Source, Sink, Transport and Transformation

There is little doubt that the hydrologic cycle drives many surface and subsurface environmental processes, but the dynamics of aqueous transport of material are only beginning to be revealed. Historically, geochemists have collected snap-shot types of data sets on rivers, springs, groundwater, and other segments of the hydrologic cycle. Consequently, they have reduced dynamic processes into static averages so that global fluxes of material and differences in weathering rates of continents could be calculated. Although these data provide a general framework for understanding feedback between climate and geologic processes, they do little to define the pathways and mechanisms that constitute environmental function. Owing to the speed with which huge numbers of samples can now be analyzed, and the availability of the computer power to synthesize the results, static images of the hydrosphere are being replaced by active, dynamic views. In the process, fundamental new insights are possible into how water, solutes, and particulates actually move, and how they are affected by biogeochemical processes in soils, rivers, sediment, groundwater, and within active biomass. As we overcome the artificial fragmentation of the environment into compartments that fit our traditional fields of scientific study, there is no going back to the status quo to provide the necessary insights. New approaches require new thinking that will take us closer to understanding how dynamic ecosystems really work.