Using s::can probes to get real-time water quality data Martin Davis SOP – Adv. Field Methods in Hydrology. Why monitor in the field?. Allows capture of data as notable events occur No need to transport samples back to the laboratory Fewer concerns with contamination risk
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LOGISTICS (MAINTENANCE REQUIREMENTS)
For this type of monitoring to work, sensors must be clean & exposed:
Mounting Options and Requirements
Cleaning and Anti-Fouling Options
Issues in controlling power to a field spectroscopy system
Left: An example of corroded battery terminals. Corrosion like this will impact instrument function. Periodic cleaning of contacts is necessary in the field, especially in sites with saltwater.
Collecting and sending data from a field unit to a central repository
Data from the probes is stored on a monitoring unit in one of two configurations:
Both the con::cube and the con::nect use the moni::tool software, either running on the user’s PC or cube. An online demonstration of the moni::tool web interface is available at: http://monitool.s-can.at/index.x.
Ensuring that data is useful and filtering out noise and interference
Interference from dissolved constituents
Interference from suspended particles
Ensuring that data is useful, and filtering out noise and other undesirable effects
Interference from dissolved constituents Interference from suspended particles
(Both actual nitrate concentrations are in 1mg/L as Nitrogen)
Reading a spectral fingerprint and compensating for background values
Other items worthy of consideration when processing field data
Sampling Interval vs. Reporting Interval
Understanding detection limitations for various instruments, algorithms, and media
Ranges of data validity
Turbidity: 0–50 NTU, precision 0.05 NTU Nitrite (NO2-N): 0–7 mg/L, precision 0.005 mg/L abs/m
DOC: 0–6 mg/L, precision 0.003 mg/L Ozone: 0 –10 mg/L, precision 0.005 mg/L
Nitrate (NO3-N): 0–7 mg/L, precision 0.005 mg/L TOC: 0–8 mg/L, precision 0.005 mg/L
Spectral Absorption (SAC254): 0–25 abs/m, precision 0.015 Color: 0–250 Hazen, precision 0.1 Hazen
From the USGS guide to optical techniques for determination of nitrate in situ.
These guidelines are applicable in many cases to a variety of target analytes when using s::can units.
Performing diagnostics and maintaining quality data collection