Other appropriate evidence would include documented product accumulation and detoxification. The strongest case is made by having multiple lines of evidence that include documentation of electron flow towards bioremediation pathways.
Current chemical methodologies for assessing contamination rates and residuals are labor intensive, expensive, and provide indirect measures of in situ processes. They may also inaccurately relate total chemical measurements to bioavailability and risk to human health. This may be true even when the concentration of chemicals, e.g., metals, radionuclides, or chemical mixtures such as total petroleum hydrocarbons, are above statutory levels as commonly determined by analytical chemistry. Research is needed to determine the short- and long-term bioavailability of contaminants to the soil community at the micro and macro level. The limitations of existing techniques are most apparent when interpreting the results of end points of bioremediation for human health risk assessment. Leaching and other harsh methods for extracting chemical constituents from the soil for analytical determination may not adequately measure availability to human or ecological receptors. Surrogate methods that represent receptors, such as simulated gastrointestinal fluids, do exist, but they have not been validated for contaminant mixtures or residual environmental concentrations following bioremediation. Surrogate end points such as molecular, genetic, cellular, and other in vitro assays also exist, but they have not been validated against whole animal standards nor have they been applied to bioremediation.
Interference from physical or chemical components in the environment also constrains assessment methodologies. Techniques for documenting the loss of contaminants from a site have been confounded by a host of problems, including natural geologic heterogeneity, variable and unpredictable distributions of contaminants, and the practice of measuring total elemental compositions of soil, sediment, or groundwater samples. Improved methods for detecting the location of contaminants, both directly and indirectly, are needed. Moreover, the influence of geologic heterogeneity and contaminant transport processes on the distribution of contaminants needs to be better understood so that optimal strategies can be developed for locating sampling and monitoring sites. Improved methods for efficiently measuring the chemical form of metals and radionuclides (e.g., redox status, complexation, and sorption) are required to more effectively evaluate bioremediation potential and document biotransformation processes.
Solving the technical issues related to measuring, monitoring, and quantifying end points for bioremediation will require the integration of ecological, chemical, hydrogeological, geophysical, engineering, and information management disciplines. For assessing communities and biodegradation rates of parent compounds and intermediates, the emphasis must be on techniques that yield information on activities of consortia or on specific strains of bioremedial groups within the consortia. When assessing bioremediation end points, the focus must be on techniques that accurately reflect the impact on human and environmental health. In addition, an emphasis on near-real-time analysis and data acquisition will provide feedback and support to other program elements on complex reactions in heterogeneous matrices.
The Assessment element, therefore, will involve efforts at the field research centers and at appropriate satellite sites and will focus on these four subelements:
Fundamental research in designing, developing, and measuring techniques to assess bioremediation activity, including community structure, biotransformation rates, and types of microbial and rhizosphere activity.
Adapt and improve existing molecular and biochemical techniques -- such as DNA and RNA molecular probes, bioreporters, biosensors, fluorescent stains, PCR techniques, and DNA and RNA fingerprinting analyses of gene products -- for application to field and laboratory measurements of microbial activity, community structure, and electron flow.
Initiate characterizations at field research centers using novel and conventional techniques.
Five-Year
Develop and evaluate new techniques -- such as isotopes of carbon, oxygen, and chloride to distinguish abiotic and biotic processes (e.g., to address mass balance and fate issues) -- for application to environmental in situ and ex situ measurements of microbial activity and community structure.
Ten-Year
Evaluate innovative techniques for cost-effective, real-time efficient laboratory field-monitoring capabilities and reliability.
Provide critical assessment of the degradative capabilities of microbial communities that degrade and transform complex mixtures of contaminants.
Fundamental research in developing techniques for measuring important geological, hydrological, and geochemical parameters that influence the bioremediation of contaminants.
Evaluate the effectiveness of geophysical techniques, such as high-resolution seismic and electrical methods, for identifying contaminants, biodegradable products, and physical properties controlling fluid transport.
Identify and apply a suite of geophysical, geochemical, hydrological, and geological characterization techniques to describe the heterogeneity of the first field site.
Five-Year
Develop a suite of noninvasive geophysical techniques for locating contaminants and documenting losses.
Develop geophysical methods for monitoring biodegradation or biotransformation byproducts.
Develop hydrological methods for better characterization of transport properties for water, dissolved contaminants, and colloids, including bacteria-sized particles.
Ten-Year
Develop cost-effective and reliable geophysical technologies for designing and monitoring long-term bioremediation processes. Couple these technologies with new diagnostics tools to develop an approach to post-closure monitoring that complies with regulatory issues.
Fundamental research in developing the diagnostics to interpret complex data sets, including temporal and spatial variability, in support of effective remediation management.
Review, evaluate, and develop methods and techniques for compiling, organizing, and analyzing data using analytic and statistical techniques.
Five-Year
Incorporate novel measurement techniques of community interaction and activity into an existing data-acquisition framework.
Develop methods for measuring and interpreting spatial heterogeneity in concentration and species of target compounds, biological communities, and hydrogeologic parameters in collaboration with the Biogeochemical Dynamics element.
Improve and validate mathematical and statistical methodologies for interpretation of data from the surveillance of large areas affected by complex contaminant mixtures over long time periods in collaboration with the System Integration, Prediction, and Optimization element.
Ten-Year
Develop diagnostic feedback models with associated hardware and software systems that can monitor bioremediation processes and provide feedback for the successful management of remediation systems.
Fundamental research in developing surrogate methods that reflect the bioavailability and stability of contaminants, to help development of performance standards for remediation.
In partnership with the Environmental Protection Agency (EPA) and other organizations sponsoring work on alternative end-points (e.g., GRI), develop methods and tools for estimating the bioavailability of residual contaminant mixtures.
Five-Year
Establish long-term monitoring programs to monitor the stability of sequestered or immobilized contaminants.
Ten-Year
Through collaborative efforts with the EPA, validate environmentally acceptable end points and performance standards for the bioremediation of complex contaminant mixtures.