Biomedical Engineering Reference
In-Depth Information
subsections discuss the fate and transport of methanol following a
release, as presented in the three scenarios introduced in Section 1.1,
namely: (1) rail car or tank truck spill to soil and/or groundwater; (2)
barge/ship spill to surface water; and (3) underground storage tank
release to soil and groundwater. Each subsection further describes the
sources of methanol into the respective environmental medium and the
ensuing loss mechanisms from that medium.
2.3.1 Soil and/or Groundwater Release
Very few data sets are available on the reported levels of methanol in
aquatic systems and subsurface environments in the United States. The
apparent lack of monitoring for methanol, particularly in aqueous
systems, is likely a result of (1) the level of difficulty associated
with methanol analysis in the water phase, (2) its short half-life due
to its high biodegradation potential, and (3) the lack of governmental
monitoring requirements or control mandates specific to methanol for
groundwater, surface water, and drinking water (e.g., Clean Water Act,
Safe Drinking Water Act).
2.3.1.1 Sources of Methanol in Soil and Groundwater
There are
several processes related to the use of methanol as a fuel that would be
directly responsible for methanol releases to soil and groundwater. The
dominant sources are expected to be those discussed in Scenarios 1 and
3—release from a rail car or tank truck and release from an underground
methanol storage tank. Precipitation may also serve as a transport
mechanism for methanol to groundwater by infiltration through the
unsaturated zone. Precipitation, however, has been shown to be a minor
source of contaminant transport into the soil and groundwater for other
highly water-soluble chemicals, such as MTBE (Zogorski et al., 1997),
and is therefore expected to be a minor transport mechanism for
methanol into groundwater.
2.3.1.2 Losses of Methanol from Soil and Groundwater
As a result of
its high solubility, low retardation factor, and ease of biodegradability,
the dominant mechanisms of methanol loss from subsurface soil and
