Uptake of Organic Contaminants from Soil into Vegetables and Fruits - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 372

Fig. 9.1 Transport and
uptake processes in the
soil-air-plant system

Inside the plant, the phloem and xylem flux may distribute the contaminants. The
xylem sap flows from the roots into the stem to the leaves and, to some extent, to
fruits. The phloem sap flows from the leaves to all growing parts of the plant and to
fruits and storage organs, such as tubers. The relative importance of these processes
varies with plant type, environmental conditions and properties of contaminants.
Active uptake processes, which involve energy or enzymes of the plant, may also
play a role, but have not yet been shown to be of large relevance for environmental
organic contaminants.

9.3 Empirical Methods for Estimating Uptake of Contaminants
into Plants

Laboratory and field experiments have been conducted to determine the uptake of
contaminants from soil into plants. Single bioconcentration factors for contami-
nants as well as regressions were established for predicting the uptake of organic
contaminants from soil into plants.

9.3.1 Bioconcentration Factors

The ratio of contaminant concentration in an organism to contaminant concen-
tration in the surrounding medium is called the bioconcentration factor ( BCF ).
Measurements of concentrations in plant tissues and concentrations in soil will yield
a BCF plant to soil, which is defined as

C plant
C soil

BCF = (9.1)