What advantages do SPMDs and POCIS offer over grab sampling?
In the case of water and air, grab samples provide data only on single point in time, and because small volumes are typically sampled (<5 L), the approach is often inadequate for the detection of trace bioconcentratable residues. For compounds with relatively large Kows, SPMDs integratively sample residues (i.e., losses of accumulated chemicals are insignificant) during an exposure period. Integrative sampling mimics the bioconcentration process and permits the concentration of trace chemicals to detectable levels. Also, episodic events can be detected without an intensive sampling program.
