Description Usage Arguments Details Value Author(s) See Also
Spectrophotometer measures opttical density (depth) (OD) or Absorbance (A), which are unit less. This program converts OD into absorption coefficent in per meter. Then a series of spectral analyses is performed.
1 | process.Ag(sample, ID, Station, Depth, Date, pathlength, DilutionFactor = 1)
|
sample |
is a data frame return by |
ID |
is the sample ID. |
Station |
is the station code (optional). |
Depth |
is the depth of the sample in meters (optional). |
Date |
is the date of sampling. |
pathlength |
is the pathlength of the cuvette in meters. |
DilutionFactor |
Is a multiplication factor to adjust the final Ag value if dilution was performed in the lab (default=1). |
The processing steps includes:
1) Ag = 2.303*OD/pathlenght.
2) Apply a null correction assuming Ag(690+/-5) = 0. If a(500) is negative after the applicatioc of the NULL correction, then the minimum a values between 500 and 690 is assume for the null correction. So Ag.offset = Ag - NULL.POINT
3) Fit an exponential model to Ag.offset for the 350 to 500 nm range:
Ag.fitted = Ag(440) exp(-S*(440-lambda)) + K.
This is done using cdom_fit_exponential
.
4) Compute spectral slope for the 275-295 and 350-400 ranges.
Compute slope ratio using cdom_slope_ratio
.
5) Compute spectral curvature using cdom_spectral_curve
.
A list with all the computed parameters decribed above is return.
Simon Belanger
The cdom package for more details on the CDOM spectral analysis.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.