Geochemical transport through the critical zone: Statistics and reconstruction

Detecting and quantifying geochemical transport through the critical zone at the continental to regional scale requires reliable  statistical procedures that can be uniquely interpreted. We present methods that provide different views on the same data sets and  formulate rules for their application and interpretation. The statistical analysis of cumulative distribution functions (CDFs) uses cumulative probability (CP) plots for spatially representative multi-element and multi-media data sets, preferably containing >1000 sites.
Mathematical models demonstrate how contamination can influence elemental CDFs of different  sample media. For example large-scale diffuse soil contamination leads to a distinctive shift of the low-concentration end of the distribution of the studied element in its top-soil CP plot, whereas high local contamination influences the high-concentration end. But also bio-geochemical processes can generate recognizable changes in elemental CDFs.
A related and partly unsolved problem is the correct interpretation of compositional data in terms of their transport through  the critical zone.