During satellite overpass days, water samples were collected between the time window of 10:15 AM - 1:15 PM. Six liters of water were collected
from each beach site at the coordinates listed below. Sample bottles were labeled with the date and location, kept on ice, and transported back
to the lab within three hours. Generic temperature and pH probes, as well as a turbidity meter, were used to record values on-site at the time
of collection. Turbidity measurements taken on-site were assumed to be the “true” turbidity values and are hereafter referred to as “on-site
probe turbidity”.
A Hydrolab Multiparameter Sonde was used to measure pH, turbidity, conductivity, and % dissolved oxygen for each sample in lab. Turbidity and pH
were measured using more than 1 device in our project in order to gather more comprehensive data
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to see the instrument used in lab and learn more about its application.
The Thermo Scientific Orion AQUAfast AQ3010 Turbidity Meter was taken to each sampling site to obtain turbidity values in the field. Turbidity
values were reported by the meter in Nephelometric Turbidity Units (NTU). A clean, dry sample vial was handled by the top cap and rinsed with 10
mL of sample water three times. On the fourth fill, the vial was capped with 10 mL of sample water and wiped dry with a soft, lint-free cloth. A
thin film of silicone oil was then applied and wiped around the vial. The vial was then inserted into the sample well of the meter for
measurement by aligning the arrow on the meter with the arrow on the outside of the vial. The meter was then turned on, the “Read/Enter” button
was pushed, and the measured value appeared several seconds later.
Three 1.5 µm filters were used to measure TSS for each
site. Before use, filters were washed, baked for sterilization,
and stored in a desiccator until needed. Initial weights of each filter were
recorded immediately before running sample water through them.
Then, a funnel manifold was set up with suction
and filters were sealed on with deionized water.
Between 100 mL-600 mL of sample water was passed through each
filter (final calculations of weight accounted
for the volume used). The filters were removed with tweezers,
placed on individual aluminum pans, and dried for 24 hours in an oven.
Lastly, filters were cooled in a desiccator and final weights were recorded.
To assess light absorbance, A spectrometer paired with the
UV Express software were used to obtain light absorbance data.
A baseline reading was established by adding 1 mL of MilliQ water
to a glass cuvette in the spectrometer. After getting the baseline,
a sampling cuvette was prepared and filled with 1 mL of sample water.
Each sample was run from a frequency of 1100 nm to 190 nm, and the sample
cuvette was rinsed 3 times with MilliQ water between each sample.
After testing all of the samples, the data was exported from the software and saved.
Phosphorus:
Prepared sample tubes with the PhosVer 3 Phosphate reagent were labeled for each sample site. The “Phosphorus, Reactive (Orthophosphate)” test
was used on the LAMBDA 365 UV/Vis Spectrophotometer with a light shield in cell compartment 2. 5.0 mL of sample water was added to the
appropriate Test ‘N Tube Vial, capped, and mixed. The vial was wiped down to remove fingerprints and inserted into the 16 mm round cell holder
to zero the spectrophotometer. One PhosVer 3 Phosphate Powder Pillow was added to the sample, capped, and shaken for 20 seconds. After two
minutes, the tube was placed inside the spectrophotometer. The detectable range of PO43- for this test is from 0.06 to 5.00 mg/L PO43-.
Nitrate:
All square sample cells were cleaned with detergent and rinsed with deionized water before use. The “351 N, Nitrate LR” test was selected on the
LAMBDA 365 UV/Vis Spectrophotometer. A 25 mL graduated mixing cylinder was filled with 15 mL of sample water, and one NitraVer 6 Reagent Powder
Pillow was added. The cylinder was closed, vigorously shaken for 3 minutes, and then left to rest for 2 minutes. Once the timer sounded, 10 mL
of the solution was added to a clean square sample cell. One NitriVer 3 Reagent Powder Pillow was then added to this cell and gently shaken for
30 seconds. The sample cell was then left to rest for a reaction period of 15 minutes during which time a pink color appeared if nitrate was
present in the sample. While the 15 minute reaction period elapsed, a new square sample cell was filled with 10 mL of the sample water and ran
to zero the spectrophotometer. After 15 minutes, the prepared sample was run through the spectrophotometer. The detectable range of NO3-- N for
this test is from 0.01 to 0.50 mg/L NO3--N.
Ammonia-Nitrogen:
All square sample cells were cleaned with detergent and rinsed with deionized water before use. The “385 N, Ammonia, Salic.” test was selected
on the LAMBDA 365 UV/Vis Spectrophotometer. One square sample cell was filled with 10 mL of the sample while another was filled with 10 mL of
deionized water. The contents of one Ammonia Salicylate powder pillow was added to each square sample cell. The square sample cells were then
shaken enough to dissolve the reagent and left to rest for 3 minutes. Once the 3 minutes elapsed, one Ammonia Cyanurate powder pillow was added
to each sample cell, shaken until the reagent was dissolved, and then left to rest for 15 minutes. If ammonia was present, a green color would
develop as the reaction occurred. Once 15 minutes had elapsed, the blank sample cell with the deionized water was wiped clean, inserted into the
cell holder of the spectrophotometer, and zeroed. The square sample cell was then wiped, inserted, and read to show results in mg/L of NH3–N.
The detectable range of NH3–N for this test was from 0.01 to 0.50 mg/L NH3–N.
