We collect water samples for color at the deepest part of the lake four times per year: February under ice, spring mixis, August stratification, and fall mixis. The samples are surface water, filtered in the field through 0.45u polycarbonate membrane filters. We run a wavelength scan from 800 to 200nm, using a 5cm rectangular quartz cell in a Beckman Coulter Model DU800 spectrophotometer. Any samples that display absorbance values above 2AU are run again from 400 to 200nm using a 1cm quartz cuvette.
Protocol Log: 1990 -- we began running color scans, using a 10cm cylindrical cell with a Kontron spectrophotometer.
2001 -- we added scans in a 1cm cell for samples with high absorbance.
July 2008 -- changed to Beckman Coulter DU800 spectrophotometer. At same time changed from 10cm to 5cm cell.
Protocol Format
Parameter
Protocol ID
param_color1
Protocol Type
field & laboratory
