R/eem_metrics.R
eem_humification_index.RdThe fluorescence humification index (HIX), which compares two broad aromatic dominated fluorescence maxima, is calculated at 254 nm excitation by dividing the sum of fluorescence intensities between emission 435 to 480 nm by the the sum of fluorescence intensities between 300 to 345 nm.
eem_humification_index(eem, scale = FALSE, verbose = TRUE)
| eem | An object of class |
|---|---|
| scale | Logical indicating if HIX should be scaled, default is FALSE. See details for more information. |
| verbose | Logical determining if additional messages should be printed. |
An object of class eemlist.
A data frame containing the humification index (HIX) for each eem.
Different excitation and emission wavelengths are often used to measure
EEMs. Hence, it is possible to have mismatchs between measured wavelengths
and wavelengths used to calculate specific metrics. In these circumstances,
EEMs are interpolated using the interp2 function from the
parcma library. A message warning the user will be prompted if data
interpolation is performed.
Ohno, T. (2002). Fluorescence Inner-Filtering Correction for Determining the Humification Index of Dissolved Organic Matter. Environmental Science & Technology, 36(4), 742-746.
http://doi.org/10.1021/es0155276
file <- system.file("extdata/cary/scans_day_1/", package = "eemR") eem <- eem_read(file, import_function = "cary") eem_humification_index(eem)#> Warning: This metric uses either excitation or emission wavelengths that were not present in the data. Data has been interpolated to fit the requested wavelengths.#> Warning: This metric uses either excitation or emission wavelengths that were not present in the data. Data has been interpolated to fit the requested wavelengths.#> Warning: This metric uses either excitation or emission wavelengths that were not present in the data. Data has been interpolated to fit the requested wavelengths.#> Warning: This metric uses either excitation or emission wavelengths that were not present in the data. Data has been interpolated to fit the requested wavelengths.#> sample hix #> 1 nano 0.5568136 #> 2 sample1 6.3795618 #> 3 sample2 4.2548483 #> 4 sample3 13.0246234