scholarly journals Comparative studies of underwater light regimes in lakes of the East-Suwałki Lakeland

2016 ◽  
Vol 16 (4) ◽  
pp. 173-183 ◽  
Author(s):  
Dariusz Borowiak ◽  
Magdalena Borowiak
Keyword(s):  
Optical Properties ◽  
Attenuation Coefficient ◽  
Suspended Solids ◽  
Trophic Status ◽  
Thermal Conditions ◽  
Secchi Disc ◽  
Eutrophic Lakes ◽  
Light Regimes ◽  
Interannual Fluctuations

Abstract Secchi disc transparency and optical properties of water, based on measurements for downward irradiance using an underwater radiometer PER-700, were studied in 23 lakes of the Suwałki Landscape Park (SLP) in 2013. Measurements of optically significant constituents of water were also performed (YSI EXO-2) and analysed. Data on water transparency from published studies were used to assess long-term changes in the optical conditions in the deepest water body in Poland – Lake Hańcza. In terms of the optical characteristics of the water, the analysed SLP lakes can essentially be divided into two distinct groups representing different optical lake types. These are optical categories of lakes most common in Poland, namely types II and IIIb. Regional equations describing the relationships between the attenuation coefficient for downward irradiance as well as optically significant constituents of water were developed. The optical properties of the SLP lakes are mainly affected by suspended solids, mostly phytoplankton. Interannual fluctuations in Sechi disc transparency, as well as the attenuation coefficient for downward irradiance and other apparent optical properties of mid-summer water calculated from it, are determined by the spring thermal conditions and intensity of phytoplankton blooms during this period. Application of the attenuation coefficient for downward irradiance as a criterion for the assessment of the trophic status of the SLP lakes indicates that these are generally eutrophic lakes. The largest and deepest lakes of the park, however, are mesotrophic. Lake Hańcza is currently in the stage of α-mesotrophy.

Investigations on the filtration of natural aquatic suspensions supported by dosing small amounts of Fe(III)-salts (βFe ≤ 0.1 mg.L-1): mode of action and basic design criteria

2002 ◽  
Vol 2 (2) ◽  
pp. 91-98
Author(s):  
R. Winzenbacher ◽  
R. Schick ◽  
H.-H. Stabel ◽  
M. Jekel
Keyword(s):  
Large Scale ◽  
Suspended Solids ◽  
Iron Hydroxides ◽  
Essential Step ◽  
Iron Salts ◽  
Alkaline Earths ◽  
Co Precipitation ◽  
Solid Liquid ◽  
Solid Liquid Separation

Improved removal of particles during the treatment of natural aquatic suspensions has been achieved by pre-ozonation and the addition of small quantities of iron salts (βFe ≤ 0.1 mg.L-1; “Fe(III)-assisted filtration”) followed by rapid filtration. As shown by investigations on a large-scale installation at Lake Constance Water Supply, this procedure reliably reduces suspended solids by at least 2-3 powers of ten in long-term use. However, the high efficacy of Fe(III)-assisted filtration cannot be explained on the basis of known coagulation mechanisms (like adsorption-charge neutralization, co-precipitation). Instead, the essential step was found to be the conditioning of the filter medium by coating it with colloids containing Fe(OH)3, and this “Fe coating” process occurs only in the presence of alkaline earths (especially Ca2+). According to further experiments, the enhanced solid-liquid separation was ultimately traced to chemical interactions such as the formation of calcium-organic association structures between the iron hydroxides and other solids. For design of Fe(III)-assisted filtration steps, finally, a βCa/DOC ratio above 40 mg.mg-1 and pre-oxidation with ozone dosages not exceeding 2 mg O3/mg DOC was recommended.

Exceedance Degree‐Hours: A new method for assessing long‐term thermal conditions

Indoor Air ◽  
2021 ◽  
Author(s):  
Shide Salimi ◽  
Esteban Estrella Guillén ◽  
Holly Samuelson
Keyword(s):  
Thermal Conditions ◽  
New Method

scholarly journals Genetic Diversity of Small Eukaryotes in Lakes Differing by Their Trophic Status

2005 ◽  
Vol 71 (10) ◽  
pp. 5935-5942 ◽  
Author(s):  
Marie Lefranc ◽  
Aurélie Thénot ◽  
Cécile Lepère ◽  
Didier Debroas
Keyword(s):  
Trophic Status ◽  
Eutrophic Lake ◽  
Rrna Genes ◽  
Eutrophic Lakes ◽  
Massif Central ◽  
Operational Taxonomic Units ◽  
Single Clone ◽  
18S Rrna Genes ◽  
Lake Pavin ◽  
Environmental Sequences

ABSTRACT Small eukaryotes, cells with a diameter of less than 5 μm, are fundamental components of lacustrine planktonic systems. In this study, small-eukaryote diversity was determined by sequencing cloned 18S rRNA genes in three libraries from lakes of differing trophic status in the Massif Central, France: the oligotrophic Lake Godivelle, the oligomesotrophic Lake Pavin, and the eutrophic Lake Aydat. This analysis shows that the least diversified library was in the eutrophic lake (12 operational taxonomic units [OTUs]) and the most diversified was in the oligomesotrophic lake (26 OTUs). Certain groups were present in at least two ecosystems, while the others were specific to one lake on the sampling date. Cryptophyta, Chrysophyceae, and the strictly heterotrophic eukaryotes, Ciliophora and fungi, were identified in the three libraries. Among the small eukaryotes found only in two lakes, Choanoflagellida and environmental sequences (LKM11) were not detected in the eutrophic system whereas Cercozoa were confined to the oligomesotrophic and eutrophic lakes. Three OTUs, linked to the Perkinsozoa, were detected only in the Aydat library, where they represented 60% of the clones of the library. Chlorophyta and Haptophyta lineages were represented by a single clone and were present only in Godivelle and Pavin, respectively. Of the 127 clones studied, classical pigmented organisms (autotrophs and mixotrophs) represented only a low proportion regardless of the library's origin. This study shows that the small-eukaryote community composition may differ as a function of trophic status; certain lineages could be detected only in a single ecosystem.

Physical and optical properties of aerosols in a free tropospheric environment: Results from long-term observations over western trans-Himalayas

2014 ◽  
Vol 84 ◽  
pp. 262-274 ◽  
Author(s):  
Mukunda M. Gogoi ◽  
K. Krishna Moorthy ◽  
Sobhan Kumar Kompalli ◽  
Jai Prakash Chaubey ◽  
S. Suresh Babu ◽  
...  
Keyword(s):  
Optical Properties

Effect of Stone Powder Content on the Diffusing Parameter and Diffusion Attenuation Coefficient of Chloride Ion of Mechanical Sand Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 1818-1822
Author(s):  
Ming Qiang Qin ◽  
Wen Zhan ◽  
Wen Bing Xu ◽  
Jin Hui Li
Keyword(s):  
Attenuation Coefficient ◽  
Chloride Ion ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
River Sand ◽  
Moderate Amount ◽  
Powder Content ◽  
And Diffusion ◽  
Better Than

The effect of stone powder content on the chloride diffusion coefficient and diffusion attenuation coefficient of chloride ion of mechanical sand (MS) concrete was studied. The results showed that the resistance to chloride ion permeability of MS concrete firstly increased and then decreased with the increase of the content of stone powder. The anti-permeability of the concrete which had moderate amount of stone powder was better than that of the natural river sand (NS) concrete. The diffusion attenuation coefficient of MS concrete was greater than that of the NS concrete, which was good for long-term durability of concrete structure.

Inter-decadal variations of surface winds off Peruvian coast

2021 ◽  
Author(s):  
Sadegh Yari ◽  
Volker Mohrholz
Keyword(s):  
Coastal Upwelling ◽  
Marine Ecosystem ◽  
Wind Forcing ◽  
Trade Wind ◽  
Positive Anomaly ◽  
Peruvian Coast ◽  
Wide Range ◽  
Decadal Variations ◽  
Interannual Fluctuations

<p>The Peruvian upwelling system (PUS) is the most productive marine ecosystem among the Eastern Boundary upwelling Systems (EBUS). The trade wind system drives a nearly continuous upwelling which is subjected to variations on a wide range of times scales. The wind forced upwelling controls crucially the nutrient supply to the euphotic surface layer and thus, the overall productivity of the system.</p><p>Using long term data from ERA5 (1979-2019) the wind forcing in the PUS was analyzed to obtain information about long term trends in the mean state and its variability.</p><p>Beside the strong annual cycle, the wind forcing is dominated by interannual and a long term interdecadal oscillation.</p><p>The interannual fluctuations with a period of 2-5 years are related to the known events of El Niño and La Niña. The wind anomaly shows a good correlation with Oceanic Niño Index (ONI). Interdecadal variation of wind depict a main period of 15-20 years whit negative anomaly values from 1979 to 1996, and positive anomaly values for 1996-2014. These long term variations can be attributed to the Interdecadal Pacific Oscillations (IPO). The spatial distribution of wind stress along the Peruvian coast is not uniform. The highest values are observed in Lima-Marcona area (12º-15.4º S) while it decreases sharply southward and gradually northward. Additionally the coastal upwelling area is modulated locally by the coupling of wind and SST.</p>

Long-Term Preservation of Microalgal Cells and their Optical Properties

Biosafety ◽  
2015 ◽  
Vol 03 (01) ◽  
Author(s):  
Rodolfo Iturriaga ◽  
Cornelius W. Sullivan
Keyword(s):  
Optical Properties ◽  
Long Term Preservation
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