Dissolved Oxygen Measurement | DO Meters, Sensors …

Also, even though aquatic plants and algae consume oxygen, they also produce oxygen in sunlight by the process of photosynthesis.

Furthermore, based on the data table and observation, it can be proved that the sample solutions that were more exposed to sunlight had a higher rate of dissolved oxygen.

Also, the data shows the relationship of temperature to saturation and dissolved oxygen content.

Example of daily water temperature fluctuation at the Gulf Jackson lease area, Levy County, Florida, on October 24, 2003. Dissolved oxygen is shown as A) mg/L, and B) % saturation. On October 24, temperature fluctuated by only 2.5°C (4.5°F) and, therefore, the variation in % saturation due to temperature change was relatively small. As a consequence, graph A and B look similar.


Dissolved Oxygen - Environmental Measurement Systems

Temperature affects the dissolved oxygen levels in water, the rate of photosynthesis, metabolic rates of organisms, etc.

In addition to seasonal variations, diurnal or daily fluctuations in dissolved oxygen are common (Figure 2). During daylight hours, photosynthesis produces oxygen faster than it is used in aerobic respiration, so dissolved oxygen remains high. However, at night, the only source of dissolved oxygen is diffusion, which is rarely as great as respiratory demands, so dissolved oxygen concentrations will decline. Therefore, the lowest oxygen concentrations over a 24-hour period can be expected to occur in the early morning hours, prior to sunrise (Figure 3).


What is Dissolved Oxygen - Mobile Bay NEP

Both physical and biological processes add dissolved oxygen to water. Physical sources of dissolved oxygen include diffusion of gas from the atmosphere, which is relatively slow, and aeration by wind and wave action. The most important biological source of dissolved oxygen is photosynthesis. During photosynthesis, plants and microscopic algae convert sunlight and nutrients into food, giving off oxygen as a by-product (see Equation 1). Because photosynthesis requires light, it occurs only during daylight hours and can be reduced by cloud cover.

OzCoasts Coastal indicators: Dissolved oxygen

Example of annual dissolved oxygen fluctuation at the Gulf Jackson lease area, Levy County, Florida, in 2003. Dissolved oxygen is shown as A) mg/L, and B) % saturation. During 2003, temperature fluctuated from 4°C (39.5°F) in January to 35°C (94.5°F) in July. As a consequence, graph A and B look different.

Dissolved Oxygen, Why is it Important? - Water on the Web

Other environmental conditions affect the ability of clams to survive hypoxic or anoxic conditions, including temperature and salinity. For example, high temperatures (greater than 32°C or 90°F) and low salinity (less than 20 ppt) will intensify the effects of low oxygen concentrations. Low oxygen is especially problematic in the summer months because warmer water not only contains less oxygen, but also stimulates clams metabolic rates and increases their demand for oxygen. Furthermore, physiological condition (energy stores and spawning stage), age, and size also determine the tolerance of a clam to low oxygen. For example, our laboratory studies indicate that larger clams (1-inch to 2 3/8-inch shell length) are able to withstand longer periods of low dissolved oxygen than smaller clams (5/8-inch to 1-inch shell length). Likewise, healthier clams are better able to withstand periods of low dissolved oxygen than diseased or stressed clams.

Dissolved Oxygen and Primary Productivity Lab - Savage Science

The maximum amount of oxygen (100% saturation) dissolved in fresh water and sea water at different temperatures, shown as milligrams of oxygen per liter of water (mg/L).