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SOP6 – Water Quality Analysis
41
Using forceps and without touching the filtered area, fold the filter in half with the material on
the inside and the number face-up (and not on the fold). Place into a labeled foil packet. Place
packet into a labeled baggie and freeze.
7.3.4. Dissolved Organic Carbon (DOC) – NASL filtering protocols
(see Appendix A)
Filter whole water within a few hours. Collect the filtrate in 3, 30-ml Teflon bottles.
Using water-proof labels, pre-label the Teflon sample bottles (or use clear tape to firmly attach a
non-waterproof labels). Load one 25 mm GF/F filter pad (nominal pore size 0.7
µ
m) into a filter
holder. Use one filter holder per replicate
. If the pad and the filter holder O-ring do not meet
correctly, the holder will leak whole water into the sample bottle
.
Vigorously shake the sample bottle. Sample rinse a 60 ml syringe body. Again, vigorously shake
the sample bottle, then fill the syringe body with sample water. Place the plunger into the body.
Tip upward to expel all air from the syringe. Screw the Gelman filter holder onto the syringe.
Using gentle pressure on the syringe, sample rinse three labeled Teflon bottles 2 times with a few
drops of filtered water. Then, filter water into each bottle until just below the top of the vertical
lines pressed into each bottle– at least 30 mls. Filling completely, then freezing can cause
sample leakage. Cap tightly, place into a labeled rack and freeze at -20°C.
7.3.5. Mineral Matter (MM)
Mineral matter is defined as the difference between TSS and particulate organic matter
(measured as POC). Therefore, MM concentrations are determined in each sample collected
during these trials on intake following analyses of TSS and POC.
7.3.6. Transmittance at 254 nm (percent)
Using a spectrophotometer, percent transmittance at 254 nm will be measured in control and
treated samples.
Samples are collected in 50-100 ml dark bottles and kept chilled, then either measured on site or
transported to NASL for analysis using a spectrophotometer set at 254 nm. Deionized water is
used as a reference to adjust the spectrophotometer to 100%T. Each sample is measured using a
sample-rinsed 1 cm wide cuvettes.
During on-site analysis, fill a cuvette with DI water. Calibrate the spectrophotometer by pressing
‘calibrate’ then insert the cuvette when the lamp is ready. Repeat the calibration if there is more
than 10 minutes in between samples.
Sample rinse another cuvette three times and fill with sample water. Press ‘compute’ on the
spectrophotometer. When the lamp is ready, insert the cuvette and wait for reading. Record
percent transmittance value and repeat two more times for a total of three readings.
Rinse the sample cuvette three times with DI water and allow to dry.