Lithological Influences on Weathering Processes and Rates in the Luquillo Mountains of Puerto Rico

Project Description: 

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.

The Rio Icacos watershed has been well studied in terms of weathering processes. Recently the USGS has instrumented several sites in the Bisley 1 watershed with nested suction pore water samplers, tensiometers, and regolith gas samplers to depths up to 52 ft. Sampling has included water, gas, solids (soil, saprolite, weathered rock, fresh rock), and plants. New data collected from the Bisley sites are being compared to data from the Icacos sites to explore the influence of lithology on various measurable parameters.

Nutrient cycling mechanisms in the deep Bisley regolith will be identified by categorizing nutrient pools as a function of depth and applying geochemical analyses to trace nutrient fluxes. Heterogeneities in the regolith profiles will be studied to examine the effects of small scale biogeochemical processes on watershed-scale cycles.

Research Location: 
Source of Funding: 
Relevant Publications: 

White et al., 1998; Murphy et al., 1998; Schulz and White 1999; Buss et al., 2008; Buss et al., 2010.

Contact Information
Person(s) Completing This Form: 
Heather L. Buss
Heather L. Buss (, U.S. Geological Survey Menlo Park, CA Art F. White (, U.S. Geological Survey, Menlo Park, CA
Investigator E-mail Addresses: