Environmental Engineering Reference
In-Depth Information
Chapter 19
Contaminant Fate and Reactive Transport
in Groundwater
Massimo Rolle, Ulrich Maier, and Peter Grathwohl
Abstract
Understanding the complex, interacting processes that determine the
fate and transport of contaminants in groundwater is a major challenge for eval-
uating and predicting risks to clean water, human and ecological receptors and
for designing effective remediation plans. Different physical and biogeochemical
processes including advection, hydrodynamic dispersion, dissolution, sorption and
biodegradation affect the migration of contaminants in saturated porous media like
a groundwater system. In this chapter an overview of these processes is presented
together with the basic theory on contaminant transport modeling, which represents
an essential tool for a quantitative description of contaminant migration in the sub-
surface. Numerical simulations of typical contamination scenarios are presented,
with the main goal of identifying the influence of different parameters on contam-
inant fate and transport such as transverse dispersivity, thickness and strength of
the contamination source, recharge, biodegradation rates and mixing enhancement
through flow focusing in high permeability zones. These numerical simulations are
complemented by two examples, i.e. the reactive transport of toluene from a LNAPL
source and a field study, where ammonium is continuously released from a leaking
landfill to the underlying aquifer. The principal processes at the landfill site have
been quantitatively integrated into the framework of a two-dimensional reactive
transport model.
Contents
19.1 Introduction
...........................................
852
19.2 Basic Theory on Contaminant Transport
..........................
853
19.2.1 Contamination Sources and Plume Formation
.................
854
19.2.2 Advection
.......................................
856
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