Characterization of Total Suspended Solids
Project Number: BQY30
Project Chief: William R. Selbig
Project Topics: xxxc
Cooperators: Wisconsin Department of Natural Resources
Period of Project: July 2005–September 2007
These new techniques in processing and analyzing whole-water samples could improve event mean concentrations of sediment and sediment-associated contaminants in urban runoff.
Problem
Commonly used sample-splitting devices such as churn and cone splitters have been shown to produce bias and precision problems when dealing with sand-sized particles. To complicate matters, widely used analytical techniques for measuring metal concentrations in aqueous samples may also be biased based on subsampling protocols.
Sample-splitting and analytical methods that reduce bias and precision error by accounting for a wide range of particle sizes in an aqueous sample would greatly benefit our understanding of sediment-associated contamination in urban runoff.
Objectives
The purpose of the investigation was to modify existing sample-splitting methods using a churn splitter when processing whole-water samples to minimize bias and (or) precision errors associated with the presence of sand-sized particles. In addition, laboratory methods to determine sediment-associated metal concentrations in both solid and aqueous phases were modified to more accurately reflect the entire water-sediment mixture.
Together, these new techniques in processing and analyzing whole-water samples could improve event mean concentrations of sediment and sediment-associated contaminants in urban runoff.
Approach
This study examined the viability of removing sand-sized particles from the aqueous portion of a whole-water sample through wet sieving techniques. Once the solid material was removed, it was analyzed independently from the remaining aqueous portion to produce a solid-phase concentration.
The experimental design was structured to test whether metal concentrations of a known mass of dried solids were the same whether the material was analyzed as a solid or added to a known volume of deionized water and analyzed as a sediment-water mixture. The experiment was performed to assess both the variability in performance of the churn splitter and accuracy of existing analytical techniques over a range of particle sizes.
Progress
A paper documenting the procedures and experimental results of this study was presented and published at the 2006 Federal Interagency Sedimentation and Hydrologic Modeling conference. A revised version of the paper with supplemental data was submitted to the Journal of Environmental Quality for publication. Additional experiments were conducted to further identify the effect of particle size on TSS concentrations.
Plans
The findings of this study to date will be presented at the 2006 STORMCON conference. Additional experiments will be conducted to learn more about the relationship of particle-size distribution and concentration of an aliquot normally used for TSS analysis. These data will be compared to particle-size distributions as well as suspended sediment concentrations of whole-water samples.
Publications and Reports
The results of the study were published as part of the proceedings for the 8th annual Federal Interagency Sedimentation Conference.
A similar version will also be published as part of the 2006 STORMCON conference proceedings.
A revised version with supplemental data was submitted to JEQ in April 2006.
Additional reports are planned that will document the results of TSS and PSD experiments. Selection of report series is yet to be determined.
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