FIELD METHODS
Field methods that were implemented mirrored that of the previous CU Denver chlorophyll-α cohort of 2019. Epilithon, epipelon, and epipsammon samples were randomly taken along ten evenly spaced transects, with 5 located upstream from SPWRP and the other 5 downstream from the wastewater treatment’s effluent. Transects were perpendicular to streamflow with 3 samples taken along each transect for a total of 30 samples. Sampling locations along each transect were predetermined as 25%, 50%, and 75% of the distance from one bank to the other. Samples were immediately stored on ice in a cooler with the lid secured to prevent photodegradation of chlorophyll-α while in the field. Immediately following sampling, the cooler was transported to CU Denver’s Geography and Environmental Science laboratory whereby samples were transferred to a freezer for future analysis.
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LABORATORY METHODS
Epilithon, epipelon, and epipsammon samples were thawed, agitated, and detached from their respective substrates according to CWQD’s SOP approximately two weeks following sampling, and chlorophyll-α was separated from the various algae types via 90% acetone solution. The previous cohorts’ acetone extraction methods in the lab, paired with the addition of hydrochloric acid (HCl) for spectrophotometric analysis caused our plastic cuvettes to dissolve when trying to run our analyses. As a result, we quickly discovered and utilized a new method whereby HCl was not required. After implementing the HCl-free method, we were able to obtain spectrophotometric readings of our samples and obtained concentrations of chlorophyll-α from our samples.
