Falmouth Group 8
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Survey Instruments and Methods Used
A fluorometer was used to analyse the chlorophyll concentration in the acetone solution that was used to store the filters through which the estuary water was passed. Once the chlorophyll values were obtained, they were multiplied by the ratio of the volumes of acetone and filtered seawater, 7/50.
Contents
Nitrate analysis was carried out according to the methods of Statham et al. 2011. 3ml of each sample were passed through a 25mm glass filter into a washed 5ml plastic syringe, and this was inserted into a system of (*mm) tubing containing a known volume ((*)) of fluid. This fluid was driven by a peristaltic pump, which also allowed the incorporation of the necessary reagents (*) into the loupe. This loupe was originally designed as a method for detecting nitrite concentrations, and so a cadmium/copper column was incorporated into the system to allow the reduction of nitrate to nitrite. Background levels of nitrite were negligible, and so these readings could be used as an indication of nitrate levels. Mixing and chemical reactions occurred within the tubing system, and the resulting fluid developed a pink colouration that depended on the amount of nitrite found in the sample. The intensity of this colour was detected using a spectrometer, and the resulting values were printed graphically. Two repeats were carried out for each sample, the average peak height was inserted into the formula derived from the line equation of the graph representing the peak height found from known standard solutions plotted against their concentrations to find the nitrate levels in the solution. Some of the nitrate concentrations observed were too high for the recorder to accurately represent, so these samples were diluted with NaCL solution to enable accurate analysis. The resulting values were then scaled up accordingly.
Five standard calibration solutions were prepared (in triplicate) for 200µl, 500µl,
1ml, 2ml, and 4ml volumes of the phosphate solution along with three blank solutions.
In order to obtain 10ml solutions. A pipette was used to place 10ml of each sample
into a labelled sample tube. For every 5 samples, 1 replicate sample was prepared
as well. 90ml of samples were to be analysed, so 100ml of reagent mixture was prepared.
This was a mixture of 20ml Ammonium Molybate solution, 50ml 2.5M Sulphuric Acid,
10ml Potassium Antimonyl tartrate solution, and 20ml Ascorbic Acid. 1ml of this reagent
mixture was added to all labelled sample tubes. All of samples, standards and blanks
were treated in the same way. The samples were left to incubate for 1.5 hours. The
phosphate samples were analysed using the U-
Upon return to the shore these samples were analysed for their silicon content using
the method proposed by Mullin and Riley (1955). The reduced silicomolybdate complex
formed from this procedure gives the solution a blue colour, which varies in intensity
depending on the silicon content of the sample. This colour was then assessed using
a spectrophotometer, which was calibrated using several pre-
The normality of the thiosulphate solution and the weight of each sample was recorded.
Each sample container taken had 1ml of sulphuric acid added to it, to break up the
reagents added. The Winkler titration method was employed to estimate the concentration
of dissolved oxygen. This involved placing the sample container within a spectrometer
and mixing using a magnetic stirrer. The magnetic stirrer ensured that the colour
from the iodate solution added was mixed evenly throughout the container. Thiosulphate
was then gradually titrated until no change was detected from the spectrometer due
to the colouration from the reagents gradually dissolving. Thiosulphate was then
added, the volume of which was used to calculate the oxygen concentration and saturation
of each sample. The in-
In order to better understand the distribution of phytoplankton along the estuary,
the samples collected at the different stations were left to settle, allowing the
phytoplankton to sink to the bottom of the 100ml bottles. The overlaying water was
then removed, leaving only the bottom 10ml and all the settled phytoplankton from
the 100ml. This was then stirred and 1ml of the samples was placed in individual
Sedgewick-
The 1L sample was shaken to redistribute the zooplankton within the liquid, 5ml was then placed onto a 5ml Bogorov chamber, and analysed under a light microscope (10x to 40x power) (model number??). Each zooplankton was classified and recorded. The reference book used was Coastal Plankton (Larink and Westheide, date). The process was completed for an additional 5ml and complied onto the single data sheet. Calculating the abundance of each planktonic organism in a cubic meter (m3) of seawater was accomplished using a series of equations. Firstly the volume of water sampled by the net was calculated using the formula:
Volume = π r2 L (r2 is the radius of the net opening (in m), squared) (L is the length of tow (in m)= Speed X Time)
Number of zooplankton in 10ml X 100 = Number of zooplankton in 1L sample
