Isotopic Bayesian mixing model for organic carbon in lake sediments. Case study: Lake Constance Obersee.

Sources of organic carbon (OC) in lake sediments:

• Autochthonous OC: produced through lake primary productivity
• Petrogenic OC: bedrock-derived OC
• Pedogenic OC: soil-derived OC

Observational data in sediment core:

• Δ¹⁴C: radiocarbon signature of sediment OC
• δ¹³C: stable isotope signature of sediment OC
• TOC/TN: mass ratio of total organic carbon to total nitrogen
• ROC/TOC: proportion of residual oxidizable carbon in sediment OC

The mixing model results for a single core are then extrapolated over the entire Lake Constance Obersee using ordinary Kriging, with depth and distance from the Rhine inflow as external drift parameters.

Associated manuscript: Mittelbach et al. (in prep.). "Pre-aged organic matter dominates modern organic carbon burial in a major perialpine lake system". Limnology and Oceanography.

• mcmc.py: Calibrate mixing model on a sediment core with MCMC using the pymc package.
• Kriging.ipynb: Perform Kriging over the entire lake using the pykrige package.
• Figures.ipynb: Produce figures for the manuscript.
• environment.yml: Package requirements for conda environment.

Skip this step if you downloaded from Zenodo.

Clone this repository with

git clone https://github.com/asb219/LakeOCMixing.git

Now the repository should be in a directory named LakeOCMixing. Move into that directory with cd LakeOCMixing.

Create and activate this project's conda environment (called sedmix by default):

conda env create -f environment.yml
conda activate sedmix

Once the virtual environment is activated, you can run the MCMC calibration of the mixing model with python mcmc.py.

To perform Kriging over Lake Constance and reproduce the plots in the manuscript, launch jupyter with jupyter notebook and run the Kriging.ipynb and Figures.ipynb notebooks, respectively.

All the resulting data files and figures will be written inside the output directory.

If you encounter a bug or other issues, please raise an issue at https://github.com/asb219/LakeOCMixing/issues.

Feel free to fork this repository and implement your own changes and features.