Environmental Sciences and Biogeography

Cave and Karst Systems


  An understanding of the interplay of hydrology and biogeochemical processes that control transport and processing of nutrients in karst watersheds is critical to the design of sustainable land-use practices over karst terrains. Our understanding of the processes operating in karst systems, however, lags considerably behind that of other aquatic ecosystems (such as marine, riverine, wetlands, and granular aquifers). The availability of dissolved organic matter, a strong control in biogeochemical cycling of nutrients within the karst soil system, is easily altered by agricultural, wastewater treatment outfalls, septic systems, and other activities in the karst watersheds. Whereas karst ground-water movement has recently received focused study, controls on the carbon availability and movement, particularly the DIC-DOC-CO2 (g) dynamics have received little attention. Carbon is the basic substrate which must be available for processing nutrients--and specifically nitrate. Basic geochemical monitoring is being conducted which includes continuous pCO2 measurement and isotopic characterization of DIC and DOC behavior moving through the karst-soil system. These data are facilitating source identification and delineation of the complex interaction between water quality and nutrient cycling in karst. This project will establish controls on the effect of carbon cycling and local hydrology on the effective processing of nutrients in mantled-karst watersheds of the Ozarks.
Currently we are working in a cave system in Madison County to help understand the interplay of climate, hydrology, and nutrient processing.  Sampling infrastructure design aims at collection of soil gas, soil water, ground water at various points moving along flow paths including caves, and cave CO2.  The data set being accrued will help draw direct correlation between the surface conditions and cave responses and enable elucidation of controls on nutrient processing.  Data also will allow for characterization of climate effects with improved understanding of CO2-speleothem dynamics and the development of the archived climate records of the cave system.