Detecting chemicals within different areas of an interconnected system can indicate how the fluids flow around the system and so how other chemicals will flow with them.
For example, the proportion of trace element Carbon-14 in the atmosphere could indicate the proportion of CO2 increase due to fossil fuels and cement production. CO2 is exchanged between the atmosphere and other reservoirs such as ground biomass, forestry, and ocean phytoplankton in relatively small amounts compared to the total contained in each reservoir.
Expected trace levels therefore need to be calculated in order to test actual levels against hypothesis.
In this study we modelled a set of internally well-mixed reservoirs connected by relatively small ‘pipes’ that exchange the contents of each reservoir with some others. We add a small trace to one reservoir and see how that mixes over time with the others. Using this model we should therefore be able to tell whether the increase in trace in that reservoir matches different hypothesis (ie, the source is that reservoir), but also from measurements of some reservoirs where the source of the introduced trace is.