TAILIEUCHUNG - ELEGANT ANALYTICAL CHEMISTRY APPLIED TO ENVIRONMENTAL PROBLEMS - A PRACTICAL SYMPOSIUM

However, these guidelines do not address the impact of drilling techniques on the collection of a representative VOC sample. Therefore, site/program QAPPs and SAPs should address the impact of all collection techniques on sample integrity and select those appropriate for the project data quality objectives (DQOs). Potential VOC losses due to drilling techniques include, but are not limited to: sample compression and loss of pore space; introduction of air into the sample matrix; mechanical heat introduced in the drilling process; and volatilization from prolonged periods in a non- hermetically sealed sampling apparatus. . | Preprints of Extended Abstracts Vol. 41 No. 1 ELEGANT ANALYTICAL CHEMISTRY APPLIED TO ENVIRONMENTAL PROBLEMS A PRACTICAL SYMPOSIUM Organized by V. Turoski . Richardson and J. Plude Symposia Papers Presented Before the Division of Environmental Chemistry American Chemical Society San Diego CA April 1-5 2001 SELECTIVE MONITORING TO ASSESS THE BIOAVAILABILITY OF ORGANIC CHEMICALS IN AQUATIC SYSTEMS S. W. Morrall C. A. Smith W. M. Begley D. J. Versteeg and J. M. Rawlings Human and Environmental Safety Division The Procter Gamble Co. PO Box 538707 Cincinnati OH 45253 The risk a chemical poses to the aquatic environment is a function of concentration toxicity and bioavailability. The concentration of a chemical in the environment represents a maximum dose that is potentially available to an organism. Bioavailability describes the fraction of this potential dose that the organism actually encounters. Bioavailability is determined to an extent by physical properties such as aqueous solubility vapor pressure and partitioning. However the entire system biota environmental compartment composition and physico-chemical properties are intimately related and their interaction ultimately defines the actual dose or bioavailability of a chemical. We can do a reasonable job of estimating both toxicity via laboratory testing and environmental concentration by direct measurement and modeling. However accurate assessment of the bioavailability of organic compounds in aquatic systems has remained elusive due to the complexity and variability inherent to the environment. In an aquatic system organic compounds can be in molecular solution associated with dissolved organic carbon DOC sorbed to colloids suspended particulates and sediment. The chemical is available to different organisms to varying degrees depending upon what form it is. For example partitioning from a dissolved phase to sediment will reduce bioavailability to many fish but increase availability to organisms that graze on

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