Environmental pollution is exacerbated by the rise in petroleum hydrocarbons due to exploration, production, transportation, and industrialization. This requires immediate remediation. Although crude oil removal using conventional techniques is efficient for cleaning up aquatic and terrestrial ecosystems, it is costly and requires specialized staff and equipment. Despite their negative environmental consequences, chemical compounds such as dispersants, cleansers, emulsifiers, biosurfactants, and soil oxidizers are highly utilized. Phytoremediation and bioremediation have emerged as cost-effective and environmentally friendly technologies. This paper aims to review the impacts of crude oil pollution and the phytoremediation of polluted ecosystems. We have reviewed various phytoremediation/bioremediation mechanisms and environmental factors. Additionally, we have discussed the degradation of crude petroleum, factors affecting petroleum hydrocarbon bioremediation, and the environmental consequences, such as DNA and epigenetic mutations. We have also compared the economics of phytoremediation and restoration of polluted sites with conventional technology. Plants can remediate the environment through phytodegradation, phytostabilization, phytovolatilization, evapotranspiration, and phytoaccumulation. The microbial activities in the plant rhizosphere enhance the degradation and accumulation of the pollutants and modulate their bioavailability, thereby remediating the polluted areas and stabilizing the soil fertility.

Petroleum oil pollution is a worldwide problem that results from the continuous exploration, production, and consumption of oil and its products. Petroleum hydrocarbons are produced as a result of natural or anthropogenic practices, and their common source is anthropogenic activities, which impose adverse effects on the ecosystem’s nonliving and living components including humans. Phytoremediation of petroleum hydrocarbon-polluted soils is an evolving, low-cost, and effective alternative technology to most traditional remediation methods. The objective of this study is to evaluate the phytoremediation potentiality of Vinca rosea for crude oil-contaminated soil by understanding its properties and involvement in the enhanced degradation of crude oil. The remediation potentiality was determined by evaluating the total petroleum hydrocarbon degradation percentage (TPH%) and changes in the molecular type composition of saturated and aromatic hydrocarbon fractions. TPH% was estimated gravimetrically, and changes in the molecular type composition of saturated and aromatic fractions were measured using gas chromatography and high-performance liquid chromatography, respectively. Sulfur concentration was measured using X-ray fluorescence. Cadmium and lead quantification was measured using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The results revealed that V. rosea enhanced total petroleum hydrocarbon (TPH) degradation and altered the molecular composition of the crude oil. The saturated hydrocarbons increased and the aromatic hydrocarbons decreased. The saturated hydrocarbon fraction in the crude oil showed a wider spectrum of n-paraffin peaks than the oil extracted from unplanted and V. rosea-planted soils. Polyaromatic hydrocarbon degradation was enhanced in the presence of V. rosea, which was reflected in the increase of monoaromatic and diaromatic constituents. This was parallel to the increased sulfur levels in planted soil. The determination of sulfur and heavy metal content in plant organs indicated that V. rosea can extract and accumulate high amounts from polluted soils. The ability of V. rosea to degrade TPH and alter the composition of crude petroleum oil by decreasing the toxicity of polyaromatic hydrocarbons in soil, as well as its capability to absorb and accumulate sulfur and heavy metals, supports the use of plant species for the phytoremediation of crude oil-polluted sites.

Phytoremediation is determined as an emerging green technology suitable for the safe remediation and restoration of polluted terrestrial and aquatic environments. In this study, the assessment of an ornamental plant, Vinca rosea L., as a phytoremediator of crude oil in polluted soils was conducted. In an open greenhouse experiment, plants were raised in sandy-clayey soils treated with 1, 3, 5, and 7% oil by weight. The experiment was conducted over 5 months. Total petroleum hydrocarbon (TPH) degradation percentage by V. rosea after a 5-month growth period ranged from 86.83 ± 0.44% to 59.05% ± 0.45% in soil treated with 1 and 7%, respectively. Plants raised in polluted soils demonstrated a dramatic reduction in germination rates, in addition to growth inhibition outcomes shown from decreased plant height. An increase in branching was observed with an increase in oil pollution percentages. Moreover, the phytomass allocated to the leaves was higher, while the phytomass witnessed lower values for fine roots, flowering and fruiting when compared to the controls. Apart from the apparent morphological changes, there was a decrease in chlorophyll a/b ratio, which was inversely proportional to the oil pollution level. The contents of carotenoids, tannins, phenolics, flavonoids, and antioxidant capacity were elevated directly with an increase in oil pollution level. The start codon-targeted (SCoT) polymorphisms and inter-simple sequence repeat (ISSR) primers showed the molecular variations between the control and plants raised in polluted soils. The genetic similarity and genomic DNA stability were negatively affected by increased levels of crude oil pollution. The ability of V. rosea to degrade TPH and balance the increased or decreased plant functional traits at the macro and micro levels of plant structure in response to crude oil pollution supports the use of the species for phytoremediation of crude oil-polluted sites. The genotoxic effects of crude oil on V. rosea still require further investigation. Further studies are required to demonstrate the mechanism of phenolic, flavonoid, and antioxidant compounds in the protection of plants against crude oil pollution stress. Testing different molecular markers and studying the differentially expressed genes will help understand the behavior of genetic polymorphism and stress-resistant genes in response to crude oil pollution.

Mangrove habitats are important ecosystems for their ecological value, and goods and services they offer. These costal habitats are currently vulnerable due to excessive human activities. The black mangrove Avicennia marina (Forssk.) Vierh. (Avicenniaceae) populations growing in Nabq protected area represents the northernmost latitudinal limit of the Indo-Pacific-East African naturally growing mangrove forests. In this study, nine A. marina populations inhabiting Gulf of Aqaba were studied to assess the genetic relationship among the populations by Start Codon Targeted (SCoT) and Inter Simple Sequence Repeat (ISSR) as DNA Markers. Variations of photosynthetic pigment content were assessed in the populations growing in different habitat types. The numbers of polymorphic bands were 18 and 6 for SCoT and ISSR, respectively. The percentage of polymorphism showed wide range amounted 40.9 for SCoT and 25 for ISSR, while the number of amplicon bands ranged from 8–10 in SCoT and 2-9 in ISSR. The genetic relationships among populations using SCoT and ISSR analysis showed close relationship between the nearby but different habitat type populations such as sand mound and littoral populations, or between populations of same habitat types in the study region. The photosynthetic pigment content of chlorophyll a and b, and carotenoids in the littoral and intertidal populations were higher than that in the sand mound and salt plain populations. Populations inhabiting Nabq protected area have wide range of polymorphism among different habitat types. Further studies are required to investigate the genetic relationships among populations of A. marina inhabiting the eastern and western sides of the Red Sea.