USGS-OWQ: TM1-D5 Maintenance and Field: Maintenance and Operation of UV nitrate sensors
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Official Method Name
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Maintenance and Field Operations; in Optical Techniques for the Determination of Nitrate in Environmental Waters: Guidelines for Instrument Selection, Operation, Deployment, Maintenance, Quality Assurance, and Data Reporting |
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Current Revision
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Media
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WATER |
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Instrumentation
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UV-Fluorescence |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Protocol
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USGS TM1-D5 - Optical Techniques for the Determination of Nitrate in Environmental Waters: Guidelines for Instrument Selection, Operation, Deployment, Maintenance, Quality Assurance, and Data Reporting |
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Brief Method Summary
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The maintenance and operation of UV nitrate sensors is to follow manufacturer recommendations and existing USGS protocols for continuous monitors (for example, Wagner and others, 2006). The general operations include instrument maintenance, sensor inspection and calibration checks, field cleaning, and troubleshooting. Other issues related to sensor operation, such as site selection and cross-section surveys, are covered in Wagner and others (2006) and are critical to the collection of representative nitrate concentrations with UV sensors. |
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Scope and Application
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This section of USGS TM1-D5 covers maintenance and operations considerations for UV nitrate sensors. Maintenance includes a variety of functions that can be performed both remotely, for sites with telemetry, and during field visits. The daily review of data and performance diagnostics for both the sensor and the system is easily completed remotely, considering that most sites are equipped with telemetry, satellite data transmission capabilities, or both. Field maintenance for continuous monitors generally includes a site inspection, instrument inspection and cleaning, field-blank or calibration checks, and discrete sample collection.
Field protocols ensure that sensors are working properly and provide critical data for interpreting and processing the water-quality record. They include visual inspections, instrument cleaning, calibration checks, data downloads (if appropriate), and documentation. The standard protocols defined by Wagner and others (2006) for continuous monitors apply to the field servicing of UV nitrate sensors and are to be followed when possible and documented when not possible. |
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Applicable Concentration Range
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Interferences
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Data from UV nitrate sensors may be affected by fouling or periodic disruption from sensor malfunction, sedimentation, pump failures, debris, ice, or vandalism.
In addition, UV photometers have a sensitive, high-power lamp that degrades over time and can be compensated for directly by the instrument (for instruments with a reference channel) or by the user. In addition, the desired output (nitrate concentration) is derived from an algorithm that can be influenced by a variety of dissolved inorganic and organic substances and particles in the sample path. Finally, the new generation of sensors provides opportunities to collect information about instrument performance that can ultimately improve data quality through early identification of problems and a subsequent reduction in data gaps. |
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Quality Control Requirements
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Sample Handling
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Maximum Holding Time
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Relative Cost
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Unknown |
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Sample Preparation Methods
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