Plankton, Chemistry, and Physics of Lakes in the Churchill Falls Region of Labrador

1974 ◽  
Vol 31 (6) ◽  
pp. 1105-1117 ◽  
Author(s):  
H. C. Duthie ◽  
M. L. Ostrofsky
Keyword(s):  
Granite Gneiss ◽  
Biological Data ◽  
Lake Area ◽  
Secchi Disc ◽  
Positive Correlation ◽  
Maximum Surface ◽  
Natural Lakes ◽  
Asterionella Formosa ◽  
Bosmina Coregoni ◽  
Cyclops Scutifer

Of 10 lakes and a reservoir in the Churchill Falls region of western Labrador studied in 1970–71, nine lakes were 12 m or less deep, humic, thermally unstratified, and had Secchi disc transparencies between 3.5 and 8.25 m. Maximum surface temperatures of 16–17 C in the nine lakes were generally reached by mid-August. Michikamau Lake (area 1980 km2, depth 84 m) rarely exceeded 12 C and had a Secchi disc transparency of 13 m. Conductivities and alkalinities (as CaCO3) ranged from about 13 μmho/cm and less than 6.5 mg/liter, for lakes draining granite, gneiss, or quartz bedrock, to about 30 and 15, for those draining gabbro or slate. Maximum live phytoplankton biomasses in 1970 ranged from 70 mg/m3, in Michikamau Lake, to 739 mg/m3, in Ossokmanuan Reservoir, and, in general, there was a positive correlation with conductivity. Diatoms were the most abundant group, in particular Asterionella formosa, Tabellaria fenestrata, and Rhizosolenia eriensis; however, flagellated Chrysophyta, mainly species of Dinobryon, were more abundant in the reservoir than in the natural lakes. Predominant zooplankters included Diaptomus minutus, Cyclops scutifer, Holopedium gibberum, Daphnia longiremis, D. galeata mendotae, and Bosmina coregoni. Maximum seasonal standing crops ranged from 1600 to 8910 individuals/m3, with the highest densities being found in the reservoir. The chemical and biological data suggested that the reservoir 8 yr after filling, showed little evidence of trophic upsurge and was possibly entering a period of trophic depression.

scholarly journals Monitoring of Inland Surface Water Quality Using Remote Sensing on the Example of Wigry Lake

2018 ◽  
Vol 63 ◽  
pp. 00017
Author(s):  
Michał Lupa ◽  
Katarzyna Adamek ◽  
Renata Stypień ◽  
Wojciech Sarlej
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Surface Water Quality ◽  
Lake Area ◽  
Landsat Images ◽  
Secchi Disc ◽  
Water Index ◽  
Normalized Difference Water Index

The study examines how LANDSAT images can be used to monitor inland surface water quality effectively by using correlations between various indicators. Wigry lake (area 21.7 km2) was selected for the study as an example. The study uses images acquired in the years 1990–2016. Analysis was performed on data from 35 months and seven water condition indicators were analyzed: turbidity, Secchi disc depth, Dissolved Organic Material (DOM), chlorophyll-a, Modified Normalized Difference Water Index (MNDWI), Normalized Difference Water Index (NDWI) and Normalized Difference Vegetation Index (NDVI). The analysis of results also took into consideration the main relationships described by the water circulation cycle. Based on the analysis of all indicators, clear trends describing a systematic improvement of water quality in Lake Wigry were observed.

scholarly journals Assessment of Water Buffer Capacity of Two Morphometrically Different, Degraded, Urban Lakes

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1512
Author(s):  
Jolanta Grochowska
Keyword(s):  
Surface Water ◽  
Chlorophyll A ◽  
Calcium Concentration ◽  
Buffer Capacity ◽  
Ph Value ◽  
Calcium Content ◽  
Lake Area ◽  
Secchi Disc ◽  
Water Layers ◽  
High Concentrations

The research was conducted in Karczemne Lake (area, 40.4 ha; maximum (max.) depth, 3.2 m) and Klasztorne Małe Lake (area, 13.7 ha; max. depth, 20.0 m) located in the Kashubian Lake District (Northern Poland). From the beginning of the 1950s, these reservoirs have received municipal and storm wastewater. The long-term process of lake contamination has shaped the specific buffer capacity conditions and influenced the circulation of carbonate and bicarbonate in the water of these ecosystems. Extremely high concentrations of nutrients (Karczemne Lake: max. total phosphorous (TP) level, 7.5 mg P L−1; max. total nitrogen (TN) level, 5.6 mg N L−1; Klasztorne Małe Lake: max. TP level, 20.6 mg P L−1; max. TN level, 43.3 mg N L−1) have caused very intensive primary production processes (Karczemne Lake: max. chlorophyll-a level, 193.40 µg m−3; max. Secchi disc visibility, 0.85 m; Klasztorne Małe Lake: max. chlorophyll-a level, 160.01 µg m−3; max. Secchi disc visibility, 1.15 m). In the polymictic Karczemne Lake, the pH value of all water columns exceeded 10.0 (max. pH, 10.41), and in the meromictic Klasztorne Małe Lake, the pH of the surface water layers oscillated around 9.5. In the polymictic Karczemne Lake, despite intensive photosynthesis, the calcium content and alkalinity were similar throughout the whole water column due to constant circulation. In the meromictic Klasztorne Małe Lake, during the growing season, a decrease in calcium concentration and alkalinity of the surface water layers and an increase in calcium concentration at the bottom were noted.

The Biology of the Surface Zone Zooplankton of a Boreo-Arctic Atlantic Ocean Area

1952 ◽  
Vol 9 (5) ◽  
pp. 223-264 ◽  
Author(s):  
William V. Kielhorn
Keyword(s):  
Late Summer ◽  
The United States ◽  
Biological Data ◽  
Coast Guard ◽  
Calanus Finmarchicus ◽  
Labrador Sea ◽  
Physical Factors ◽  
Minor Importance ◽  
Surface Zone ◽  
Secchi Disc

Zooplankton samples were taken from the surface zone waters of the central Labrador Sea at International Ocean Station "B" (56° − 30′N., 51° − 00′W.) at weekly intervals throughout one calendar year for the purpose of determining the composition of the zooplankton, the seasonal progression, fluctuations and pertinent physical factors. An attempt was made to correlate the physical and biological factors.Ships of the United States Coast Guard and the Royal Canadian Navy were used as collecting units, and these were provided with nets, samplers and other equipment with which to carry out the shipboard phase of the investigation. Mid-day, 20 minute oblique hauls from 150-0 metres were made with the Clarke-Bumpus plankton sampler using No. 2 and No. 12 mesh silk nets, along with bathythermograph and Secchi disc lowerings. Later in the day, but at least one hour after dark, an open half-metre net 20 minute surface tow was made for additional qualitative data. Bioluminescence records also were obtained at this time.All available physical and biological data pertaining to the area under investigation were examined to provide a basis for comparison.Synopses of the species found in the material are presented individually, including their seasonal occurrence, probable breeding seasons, numerical and economic importance, and values as indicator forms. In all, 61 species in seven phyla, 10 classes and 17 orders are represented.The zooplankton population of the surface zone in the central Labrador Sea is characterized by relatively few species, but at the same time by large numbers of individuals. The plankton consists mainly of Calanus finmarchicus, Thysanoessa longicaudata, Oithona atlantica, Scolecithricella minor, Oikopleura labradoriensis and Eukrohnia hamata. The remainder of the species assume comparatively minor importance in the economy of the region.The main augmentation season was found to occur generally in late summer, although mid-winter breeding was noted for a few animals. The zooplankton of this region was found to be distinctive, being consistently oceanic, but neither true arctic nor true boreal. Definite biological evidence was obtained that indicated the influx of boreal-subtropical surface waters into the area in winter.Extinction coefficients determined from white Secchi disc readings are graphed, as are comparisons between black and white disc readings. It was concluded that the great variations of transparency were caused by fluctuations in the amount and kinds of phytoplankton and detritus in the water, and that the zooplankton density had little effect on water clarity.No direct correlation was noted between the occurrence of bioluminescence and individuin species or planktonic groups, but it was found that the greatest bioluminescence was observed al the summer and fall.

scholarly journals Evaluating Primary Productivity Based on Chlorophyll-a in Ciburuy Lake, West Java Indonesia

2021 ◽  
pp. 1-8
Author(s):  
Regy Pratama Rusdiansyah ◽  
. Zahidah ◽  
Dedi Supriadi ◽  
Herman Hamdani
Keyword(s):  
Chlorophyll A ◽  
Primary Productivity ◽  
Management Plan ◽  
Lake Area ◽  
West Java ◽  
Chlorophyll A Concentration ◽  
Natural Lakes ◽  
Ph Range ◽  
The One ◽  
Depth Water

Ciburuy Lake is the one of many natural lakes in Padalarang, West Java. Padalarang is industries area and pruduce huge waste water to contamination Ciburuy Lake. Ciburuy Lake area has many functions such as tourism, settlement, agriculture and industry. This study aim to evaluate velue of primary productivity based on chlrophyill-a. Chlorophyll-a is one of the indicator to creat management plan of water resources in Ciburuy Lake. This research was conducted from January to March 2021. Sampling carried out in 4 station with deferent water situation. This research used chlorophyll-a concentration measurment method to determine primary productivity. Result obtained in terms of water quality are: temperature  range of 24 - 28 oC; depth water range of 151,83 – 190,83 cm; Transparation range of 22,83 – 27,67 cm; pH range of 5,94 – 8,00; CO2 range of 6,98 – 33,52 mg/L; BOD range of 7,84 – 12,14 mg/L; nitrate range of 0,235 – 0,312 mg/L; fosfate range of 0,142 --0,156 mg/L, and chlorophyll-a concentration range of 0.024 - 0.065 mg/L . This research showed that Ciburuy Lake has water condition eutrophic to hypertrophic because primary productivity in Ciburuy Lake has middle to high condition based on chlorophyll-a concentration.

scholarly journals Trophic state and recreational value of Lake Mikołajskie

2016 ◽  
Vol 16 (3) ◽  
pp. 147-154 ◽  
Author(s):  
Justyna Sieńska ◽  
Julita Dunalska ◽  
Michał Łopata ◽  
Katarzyna Parszuto ◽  
Renata Tandyrak
Keyword(s):  
Total Phosphorus ◽  
Surface Waters ◽  
Trophic State ◽  
Trophic Status ◽  
Water Environment ◽  
Eutrophic Lake ◽  
Lake Area ◽  
Negative Effects ◽  
Secchi Disc ◽  
Status Index

Abstract Lakes along with their surroundings are an attractive landscape component that play an important role in recreation and relaxation. In Poland, the Great Masurian Lakeland, visited by a million tourists every year, is considered to be the most attractive lake area. However, tourist pressure has several negative effects which cause degradation of the water environment. The aim of this study was to determine the trophic state of Lake Mikołajskie which is a hub for sailing and motorboating traffic. Values of the trophic status index were calculated from the content of total phosphorus, chlorophyll a and Secchi disc visibility, according to the data from the Voivodeship Inspectorate for Environmental Protection. In summer, the concentration of total phosphorus was 0.019–0.042 mg dm−3 in 2013 and 0.022–0.055 mg dm−3 in 2014. The concentration of chlorophyll a was in the range of 8.3–45.0 μg dm−3 in 2013 and 8.9–22.0 μg dm−3 in 2014. The maximum visibility of Secchi disc reached 2.0 m (2013) and 1.8 m (2014). Based on the calculated, Lake Mikołajskie can be classified as a eutrophic lake. In order to protect lakes from degradation tourists should be educated about the rational use of surface waters and the surrounding catchment. However, it is not only the massive influx of tourists, but also the activity of residents (dictated by economic reasons) that contribute to the pollution of lakes. Therefore, the development of tourism and the economy of the whole region should be harmonious and balanced so that the natural resources can serve us and future generations for as long as possible.

Field relations, U-Pb geochronology, and Sm-Nd isotope geochemistry of the Point Lake greenstone belt and adjacent gneisses, central Slave craton, N.W.T., Canada

1999 ◽  
Vol 36 (7) ◽  
pp. 1043-1059 ◽  
Author(s):  
C J Northrup ◽  
C Isachsen ◽  
S A Bowring
Keyword(s):  
Greenstone Belt ◽  
Isotope Geochemistry ◽  
Volcanic Rocks ◽  
Granite Gneiss ◽  
Lake Area ◽  
Slave Craton ◽  
Mafic Dykes ◽  
Depleted Mantle ◽  
Zircon Crystallization ◽  
Back Arc

Data from the Point Lake area, central Slave craton, suggest an intimate tectonic and paleogeographic association between volcano-sedimentary supracrustal rocks and adjacent gneisses. Granite plutons and orthogneisses yield U-Pb zircon crystallization ages ranging from ca. 3230 to 2818 Ma. Numerous mafic dykes cut the gneisses, and two have been dated by U-Pb zircon geochronometry at 2673 ± 3 and 2690 ± 3 Ma, ages similar to those of volcanic rocks in the Point Lake greenstone belt. Although high-strain zones form the greenstone-gneiss in most places, a structural repetition of granite about 4 km east of Keskarrah Bay is cut by numerous mafic dykes and apparently overlain depositionally(?) by pillow basalt. Mafic volcanic and plutonic rocks from Point Lake have initial (2.7 Ga) εNd values ranging from about +2.2 to -6.3, significantly lower than the depleted mantle at that time. The Nd data suggest either derivation from a more isotopically evolved reservoir, or assimilation of crust similar to the granite gneiss at Point Lake. We infer from the presence of mafic dykes of appropriate age in the basement and the low initial εNd values of some pillow basalts that the volcanic sequence developed on the older granitic crust. The supracrustal rocks may have been deposited in a back-arc basin floored at least in part by attenuated continental material. Closure of the basin, bulk east-west shortening, and sinistral oblique or strike-slip faulting then obscured the original relations between the volcanic and gneissic rocks.

Relationship of Sense of Coherence to Other Psychosocial Indices

2004 ◽  
Vol 20 (4) ◽  
pp. 227-236 ◽  
Author(s):  
Sara Holmberg ◽  
Anders Thelin ◽  
Eva-Lena Stiernström
Keyword(s):  
Social Support ◽  
Psychosocial Factors ◽  
Sense Of Coherence ◽  
Living Conditions ◽  
Strong Negative Correlation ◽  
Cross Sectional ◽  
Positive Correlation ◽  
Work Related ◽  
Job Demand ◽  
The Mean

Summary: The concept of “sense of coherence” (SOC) has been widely recognized since it was first introduced by Antonovsky. The originality and usefulness of the SOC scale and its relation to other psychosocial measures has been the subject of lively debate. The aim of this paper was to test for associations between SOC and work-related psychosocial factors (mainly the Job Demand-Control model), general living conditions, education, and social network factors. Cross-sectional data from a population-based sample of 1782 rural males from nine counties in Sweden were analyzed with a multiple regression technique. The subjects were occupationally active at inclusion and the mean age was 50 years (range 40-60). SOC was assessed with the original 29-item questionnaire. Psychosocial variables and lifestyle factors were assessed using questionnaires and structured interviews. The mean SOC among the subjects was 152.3 (standard deviation, 19.4). A strong negative correlation was found between SOC and job demand, whereas a positive correlation with job control was demonstrated. A positive correlation with general living conditions and with social support was also found. However, there was no correlation to education and occupation. Thus, SOC was shown to be strongly correlated to work-related psychosocial factors and social support, but independent of sociodemographic factors.

Locus of Control, Safety Attitudes and Involvement in Hazardous Events in Indian Army Aviators

2013 ◽  
Vol 3 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Catherine Joseph ◽  
Suhasini Reddy ◽  
Kanwal Kashore Sharma
Keyword(s):  
Locus Of Control ◽  
Future Research ◽  
Research Needs ◽  
Negative Attitudes ◽  
Human Errors ◽  
Safety Attitudes ◽  
Positive Correlation ◽  
Self Confidence

Locus of control (LOC), safety attitudes, and involvement in hazardous events were studied in 205 Indian Army aviators using a questionnaire-based method. A positive correlation was found between external LOC and involvement in hazardous events. Higher impulsivity and anxiety, and decreased self-confidence, safety orientation, and denial were associated with a greater number of hazardous events. Higher external LOC was associated with higher impulsivity, anxiety, and weather anxiety and with lower self-confidence, safety orientation, and denial. Internal LOC was associated with increased self-confidence, safety orientation, and denial. Hazardous events and self-confidence were higher in those involved in accidents than those not involved in accidents. Future research needs to address whether training can effectively modify LOC and negative attitudes, and whether this would cause a reduction in, and better management of, human errors.

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