Environmental Fate and Transport of Solvent-Stabilizer Compounds - Environmental Investigation and Remediation - page 114

3 Environmental Fate and

Transport of Solvent-Stabilizer
Compounds

Thomas K.G. Mohr

Industrial waste discharges to the environment are universally associated with degradation of water
quality and risk to human and ecological health. Many chemicals in industrial efl uents do not per-
sist because of physical removal, chemical reaction, or biodegradation to less harmful by-products.
The factors that differentiate compounds that are recalcitrant and compounds that are assimilated
into environmental systems without appreciable consequences are called contaminant fate and
transport properties . Fate and transport properties describe the propensity for a chemical to volatil-
ize, photo-oxidize, adsorb, hydrolyze, or biodegrade and, if the chemical survives these fates, how
it may advect, diffuse, or otherwise migrate through soil, groundwater, surface water, and air. These
processes not only eliminate some compounds and retard the movement of others, but also affect
the phase in which the chemical is present (gas, liquid, or solid). Some compounds are relatively
immune to degradation and will persist in the environment for long periods of time. If released in
sufi cient mass, those contaminants that are persistent, mobile, and also toxic constitute the greatest
potential threat to drinking water resources.
Chapter 1 proi led the industrial fate of solvent-stabilizer compounds. The environmental fate of
the stabilizers discussed in Chapter 1 is summarized here in brief descriptions and tables.
In this chapter, the environmental fate and transport of stabilizer compounds is examined by proi l-
ing their potential to persist in air, surface water, soil, and groundwater. The focus is on those stabi-
lizer compounds that become concentrated by the industrial processes that precede their discharge.
A more detailed review is provided of the fate and transport of 1,4-dioxane, a solvent stabilizer that
may pose an elevated threat to drinking water resources because of its persistence and mobility.

3.1 FATE AND TRANSPORT PROCESSES
The processes governing the fate and transport of contaminants following their release to the envi-
ronment are the subject of a number of topics and thousands of peer-reviewed papers. Authoritative
works on this subject include Freeze and Cherry (1979), Lyman (1990), Dragun (1988), Howard et al.
(1991), Chappelle (1993), Mackay et al. (1993), Schwarzenbach et al. (1993), Thibodeaux (1996),
Hemond and Fechner (1994), Verschueren (1996), Domenico and Schwarz (1997), Suthersan (2002),
and many others. This section briel y reviews the key processes that determine the environmental
fate and transport properties for 1,4-dioxane and some of the other solvent-stabilizer compounds.
Fate and transport properties of stabilizer compounds are estimated through a variety of approaches
where literature citations of measured or estimated values are not available. The leading approach to
property estimation is quantitative structure-activity relationships (QSARs); related approaches include
quantitative property-property relationships (QPPRs), quantitative structure-property relationships
(QSPRs), group contribution models (GCMs), and similarity-based models (Reinhard and Drefahl,
1999). These methods relate chemical structure to chemical behavior. For example, the measured
relationship between molecular weight and boiling point for many compounds permits estimation

115