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16 BIOLOGIC LABORATORY ANALYSES - Background Physicochemical, Microbiological and Routine Bioprocess Monitoring Evaluations Regardless of which methodology is desired by a client, establishing microbiological and physicochemical markers of existing biological activity and biotoxic influences, and correlating the results with concurrent analytical data(contaminant concentrations) can typically provide the simplest and most direct evidence of current microbial activity, prospective operational requirements and/or the preclusion of a desired approach. BioLogic provides various background parameter evaluations commonly used by experience bioremedial practitioners, and/or developed by BioLogic, designed to define critical features which are important to the operation and efficiency of in situ or ex situ bioremediation of contaminated soil and groundwater. The following presents the minimum analyses which should routinely be performed for any site characterization (in situ or ex situ) or bioprocess monitoring event. Additionally, a brief description is provided for each of these analyses stating the purpose of the evaluations, how they are performed, and, more importantly, how the information is interpreted and/or used to determine what limiting environmental factors, if any need to be addressed for successful site remediation. Baseline Laboratory Analyses: Heterotrophic and Selective Microbial Enumeration (General and Biodegrader Counts): Microbiological evaluations are conducted to evaluate heterotrophic (general) and selective degrader populations with regard to actual microbial numbers and, more significantly, to determine the relative proportion of biodegraders with respect to the overall (heterotrophic) microbial population. Using standard microbiological plate count techniques, these evaluations are performed on both nutritionally complex culture media(for heterotrophs) and contaminant-supplemented(sole carbon source) minimal salts media (for selective degraders). In conjunction with information generated from physicochemical analyses, the results of these tests are used to determine environmental compatibility with microbial growth requirements, potential biotoxicity detection, and document differential growth kinetics between indigenous heterotrophic and selective contaminant degrading microbial populations. Selective microbial enumerations are performed using the target contaminant as the sole carbon source to determine the actual number of organisms capable of degrading the specific substrate. On sites where multiple contaminants are present, it is advisable that selective microbial evalua- tions be performed against each of the specific contaminant substrates. - General Physicochemistry: Physicochemical analyses are conducted to evaluate site-specific environmental parameters. This generally includes the analysis of moisture content, pH, and inor- ganic nutrient concentrations of nitrogen (nitrate, nitrite, ammonia), phosphorous (as phosphates), and potassium. The tests are performed in order to determine whether current physicochemical (environmental) conditions are adequate to promote microbial growth and reproduction for con- taminant biodegradation. Results generated from these analyses can be used to identify and quantitatively correct any nutrient deficiencies which may have been detected. For the analysis of nitrogen compounds, both ionic and molecular forms are reported. - Total Organic Carbon (TOC): Total Organic Carbon is a critical parameter often overlooked by bioremedial practitioners. TOC is initially analyzed to determine the amount and potential effects of alternative competing carbon sources (noncontaminant) which can significantly influence microbiological processes. Direct correlations can often be made between heterotrophic microbial activity and TOC content. The presence of one or more alternative carbon source(s) (such as decaying plant matter or other noncontaminant organic matter) can result in the enhanced growth 4