Sediment traps dataset at LéXPLORE Platform (2020–2024): Fluxes for total mass, carbon-nitrogen-phosphorus content, and metal analyses

General information or Introduction section

Sediment Traps and Sample Collection
Sinking particulate matter was collected from January 2020 to December 2024 using cylindrical sediment traps (aspect ratio 10.9) deployed near the LéXPLORE platform at depths of 10, 30, 50, and 100 meters. Traps were retrieved twice monthly during summer months (June to September) and monthly otherwise. Contents were freeze-dried and weighed, and mass fluxes were calculated based on the dry mass, trap area, and deployment duration. Some temporal gaps occurred in sampling, notably from November 2021 to May 2022.

Sample Processing and Chemical Analyses
Sediment samples were milled and analyzed for total nitrogen, total phosphorus, total organic and inorganic carbon, and major element concentrations (Ca, Mg, Al, Fe, K, Mn, Ti, Sr, Ba) at Eawag. Elemental carbon and nitrogen were measured with combustion elemental analyzers, phosphorus via flow-injection photometric analysis, and major elements using ICP-MS following acid digestion. Elemental fluxes were derived from concentration measurements combined with mass flux data.

Mass Balance and Fractional Contributions
The dataset includes calculated fluxes for biomass, calcite (as CaCO₃), and mineral oxides typical of Rhône sediments. Biomass flux is estimated from organic elemental composition and stoichiometric ratios, while calcite flux is based on inorganic carbon measurements. Mineral oxide contributions (e.g., MgO, Al₂O₃, Fe₂O₃) were derived using conversions established for Rhône river sediments.

--------------------------------

- author(s) info: Natacha Pasche, EPFL ENAC Limmnology Center, Guillaume Cunillera, EPFL ENAC Limmnology Center, Jérémy Keller, EPFL ENAC Limmnology Center
- date of collection (dd.mm.yyyy): 18.12.2019 to 15.01.2025
- geolocation data (use format): LéXPLORE platform, Lake Geneva, Switzerland. Coordinates: latitude 46°30'0.819" N and longitudes, 6°39'39.007" E. Depths: 10, 30, 50, and 100 m below water surface.
- funding or sponsorship info: EPFL ENAC Limnology Center for the SEDTRAP project

--------------------------------

Sharing / Access information or License section
- licenses: CC-BY
- terms of use: The datasets generated during and/or analysed during the current study are available in the Zenodo repository, 10.5281/zenodo.17607859.
- citation instructions: Cite as: Pasche Natacha, Cunillera Guillaume, Keller Jérémy:(2025). Sediment traps dataset at LéXPLORE Platform (2020–2024): Fluxes for total mass, carbon-nitrogen-phosphorus content, and metal analyses in Lake Geneva.[Dataset]. EPFL. 10.5281/zenodo.17607859
- links to related publications: Faval E, Cunillera G, Keller J, Dubois N, Janssen DJ, Pasche N. (2025) Rivers beneath the surface: how riverine inputs shape sedimentation in a large peri-alpine lake, submitted to Aquatic Sciences
- links to other research outputs and datasets: LéXPLORE thermistor chain: https://www.datalakes-eawag.ch/datadetail/448, LéXPLORE CTD profiles: https://www.datalakes-eawag.ch/datadetail/674, LéXPLORE Idronaut: https://www.datalakes-eawag.ch/datadetail/666, LéXPLORE meteostation: https://www.datalakes-eawag.ch/datadetail/459
- URL in repository: 10.5281/zenodo.17607859

--------------------------------

Data and file(s) overview or Data section
- files and folders structure description: Excel (.xlsx) and .csv for the dataset; figure in .jpg for the detailed deployment. Readme file in .txt
- file formats: .txt, .csv and .xls, and .txt
- additional related data: The LéXPLORE core dataset with background information is also available on https://www.datalakes-eawag.ch/datadetail/

--------------------------------

Methodological info or Preparation section and acknowledgment section
- link to publications used as a base for methods: Faval E, Cunillera G, Keller J, Dubois N, Janssen DJ, Pasche N. (2025) Rivers beneath the surface: how riverine inputs shape sedimentation in a large peri-alpine lake, submitted to Aquatic Sciences
- methods for processing data:  Sediment traps deployed at fixed depths (10, 30, 50, 100 m) at LéXPLORE platform (see jpg). Recovery, sample weighting, lyophylisation and laboratory analyses following standardized protocol, which are explained in detail in the publication in Aquatic Sciences. 
- technical requirements: none
- people involved in fieldwork and analysis: Irene Brunner and Marcel Walter for the analysis of carbon, nitrogen and metal content. Patrick Kathriner for analysing the TP fraction. The Central Environmental Laboratory of EPFL, especially Florian Breider, Karin Vernez, and Sylvain Coudret, to help to retrieve and deploy the mooring. 

--------------------------------

Data specific info
- data format: Tabular, .xlsx. with four sheets, and three derived .csv (all data, minerals, massCNP). Rows for deployment or recovery events, one event is composed of 8 samples (duplicates at 4 depths) or one average value per depth; columns specify sample ID, depth, date in and date out, mass, total mass flux, concentrations for CNP/metal and the calculated fluxes CNP/metal: Total mass flux = mass/trap area (0.0065 m2)/deployment time in day, CNP metal fluxes = total mass flux x concentration
- data dictionary or data codebook: 
ID #: Unique identifier for each sediment trap sample.
depth (m): Depth in meters where the trap was deployed.
trap: Trap number or label at each depth. Z1 is for the trap at 10m, Z2 at 30 m, Z3 at 50m and Z4 at 100m
Replicate: A and B to assess the variability
Date in: Deployment date of the trap (start).
Date out: Retrieval date of the trap (end).
days: Number of days the trap was deployed (exposure duration).
tara (mg): Tare (empty) weight of the collection vessel in milligrams.
gross (mg): Weight of trap plus sediment (gross) in milligrams.
net (mg): Net sediment mass collected (gross minus tara) in milligrams.
mass flux (g/m²/d): Daily sediment mass flux, normalized by trap area (0.0065 m2) in grams per square meter per day.
mean mass flux (g/m²/d): average mass flux of replicates A and B over the deployment period.
Nutrient and Carbon Parameters
TP (mg/g): Total phosphorus content (mg per gram of dry sediment).
TN (mg/g): Total nitrogen content.
TOC (mg/g): Total organic carbon(TC-TIC).
TIC (mg/g): Total inorganic carbon.
TC (mg/g): Total carbon
aver. TP, TN, TOC, TIC (mg/g): Mean content of each for replicates or trap depth.
P-Flux, N-Flux, TOC-Flux, TIC-Flux (mg/m²/d): Daily fluxes of phosphorus, nitrogen, organic carbon, inorganic carbon, derived by multiplying concentration by sediment mass flux.
C:P: Carbon-to-phosphorus molar or mass ratio.
Elemental/Mineral Content
[Element] (mg/g or µg/g): Concentration of the specified element (e.g., Mg, Al, Fe, K, Mn, Ti, Sr, Ba, Li, V, Cr, Ni, Cu, Zn, As, Se, Mo, Cd, Pb, U), reported in mg per gram or µg per gram of dry sediment.
[Element]-Flux (mg/m²/d or µg/m²/d): Daily deposition flux of each element, calculated as concentration times mass flux, units as indicated.
Biomasse (mg m-2 d-1): sum of TOC, TP, TN and O using O:C =110:106 and H using H:C= 263:106. 
Calcite (mg m-2 d-1): calculate from TIC converted into CaCO3
Metals (mg m-2 d-1): sum of all the metals converted in oxydes (MgO, Al₂O₃, K₂O, TiO₂, Cr₂O₃, MnO, and Fe₂O₃)except Ca