Pore Water Collection, Analysis and Evolution: The Need for Standardization

Investigating the ecological impacts of contaminants released into the environment requires integration of multiple lines of evidence. Collection and analysis of interstitial water is an often-used line of evidence for developing benthic exposure estimates in aquatic ecosystems. It is a well-established principle that chemical and toxicity data on interstitial water samples should represent in-situ conditions; i.e., sample integrity must be maintained throughout the sample collection process to avoid alteration of the in-situ geochemical conditions. Unfortunately, collection and processing of pore water is not standardized to address possible geochemical transformations introduced by atmospheric exposure. Furthermore, there are no suitable benchmarks (ecological or human health) against which to evaluate adverse effects from chemicals in pore water; i.e., empirical data is lacking on the toxicity of inorganic contaminants in sediment interstitial water. It is clear that pore water data is best evaluated by considering the bioavailability of trace elements and the partitioning of contaminants between the aqueous and solid phases. It is also evident that there is a need for sediment researchers and regulatory agencies to collaborate in developing a standardized approach for sediment/pore water collection and data evaluation. Without such guidelines, the number of different pore water collection and extraction techniques will continue to expand, and investigators will continue to evaluate potentially questionable data by comparison to inappropriate criteria.