The Role of Converging Technologies

In order to comprehensively understand how environmental systems operate at all scales, convergence of biological, technological, and geoscientific approaches is essential. Three important tasks are described below.

Identification and Analysis of Reactive Components in Complex Natural Systems

Nanoparticles and microorganisms are among the most abundant, most reactive components in natural systems. Natural nanoparticles (often < 5 nm in diameter) exhibit the same novel size-dependent properties that make their synthetic equivalents technologically useful. The functions of some microbial cell components (e.g., cell membranes, ribosomes) probably also depend on size-related reactivity. A challenge for the immediate future is determination of the origin, diversity, and roles of nanoparticles in the environment. Similarly, it is critical that we move from detecting the full diversity of microorganisms in most natural systems to understanding their ranges of metabolic capabilities and the ways in which they shape their environments. These tasks require integrated characterization studies that provide molecular-level (inorganic and biochemical) resolution.

Massive numbers of genetic measurements are needed in order to identify and determine the activity of thousands of organisms in air, water, soils, and sediments. Enormous numbers of chemical measurements are also required in order to characterize the physical environment and to evaluate how biological and geochemical processes are interconnected. This task demands laboratory and field data that is spatially resolved at the submicron-scale at which heterogeneities are important, especially in interfacial regions where reactions are fastest. The use of robots in oceanographic monitoring studies is now standard, but this is only the beginning. Microscopic devices are needed to make in situ, fine-scale measurements of all parameters and to conduct in situ experiments (e.g., to assay microbial population makeup in algal blooms in the ocean or to determine which specific organism is responsible for biodegradation of an organic pollutant in a contaminated aquifer). These devices are also required for instrumentation of field sites to permit monitoring over hundreds of meters to kilometer-scale distances. Development of appropriate microsensors for these applications is essential.

Environmental science stands to benefit greatly from nanotechnology, especially if new sensors are developed with environmental monitoring needs in mind. In the most optimistic extreme, the sensors may be sufficiently small to penetrate the deep subsurface via submicron-scale pores and be able to relay their findings to data collection sites. It is likely that these extremely small, durable devices also will be useful for extraterrestrial exploration (e.g., Mars exploration).

Monitoring Processes in the Deep Subsurface

Many of the inorganic and organic contaminants and nutrients of interest in the environment may be sequestered at considerable depths in aquifers or geological repositories. Methods are needed to image the structure of the subsurface to locate and identify these compounds, determine the nature of their surroundings, and monitor changes occurring during natural or enhanced in situ remediation. Examples of problems for study include detection of nanoparticulate metal sulfide or uranium oxide minerals produced by biological reduction, possibly via geophysical methods; analysis of the role of transport of nanoparticulate contaminants away from underground nuclear waste repositories; and monitoring of the detailed pathways for groundwater flow and colloid transport.

Development of Models to Assist in Analysis of Complex, Interdependent Phenomena

After we have identified and determined the distributions of the reactive inorganic and organic nanoscale materials in natural systems, it is essential that we understand how interactions between these components shape the environment. For example, we anticipate development and validation of comprehensive new models that integrate predictions of particle-particle organic aggregation and crystal growth with models that describe how aggregates are transported through porous materials in the subsurface. These developments are essential for prediction of the transport and fate of contaminants during and after environmental remediation.

Environmental processes operate across very large scales on continents and in the oceans. Thus, remote collection of high-resolution data sets (e.g., by satellite-based remote sensing) can also be anticipated. The large quantities of data from direct and indirect monitoring programs will benefit from new methodologies for information management. Mathematical models are essential to guide cognition and to communicate the principles that emerge from the analyses. An example of an ecosystem model is shown in Figure D.1. Input from the cognitive sciences will be invaluable to guide development of supermodels of complex processes.

Figure D.1. Example of an ecosystem model that incorporates information about the physical and chemical environment with information about population size and structure and gene expression to analyze community interactions and predict response of the system to perturbations.

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