
Angélica Costa Malheiros ◽  
Aline Aparecida Ludvichak ◽  
...  
Keyword(s):  
Southern Brazil ◽  
Wood Drying ◽  
Drying Curve

Phytoplankton of the La Trobe River, Victoria

1985 ◽  
Vol 36 (1) ◽  
pp. 115 ◽  
Author(s):  
BC Chessman
Keyword(s):  
Chlorophyll A ◽  
Marked Reduction ◽  
Benthic Diatoms ◽  
Monthly Basis ◽  
Centric Diatoms ◽  
Cell Densities

Phytoplankton was sampled on a monthly basis for 1 year at five stations on the La Trobe River in Gippsland, Victoria. In the upper, mostly forested, reaches of the river, chlorophyll a concentrations and cell densities were uniformly very low, and the dominant algae were detached benthic diatoms and flagellated species. In the plains section of the river, downstream of an impoundment (Lake Narracan), spring and autumn blooms occurred, with a marked reduction in abundance in midsummer and midwinter. The lowland planktonic flora was dominated by centric diatoms, particularly Melosira distans in autumn and Skeletonema potamos in spring.

Determination of interface layer effects on magnetic properties of nanocomposite magnets and exchange coupling between magnetic entities

2019 ◽  
Vol 480 ◽  
pp. 454-462 ◽  
Author(s):  
Nadeem Abbas ◽  
Fang Wang ◽  
Hanyang Ren ◽  
J. Ping Liu ◽  
Weixing Xia ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Exchange Coupling ◽  
Interface Layer ◽  
Nanocomposite Magnets
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