TitleAn approach for calculating a confidence interval from a single aquatic sample for monitoring hydrophobic organic contaminants.
Publication TypeJournal Article
Year of Publication2012
AuthorsMatzke MM, Allan SE, Anderson KA, Waters KM
JournalEnviron Toxicol Chem
Date Published12/2012
Confidence Intervals, Environmental Monitoring, Hydrophobic and Hydrophilic Interactions, Pilot Projects, Polycyclic Hydrocarbons, Aromatic, Water Pollutants, Chemical, Water Pollution, Chemical

The use of passive sampling devices (PSDs) for monitoring hydrophobic organic contaminants in aquatic environments can entail logistical constraints that often limit a comprehensive statistical sampling plan, thus resulting in a restricted number of samples. The present study demonstrates an approach for using the results of a pilot study designed to estimate sampling variability, which in turn can be used as variance estimates for confidence intervals for future nā€‰=ā€‰1 PSD samples of the same aquatic system. Sets of three to five PSDs were deployed in the Portland Harbor Superfund site for three sampling periods over the course of two years. The PSD filters were extracted and, as a composite sample, analyzed for 33 polycyclic aromatic hydrocarbon compounds. The between-sample and within-sample variances were calculated to characterize sources of variability in the environment and sampling methodology. A method for calculating a statistically reliable and defensible confidence interval for the mean of a single aquatic passive sampler observation (i.e., nā€‰=ā€‰1) using an estimate of sample variance derived from a pilot study is presented. Coverage probabilities are explored over a range of variance values using a Monte Carlo simulation.

Alternate JournalEnviron. Toxicol. Chem.
PubMed ID22997050
PubMed Central IDPMC3581149
Grant ListP42 ES016465 / ES / NIEHS NIH HHS / United States
P42 ES016465 / ES / NIEHS NIH HHS / United States
Projects Reference: 
LDPE Passive Sampling Devices
Portland Harbor