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Continuous Water-Quality Field Methods

Continuous Water-Quality Field Methods. Micelis Doyle & Joe Rinella U.S. Geological Survey 503-251-3226 & 503-251-3278 mcdoyle@usgs.gov jrinella@usgs.gov. Course Overview. 4/23/08, Wednesday, 11:30 AM to 12:20 PM Description of water-quality monitors

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Continuous Water-Quality Field Methods

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  1. Continuous Water-Quality Field Methods Micelis Doyle & Joe Rinella U.S. Geological Survey 503-251-3226 & 503-251-3278 mcdoyle@usgs.gov jrinella@usgs.gov

  2. Course Overview 4/23/08, Wednesday, 11:30 AM to 12:20 PM Description of water-quality monitors Description of parameters and their use Overview of field trip activities 4/25/08, Friday, 12:45 PM to 16:45 PM Field trip to Clackamas River at Oregon City to calibrate a water-quality monitor 4/28/08, Monday, 11:30 AM to 12:20 PM Debriefing of field work, discussion, and review of homework

  3. Reading Assignment Guidelines and Standard procedures for Continuous Water-Quality Monitors: station Operation, Record Computation, and Data Recording (USGS Techniques and Methods 1-D3) Read pages 1-22 http://pubs.usgs.gov/tm/2006/tm1D3/ Homework question set is due on 4/28/08

  4. Instructions for driving to Clackamas River at Oregon City field site on Friday, 4/25/08 • Meet at the site at 1:15 PM • Bring clipboards and pencils • See map with driving instructions • If lost, call 503-730-6706

  5. Water Quality • Water temperature • Dissolved oxygen • pH • Major ions and specific conductance • Alkalinity and acidity • Erosion and sedimentation--suspended sediment and turbidity • Eutrophication—nutrients (e.g. nitrate, ammonia, phosphates—not measured in the Clackamas River) • Contaminants Inorganic chemicals (e.g. trace metals) Organic (e.g. pesticides and industrial chemicals) • Fecal indicator bacteria • Total dissolved gas • Health of biota (including chlorophyll)

  6. Types of sensors • Water temperature • Specific conductance • Dissolved oxygen • pH • Turbidity • Chlorophyll—free-floating algae • Total dissolved gas • Chemical species (e.g. nitrate, ammonia, phosphates)

  7. Conditions that change water temperature • Solar heating — seasonal/daily • Thermal loss — air or streambed • Inflows — Ground water or surface water • Outflow — less dilution water

  8. Conditions that change specific conductance (Measure of the capacity of water to conduct an electrical current—function of dissolved ions) • Dilution (e.g. rain water runoff) • Evaporation — concentrates chemicals in water • Inflow/outflow • Chemistry (e.g. weathering of minerals, runoff from land applications, & point sources)

  9. Conditions that change dissolved oxygen • Temperature • Aeration • Biological activity Photosynthesis in presence of sunlight 6 CO2 + 6 H2O  C6H12O6 (sugar) + 6 O2 (consumes CO2 and produces O2) • Salinity • Atmospheric pressure

  10. Conditions that change pH(- Log of the hydrogen ion activity) • Dissolved gas exchange • Temperature change • Weathering of minerals • Biological activity Photosynthesis in presence of sunlight 6 CO2 + 6 H2O  C6H12O6 (sugar) + 6 O2 Respiration (O2 is consumed and CO2 is formed) CO2 + H2O  HCO-3 + H+ CO3-2 + 2 H+

  11. Conditions that change turbidity(measure of light that scatters off suspended particles) • High flow events — erosion and sedimentation • Inflows with different turbidity levels • Stream channel disturbance • Biological activity — algal production

  12. Advantages of continuous, near real-time, water-quality data • Quickly identify transmission problems • Recognize erroneous data due to: Fouling Calibration drift Other problems • Quickly recognize sensor or monitor malfunctions • Can quickly respond to problems and optimize the quality of the data • Early warning of water-quality problems

  13. Operation of water-quality monitors includes: • Quality assurance and quality control Accuracy Precision Reliability • Water-quality monitor site operation Routine cleaning, calibration, and maintenance • Record storage • Record computations to apply data corrections • Publication • Archiving

  14. Site Visit Activities • Arrive at site at 1:15 PM • Wait for all to arrive so that we can enter plant as a group • Inspect water-quality monitor vehicle and supplies • Enter plant to perform site maintenance and calibration check as group; once the group is inside, no one else will be able to enter the facility

  15. Site Visit Activities (continued) • Explanation and inspection of equipment • Review initial site checks performed while servicing station • Download data from data logger • Note river gage height for stream discharge information • Note any other station information

  16. Site Maintenance and Calibration • Compare “Before Cleaning” the water-quality monitor (WQM) readings at the site with field (portable) WQM readings in the river • Remove and clean WQM at the site • Return site’s WQM to conduit to obtain “After Cleaning” comparison readings with field WQM • Remove site’s WQM for calibration check • Calibrate site’s WQM • Return site’s WQM to conduit and obtain final comparison readings

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