Chemistry Reference
In-Depth Information
However, some recent serious works have identified some of these bacteria from different
Qatari polluted soils using modern techniques [90, 91]. Bioremediation has obvious
advantages over physicochemical remediation methods due to several merits: cost-effective,
convenient, complete degradation of organic pollutants and no collateral destruction of the site
material or its indigenous flora and fauna. Nutrients such as nitrogen and phosphorus can be
added to the soil to improve the effectiveness of land farming alone. These nutrients can boost
the population of naturally occurring microbes. Numerous soil bacteria, including
Pseudomonas
sp. have the ability to degrade organic contaminants so some remediation will
occur. Even with this augmentation, however, larger and more recalcitrant compounds
generally are not remediating at satisfactory rates. The concept of using plants for remediation
of organic pollutants emerged a few decades ago with the recognition that plants were capable
of metabolizing many toxic compounds. There are many studies suggesting the usefulness of
plant-microbe systems in the bioremediation of residual chemicals [92-95]. The presence of
Plant growth-promoting rhizobacteria (PGPR) in rhizosphere can enable plants to achieve high
levels of biomass in contaminated soils despite extreme conditions. Generally, PGPR function
in three different ways: (i) by synthesizing particular compounds for the plants, (ii) facilitating
the uptake of certain nutrients from the environment and (iii) preventing the plants from
diseases [96]. The common traits of growth promotion includes production or changes in the
concentration of plant hormones such as auxin, gibberellins, cytokinins and ethylene [95].
Bioaugmentation is a method to improve degradation and enhance the transformation rate of
xenobiotics by the seeding of specific microbes, able to degrade the xenobiotics of interest.
Extensive degradation of petroleum pollutants generally is accomplished by mixed microbial
populations, rather than single microbial species. Many microbes are described to have the
genetic tools to mineralize recalcitrant pollutants such as PAHs, chlorinated aliphatics and
aromatics, nitroaromatics and long-chain alkanes. These microbes can be wild-type isolates
and genetically modified strains equipped with catabolic plasmids, containing the relevant
degradation genes [93, 94].
5.1. Restoration of habitats
Many habitats are disappearing from several locations in the Gulf region in general and in the
State of Qatar in particular, with the completion of constructions and urban development due
to the great expansion caused by the establishment of infrastructure of the extraction and
industry of oil and gas [4, 97]. Also, cconsiderable achievements being accomplished in Qatar
in the development of land and establishment of roads, high ways, new buildings and many
facilities as preparations to host major political, sport and social activities in the next decade. In
fact, during the last decade and with the beginning of these developments, many reports and
studies have warned the decision makers and scientists that the natural wildlife in the Gulf
area is at real risk and facing serious threat due to the human and industrial activities [41, 46,
98]. Such threat and damage to the environment could be deepened if these activities and
industrial constructions are not coupled by any studies on habitat destruction, fragmentation
or disturbances, and restoration and conservation measures to maintain the natural habitats.
There is fear that before knowledge is obtained on the flora and fauna and their
ecophysiological aspects, these habitats will be lost. Therefore, some serious measures should
