What is Dissolved Oxygen (DO)?

Dissolved oxygen (DO) refers to the amount of oxygen gas (O₂) that is dissolved in water. It is a critical parameter in assessing water quality because it directly impacts the survival and health of aquatic organisms such as fish, invertebrates, and microorganisms. The level of dissolved oxygen in water is essential for the overall health of aquatic ecosystems and influences various physical, chemical, and biological processes.

Yosemitech Dissolved Oxygen Meters and Sensors Types

Yosemitech supply one type of Portable Dissolved Oxygen Meter and two types of Dissolved Oxygen Sensors for do measurement and detector in water. Our dissolved oxygen Meters and Sensors provide high-precision measurement and are built to withstand the harshest applications, requiring minimum maintenance and helping you achieve increased efficiency and reduced operating costs. 

Why need to Measure the Dissolved Oxygen?

Measuring dissolved oxygen (DO) in water is crucial for several reasons across different fields.

1. Aquaculture: Fish farms and aquaculture operations rely on stable DO levels to maintain fish health and growth rates. Low DO can lead to fish stress, poor growth, or even mass mortality.

2. Wastewater Treatment: In treatment plants, DO is monitored to ensure efficient biological processes. Aerobic bacteria in the treatment process require sufficient oxygen to break down organic matter.

3. Predicting Ecosystem Changes: Regular DO monitoring can serve as an early warning system for ecosystem changes, such as algal blooms or fish kills, allowing for timely interventions.

4. Indicator of Water Quality: DO levels are a key indicator of the health of aquatic ecosystems. Adequate oxygen levels are essential for the survival of fish and other aquatic organisms. Low DO can lead to hypoxic conditions, which can cause stress or death for aquatic life.

5. Biological and Chemical Studies: Understanding the oxygen dynamics in water bodies is essential for research in limnology, oceanography, and environmental science. DO levels affect chemical reactions and biological processes in water.

Factors Affecting Dissolved Oxygen Levels

Several factors influence the concentration of dissolved oxygen in water:

1. Temperature:

Colder water holds more oxygen than warmer water. As the temperature increases, the solubility of oxygen decreases, leading to lower DO levels.

2. Salinity:

Higher salinity reduces the water's ability to hold oxygen. Thus, saline water (like seawater) generally has lower DO levels than freshwater.

3. Atmospheric Pressure:

Higher atmospheric pressure increases the solubility of oxygen in water. At higher altitudes, where pressure is lower, water typically contains less dissolved oxygen.

4. Water Movement:

Turbulent water, such as in fast-moving streams or waves, has higher oxygen levels due to increased air-water mixing.

5. Biological Activity:

The density and activity of aquatic organisms, such as high concentrations of algae or fish, can significantly impact DO levels through their metabolic processes.

Yosemitech Optical Dissolved Oxygen Sensor

An optical dissolved oxygen (DO) sensor is a device used to measure the concentration of dissolved oxygen in water. Unlike traditional electrochemical DO sensors, which rely on the electrochemical reduction of oxygen, optical sensors use a luminescent or fluorescent approach to detect oxygen levels.

Optical Dissolved Oxygen Sensor Principles of Operation

Luminescence Quenching:

Basics: Optical DO sensors operate on the principle of luminescence quenching. A fluorescent or luminescent dye, often embedded in a sensor tip, emits light when exposed to a light source (usually an LED).

Oxygen Interaction: When oxygen molecules come into contact with this luminescent dye, they reduce the dye’s light emission through a process known as quenching. The degree of quenching is proportional to the concentration of dissolved oxygen.

Sensing Mechanism:

Excitation and Emission: The sensor's dye is excited by an LED, causing it to emit light at a specific wavelength.

Quenching Measurement: The emitted light's intensity or the time delay (phase shift) between excitation and emission is measured. The decrease in light intensity or the phase shift indicates the amount of dissolved oxygen present.

Advantages of Optical Dissolved Oxygen Sensor

1. High Precision and Stability:

Optical sensors often provide more stable and precise measurements over time compared to electrochemical sensors.

They are less prone to drift and fouling.

2. Low Maintenance:

There is no need for frequent calibration or replacement of electrolytes, as required in electrochemical sensors.

3. No Flow Dependency:

Optical sensors do not require water flow across the sensor for accurate readings, making them suitable for stagnant or low-flow environments.

4. Resilience to Interference:

They are less affected by chemical interferences, such as those from sulfides or ammonia, which can impact electrochemical sensors.

FAQs

What is a dissolved oxygen sensor?

A dissolved oxygen sensor is a device used to measure the concentration of oxygen dissolved in a liquid, typically water. These sensors are essential in various fields such as environmental monitoring, water treatment, aquaculture, and industrial processes. They provide critical data for understanding the health and quality of water bodies by measuring the amount of oxygen available to aquatic organisms.

What is a dissolved oxygen meter?

A dissolved oxygen meter is composed of two parts: dissolved oxygen sensor and display instrument.

What Are the Methods for Measuring Dissolved Oxygen?

Dissolved oxygen can be measured using several methods, each suitable for different applications:

Chemical Methods (e.g., Winkler Titration):

This involves adding reagents to a water sample that react with oxygen, followed by a titration process to determine the oxygen concentration.

Electrochemical Methods:

These use sensors, such as polarographic or galvanic oxygen electrodes, that measure the electrical current generated by oxygen reduction, providing a direct reading of DO levels.

Optical Methods:

These involve optical sensors based on the principle of fluorescence quenching, where the presence of oxygen affects the fluorescence emitted by a dye. This method is highly accurate and suitable for continuous monitoring.

Videos about Yosemitech Dissolved Oxygen Sensor

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