Fraunhofer Institute for Molecular Biology and Applied Ecology IME
Fraunhofer Institute for Molecular Biology and Applied Ecology IME

Leaching Calculator

An example activity of the Department of Modelling & Bioinformatics: estimating soil leachability and mobility classes (PMT/vPvM) from log Koc and DegT50soil.

© Edited with DALL-E.

Key message

The Leaching Calculator proposes leachability as a mobility metric: the fraction of a substance predicted to be transported through an unsaturated 1 m soil profile to shallow groundwater under European (pedo‑climatic) conditions.

 

Challenge

With the new EU hazard classes PMT and vPvM, mobility needs a more robust definition than log Koc alone. Degradation, soil and climate can strongly change whether a substance passes natural barriers (soil/sediment) and reaches drinking-water sources.

 

Leaching Calculator

  • Inputs: log Koc (sorption to organic carbon) and DegT50soil (degradation half-life in soil).
  • Output: predicted leachability (% of mass) leached to 100 cm depth under conservative (worst-case) pedo‑climatic boundary conditions.
  • Derived result: mobility class (not mobile / mobile / very mobile) using transparent thresholds.

 

How to use

  1. Enter log Koc and DegT50soil.
  2. Read the predicted leachability (%) to 100 cm depth.
  3. Use the mobility class for PMT/vPvM screening and prioritisation.
  4. Interpret the class using the thresholds (not mobile, mobile, very mobile).

 

Model basis

  • Underlying model: FOCUS‑PELMO (v6.6.4).
  • Parameter grid: 41 DT50 values × 21 Koc values (861 combinations).
  • European scenarios: 9 FOCUS locations; simulations over 120 years.

 

Interpretation

For pragmatic screening, the predicted leachability (L) is mapped to mobility classes:

Leachability L

Mobility class

< 1 %

not mobile

1 % – 10 %

mobile

> 10 %

very mobile

 

Implications

Why it matters (Modelling & Bioinformatics):

  • Bridges tiers: combines a mechanistic model basis with a two-parameter interface for fast screening.
  • European relevance: embeds soil and climate variability via FOCUS scenarios.
  • Decision support: translates leachability to transparent mobility classes (<1%, 1–10%, >10%).

 

Outlook

Note: Screening tool for mobility (passing drinking-water barriers such as soil/sediment). Use dedicated modelling when substance behaviour or use patterns require higher-tier detail.

Futher Use Case