Dissolved oxygen (DO) is a measure of just how much oxygen is dissolved in the water - the lot of oxygen accessible to living aquatic organisms. The quantity of liquified oxygen in a currently or lake can tell united state a lot about its water quality.

You are watching: In a scientific investigation of lakes, the depth of a lake is most likely to be measured in


brickandmortarphilly.com scientist is measuring various water-quality conditions in feet Creek in ~ Huffman Park in Kettering, Ohio.

The brickandmortarphilly.com has to be measuring water for decades. Some measurements, such as temperaturepH, and specific conductance are taken practically every time water is sampled and also investigated, no issue where in the U.S. The water is being studied. Another common measurement frequently taken is liquified oxygen (DO), which is a measure up of how much oxygen is dissolved in the water - DO deserve to tell united state a lot about water quality.


Dissolved Oxygen and also Water

Although water molecule contain an oxygen atom, this oxygen is no what is necessary by aquatic organisms life in natural waters. A little amount the oxygen, increase to around ten molecules of oxygen every million of water, is actually liquified in water. Oxygen start a stream greatly from the environment and, in areas where underground water discharge into streams is a big portion of streamflow, indigenous groundwater discharge. This dissolved oxygen is breathed by fish and zooplankton and also is required by them come survive.


Dissolved oxygen and also water quality


A eutrophic lake where dissolved-oxygen concentrations room low. Algal blooms can occur under together conditions.

Rapidly moving water, such as in a hill stream or large river, often tends to save a lot of of liquified oxygen, conversely, stagnant water contains less. Bacteria in water have the right to consume oxygen as organic matter decays. Thus, overabundance organic material in lakes and rivers can cause eutrophic conditions, i beg your pardon is an oxygen-deficient situation that can reason a water body to \"die.\" Aquatic life have the right to have a tough time in stagnant water that has actually a lot of rotting, organic material in it, especially in summer (the concentration of dissolved oxygen is inversely pertained to water temperature), when dissolved-oxygen levels space at a seasonal low. Water near the surface of the lake– the epilimnion– is too warm for them, if water near the bottom–the hypolimnion– has too tiny oxygen. Problems may become especially serious during a period of hot, calm weather, causing the lose of numerous fish. You may have actually heard about summertime fish death in regional lakes the likely result from this problem.

(Source: A Citizen\"s guide to Understanding and Monitoring Lakes and Streams)



Dissolved oxygen, temperature, and also aquatic life


As the graph shows, the concentration of liquified oxygen in surface water is influenced by temperature and also has both a seasonal and a day-to-day cycle. Cold water have the right to hold more dissolved oxygen than warmth water. In winter and also early spring, when the water temperature is low, the dissolved oxygen concentration is high. In summer and also fall, as soon as the water temperature is high, the dissolved-oxygen concentration is often lower.

Dissolved oxygen in surface ar water is offered by all creates of aquatic life; therefore, this constituent commonly is measured to assess the \"health\" of lakes and streams. Oxygen enters a stream native the atmosphere and from groundwater discharge. The contribution of oxygen from groundwater discharge is significant, however, only in areas where groundwater is a huge component that streamflow, such together in locations of glacial deposits. Photosynthesis is the primary process affecting the dissolved-oxygen/temperature relation; water clarity and strength and also duration that sunlight, in turn, affect the price of photosynthesis.


Hypoxia and \"Dead zones\"

You may have heard about a Gulf the Mexico \"dead zone\" in locations of the Gulf south of Louisiana, whereby the Mississippi and Atchafalaya Rivers discharge. A dead zone creates seasonally in the northern Gulf of Mexico when subsurface waters end up being depleted in dissolved oxygen and cannot support most life. The zone develops west the the Mississippi Delta over the continental shelf off Louisiana and sometimes extends off Texas. The oxygen depletion begins in so late spring, boosts in summer, and also ends in the fall.


Dissolved oxygen in bottom waters, measured from June 8 through July 17, 2009, throughout the annual summer Gulf that Mexico southeast Area Monitoring and Assessment program (SEAMAP) cruise in the northern Gulf that Mexico. Orange and also red colors show lower liquified oxygen concentrations.

The development of oxygen-depleted subsurface waters has been associated with nutrient-rich (nitrogen and also phosphorus) discharge native the Mississippi and Atchafalaya Rivers. Bio-available nutrients in the discharge have the right to stimulate algal blooms, which die and also are eaten by bacteria, depleting the oxygen in the subsurface water. The oxygen contents of surface ar waters of typical salinity in the summer is typically an ext than 8 milligrams per liter (8 mg/L); when oxygen concentration are much less than 2 mg/L, the water is identified as hypoxic (CENR, 2000). The hypoxia kills plenty of organisms that cannot escape, and also thus the hypoxic ar is informally well-known as the “dead zone.”

The hypoxic ar in the northern Gulf the Mexico is in the facility of a productive and an useful fishery. The boosted frequency and also expansion the hypoxic zones have become an important economic and also environmental problem to commercial and recreational individuals of the fishery.


Measuring dissolved oxygen


Field and also lab meter to measure dissolved oxygen have been roughly for a lengthy time. Together this snapshot shows, modern-day meters are little and extremely electronic. Castle still use a probe, i beg your pardon is located at the end of the cable. Dissolved oxygen is dependence on temperature (an inverse relation), so the meter should be calibrated properly before each use.

Do you desire to test your local water quality?

Water test kits are obtainable from World Water surveillance Challenge (WWMC), an worldwide education and also outreach program that build public awareness and involvement in protecting water resources around the world. Teachers and also water-science enthusiasts: carry out you want to be able to perform simple water-quality tests on local waters? WWMC supplies inexpensive test kit so you have the right to perform your very own tests for temperaturepHturbidity, and dissolved oxygen.

See more: Jack The Ripper Creepypasta S, Jeff The Killer Origins And History



Do friend think you understand a lot about water properties?Take our interactive water-properties true/false quiz and test her water knowledge.







Want to know an ext about dissolved oxygen and water? Follow me to the Nutrients and Eutrophication website!