scholarly journals Analysis of a High Andean River's Behavior at Loads of Organic Matter Through the Use of Mathematical Models with Experimentally Determined Kinetic Rates

2021 ◽  
Vol 16 (4) ◽  
pp. 675-682
Author(s):  
Carlos Matovelle
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Control Points ◽  
Organic Matter Degradation ◽  
River Section ◽  
Quality Model ◽  
Secondary Sources ◽  
Kinetic Rates ◽  
Kinetics Of

Using models of organic matter degradation and dissolved oxygen consumption, the concentrations of these compounds are analyzed in two stretches of a river after a discharge of raw sewage. The analyzed river has low drafts and widths, so the velocity is high and the aeration coefficient kr calculated with the Covar method is high, this indicates a rapid recovery of oxygen from the water consumed by the organic matter degradation processes, the river has been instrumented to measure flows and organic matter at various points to calibrate the model. The hydraulic parameters of the river section are analyzed in three control points, in each one sample are taken to analyze oxygen consumption by organic matter and nitrification through laboratory tests to determine and adjust the kinetics of the processes (kd; knit). This kinetics have been used in the development of a water quality model to verify its adjustment, obtaining higher RMSE results than with kinetics from secondary sources. It is observed that the river has an excellent capacity for self-purification due to the high income of dissolved oxygen, with a kr > 9 d-1.

scholarly journals Ion fluxes in silver catfish (Rhamdia quelen) juveniles exposed to different dissolved oxygen levels

2006 ◽  
Vol 4 (4) ◽  
pp. 435-440 ◽  
Author(s):  
Felipe Link de Rosso ◽  
Keidi C. S. Bolner ◽  
Bernardo Baldisserotto
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Ammonia Excretion ◽  
Ion Fluxes ◽  
Phytoplankton Blooms ◽  
Silver Catfish ◽  
Oxygen Levels ◽  
Rhamdia Quelen ◽  
Series Of Experiments

Low dissolved oxygen levels in the water (hypoxia) can be provoked by oxygen consumption by fish and other organisms, organic matter decomposition, phytoplankton blooms, and temperature increase. The objective of the present study was to investigate Na+, Cl-, K+, and ammonia fluxes in silver catfish (Rhamdia quelen) exposed to different dissolved oxygen levels. Juveniles (9 ± 1g) maintained at 6.0 mg.L-1 dissolved oxygen were transferred to four 40 L aquaria with different dissolved oxygen levels (in mg.L-1): 6.0, 4.5, 3.5, and 2.5. In another series of experiments, juveniles were acclimated at 6.0 or 2.5 mg.L-1 dissolved oxygen levels, and then placed in two 40 L aquaria with 6.0 mg.L-1 dissolved oxygen. For both series of experiments, 1, 24, 48 or 120 h after transference juveniles were placed in individual chambers of 200 mL (with the same dissolved oxygen levels of their respective aquaria) for 3 h. Water samples were collected for analysis of Na+, Cl-, K+, and ammonia levels. The obtained results allow concluding that exposure to 2.5 mg.L-1 dissolved oxygen levels promotes loss of ions and lower ammonia excretion in silver catfish juveniles, but these losses are rapidly stabilized for Na+ and Cl-. Exposure to less hypoxic levels also changes ion fluxes and ammonia excretion, but there is no clear relationship between both parameters in this species. Therefore, silver catfish osmoregulation seems to be affected when this species is transferred from normoxic to hypoxic waters and vice-versa.

scholarly journals Effect of lead in the aerobic decomposition of Myriophyllum aquaticum (Vellozo) Verdecourt

2020 ◽  
Vol 15 ◽  
pp. 43-49
Author(s):  
B.S. Soares ◽  
I Bianchini Junior ◽  
M.B. Cunha-Santino
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Dissolved Oxygen ◽  
Aquatic Environment ◽  
Toxic Element ◽  
Industrial Processes ◽  
Myriophyllum Aquaticum ◽  
Cycling Rate ◽  
Aerobic Decomposition ◽  
The Impact

Lead is a toxic element that has been used since early times and is still employed today in several industrial processes. Events as the collapse of the Fundão dam in Bento Rodrigues, district of Mariana (MG) on November 2015, significantly increase concentrations of metals above-recommended levels, including lead. In this context, this study aims to evaluate the impact of lead in the cycling rate of organic matter in the aquatic environment. Thus, the rates of aerobic decomposition of Myriophyllum aquaticum (Vell.) Verdec at different concentrations of lead (5.0, 10.0, 20.0 and 30.0 mg L-1) were measured, analyzing the dissolved oxygen consumption. Decomposition chambers filled with samples of water and M. aquaticum were incubated at 20° C in the dark for 80 days and periodically had the oxygen concentrations determined by polarography, when the concentrations were less than 2 mg L-1, the incubations were re-aerated. At the lowest concentrations (5.0 and 10.0 mg L-1) of lead the mineralization was lower, however, the reaction coefficients and the amount of oxygen consumed were equivalent to the control. At the highest concentrations (20.0 and 30.0 mg L-1) the mineralization was increased, with the reduction of reaction coefficients and higher oxygen consumption.

Characterisation of production of organic rich topsoil from sludge

2000 ◽  
Vol 42 (9) ◽  
pp. 195-201 ◽  
Author(s):  
P. Andreasen ◽  
P. B. Mortensen ◽  
A. Stubsgaard ◽  
B. Langdahl
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Oxygen Transport ◽  
Mineral Soil ◽  
Climatic Conditions ◽  
Growth Media ◽  
Soil Mixture ◽  
Water Suspension ◽  
Aerobic Process ◽  
Stable Product

The stabilisation of a sludge-mineral soil mixture and a method to evaluate the state of stabilisation were investigated. The organic matter and nitrogen content are reduced up to 50% during a stabilisation process of three months under Danish climatic conditions. The stabilisation was shown to be an aerobic process limited by oxygen transport within the mixture. The degree of stabilisation was evaluated by oxygen consumption in a water suspension and the results showed that a stable product was achieved when oxygen consumption was stable and in the level of natural occurring aerobic soils (0.1 mgO2/(g DS*hr). The study thereby demonstrates that a stability of a growth media can be controlled by the oxygen consumption method tested.

Prolonged Kinetics of Recovery of Oxygen Consumption After Maximal Graded Exercise in Patients With Chronic Heart Failure

Circulation ◽  
1995 ◽  
Vol 91 (12) ◽  
pp. 2924-2932 ◽  
Author(s):  
Alain Cohen-Solal ◽  
Thierry Laperche ◽  
Daniel Morvan ◽  
Michel Geneves ◽  
Bernard Caviezel ◽  
...  
Keyword(s):  
Heart Failure ◽  
Oxygen Consumption ◽  
Chronic Heart Failure ◽  
Graded Exercise ◽  
Kinetics Of
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