A scientific understanding of complex environmental systems typically requires studies ranging from well controlled laboratory studies that are overly simplistic, up to field studies that embody the full complexity of the system, but for which we lack adequate control or detail.
 

Because of the inherent difficulties in field studies (sampling, repeatability, boundary forcings, etc.)  we are seldom able to quantitatively describe "real world" processes to our satisfaction.  Consequently, we are often forced to simplify these complex systems to a level that may be studied in a well-controlled (i.e. laboratory) setting.

In the processes of simplifying systems for laboratory studies, we extract from the "big picture" a subset of all the processes that are occurring (process isolation).  We formulate a mechanistic  description of the these processes (conceptual model formulation).  Finally, we test our conceptual model (experimentation).  Results from the experimentation step either verify (fail to disprove) our description, or else suggest revision of the conceptual model.

As our understanding of basic processes becomes more complete we begin to composite processes, and our need for more complex experimental systems increases.  We proceed through a series of "diagnostic stepping stones", whereby we incrementally increase the level of experimental complexity (number and types of significant processes).  Eventually, we reach a level at which our conceptual model breaks down, and we are forced to revise it.  It is through this stepwise increase in complexity that we begin to tease out the interactions between multiple processes that occurs in "real-world" systems.  Unfortunately, the current laboratory methodologies for studying sediment biogeochemistry fail to provide systems that are sufficiently complex to incorporate the physical processes that occur within dynamically reworked sediments.

Current laboratory methodologies (intermediate steps) include:
 

Well-mixed beaker studies 0-dimensional 1-phase "Frapped" Sediment Quiescent micro-/mesocosm studies  1-dimensional 2-phase Stationary Sediment Turbulence grid studies 1-dimensional 2-phase Disrupted Sediment
Biogeochemical Rotating Annular Flume Studies (proposed methodology) 3-dimensional 2-phase Disrupted Sediment

The primary utility in RALF is not the acquisition of biogeochemical or physical parameters for direct use in field-scale models.  Rather, we see RALF as complimenting an existing set of diagnostic tools (numerical models and laboratory methodologies), allowing us to begin to explore the complex coupling of physics to the biogeochemistry in dynamically reowrked sediments.