The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes.
waters hold far less oxygen than surface waters because they haven't been in contact with air for centuries. And in many places, decomposing organic matter raining down from the surface uses up what little oxygen remains.
Below the oxygen minimum layer there is often an increase in dissolved oxygen at the greatest depths (Figures 5.4. 1, 5.4. 2). This bottom water is usually colder than the surface water and is under enormous pressure; as stated above, lower temperatures and higher pressure increase the solubility of dissolved gases.
At deeper depths, oxygen gradually increases as lower temperatures increase the solubility of oxygen. The increase gradually stops around 1500 m and remains more or less constant to the maximum depth of the cast at 2000 m.
During stratification, the bottom of the lake becomes anoxic, void of oxygen. Anoxia occurs because respiration and decomposition takes place at the bottom of the lake and use up oxygen. The oxygen can't be replenished at the bottom of the lake because it is cut off from the top of the lake.
Does surface water have more oxygen than deep water?
The actual amount of dissolved oxygen (in mg/L) will vary depending on temperature, pressure and salinity ¹. First, the solubility of oxygen decreases as temperature increases ¹. This means that warmer surface water requires less dissolved oxygen to reach 100% air saturation than does deeper, cooler water.
Cold water can hold more dissolved oxygen than warm water. In winter and early spring, when the water temperature is low, the dissolved oxygen concentration is high. In summer and fall, when the water temperature is high, the dissolved-oxygen concentration is often lower.
Extensive measurements have shown that the highest oxygen concentrations are found at high latitudes, where the ocean is cold, especially well-mixed and ventilated. The mid-latitudes, by contrast, especially on the western coasts of the continents, are characterized by marked oxygen-deficient zones.
Oxygen in lakes changes with depth. In deep lakes that do not get very much wind, oxygen levels go down as we get deeper. In all lakes, oxygen is generally low right at the bottom where water meets the lake sediment or mud. This is because there are many bacteria and animals that live and breathe in the sediment.
Oxygen is more soluble in cold than warm water. Most lakes over 20 feet deep stratify during the summer into a warm, lighted upper layer (epilimnion) and a co ld, dark lower layer (hypolimnion). Thus, the cold lower layer can potentially hold more oxygen than the warmer upper layer.
Oxygen enters water through diffusion from air, wind and wave action and plant photosynthesis. Dissolved oxygen levels are increased by supplementing wind and wave action, adding plants to water and exposing water to purified oxygen.
Oxygen toxicity occurs in most people when the partial pressure of oxygen reaches 1.4 atmospheres or greater, equivalent to slightly over 187 feet (57 meters) depth when breathing air (shallower depths when breathing oxygen concentrations greater than 20%).
What affects it? The temperature and salinity of water influence how much oxygen it can hold. Warm water holds less dissolved oxygen than cold water because the molecules are moving faster than in cold water and thereby allow oxygen to escape from the water.
Oxygen from the surface can no longer mix in with the cold bottom layer; Oxygen is not being created through photosynthesis because the water is too deep for enough sunlight to reach plant life; and. The DO that is present is being used by aquatic organisms that live in the hypolimnion and by the decomposition process.
The reason you may feel out of breath or sick in higher altitudes has to do with air pressure and the amount of oxygen you take into your body with each breath. Oxygen molecules are squeezed together at lower elevations with higher pressure. They spread out at higher elevations with lower pressure.
It refers to altitudes above a certain point where the amount of oxygen is insufficient to sustain human life for an extended time span. This point is generally tagged as 8,000 m (26,000 ft, less than 356 millibars of atmospheric pressure).
The amount of oxygen in the air goes down as you climb higher above sea level and becomes very low at altitudes above 8,000 feet. If you travel to a high altitude, you may feel ill because the air has less oxygen in it.
Concentrations of oxygen can decrease significantly during the night, due to respiration. DO concentrations are usually highest in the late afternoon, because photosynthesis has been occurring all day.
The oxygen minimum zone (OMZ), sometimes referred to as the shadow zone, is the zone in which oxygen saturation in seawater in the ocean is at its lowest. This zone occurs at depths of about 200 to 1,500 m (660–4,920 ft), depending on local circumstances.
Like the air we breathe, the survival of aquatic life depends on a sufficient level of oxygen dissolved in water. When it drops below levels necessary for sustaining aquatic life, it becomes a significant water quality impairment, often referred to as low dissolved oxygen (DO).
Temperature- Cold water holds more dissolved oxygen than warm water. Turbulence- More turbulence creates more opportunities for oxygen to enter streams. Aquatic Vegetation- Aquatic vegetation and algae directly release oxygen into the water during photosynthesis (during the day).