You are here:
IDENTIFYING SOURCES OF VARIABILITY IN INTERSTITIAL WATER SAMPLING USING THE DIALYSIS (PEEPER) METHOD
Citation:
Serbst, J R., R M. Burgess, AND M G. Cantwell. IDENTIFYING SOURCES OF VARIABILITY IN INTERSTITIAL WATER SAMPLING USING THE DIALYSIS (PEEPER) METHOD. Presented at The Society of Environmental Toxicology & Chemistry Annual Meeting, Nashville, TN, November 12-16, 2000.
Description:
The practice of measuring contaminants in interstitial water (IW) during sediment toxicity tests enables researchers to relate contaminant concentrations to organism responses. It is critical that contaminant concentrations are quantified in a precise manner when making these measures. The dialysis or 'peeper' method is one of several IW sampling methods used when studying metal contaminated sediments in the laboratory and field. However, in an earlier laboratory study using several concentrations of cadmium spiked sediment and several sampling periods, a large IW data set was produced that displayed widespread variability (CV ranged from 38.9-104%). We hypothesized that sources of variability included (1) peeper design resulting in contamination during IW removal and (2) spatial artifacts related to peeper deployment in the toxicity testing chamber. The present study addressed these two hypotheses. Results of evaluations of the peeper membrane design indicate addition of a second membrane, to serve as a protective film and reduce contamination, do not significantly affect performance. Spatial distribution of peepers in the testing chamber was far more important in affecting the magnitude of variability in IW measurements. Specifically, peepers deployed close to the biologically active zone in the toxicity testing chamber (~0.5 cm depth) showed significant variability compared to peepers deployed at greater depths. These data demonstrate that care must be taken in deploying peepers to collect IW samples of the greatest biological relevance while avoiding excessive variability.