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COLLECTION OF UNDISTURBED SURFACE SEDIMENTS
Citation:
CAPRI, J., B. A. SCHUMACHER, S. WANNING, E. SMITH, J. ZIMMERMAN, AND J. D. VANOVER. COLLECTION OF UNDISTURBED SURFACE SEDIMENTS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-05/076 (NTIS PB2006-100580), 2005.
Impact/Purpose:
The overall objective of this task is to provide the Agency with improved state-of-the-science guidance, strategies, and techniques to more accurately and effectively collect environmental samples. Under this umbrella objective, research is being conducted to: (a) reduce/minimize the loss of VOCs during sample collection, handling, and preservation, (b) collect undisturbed surface sediments so that the effects of recent depositional events (e.g., flooding or dredging) can clearly be delineated as to their influence on the contamination concentrations present downstream (or where the sediments are deposited), and (c) to determine an effective method to effectively and efficiently separate asbestos in soils from the rest of the soil matrix while maintaining the integrity (i.e, no fiber size reduction) of the asbestos fibers.
Description:
The National Resource Council identified the need for a capability to collect undisturbed surface sediments. Surface sediments are an important source for most exposure of fish to polychlorinated biphenyls via direct uptake from water in contact with sediments. An innovative sediment sampler was designed and fabricated that is capable of collecting undisturbed samples of surface sediment. The sampler consists of a core tube housed within a stand that provides isolated, mechanical support in a sediment bed. The collected sample is maintained undisturbed inside of the core tube until it is removed for subsampling. To subsample, a slicer block is set over the top of the core tube, the sediment is pushed up into the slicer block until the desired sample thickness is obtained, and the slicer block cuts the sediment column into increments as thin as 1 centimeter.
The undisturbed surface sediment (USS) sampler was Compared with representative core, grab, and dredge sampling devices in the laboratory and against the Ponar (a common grab) sampler in the field. Evaluation of the sample collection process was made through video assessment and physical measurement of several parameters, such as particle-size distribution. Visually, the disturbance of the surface sediments was reduced during collection events with the USS sampler when compared to the other devices tested. Samples collected with the USS sampler exhibited significantly less variability from location to location in the field indicating that a consistent depth of sampling was obtained with the USS sampler.