scholarly journals Ice-on and ice-off dynamics of ciliates and metazooplankton in the Łuczański Canal (Poland)

2020 ◽  
Vol 54 (4) ◽  
pp. 1121-1134
Author(s):  
Krystyna Kalinowska ◽  
Maciej Karpowicz
Keyword(s):  
Field Experiments ◽  
Cold Water ◽  
Ice Cover ◽  
Zooplankton Biomass ◽  
Zooplankton Grazing ◽  
Top Down ◽  
Cover Time ◽  
Trophic Coupling ◽  
Cold Water Temperature ◽  
Zooplankton Communities

Abstract The ciliate–metazooplankton trophic coupling is well documented from both laboratory and field experiments. The knowledge about these relationships during winter ice-covered periods is very scarce. The abundance and composition of planktonic ciliates, rotifers and crustaceans were studied during the ice-covered and ice-free periods in the Łuczański Canal (Masurian Lakeland, Poland). We hypothesised that in winter, rotifers play a major role in the top-down control of ciliates and that ciliate–metazooplankton relationships differ not only between the ice-covered and ice-free periods, but also between ice-covered months. Our study showed that ciliates formed a significant part of zooplankton biomass during the winter ice-covered period when crustaceans occurred in very low abundances. Despite cold water temperature and the presence of ice cover, time was probably a cue that initiates zooplankton development. The ciliate, rotifer and crustacean numbers and biomass, as well as chlorophyll a concentrations, were lower in February than in ice-free periods. In the winter month with ice cover, bottom-up control by resources was more important than top-down control by zooplankton grazing in regulating ciliates. In the spring month with ice cover, crustaceans and rotifers may include ciliates as an important part of their diets. In April, the studied groups of organisms were not related to each other in contrast to the summer, when zooplankton communities were closely related to each other. In autumn, rotifers may play an important role in controlling ciliates. The abundance, composition and ciliate–metazoan relationships can vary considerably not only across seasons, but also across ice-covered months.

scholarly journals Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1682
Author(s):  
Yoonja Kang ◽  
Yeongji Oh
Keyword(s):  
Nutrient Availability ◽  
Fast Response ◽  
Nutrient Addition ◽  
The Other ◽  
Zooplankton Grazing ◽  
Top Down ◽  
Bottom Up ◽  
Phytoplankton Distribution ◽  
Summer Bloom ◽  
Gwangyang Bay

The interactive roles of zooplankton grazing (top-down) and nutrient (bottom-up) processes on phytoplankton distribution in a temperate estuary were investigated via dilution and nutrient addition experiments. The responses of size-fractionated phytoplankton and major phytoplankton groups, as determined by flow cytometry, were examined in association with zooplankton grazing and nutrient availability. The summer bloom was attributed to nanoplankton, and microplankton was largely responsible for the winter bloom, whereas the picoplankton biomass was relatively consistent throughout the sampling periods, except for the fall. The nutrient addition experiments illustrated that nanoplankton responded more quickly to phosphate than the other groups in the summer, whereas microplankton had a faster response to most nutrients in the winter. The dilution experiments ascribed that the grazing mortality rates of eukaryotes were low compared to those of the other groups, whereas autotrophic cyanobacteria were more palatable to zooplankton than cryptophytes and eukaryotes. Our experimental results indicate that efficient escape from zooplankton grazing and fast response to nutrient availability synergistically caused the microplankton to bloom in the winter, whereas the bottom-up process (i.e., the phosphate effect) largely governed the nanoplankton bloom in the summer.

scholarly journals Fluctuating temperature of the mains water throughout the year and its influence on the consumption of energy for the purposes of DHW preparation

2018 ◽  
Vol 44 ◽  
pp. 00017 ◽  
Author(s):  
Agnieszka Chmielewska
Keyword(s):  
Water Treatment ◽  
Water Temperature ◽  
Cold Water ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Monthly Basis ◽  
New Model ◽  
Water Influence ◽  
Family Building ◽  
Cold Water Temperature

The article discusses the influence of the cold water temperature on the amount of energy consumed for the purposes of the DHW preparation in multi-family buildings. The article begins with a presentation of the DHW consumption readings from a multi-family building, recorded on a monthly basis during the period of 4 years. The readings constituted the base for calculating the demand for energy for the purposes of the DHW preparation. Subsequently, basing on the output water temperature readings from the water treatment plant, it was proved that the temperature of the mains water fluctuates throughout the year. The review of the available literature, as well as the measurements, confirmed that it is necessary to develop a new model of the cold water temperature that would take into account the type of intake in a water treatment plant. The final part of the article presents how the accepted assumptions about the temperature of the mains water influence the consumption of energy for the purposes of the DHW preparation.

ZOOBENTHOS OF WATERCOURSES IN THE BUKHTARMA RIVER BASIN (UPPER IRTYSH, SOUTH-WESTERN ALTAI) AT REFERENCE SITES AND IN THE IMPACT ZONE

2021 ◽  
pp. 66-83
Author(s):  
A. Evseeva
Keyword(s):  
River Basin ◽  
Cold Water ◽  
Taxonomic Composition ◽  
Anthropogenic Factors ◽  
Impact Zone ◽  
High Oxygen Content ◽  
Water Courses ◽  
Cold Water Temperature ◽  
Composition Structure ◽  
The Impact

The composition, structure, and spatial distribution of zoobenthos in streams of the Bukhtarma River basin are described and quantitative indicators of benthos in the lower course of the Bukhtarma River are given. The predominance of insects from the orders of mayflies, caddisflies, and freckles is characteristic of the water-courses in the Bukhtarma River basin and is associated with the presence of stony soils in the rivers, rapid flow, moderate-cold-water temperature regime, and high oxygen content in the water – factors that are most favorable for these groups of invertebrates. To assess the ecological state of surface waters in the streams under study by bioindication methods, TBI, BMWP, ASPT, and ERT biotic indices are used. The taxonomic composition of each of the studied watercourses and river sections is formed in accordance with specific environmental conditions associated with natural and anthropogenic factors. It is established that watercourses in the reference areas can be used as reference ones in accordance with the requirements of the EU Framework Water Directive, and the characteristics of invariant States of biocenoses of the lower course of the Bukhtarma River in the impact zone are also given using the criteria of the V. A. Abakumov system of ecological modulations.

scholarly journals A novel design for sampling benthic zooplankton communities in disparate Gulf of Alaska habitats using an autonomous deep-water plankton pump

2020 ◽  
Vol 42 (4) ◽  
pp. 457-466
Author(s):  
Rachel E Wilborn ◽  
Christopher N Rooper ◽  
Pam Goddard ◽  
Kresimir Williams ◽  
Rick Towler
Keyword(s):  
Deep Water ◽  
Cold Water ◽  
Larval Fish ◽  
Low Cost ◽  
Benthic Communities ◽  
Gulf Of Alaska ◽  
Design Parameters ◽  
Benthic Habitat ◽  
Pump Design ◽  
Zooplankton Communities

Abstract Deep-water larval fish and zooplankton utilize structurally complex, cold-water coral and sponge (CWCS) habitats as refuges, nurseries and feeding grounds. Fine-scale sampling of these habitats for larval fish and zooplankton has proven difficult. This study implemented a newly designed, autonomous, noninvasive plankton pump sampler that collected large mesozooplankton within 1 m of the seafloor. It was successfully deployed in the western Gulf of Alaska between the Shumagin Islands (~158°W) and Samalga Pass (−170°W), and collected in situ zooplankton from diverse benthic communities (coral, sponge and bare substrates) at depths in excess of 100 m. Key design parameters of the plankton pump were its ability to be deployed from ships of opportunity, be untethered from the vessel during sampling and be deployed and retrieved in high-relief, rocky areas where CWCS are typically present. The plankton pump remains stationary while collecting from the water column, rests within 1 m of the seafloor and captures images of the surrounding habitat and substrate. This plankton pump design is a low-cost, highly portable solution for assessing the role of benthic habitat in the life cycle of mesozooplankton, a linkage that has been relatively underexplored due to the difficulty in obtaining near-bottom samples.

scholarly journals Evaluation of Legionella spp. Colonization in Residential Buildings Having Solar Thermal System for Hot Water Production

2020 ◽  
Vol 17 (19) ◽  
pp. 7050
Author(s):  
Michele Totaro ◽  
Anna Laura Costa ◽  
Lorenzo Frendo ◽  
Sara Profeti ◽  
Beatrice Casini ◽  
...  
Keyword(s):  
Cold Water ◽  
Disease Risk ◽  
Residential Buildings ◽  
Water Systems ◽  
Hot Water ◽  
Solar Thermal ◽  
Water Production ◽  
Systems Maintenance ◽  
Legionnaires Disease ◽  
Cold Water Temperature

Despite an increase of literature data on Legionella spp. presence in private water systems, epidemiological reports assert a continuing high incidence of Legionnaires’ disease infection in Italy. In this study, we report a survey on Legionella spp. colonization in 58 buildings with solar thermal systems for hot water production (TB). In all buildings, Legionella spp. presence was enumerated in hot and cold water samples. Microbiological potability standards of cold water were also evaluated. Legionella spp. was detected in 40% of the buildings. Moreover, we detected correlations between the count of Legionella spp. and the presence of the optimal temperature for the microorganism growth (less than 40 °C). Our results showed that cold water was free from microbiological hazards, but Legionella spp., was detected when the mean cold water temperature was 19.1 ± 2.2 °C. This may considered close to the suboptimal value for the Legionella growth (more then 20 °C). In conclusion, we observed the presence of a Legionnaires’ disease risk and the need of some strategies aimed to reduce it, such as the application of training programs for all the workers involved in water systems maintenance.

Common Design Deficiencies in Counterflow Cooling Towers

2004 ◽  
Author(s):  
Hector L. Cruz
Keyword(s):  
Power Plant ◽  
Cooling Tower ◽  
Cold Water ◽  
Industrial Plant ◽  
Project Design ◽  
Minimum Standards ◽  
Operational Design ◽  
Cold Water Temperature ◽  
Design Deficiencies ◽  
Base Load

One of the best methods for insuring a power plant will produce its guaranteed base load is to have an excess of circulating cold water or at least the expected guaranteed cold water temperature throughout the year. Yet, within industry today, numerous mistakes continue to be made when purchasing a cooling tower, by both the Subcontractor, and the Contractor. Only following only normal design criteria established by cooling tower Subcontractors, or an industry association, is not sufficient. Guidelines in the cooling tower industry have been established to set forth minimum standards that have helped to eliminate obvious past deficiencies. They were not established to protect the Subcontractor. Nor were they established to guarantee the Contractor receives what is thermally and mechanically necessary for a given project. Design of a cogeneration or industrial plant does not always consider the necessary requirements on a cooling tower over the range of expected operation. This type of design for a cooling tower is more complicated than the single guarantee point operational design of a power plant that is the current norm. Just as the Contractor needs to consider how to meet the thermal energy requirements over the range of expected operation of the plant, the Subcontractor of the cooling tower must do the same. Contractors must be aware that the cooling tower designer does not consider aspects that are often applicable to cogeneration plants and therefore they must include exceptions to the Subcontractors’ optimized offering in their standard cooling tower specifications. These exceptions in no way disagree with the Codes and Standards adopted by the cooling tower industry or any governing agency. This paper will address exceptions that the power plant and cooling tower designer needs to take into consideration to ensure that a reliable supply of cold water relates to the thermal duty requirements from the plant throughout the year.

Modelling creep deformation in floating ice

2003 ◽  
Vol 30 (1) ◽  
pp. 28-41 ◽  
Author(s):  
K van Steenis ◽  
F E Hicks ◽  
T M Hrudey ◽  
S Beltaos
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Numerical Models ◽  
Ice Sheet ◽  
Transversely Isotropic ◽  
Element Model ◽  
Ice Cover ◽  
Load Test ◽  
Drilling Rig

The ability to predict the response of an ice sheet to long-term loading is important in many situations. In northern regions, ice sheets have been used as construction platforms, drilling rig platforms, airfields, parking lots, and festival platforms. Numerical models can be used to predict the deflection of an ice sheet over time and, together with a failure criterion based on allowable deflection, can facilitate the safe use of an ice cover under long-term loading situations. In this study, a two-dimensional axisymmetric finite element model was developed to model the behaviour of a homogeneous, transversely isotropic, infinite ice cover under long-term loading. The model was validated using 33 sets of long-term load test data from large-scale field experiments performed on lake, bay, and reservoir ice and was shown to be capable of reliably predicting deflections under a variety of loading scenarios.Key words: bearing capacity of ice, long-term loading, ice platforms.

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