Environmental Engineering Reference
In-Depth Information
Chapter 9
Uptake of Organic Contaminants from Soil
into Vegetables and Fruits
Stefan Trapp and Charlotte N. Legind
Abstract
Contaminants may enter vegetables and fruits by several pathways: by
uptake with soil pore water, by diffusion from soil or air, by deposition of soil
or airborne particles, or by direct application. The contaminant-specific and plant-
specific properties that determine the importance of these pathways are described in
this chapter. A variety of models have been developed, specific for crop types and
with steady-state or dynamic solutions. Model simulations can identify sensitive
properties and relevant processes. Persistent, polar (log
K
OW
< 3) and non-volatile
(
K
AW
<10
-6
) contaminants have the highest potential for accumulation from soil,
and concentrations in leaves may be several hundred times higher than in soil.
However, for most contaminants the accumulation in vegetables or fruits is much
lower. Lipophilic (log
K
OW
> 3) contaminants are mainly transported to leaves
by attached soil particles, or from air. Volatile contaminants have a low poten-
tial for accumulation because they quickly escape to air. Experimental data are
listed that support these model predictions, but underline also the high variabil-
ity of accumulation under field conditions. Plant uptake predictions are uncertain,
due to the immense variation in environmental and plant physiological conditions.
Uptake of organic contaminants into vegetables and fruits may lead to human health
risks, but it may also be used to delineate subsurface plumes and monitor Natural
Attenuation. Most models mentioned in this chapter are freely available from the
authors.
Contents
Introduction
...........................................
9.1
371
9.2 Uptake and Transport Processes
...............................
371
Empirical Methods for Estimating Uptake of Contaminants into Plants
.......
9.3
372
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