Petroleum hydrocarbons are among the major organic environmental pollutants whose toxicity and carcinogenicity effects have raised great concerns while the numerous available physical and chemical methods to remove petroleum hydrocarbons are rarely employed due to their extreme costs and harmful side effects, biological methods, including phytoremediation, have attracted wide attention during the recent years. The current study used sorghum (Sorghum vulgare) and barley (Hordeum vulgare) to decrease petroleum hydrocarbon content of contaminated soil around Isfahan Oil Refinery (Isfahan, Iran). It also assessed the concentrations of petroleum hydrocarbons and petroleum-degrading bacteria at different depths of soil following phytoremediation. Polyvinyl chloride (PVC) pipes (20 cm in diameter and 130 cm long) were employed for phytoremediation. In each pot, hordeum or sorghum seeds were separately sown approximately 1-2 cm below the soil surface. Thirteen weeks after sowing of the plants, soil columns were sampled at 25, 50, 75, and 100 cm depths and concentration of petroleum hydrocarbons and number of oil-degrading bacteria was determined. Statistical analyses indicated the two plants to reduce the concentration of petroleum hydrocarbons to a significantly higher extent (23%-35%) than the control treatment Obviously, such an effect was only detected in depths where plant roots penetrated (especially 0-50 cm), i.e. the absence of roots in deeper parts of the soil column (50-100 cm) was accompanied by lower number of oil-degrading bacteria and higher concentration of petroleum hydrocarbons. Accordingly, future studies are recommended to investigate the efficacy of landfarming and stimulation and injection of oil-degrading microorganisms in eliminating deep soil contamination.

The pearl oyster (Pinctada fucata) is considered as a valuable resources in the Persian Gulf. The aim of this research was to investigate the impact of petroleum hydrocarbons on density as well as destruction of this oyster. For this purpos, the Lavan region (Dardur, Hedabad, Chalil), Nakhilou and Hendurabi were chosen as the present habitat of the pearl oyster and Bostaneh, Moghooyeh, Molou and Geshe as the former habitat.
The statistical analysis showed that the amount of petroleum hydrocarbons in sediments and soft tissues of oysters of Lavan stations is significantly different and Lavan region due to being close to oil terminals is more polluted. Meanwhile in winter petroleum hydrocarbons was found more than summer. Regarding to the density of oyters, it can be concluded that in present habitats with the increase of petroleum hydrocarbons in the body of oysters and sediments, the density of oyster was decreased.

Today oil removal from contaminated soil by new methods such as bioremediation is necessary. In this paper, the effect of chemical fertilizers and aeration on bioremediation of oil-contaminated soil has been investigated. Also the control group, (bioremediation of petroleum hydrocarbons in contaminated soil without treatment by chemical fertilizers and aeration treatment was examined. The condition of experiment is as following: those were treated 70 days in glass columns (30×30×30cm dimensions), ambient temperature (25-30 0C), relative humidity 70%, aeration operation with flow 0.7 lit/min. The total number of heterotrophic bacteria of break down oil and the total of petroleum hydrocarbons were analyzed using gas chromatography analysis. all experiments were replicated three times. The microbial population results for control soil, treated soil by aeration and treated soil by aeration and chemical fertilizers columns are 2.3×105, 1.04×1010, and 1.14×1011 CFU/gr, respectively. The concentrations of total petroleum hydrocarbons of remaining are 46965, 38124, and 22187 mg kg-1respectively. The obtained results show that the aeration operation and chemical fertilizers have effective role on degradation of petroleum hydrocarbon by oil degrading bacteria from soil.

Elimination or reduction of petroleum hydrocarbons from natural resources such as water and soil is a serious problem of countries, particularly oil-rich countries of the world. Using white rotting fungi compost for bioremediation of soils contaminated by petroleum hydrocarbons is effective. The aim of this study is molecular identification and potential of anisolate of white rot fungi in bioremediation of petroleum contaminated soils.
Spent compost of white rotting fungi was inoculated with petroleum contaminated soil into 3%, 5% and 10% (w/w). Treatments were incubated at 25-23 °C for 3 months. Reduction of petroleum hydrocarbons in treated soil was determined by gas chromatography. Ecotoxicity of soil was evaluated by seed germination test.
Based on the genome sequence of 18s rRNA, it is revealed that this isolate is Ganoderma lucidum and this isolate is deposited as accession KX525204 in the Gene Bank database. Reduction of petroleum hydrocarbons in soil treated with compost (3, 5 and 10%) ranged from 42% to 71%. The germination index (%) in ecotoxicity tests ranged from 20.8% to 70.8%. Gas chromatography results also showed a decrease in soil Hydrocarbons compounds.
Discussion and The compost of Ganoderma lucidum, a white rot fungus, has a potential ability to remove petroleum hydrocarbons in contaminated soil. Removal of hydrocarbons was increased with increase in compost mixed with contaminated soil. Petroleum contaminated soil amended with spent compost of G.lucidum 10% during three months is appropriate to remove this pollutant.

Crude oil is a complex combination of many hydrocarbon and non-hydrocarbon compounds, including heavy metals, which affect the physical and chemical properties of the soil, cause the soil particles to stick and connect and then cause the soil to become stiff and impenetrable. Contamination of soil with petroleum hydrocarbons is a significant environmental problem, which has received remarkable attention in recent decades. Petroleum hydrocarbons are resistant and hazardous pollutants. Some petroleum hydrocarbons such as benzene are mutagenic and carcinogenic materials for humans. There are many physical and chemical methods to remediate oil-contaminated soils. Phytoremediation is a relatively new technology for refining contaminated soils in which resistant plants are used to remove or reduce the concentration of inorganic, radioactive, and organic pollutants, especially petroleum compounds, from the environment.

Sufficient amounts of about 50 kg of soil contaminated with petroleum hydrocarbons were collected from regions (0-30 cm soil depth) adjacent to the oil wells west of Kermanshah province. Uncontaminated soil samples were also taken from sites at the lowest distance to the contaminated sites. The aim of this study was to compare the efficiency of different plants to remove total petroleum hydrocarbons from oilfield soils. In this study, after determining the total amount of petroleum hydrocarbons, the contaminated and uncontaminated soils were mixed in 4 treatments with different weight ratios (0, 10, 25, and 35%). This experiment was established as completely randomized design with 3 replications for 6 different plants (Barley, Grass, Alfalfa, Hemp, Camelina, and Vicia ervilia). One treatment without plant was considered to remove soil matrix effects on petroleum hydrocarbon concentrations. Plants were harvested at the end of their growing season (90-120 days). Soils and plant samples from the experimental pots were analyzed for their important properties (including some physiological characteristics of the plants, as well as the percentage of reduced petroleum hydrocarbons in the soils). The gravimetric method was used to determine the concentration of petroleum hydrocarbons in the soil. After measuring the properties of the soil and plant, the normality of the data was checked by the Anderson–Darling test, and the homogeneity of the variance of the treatments was checked by using Levene's test. Analysis of data variance was done using ANOVA and average data comparison was done using LSD test at 5 and 1 percent probability levels (SAS 9.4 and SPSS 26).

In general, the growth of most plants showed a decreasing trend in proportion to the increase in soil pollution levels. However, the growth decline rates of different plants were not similar. Camelina was very sensitive to oil pollution and the plant could not tolerate pollution even at 10% level. After camelina, alfalfa was highly sensitive to oil pollution. The highest dry weight of the aerial parts of the hemp plant in the soil without oil contamination was observed at the rate of 111.22 grams in the pot. The leaf area of all studied plants in contaminated soils decreased compared to the control treatment (without contamination) so with the increase in the percentage of contamination, the leaf area of the plants was significantly reduced. The highest amount of leaf surface was observed in unpolluted soil and in the hemp plant. Except for the Camelina plant, which was completely destroyed at different levels of pollution, the rest of the plants showed a noticeable decrease in growth. The total petroleum hydrocarbons in soil were measured again 120 days after the start of cultivation, and its difference with the total amount of petroleum hydrocarbons at the beginning of cultivation was determined as the reduction of petroleum hydrocarbons and reported as a percentage. According to the mean comparison results, the percentage of reduced petroleum hydrocarbons was not significantly different among cultivated and non-cultivated treatments, although, it was significantly affected by soil pollution levels. Since all the studied soils contained natural bacteria and were not sterilized, the eliminated part of petroleum hydrocarbons is probably decomposed and removed by native bacteria in the soils. Therefore, the strengthening of native bacteria in these soils may increase the decomposition and degradation of petroleum hydrocarbons.

The results of this research show that the presence of petroleum hydrocarbons in the soil caused a decrease in growth and other physiological characteristics in all studied plants. Although the Camelina was able to germinate in soils contaminated with petroleum hydrocarbons, the presence of these pollutants in the soil prevented the optimum growth of the plant, so its use in subsequent studies of phytoremediation of oil-contaminated soils, was not recommended. The results showed that there is no statistically significant difference between cultivated and non-cultivated treatments at different pollution levels, and the reduction of the total petroleum hydrocarbons in the soil was probably done by native microorganisms in the soil. It is recommended to take into consideration the efficiency of the plant species used, the type of polluting hydrocarbons, and the duration of contamination in future research to obtain better results.

These days, one of the most important environmental problems is soil pollution due to the contamination by petroleum hydrocarbons. One of the methods for reducing of soil contamination is the use of the electrokinetic process for remediation of hydrocarbons contaminated soils. Electrokinetic process causes the movement of water, ions and charged particles in the soil by electric field voltage. In this study, the effect of pH control in catholyte and anolyte on electrokinetic for removal of petroleum hydrocarbons from a clay soil, was evaluated. For this purpose, two experiments; one without pH control and second with pH control (in the range of 6-9) in electrolytes were carried out. Initial concentration of petroleum hydrocarbons in soil was 5%. The amount and type of petroleum hydrocarbons in the soil samples were measured by GC-MS. The results of both experiments showed that after 30 days, and 1 Vcm-1 electric field voltage, the highest percentage hydrocarbons was near anodes with little movement in the middle column. The average of petroleum hydrocarbons removal of two experiments was 16.67% and 31.5%, respectively. In addition, in the second experiment, about 26% of paraffin hydrocarbon and 37% of naphthalene hydrocarbons were removed from the soil column.

Due to the location of a domestic, industrial and agricultural zone near the Caspian Sea, this water body has long been under pressure and environmental threat. As a result of development of oil production activities in Caspian region, such as oil exploration and extraction, a large volume of oil related pollutants is released annually into this important water body. Considering the fact that hydrocarbons may cause adverse impacts on the aquatic and marginal life, the monitoring of sediment as hydrocarbons in the sea has been considered. The purpose of this article is determination of total petroleum hydrocarbon (TPH) and comparing it with other coastal area in Caspian region-in Gilan, Mazandaran and Golestan from spring 2010 to spring 2011. 225 water sample and 75 sediment sample in 15 stations during of 5 seasons have been collected and the levels of total petroleum hydrocarbon (TPH) using FT-IR were determined. Based on results level of total petroleum hydrocarbon (TPH) is the most level in autumn 2010. Also the highest and lowest level of total petroleum hydrocarbon in water were recorded in station 7 (Dastak region) and station 1 (Astara), respectively. Moreover, the highest and lowest level of total petroleum hydrocarbon in sediment were recorded in station 13 (Neka powerhouse) and station 8 (Ghasem abad), respectively. The results of ANOVA show that level of TPH in water and sediment among different seasons is significant, but there isn’t a significant difference among different stations.

Reducing the entry of heavy metals into the food chain in plant cultivated in the areas contaminated with heavy compounds or petroleum compounds is one of the main environmental issues. This research was conducted to evaluate the role of co-inoculation of wheat with piriformospora indica and pseudomonas putida on plant Cd concentration which has been planted in the Cd and petroleum hydrocarbon -polluted soil and treated with Zn oxide nanoparticles and agricultural steel slag. Treatments consisted of Cd-polluted soil (0, 10 and 20 mg kg-1 soil) that was amended with 0 and 2 % (W/W) Zn oxide nanoparticles and agricultural steel slag and the wheat plant that was co-inoculated with P.indica and P.putida that which was cultivated in a soil that was naturally polluted with petroleum hydrocarbon. After 90 days, plants were harvested and the Cd concentration was measured using atomic absorption spectroscopy. In addition the degradation rate of petroleum hydrocarbon in the soil was determined. Plant co-inoculation with P.indica and P.putida significantly decreased and increased the plant Cd concentration and degradation rate of petroleum hydrocarbon in the soil by 13.1 and 14.9%, respectively. In addition, using 2 % (W/W) Zn oxide nanoparticles and agricultural steel slag significantly decresed the plant Cd concentration by 18.2 and 15.4%, respectively. It can be concluded that plant co-inoculation with P.indica and P.putida had additive effect on degradation of petroleum hydrocarbon in the soil that was amended with Zn oxide nanoparticles and agricultural steel slag.

Oil pollution is recognized as one of the significant threat to soil fertility and plant production. Pollution caused by petroleum hydrocarbons, reduces the hydraulic conductivity of soils, leading to increased erosion and runoff, and decreased plant growth. One practical approach for remediating soils contaminated with petroleum hydrocarbons is using biosurfactant-producing microorganisms that can degrade these compounds. This study examined the efficacy of a microbial consortium comprising the bacterial strains Dietzia aerolata PS14B1, Kocuria salina PS12B2, and Mesobacillus harenae PS9D12 in altering the permeability coefficient of soil contaminated with high pollution (TPH). In the hydrocarbon growth and degradation test in the mineral base medium after seven days of incubation, the results showed that strains PS14B1, PS12B2, and PS9D12 were successful in reducing Total Petroleum Hydrocarbons (TPH) by 25.63%, 24.11%, and 22.83%, respectively, which was significantly different from the control (P<0.05).  The inoculation of the bacterial strains into the soil and subsequent 30-day incubation demonstrated a significant increase in soil hydraulic conductivity, from 1.18 cm h-1 to 9.12 cm h-1, compared to the control treatment (3.24 cm h-1). These findings suggest that the bacterial consortium holds potential for the sustainable remediation of oil-contaminated sites and the enhancement of soil permeability in polluted areas.

Cutting and drilling mud contains significant amounts of petroleum hydrocarbons that are detrimental to both the environment and public health. The objective of this study was to remove the hazardous components of drill cutting mud using the two biological processes of sewage sludge vermicomposting and biocomposting. In an experimental laboratory research, two pilot composting and vermicomposting processes, each over a period of two months with 2 repetitions, were conducted using the the same biological sludge mixed with drill cuttings contaminated with total petroleum hydrocarbon (TPH) along with sawdust and yard waste. The GC-FID unit was used to determine the residual total petroleum hydrocarbon concentrations. Results showed that the vermicomposting pilot had a higher TPH removal efficiency than did the composting one so that TPH concentration in the mixed waste mass declined after 60 days from its original value of 42.004 g/kg to 11.316 g/kg. In other words, TPH removal in the pilots A (vermicomposting) and B (biocomposting) were 73/06% and 55/3%, respectively. Moreover, the TPH levels in the two composting and vermicomposting pilots on the 45th and 60th days showed significant differences (p