The ability to quantify how fast weathering profiles develop is crucial to assessing soil resource depletion and quantifying how landscapes evolve over millennia. Uranium-series isotopes can be used to determine the age of the weathering front throughout a profile and to infer estimates of regolith production rates, because the abundance of U-series isotopes in a weathering profile is a function of chemical weathering and time. This technique is applied to a weathering profile in Puerto Rico developed over a volcaniclastic bedrock.

Ca and Mg are released from silicate minerals during chemical weathering, react with atmospheric CO2, and are deposited as carbonate in the oceans, regulating global climate on geological time scales. Thus to estimate and predict CO2 consumption rates, it is important to identify and quantify the sources and fluxes of Ca and Mg that are discharged to the world’s oceans via rivers, and the weathering processes that produce those fluxes.

Rapid weathering and erosion rates in mountainous tropical watersheds lead to highly variable soil and saprolite thicknesses which in turn impact, nutrient fluxes, and biological populations. To understand mineral nutrient cycling in such environments requires tracing nutrients through the entire critical zone: weathering bedrock, saprolite, soil, soil water, precipitation, vegetation, and microorganisms. A thorough understanding of nutrient cycling in tropical uplands is necessary in order to predict the effects of human impacts.