USGS-NAWQA: NAWQA Light 2002 (Wade): Water column light intensity of wadeable streams by light meter
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Official Method Name
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Revised Protocols for Sampling Algal, Invertebrate, and Fish Communities as Part of the National Water-Quality Assessment Program |
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Current Revision
| 2002 |
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Media
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WATER (Waterbody type - Wadeable stream) |
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Instrumentation
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Photometer, Light Meter, Photosensors |
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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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Protocol
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NAWQA Habitat Protocols (1998) - Revised Methods for Characterizing Stream Habitat in the USGS National Water-Quality Assessment Program |
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Brief Method Summary
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Various methods, including specific instruments, are described. The specific method of the NAWQA program using a light meter and underwater light sensor are outlined. |
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Scope and Application
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Light availability is a major factor affecting plant productivity in aquatic systems. Therefore, quantitative measurements of water clarity are important for evaluating the biological community structure of streams in relation to water quality. Water clarity can be determined using several methods. Light meters and underwater sensors are used in the NAWQA program to obtain a direct measure of the solar energy available for algal growth. See section 4.3.6 of the report about how to determine light availability. |
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Applicable Concentration Range
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Interferences
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Light readings are sensitive to changes in the wind, cloud cover, and disturbance at the water surface. Be quick and consider taking multiple. |
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Quality Control Requirements
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It may be necessary to take multiple readings at the same location or take a readings from multiple locations. |
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Sample Handling
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N/A |
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Maximum Holding Time
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N/A |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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N/A |
