Geoscience Reference
In-Depth Information
Part VI
Contaminant Induced Irreversible
Changes in the Soil-Subsurface Regime
Current studies on contaminant interactions in the soil-subsurface region focus
mainly on contaminant retention, persistence and transport, and on potential
remediation of polluted geological media. Soil-subsurface region properties
altered by human intervention are often considered as deviations from a normal
geochemical environment, which will disappear via natural processes or following
specific remediation procedures. When writing the first edition of this topic (2008),
during a comprehensive literature review, we observed that in addition to their
environmental effects, contaminants may lead—under specific conditions—to
irreversible changes in soil-subsurface properties. We subsequently developed this
recognition in a number of publications (Yaron et al. 2008, 2009, 2010, 2012). In
this second edition of the topic, we include Part VI, which discusses irreversible
changes that occur in groundwater and in the matrix properties of the vadose zone,
due to anthropogenic chemical contamination. Here, we use the term ''contam-
inants of anthropogenic origin'' to refer to inorganic and organic compounds that
reach the subsurface region during agricultural and soil remediation management,
and
to
industrial
and
municipal
residues
that
are
accidentally
released
or
The literature contains a broad spectrum of research results on contaminant-
subsurface interactions. The main emphasis is on contaminant fate as affected by
the solid and water phases of the vadose zone. There are, however, specific
anthropogenic contamination impacts which may lead to long-term changes in the
natural properties of the subsurface geochemical system. These changes are often
resistant to remediation procedures and natural attenuation, and are thus
irreversible at least on a human lifetime scale. While natural processes that affect
the genesis of subsurface formation factors act slowly, over a prolonged
''geological'' timescale, chemical contaminants may rapidly change the natural
soil-subsurface regime. For this reason, chemical contamination may be consid-
ered as an additional factor in contemporary soil formation.
