Phytostabilization of arsenic - In-Situ Remediation of Arsenic-Contaminated Sites - page 57

LOW [As] shoot

PLANTS SHOULD HAVE THE ABILITY TO:
- grow in high [As] soil
- send roots to suitable depths
- restrict As accumulation in shoots and
promote root/rhizosphere As adsorption
- reduce the bioavailability of As
- reduce wind erosion and As leaching
- provide supplementary benefits, such as
bioenergy

HIGH [As] root

MYCORRHIZAE

As

H

ROOT MINERALIZATION

O 2

AS-OXIDES

MICROBIAL COMMUNITY AS MOBILITY

Figure 3.4. Phytostabilization of As includes low [As] shoot , the accumulation and adsorption of As to
the roots, and immobilization through the formation of As oxides (mainly Fe, Mn, and Al) in the root zone. The
pH should be kept around neutral to reduce the availability of As. Root mineralization should enhance
the microorganism community but not increase As mobility. Mycorrhizae increase the plant phosphorous
uptake and help regulate the symplastic As accumulation through As efflux.

3.5 PHYTOSTABILIZATION OF ARSENIC

The general mechanisms and required plant characteristics for the phytostabilization of
As-polluted soils, as summarized in Figure 3.4 , include an ability to grow and reach suitable
root depths in soils contaminated with high concentrations of As. Furthermore, the figure shows
that suitable plants should reduce As leaching/availability and wind erosion. In addition, supple-
mentary benefits, preferably economic, as is the case with bioenergy crops, should be favored
(Robinson et al ., 2009).