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United States Department of Agriculture

Agricultural Research Service

Title: Flat-Plate Freeze Sampler for Stratified Sediment Sampling in Ponds and Wetlands

Authors
item Parker, David - UNIVERSITY OF NEBRASKA
item Schulte, Dennis - UNIVERSITY OF NEBRASKA
item Nienaber, John
item Eisenhauer, Dean - UNIVERSITY OF NEBRASKA

Submitted to: American Society of Agri Engineers Special Meetings and Conferences Papers
Publication Type: Other
Publication Acceptance Date: June 28, 1995
Publication Date: N/A

Interpretive Summary: A sampler was developed and tested to obtain a representation of material in a very soft and watery condition without disturbing the layers of solids that form the sediment. The sampler was constructed from thin sheets of stainless steel which formed a 2 compartment container. One compartment (backside) was filled with insulation to prevent freezing of material to the sampler. The second compartment was filled with dry ice to provide rapid freezing of the soft material to the front surface of the sampler. Alcohol was added to the dry ice compartment to help the sediment rapidly freeze to the surface. The sampler was tested on the sediment within a beef cattle feedlot runoff pond. Samples removed from the frozen surface were easily separated by color and were chemically different from each other. The sampler is to be used to study how layers form over time.

Technical Abstract: An improved sampling apparatus, the flat-plate freeze sampler, was developed for obtaining undisturbed samples in soft, saturated, stratified sediments. The sampler was constructed of stainless steel and was 1 m long, 0.15 m wide, and 0.038 m deep. The interior of the sampler was filled with dry ice and isopropyl alcohol and pushed into the sediment, allowing the sediment to freeze to the outside of the sampler. After removal of the sampler, individual layers were easily subdivided while still frozen to the side of the sampler. The sampler was used successfully to sample sludges from the bottoms of both a sedimentation basin and a storage pond at a beef cattle feedlot. The sludges were too soft for conventional sampling techniques, with moisture contents ranging from 1.30-2.52 kg/kg, dry basis. Soil layers were delineated in the field by color. Colors were assigned visually using color charts, and electronically using a tristimulus color analyzer. Each layer was analyzed for moisture content, organic matter, various chemical compounds, total volatile solids and electrical conductivity. There was a correlation between organic matter and color (r squared = 0.31). Color also changed when the sediments were exposed to air, a result of oxidation effects. Chemical concentrations varied noticeably by layer, demonstrating the importance of proper sampling procedures, especially for animal waste sludges that will be land applied. The flat-plate freeze sampler proved to be an efficient method for obtaining an undisturbed, visual representation of soft sediments and sludges.

Last Modified: 4/21/2014
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