Dissolved Oxygen Flashcards
True/False
Higher DO indicates better water quality
True
It is characterized by the presence of DO. “Aerobic
” is also used to describe biological or chemical processes that occur in the
presence of oxygen.
Aerobic (oxic)
It is n environmental condition in which the concentration of DO is
low enough to have biological effects. According to the USEPA (2000b), water with oxygen concentrations of 2mg/L or less is of concern.
Hypoxia
It is used to
describe biological or chemical processes that occur in the absence of
Anaerobic (anoxic)
It is a DO level concentration that can suffocate sport fishes.
3-4 mg/L
Large and juvenile fish require higher DO
concentration, ranging from
5-8 mg/L
True/False
Adequate dissolved oxygen is necessary for good water
quality.
True
True /False
The energy from sunlight is used to split carbon dioxide and water into oxygen and sugar.
True/False
CO2 + H2O -> O2 + sugar
True
A process by which oxygen is transferred across the
atmosphere and waterbody.
Reaeration
True/False
Reaeration cannot produce dissolved
oxygen even in night.
False (can)
3 Dissolved Oxygen measurement methods
Colorimetric
Titrimetric
Polarographic
Best-known titrimetric method
Winkler method
It provide for rough
and rapid measurement: they are often used for screening for low-oxygen conditions and can be easily used by non-professional operators.
Colorimetric
A method for measuring DO where Chemical reagents added in excess interact with oxygen to form a product, and another chemical (the
“titrant”) is used quantitatively to neutralize that product.
Titrimetric
DO method where Electrodes measure the flux of oxygen across a membrane.
Oxygen is consumed in the
process, and the traditional
electrodes require flushing of measured liquid at the
membrane surface to constantly replace the oxygen consumed.
Polarographic
It indicates the quantity of oxygen used by bacteria and other microorganisms during the aerobic (oxygen-containing) decomposition
of organic materials at a particular temperature.
Biochemical Oxygen Demand
True/False
Higher BOD, more pure water
Lower BOD, more polluted
False (interchange description)
True/False
Low concentration of DO in the water indicates contamination.
True
True/false
The temperature and altitude of the water affect
the DO in a saturated solution.
True
3 Major sources of DO
Reaeration
Photosynthesis
External loads
5 Major sinks of DO
DOC Oxidation
Nitrification
Respiration
SOD
COD
Consumes oxygen to oxidize NH4+ to NO2- and then to NO3-.
Nitrification
Carbon dioxide and water is converted from organic carbon dioxide in the presence of oxygen
Respiration
Represents oxygen depletion caused by benthic reactions. It it the rate of oxygen consumption exerted by the bottom sediment to the overlying water.
SOD
Chemicals such as Sulfide and Methane give rise to more oxygen demand. Stratification may intercept the DO from the surface to reach at the bottom.
COD
This model takes into account the DO contribution in the reaeration process as well as the consumption of DO by aerobic bacteria that oxidize organic materials.
DO Kinetic Equation
Used to show how surface waters’ dissolved oxygen is
affected by sewage and organic pollutants such as soils, sediments, garbage, sludg
BOD5 Test
An examination designed to
quantify the oxygen needed for the chemical oxidation of both organic matter and inorganic nutrients like Ammonia or Nitrate found in water.
COD
True/False
Higher COD, more polluted
True
3 Factors Affecting DO
Water temperature
Salinity
Pressure
True/False
Cooler water has a
greater capacity to retain dissolved oxygen compared to
warmer water.
True
True/False
Water with higher salinity retains a lower amount of oxygen compared to freshwater.
True
True/False
Lowering the salt concentration results in a reduction in the solubility of oxygen.
False (Raising)
True/False
Lower atmospheric pressure enables bodies of water to retain increased levels of dissolved oxygen.
False (Greater)
