Lake Dynamics and the Effects of Flooding on Total Phosphorus

1990 ◽  
Vol 47 (3) ◽  
pp. 480-485 ◽  
Author(s):  
Bernard C. Kenney
Keyword(s):  
Total Phosphorus ◽  
Time Scale ◽  
Forced Response ◽  
Phosphorus Concentration ◽  
Water Renewal ◽  
Renewal Time ◽  
Before And After ◽  
Lake Washington ◽  
High Flows ◽  
High Concentrations

The concentration of total phosphorus in Lake Washington before and after the sewage diversion project was simulated using first-order linear dynamics. Fluctuation in total phosphorus in the lake occurred as a forced response to changes in inflow phosphorus concentration. The dynamics of total phosphorus in Lake Washington was adequately represented by two independent time scales based on water renewal and sedimentation. The water renewal time scale was modelled as a time dependent process. Sedimentation of total phosphorus, on the other hand, appeared constant over the 16-yr period that data were available. A marked increase of total phosphorus in the lake occurred during two flood periods when high concentrations of total phosphorus corresponded to small values of the water renewal time scale (i.e., high flows). At other times, peak concentrations of total phosphorus in the inflow coincided with large values of the water renewal time scale and the lake was dynamically unable to respond to these peaks.

Maintenance of Iron Meromixis by Iron Redeposition in a Rapidly Flushed Monimolimnion

1980 ◽  
Vol 37 (8) ◽  
pp. 1303-1313 ◽  
Author(s):  
P. Campbell ◽  
T. Torgersen
Keyword(s):  
Organic Matter ◽  
Residence Time ◽  
Deep Water ◽  
Lake Water ◽  
Redox Reactions ◽  
Water Mass ◽  
Experimental Lakes Area ◽  
Water Renewal ◽  
Renewal Time ◽  
High Concentrations

Water mass ages determined by the 3H–3He method gave a water renewal time of 2.5 ± 1 yr for the monimolimnion of softwater iron meromictic Lake 120. The water renewal time of the monimolimnion is less than, or equal to, the renewal time of the whole lake. The monimolimnion of Lake 120 was, therefore, not found to be a stratum of "perennially stagnant deep water." The rates of supply to, and degradation of, organic matter in the monimolimnion are responsible, in the first place, for the low redox potential necessary to establish the high concentrations of soluble Fe2+ observed (up to 4.2 mmol∙L−1). However, it was found that the major key to maintenance of high monimolimnetic concentrations of Fe, i.e. maintenance of iron meromixis, is recycling of Fe at the chemocline by an [Formula: see text] "Ferrous Wheel." Up to 90% recycling of iron between chemocline and monimolimnion results in an iron residence time of [Formula: see text] for the whole lake (greater than 4 times the whole lake water renewal time).Key words: meromixis, iron recycling, 3H–3He water ages, water renewal times, chemical budgets, sediment funneling, redox reactions, Experimental Lakes Area (ELA).

Phosphorus Dynamics in Riverine Lakes

1994 ◽  
Vol 29 (2-3) ◽  
pp. 185-202
Author(s):  
B.C. Kenney
Keyword(s):  
Time Scales ◽  
Total Phosphorus ◽  
Shallow Lakes ◽  
Model Calibration ◽  
Forced Response ◽  
Mass Capture ◽  
High Concentrations ◽  
Water Outflow ◽  
Lake Dynamics ◽  
Simple Models

Abstract Simple models based on conservation of mass capture the essential dynamics of total phosphorus in lakes. The concentration of total phosphorus in shallow riverine lakes on the Prairies was simulated as a forced response to the inflow concentration. The lake dynamics were characterized by three independent time scales based on water inflow, water outflow and sedimentation. Both inflow and outflow time scales were necessary to model lakes with non-stationary hydrographe and varying lake levels. Flood periods had a pronounced effect on lake phosphorus because high concentrations in the inflow occurred when the lake was dynamically able to respond. In the Fishing Lakes, the 1974 flood appears to have established the lake conditions for the next decade. Most other large peaks in the concentration of total phosphorus in the inflow occurred when the outflow time scale was large and the lakes were dynamically unable to respond. Net sedimentation of total phosphorus appeared to be zero in these lakes over the two decades for which data were available. Verification of the lack of net sedimentation in shallow lakes means that no model calibration is needed to apply these simple models to other shallow lakes. Presently, however, even the simplest models are restricted by the lack of appropriate data required for verification.

Limnological Conditions in Five Small Oligotrophic Lakes in Terra Nova National Park, Newfoundland

1974 ◽  
Vol 31 (5) ◽  
pp. 555-583 ◽  
Author(s):  
Joseph J. Kerekes
Keyword(s):  
Primary Production ◽  
Total Phosphorus ◽  
National Park ◽  
Phosphorus Concentration ◽  
Water Color ◽  
Oligotrophic Lakes ◽  
Water Renewal ◽  
Renewal Rate ◽  
Catchment Areas ◽  
Terra Nova

Five oligotrophic lakes in Terra Nova National Park, Newfoundland, varying in mean depth (1.06–9.22 m), in water renewal rate (0.2–20.7 times per annum), in salinity (18.2–42.6 mg/liter), in total phosphorus (0.1–0.6 mg-at P/m3), and in chlorophyll a concentration (0.5–3.2 mg/m3), were investigated for 17 mo in 1969 and 1970. Hypolimnetic oxygen deficits ranged between 111 and 217 mg O2 per m2/day. Low levels of nutrients, reduced solar radiation, and low underwater light penetration, owing to excessive cloudiness and high water color, seriously limited planktonic primary production. The relation between primary production at optimum light, and water renewal per annum, appeared to be curvilinear when the rate of primary production began to decline above an optimum water renewal rate. The seasonal and annual variations in water color and salinity were dependent on the rate of water renewal, but other lakes on the catchment areas modified that relation. Winter road salting operations within the catchment area caused a considerable increase in salinity, total phosphorus concentration, and primary production in one lake. A new morphometric index which reflects the littoral effect on basin volume was proposed.

Lake Paranoá, Brasília, Brazil: Integrated Management Plan for its Restoration

1992 ◽  
Vol 27 (2) ◽  
pp. 271-286 ◽  
Author(s):  
Sonia Paulino Mattos ◽  
Irene Guimarães Altafin ◽  
Hélio José de Freitas ◽  
Cristine Gobbato Brandão Cavalcanti ◽  
Vera Regina Estuqui Alves
Keyword(s):  
Total Phosphorus ◽  
Drainage Basin ◽  
Integrated Management ◽  
Algal Growth ◽  
Nutrient Content ◽  
Management Plan ◽  
Cylindrospermopsis Raciborskii ◽  
Phosphorus Concentration ◽  
Limiting Factor ◽  
Total Phosphorus Concentration

Abstract Built in 1959, Lake Paranoá, in Brasilia, Brazil, has been undergoing an accelerated process of nutrient enrichment, due to inputs of inadequately treated raw sewage, generated by a population of 600,000 inhabitants. Consequently, it shows high nutrient content (40 µg/L of total phosphorus and 1800 µg/L of total nitrogen), low transparency (0.65 m) and high levels of chlorophyll a (65 µg/L), represented mainly by Cylindrospermopsis raciborskii and sporadic bloom of Microcystis aeruginosa, which is being combatted with copper sulphate. With the absence of seasonality and a vertical distribution which is not very evident, the horizontal pattern assumes great importance in this reservoir, in which five compartments stand out. Based on this segmentation and on the identification of the total phosphorus parameter as the limiting factor for algal growth, mathematical models were developed which demonstrate the need for advanced treatment of all the sewage produced in its drainage basin. With this, it is expected that a process of restoration will be initiated, with a decline in total phosphorus concentration to readings below 25 µg/L. Additional measures are proposed to accelerate this process.

scholarly journals Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1757
Author(s):  
Yesica Vicente-Martínez ◽  
Manuel Caravaca ◽  
Antonio Soto-Meca ◽  
Miguel Ángel Martín-Pereira ◽  
María del Carmen García-Onsurbe
Keyword(s):  
Magnetic Nanoparticles ◽  
Nitrate Content ◽  
Adsorption Efficiency ◽  
Experimental Conditions ◽  
Dependent Behavior ◽  
Before And After ◽  
Naoh Solution ◽  
High Concentrations ◽  
Interference Studies

This paper presents a novel procedure for the treatment of contaminated water with high concentrations of nitrates, which are considered as one of the main causes of the eutrophication phenomena. For this purpose, magnetic nanoparticles functionalized with silver (Fe3O4@AgNPs) were synthesized and used as an adsorbent of nitrates. Experimental conditions, including the pH, adsorbent and adsorbate dose, temperature and contact time, were analyzed to obtain the highest adsorption efficiency for different concentration of nitrates in water. A maximum removal efficiency of 100% was reached for 2, 5, 10 and 50 mg/L of nitrate at pH = 5, room temperature, and 50, 100, 250 and 500 µL of Fe3O4@AgNPs, respectively. The characterization of the adsorbent, before and after adsorption, was performed by energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. Nitrates can be desorbed, and the adsorbent can be reused using 500 µL of NaOH solution 0.01 M, remaining unchanged for the first three cycles, and exhibiting 90% adsorption efficiency after three regenerations. A deep study on equilibrium isotherms reveals a pH-dependent behavior, characterized by Langmuir and Freundlich models at pH = 5 and pH = 1, respectively. Thermodynamic studies were consistent with physicochemical adsorption for all experiments but showed a change from endothermic to exothermic behavior as the temperature increases. Interference studies of other ions commonly present in water were carried out, enabling this procedure as very selective for nitrate ions. In addition, the method was applied to real samples of seawater, showing its ability to eliminate the total nitrate content in eutrophized waters.

Bacterioplankton, Phytoplankton, and Zooplankton Communities in a British Columbia Coastal Lake Before and After Nutrient Reduction

1986 ◽  
Vol 43 (8) ◽  
pp. 1504-1514 ◽  
Author(s):  
F. Joan Hardy ◽  
Ken S. Shortreed ◽  
John G. Stockner
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Inorganic Nitrogen ◽  
Size Fraction ◽  
Growing Season ◽  
Nutrient Reduction ◽  
Nitrogen And Phosphorus ◽  
Coastal Lake ◽  
Before And After ◽  
High Concentrations

Inorganic nitrogen and phosphorus were applied weekly during the growing season from 1980 to 1982 and twice weekly in 1983 to Hobiton Lake, a warm monomictic coastal lake in British Columbia. The lake was not fertilized in 1984. Average numbers of bacteria during the growing season decreased from a high of 1.53 × 106∙mL−1 in the fertilized condition to 0.84 × 106∙mL−1 in the unfertilized condition. Chlorophyll a concentrations decreased from a maximum seasonal average of 2.69 μg∙L−1 (1981) to 1.30 μg∙L−1 (1984), and algal numbers decreased from 5.83 × 104∙mL−1 (1983) to 2.29 × 104∙mL−1 (1984). Although the numbers of phytoplankton in each size fraction (picoplankton, nanoplankton, or microplankton) decreased in the unfertilized condition, the greatest change was an almost fourfold decrease in picoplankton, which consisted of 90% cyanobacteria (primarily Synechococcus spp.). Abundance of the large diatoms Rhizosolenia spp. and Melosira spp. increased in 1984, resulting in an increase in average seasonal algal volume. Average densities of medium (0.15–0.84 mm) and large (0.85–1.5 mm) zooplankton were greatest in 1982, while rotifers and small zooplankton (0.10–0.14 mm) were most dense in 1984 following nutrient reduction. The lake had relatively high concentrations of planktivorous juvenile sockeye salmon (Oncorhynchus nerka) that appeared to minimize any direct effect of nutrient additions on zooplankton densities.

Practical Method for Burner Staging Turbine Forced Response Evaluation

2021 ◽  
Author(s):  
Nikola Kafedzhiyski ◽  
Maria Mayorca
Keyword(s):  
Parametric Method ◽  
Practical Method ◽  
Forced Response ◽  
Base Case ◽  
Inlet Temperature ◽  
Before And After ◽  
Efficiency Increase ◽  
Annular Combustor ◽  
Time Marching ◽  
To Come

Abstract Decarbonization and sustainability efforts challenge gas turbine engineers to come up with creative strategies for reduction of emissions and efficiency increase over the whole operating range. Burner staging at part loads presents a flexible solution to achieve these goals through selective burner deactivation. Shutting off burners could also be required for combustion of increased H2 content at some conditions. Burner staging will create circumferential unevenness with patterns of hot and cold streaks that could excite blade rows through the entire turbine. This paper presents a parametric method for annular combustor staging patterns profile generation intended for use for forced response predictions from a limited number of combustor CFD calculations while keeping the key phenomenological features. Two cases with burner staging turbine inlet temperature distributions are considered and compared to a base case with uniform temperature distribution. The unsteady aerodynamic forcing was obtained from full wheel time marching unsteady computational fluid dynamics calculations. The results show that the hot streaks generate important and noticeable excitation sources. Additionally, the results show that the pattern generator could be used extensively before and after the unsteady calculations phase to minimize the excitation levels and the computational load.

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