A.6.4.4 Sample support

SS can be thought of as a portion of soil mass collected from a sampling location of the DU that yields a single incremental sample (pooled across locations). The concept of SS was introduced to address small-scale DH and to minimize GSE. Soil samples with appropriate and practical SS obtained using proper sampling tools (e.g., Gerlach and Nocerino 2003) tend to yield more accurate analytical results. Examples illustrating the influence of the size of SS on the unbiasedness of the estimate of DU mean obtained using an ISM sample were explored, but conclusions are beyond the scope of this document.

The size of the SS and sampling tools used play an important role in collecting representative samples. For example, if one uses large SS exceeding the extent of small-scale DH to collect increments, then the resulting incremental samples may not be representative of the bulk material contained in the DU. Consequently, the analytical result for the composited sample may not represent an unbiased estimate of the mean concentration.

The appropriate size of the SS can be determined by evaluating the particle size distribution of the particles present in the environmental DU under investigation. Further details regarding these concepts can be found in the environmental sampling literature (e.g., Pitard 1993).