USGS-OWQ: NFM 6.3.3.A-SW: Specific conductance of surface water, electrometric measurement
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Official Method Name
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Specific Electrical Conductivity of Surface Water |
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Current Revision
| 02/07/2006 |
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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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In situ measurement of specific electrical conductivity (conductance) in surface water, performed using a conductivity meter with temperature-compensation capability and submersible electrometric sensors. 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 surface 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 natural surface waters within the range of 10 to 2,000 uS/cm. The method covers in situ measurement and measurement of subsamples withdrawn from the source water. Waters susceptible to significant gain or loss of dissolved gases must be measured in an enclosed environment and require additional equipment and more rigorous procedures. Sampling methods depend on data-collection and data-quality objectives and are described in USGS TWRI Book 9 Chapter A4. |
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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. Suspended materials can interfere with the stability of the readings. |
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Quality Control Requirements
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Monitor conductivity readings until they remain within the 5-percent criterion for conductivity less than or equal to 100 uS/cm, or within the 3-percent criterion for conductivity greater than 100 uS/cm. |
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Sample Handling
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For measurements made in situ, there is no sample handling. For measurements made in a subsample, complete the determination on-site soon after sample collection, shielding sample to the extent possible from temperature changes. Filter the sample if sediment concentrations cause fluctuating readings. |
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Maximum Holding Time
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Field measurement performed 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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Filtration might be required. |
