Quality control in the analysis of lake sediments for spheroidal carbonaceous particles
Limnol. Oceanogr. Methods 6:172-179 (2008) | DOI: 10.4319/lom.2008.6.172
ABSTRACT: The use of spheroidal carbonaceous particles (SCPs) in environmental studies as a means to identify atmospherically deposited contamination, or as a technique to provide a chronology for lake sediment cores, is rapidly increasing. However, currently there are no internationally accepted quality controls for this methodology. No reference standard exists to provide inter-calibration, and no standardized criteria for identification have been proposed. This paper addresses these issues. It is suggested that morphology (spheroidal but not spherical), color (black only), depth (i.e., three-dimensional rather than disc-like), and porosity (characteristic when present) should be used as criteria for SCP identification under the light microscope. A sediment reference material for SCP analysis has also been developed. Two hundred ten replicate analytical measurements were made on a homogenized sediment material resulting in a reliable estimate of the mean SCP concentration of 6005 ± 70 SCP per gram dry sediment (gDM-1). This material is available to SCP analysts for quality control purposes.