Chemistry Reference
In-Depth Information
heavy metals or organic compounds from wastewater or contaminated soil. About 300 years
ago some plants like
Thlaspi caerulescens
and
Viola calaminaria
were reported to accumulate high
concentrations of heavy metals [118-120]. In the twentieth century, these efforts continued to
add more plants that have the potential in removing toxic metals and organic compounds
from soil and water. Many benefits have been reported of phytoremediation as compared to
the conventional methods as follows: (1) less invasive and destructive, (2) less costs, (3)
promote the biodiversity and enhance the restoration of the damaged habitats, (4) improve the
environment components of water, soil and air, (5) reduce erosion by micrometeorological
factors, (6) improve the general social life such as providing shade to buildings, decreasing
energy consumption and reducing the carbon emitted from many sources [121].
Concerning the plant species growing in the State of Qatar that have been used in many
studies of phytoremediation of pollutants from soils and waters elsewhere of the world
included: (1)
Typha domingensis
Pers.: this plant has been used in phytoremediation studies
to remove heavy metals from industrial wastewater and solution cultures [122, 123], (2)
Phragmites australis
: this species has been used in the phytoremediation of petroleum-
polluted soils in China [11, 124], (3) Brassicaceae: members of this family are very important
in phytoremediation of heavy metals [125-127], (4)
Juncus rigidus
Desf. members of the
family Juncaceae might be used in the phytoremediation of contaminated soils [128], (5)
Tamarix
spp.: species of this genus had been used to produce wood by growing them in arid
lands and irrigated them with salty effluent from desalinization plants or with recycled
sewage [129], (6)
Prosopis Juliflora
: this tree can be used in phytoremediation of heavy metals
[130, 131], (7)
Medicago
spp.: species of this genus like
Medicago sativa
have been used in
phytoremediation of soil polluted with petroleum compounds [113]. Both species
Medicago
laciniata
and
medicago polymorpha
are found within the flora of Qatar, and can be tested as an
option in the phytoremediation, and (8)
Glycine max
has been successfully used in removing
toxic petroleum products from contaminated soil [132]. More investigations are needed to
increase the list of native plants that are efficient in removing pollutants from soil and water
as expansion in the oil and gas industry and other human activities increased in the coming
years. In Qatar, some serious research projects are being conducted to test some native
plants to clean up soils and wastewater from organic and inorganic contaminants.
Bioremediation (phytoremediation) processes have been considered as necessary and first
step in successful ecological restoration of polluted habitats [133, 134].
7. Genetic approach
Since 1980 there have been serious and strenuous efforts by many scientists and researchers
to develop crops with high resistance to the environmental stresses especially salinity and
drought [135]. Since then great deal of achievements have been accomplished to identify
many plants having some morphological, physiological and biochemical characteristics
associated with the resistance to these abiotic stresses. Among these plants are wild plants
and local varieties of some crops such as wheat, barley, rice and tomato [60, 136-144]. In
Qatar and other Gulf States, native plants like halophytes and xerophytes deserve special
attention, in addition to their economic and medicinal importance [106, 145], they could
