Specific Conductance & Salinity Determination

Water pollution can cause the deterioration of water quality. Water pollution routine analysis index (such as total dissolved solids and salinity) is important indicator to reflect the water quality status, and is the main basis for monitoring, evaluation, utilization and pollution management of water bodies. Specific conductance measurements can be used to estimate total dissolved solids (TDS) and salinity in ambient water samples, further estimating sodium and chloride concentrations and determining whether they exceed drinking water standards. Therefore, specific conductance is a good indicator of good or bad ambient water quality. The higher the value of specific conductance, the more likely it is that more harmful things such as nitrates, trace metals and bacteria are present in the water. BOC Sciences can provide high quality specific conductance testing and salinity determination to assess the safety of water.

• What is specific conductance?

Salts and inorganic substances such as bases, chlorides, sulfides and carbonate compounds dissolve in water to produce anions and cations which form the basis of the conductivity of the water. TDS value represents the content of dissolved impurities in the water, the larger the TDS value, the greater the content of impurities in the water. Specific conductance is an indirect measurement of the total concentration of dissolved ions (TDS) in a solution.

• What is salinity?

Salinity is the total concentration of all dissolved salts in water, which cannot be measured directly but can be derived from conductivity measurements. The major salts in seawater are: chloride, sodium and so on. The ionic composition of inland water sources depends heavily on the surrounding environment. Most lakes and rivers have alkali and alkaline earth metal salt.

Why is Specific Conductance Important?

Heavy rainfall or evaporation can affect conductivity, however, in modern industrial societies, runoff or flooding from soils with high salinity or mineral content due to anthropogenic pollution is a more important cause of conductivity spikes in water samples. Therefore, specific conductance is one of the most useful and commonly used parameters to measure water quality. The application of agricultural chemical compounds can cause large amounts of chloride, phosphate and nitrate ions to enter the environment, resulting in an increase in the specific conductance of water. In addition, oil spills can also reduce specific conductance. Water salinity has a large impact on aquatic organisms; most aquatic organisms can only tolerate a specific range of salinity, and an influx of specific salts can often negatively affect a species. Since specific conductivity and salinity are closely related, chemists often estimate salinity by measuring specific conductivity.

Measurement of Specific Conductance of Surface Water

At BOC Sciences, we can measure the specific conductance of surface water in situ or in flowing surface water by employing a dip-style conductivity probe for the measurement.

• First, we check the accuracy of the specific conductance: check the accuracy of the field measurement by measuring the specific conductivity of a check standard
• Then, we determine the variation of specific conductance: select the appropriate measurement method to determine the variation of specific conductance along a cross-sectional profile
• Measurement of specific conductance: The conductivity probe is immersed in water until the probe equilibrates to suit the water conditions. We record the measurement results of the specific conductance and temperature without removing the probe from the water. After the measurement is complete, the probe is removed from the water.
• Next, we remove the probe from the water, rinse it with deionized water, and store the meter and probe in the protective case
• If there appears to be a significant amount of suspended material in the water sample, we will provide specific conductance measurements for both unfiltered and filtered water samples

Application of Specific Conductance Testing

• Measure how healthy the ocean and the organisms in it remain
• Identify the amount of total dissolved solids and salinity concentration in the water
• Prevent pollution of water bodies