water temperature

Many physical and chemical properties of water, such as density, viscosity, etc., are closely related to water temperature. At the same time, the solubility of dissolved gases (such as oxygen, carbon dioxide, etc.) in water, the activity of aquatic organisms and microorganisms, the rate of chemical and biochemical reactions, salinity, pH value, etc., can also be affected by changes in water temperature.

The temperature of water varies greatly depending on the source of the water. Generally speaking, the temperature of groundwater is relatively stable, usually between 8-12 ℃; Surface water varies greatly with seasons and climate, with a rough range of 0-30 ℃. The temperature of industrial wastewater varies greatly depending on the type of industry and production process.

Water temperature measurement should be conducted on-site. Common measuring instruments include water temperature gauges, inverted thermometers, and thermistor thermometers. Note: The thermometer should be calibrated regularly.

（1） Water Temperature Gauge Method (GB13195-91)

The mercury thermometer is installed inside a specially designed metal sleeve, which has a window for reading the thermometer. There is a lifting ring at the upper end of the sleeve to tie the rope, and a water holding cylinder with a hole is tightened at the lower end of the sleeve. The ball of the water temperature gauge should be located in the center of the metal cylinder. The measurement range is -6 to+40 ℃, with a division value of 0.2 ℃. This method is suitable for measuring surface water temperature.

（2） Inverted thermometer method

The closed end (anti pressure) inverted thermometer (Figure 3-12) consists of a main thermometer and an auxiliary thermometer assembled in a thick walled glass sleeve, with both ends of the sleeve completely closed. The main thermometer has a measurement range of -2 to+32 ℃ with a division value of 0.10 ℃, while the auxiliary thermometer has a measurement range of -20 to+50 ℃ with a division value of 0.5 ℃. The mercury column of the main thermometer should break flexibly, and the breakpoint position should be fixed. When resetting the thermometer, all the silver in the water should be refluxed. The main and auxiliary thermometers should be firmly fixed. The inverted thermometer needs to be installed on the inverted water sampler for use. Suitable for measuring water temperature in various layers with a depth of over 40m.