USGS-OWQ: NFM 6.3.3.B-GW: Specific conductance of ground water, electrometric measurement
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Official Method Name
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Specific Electrical Conductance of Ground Water |
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Current Revision
| 02/07/2007 |
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Media
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WATER |
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Instrumentation
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Conductivity Sensor |
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Method Subcategory
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Physical |
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Method Source
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Citation
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Brief Method Summary
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Specific conductance of ground water (at wells) is measured on-site and performed using a conductivity meter with temperature-compensation capability and submersible electrometric sensors. Method includes downhole (in situ) and flowthrough-chamber procedures. The conductivity sensors must be calibrated on-site using a minimum of two standards that bracket the expected range of conductivity values and that have been brought to the approximate temperature of the ambient ground water. Method includes guidance for equipment selection (ref. TWRI Book 9 Ch. A6.3.1) and USGS calibration procedures and protocols (ref. TWRI Book 9 Ch. A6.3.2). |
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Scope and Application
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This method covers electrometric measurement of specific electrical conductance in ground water within the range of 10 to 2,000 uS/cm, using either in situ (downhole) or on-site flow-through-chamber procedures. |
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Applicable Concentration Range
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10 to 2,000 |
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Interferences
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Measurement is temperature dependent and can be affected by chemical precipitation, adsorption, ion exchange, oxidation, and reduction processes if delayed. Waters susceptible to significant gain or loss of dissolved gases require special handling in an enclosed environment and additional equipment. |
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Quality Control Requirements
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Monitor readings during well purging until they remain within the 5-percent (conductivity 100 uS/cm) criterion. Then record the conductivity value as the median of the next three to five readings. |
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Sample Handling
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Downhole procedure: sample is measured in situ and requires no handling. Flowthrough-chamber procedure: ensure that flow from the pump (sample) line to a sealed flowthrough chamber (cell) is constant and laminar, with no air bubbles entrained and is shielded to the extent possible from temperature changes. |
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Maximum Holding Time
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Field measurement performed in situ or as soon as possible. |
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Relative Cost
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Unknown |
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Sample Preparation Methods
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Not applicable |
