Habitat Preferences in Net-Spinning Caddis Larvae with Special Reference to the Influence of Water Velocity

10.2307/3081 ◽  
1968 ◽  
Vol 37 (3) ◽  
pp. 675 ◽  
Author(s):  
J. M. Edington
Keyword(s):  
Special Reference ◽  
Habitat Preferences ◽  
Water Velocity ◽  
Influence Of Water

High nitrification rate with upflow biofiltration

1996 ◽  
Vol 34 (1-2) ◽  
pp. 347-353 ◽  
Author(s):  
J.-G. Peladan ◽  
H. Lemmel ◽  
R. Pujol
Keyword(s):  
Contact Time ◽  
Pilot Scale ◽  
Ammonium Nitrogen ◽  
Water Velocity ◽  
Nitrification Rate ◽  
Air Velocity ◽  
Influence Of Water ◽  
Hydraulic Load ◽  
Series Of Experiments ◽  
Positive Effect

In order to investigate the upper limit of aerated biofilm processes, a series of experiments has been carried out on a pilot scale with a synthetic effluent containing only ammonium nitrogen and inorganic carbon as substrates. The influence of water velocity, air velocity and media height has been studied without the interaction of organic carbon and suspended solids. Under these conditions, the increase of the hydraulic load has a positive effect on the maximum nitrified load, despite the shortening of contact time. The pilot plant was able to nitrify 2.7 kg NH4+-N/m3.d at 14° C with an empty bed hydraulic retention time as short as 6 minutes - under a 30 m3/m2.h hydraulic load. It was also demonstrated that a cubic meter of granular bed presents the same nitrification capacity in a 3 m or in a 4 m media high biofilter, only if placed under the same conditions of air and water velocities. The results confirmed that water velocity significantly improves substrate bulk/biofilm transfer, and demonstrated that neither a contact time - based on the pore volume - as short as 2 minutes nor a media height of 4 m limit the nitrification rate.

Seasonal dynamics of Bythonomus lemani and Bothrioneurum vejdovskyanum (Oligochaeta, Annelida) in relation to environmental variables

Biologia ◽  
2006 ◽  
Vol 61 (5) ◽  
Author(s):  
Jana Schenková ◽  
Jan Helešic ◽  
Jiří Jarkovský
Keyword(s):  
Seasonal Dynamics ◽  
Environmental Variables ◽  
Habitat Preferences ◽  
Oxygen Demand ◽  
Significant Negative Correlation ◽  
Life Cycles ◽  
Reproduction Cycle ◽  
Influence Of Water ◽  
One Year ◽  
First Time

AbstractThe seasonal dynamics of Bythonomus lemani (Lumbriculidae) were studied for the first time and the knowledge of Bothrioneurum vejdovskyanum (Tubificidae) was extended based on four quantitative samples of oligochaetes taken monthly in the Rokytná River (Czech Republic) during a two-year study (April 1999–April 2001). The influence of water temperature, velocity, depth, discharge, pH, conductivity, dissolved oxygen amount and biochemical oxygen demand (BOD) on their life cycles was evaluated. Habitat preferences of the juvenile and adult stages were recorded. Time series analysis was used to determine the worm densities, seasonality and trends. For Byth. lemani one distinct reproduction cycle per year was found and this was regulated by temperature, while Both. vejdovskyanum showed a one-year cycle not significantly dependent on measured environmental variables. The overall trend was an increase in density for Byth. lemani and a decrease in density for Both. vejdovskyanum. Byth. lemani showed a significant negative correlation between the trend of its density and BOD concentration.

Combined filter for ammonia removal – part I: Minimal zeolite contact time and requirements for desorption

1999 ◽  
Vol 39 (8) ◽  
pp. 123-129 ◽  
Author(s):  
G. Dimova ◽  
G. Mihailov ◽  
Tz. Tzankov
Keyword(s):  
Ion Exchange ◽  
Contact Time ◽  
Water Hardness ◽  
Ammonia Concentration ◽  
Water Velocity ◽  
Ammonia Removal ◽  
Design Parameters ◽  
Influence Of Water ◽  
Minimal Contact ◽  
Differential Element

The minimal contact time in removal of ammonia ions by ion-exchange with zeolite, Na-form, is determined using the method of differential element. The relationship between the contact time, the water velocity, the effect of removal and the initial ammonia concentration is investigated. The obtained data serve as a basis for mathematical modeling of the ion exchange kinetics and give valuable information about some design parameters of ion-exchange facilities. Some basic analyses, concerning the desorption of ammonia from zeolite, induced mainly from the cations naturally present in surface waters are made. The influence of water velocity and water hardness on such desorption is investigated. These experimental data and analyses are an essential part of a study, the purpose of which is to investigate the possibilities for ammonia removal and biological regeneration of zeolite in a combined facility, using the processes: ion-exchange, desorption induced by small concentrations of cations and biological nitrification.

scholarly journals Influence of Water Temperature on Results of Current Meter Calibration and Measurement

2013 ◽  
Vol 61 (3) ◽  
pp. 208-213 ◽  
Author(s):  
Daniel Mattas ◽  
Libuše Ramešová
Keyword(s):  
Water Temperature ◽  
Rotational Velocity ◽  
Rotational Frequency ◽  
Water Velocity ◽  
Uncertainty Of Measurements ◽  
Influence Of Water ◽  
Type 3 ◽  
Measured Water ◽  
Term Data

Abstract On the basis of the results of calibration of current meters at water of varying temperatures, a hypothesis that water temperature influences measured water velocities was formulated. The analysis of our long-term data showed that the water temperature does have an influence on measured water velocity. This influence can be taken into account for practical purposes as a contribution to the uncertainty of measurements. The influence depends on the type of current meter propeller. This paper presents results obtained for the Ott C-2 current meter with propellers of the types 1, 2, 3, 5 and 6. Our analysis showed that the uncertainty is equal or less than 5% for measurements carried out in water with temperatures above 8°C. The differences between measured water velocities for water temperatures 5°C and 20°C reached maximum 6% (depending on the propeller) in a slowly flowing water (rotational frequency n = 1 s-1). For rotational velocity n ≥ 2 s-1 the differences between velocities measured at water temperatures 5 and 20°C were mostly under 3%. The less influenced propeller is of type 3 for which the uncertainty of measurement does not reach 5% even for water temperature 1°C if the rotational frequency is bigger than 0.7 s-1.

scholarly journals Species distribution modelling of Bryde’s whales, humpback whales, southern right whales, and sperm whales in the southern African region to inform their conservation in expanding economies

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9997 ◽  
Author(s):  
Jean Purdon ◽  
Fannie W. Shabangu ◽  
Dawit Yemane ◽  
Marc Pienaar ◽  
Michael J. Somers ◽  
...  
Keyword(s):  
Species Distribution ◽  
Environmental Variables ◽  
Sea Water ◽  
Habitat Preferences ◽  
Water Velocity ◽  
Humpback Whales ◽  
Environmental Drivers ◽  
Sperm Whales ◽  
Right Whales ◽  
Southern Right Whales

In southern African waters, information about species distribution and habitat preferences of many cetacean species is limited, despite the recent economic growth that may affect them. We determined the relative importance of eight environmental variables (bathymetry, distance to shore, slope, chlorophyll-a, salinity, eastwards sea water velocity, northwards sea water velocity and sea surface temperature) as drivers of seasonal habitat preferences of Bryde’s whales (Balaenoptera brydei), humpback whales (Megaptera novaeangliae), southern right whales (Eubalaena australis) and sperm whales (Physeter macrocephalus). Using presence only data from multiple sources, we constructed predictive species distribution models (SDMs) consisting of ensembles of seven algorithms for these species during both summer and winter. Predicted distribution for all cetaceans was high in southern Africa and, in particular, within the South African Exclusive Economic Zone (EEZ). Predictive models indicated a more pronounced seasonal variation for humpback, sperm and southern right whales than for Bryde’s whales. Southern right whales occurred closer to shore during winter, humpback whales were more likely to occur along the east coast in winter and the west coast in summer, and sperm whales were more concentrated off the shelf in winter. Our study shows that ensemble models using historical, incidental and scientific data, in conjunction with modern environmental variables, can provide baseline knowledge on important environmental drivers of cetacean distribution for conservation purposes. Results of this study can further be used to help develop marine spatial plans and identify important marine mammal areas.

Influence of Water Velocity on Marine Immersion Corrosion of Mild Steel

CORROSION ◽  
2004 ◽  
Vol 60 (1) ◽  
pp. 84-94 ◽  
Author(s):  
R. E. Melchers ◽  
R. Jeffrey
Keyword(s):  
Mild Steel ◽  
Water Velocity ◽  
Immersion Corrosion ◽  
Influence Of Water
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