# Fluorescence data of natural organic matter in groundwater from the Fontaine de Vaucluse karst system (2020 to 2021): Excitation-emission matrix (EEM) and 2D spectra at 254 nm excitation wavelength

## TL;DR

This paper presents a 20-month dataset of fluorescence measurements from various groundwater sources in a French karst system to study organic matter and improve understanding of the carbon cycle.

## Contribution

The novelty lies in the long-term monitoring of diverse karst waters and the provision of raw data for flexible analysis.

## Key findings

- Fluorescence data was collected from 4 springs, 1 loss, and 9 unsaturated zone flows over 20 months.
- The dataset includes EEMs and 2D spectra for organic matter analysis and Raman diffraction correction.
- The dataset supports the development of new fluorescence indices for groundwater transit time assessment.

## Abstract

This dataset provides bimonthly fluorescence data from February 2020 to October 2021 at 4 springs, 1 loss and 9 unsaturated zone flows of the Fontaine de Vaucluse karst system (France). The data correspond to Excitation Emission Matrices (EEM) and emission spectra at 254 nm excitation wavelength of organic matter fluorescence. Analyses were performed with a SHIMADZU RF-5301 PC spectrofluorometer at the following wavelengths: EEM at λex= [220; 450] nm, interval=10 nm; λem= [250; 550] nm, interval=1 nm; and 2D emission spectra at λex=254nm, λem= [250; 530] nm, interval=1 nm. Milli-Q water EEMs are also provided, one for each day of analysis, to allow later correction of the Raman diffraction. Only raw data are provided to allow the user to adapt the corrections to his purpose. The originality of this dataset is the 20-months monitoring of different types of karst waters, from the saturated zone (springs with small or large catchments) to the unsaturated zone which was exceptionally accessible thanks to the Low Noise Underground Laboratory (LSBB, https://lsbb.cnrs.fr/). This dataset was carried out to question the use of the main fluorescence indices (FI, BIX, HIX, [1] and to develop a new index to assess the qualitative groundwater transit time [2,3]. The use of this dataset could be extended to fields other than hydrogeology, such as pedology, microbiology or hydrobiology. It could be usefull to improve the understanding of the carbon cycle as carbon is the main atom constituting organic matter and fluorescence allows the characterization of the molecular structure of the molecule.