Petroleum Hydrocarbon Concentrations Research Articles

Legacy Effects of Phytoremediation on Plant-Associated Prokaryotic Communities in Remediated Subarctic Soil Historically Contaminated with Petroleum Hydrocarbons.

Phytoremediation of petroleum hydrocarbons in subarctic regions relies on the successful establishment of plants that stimulate petroleum-degrading microorganisms, which can be challenging due to the extreme climate, limited nutrients, and difficulties in maintaining sites in remote locations. A long-term phytoremediation experiment was initiated in Alaska in 1995 with the introduction of grasses and/or fertilizer to petroleum hydrocarbon (PHC)-contaminated soils that were subsequently left unmanaged. In 2011, the PHC concentrations were below detection limits in all soils tested and the originally planted grasses had been replaced by volunteer plant species that had colonized the site. Here, we sought to understand how the original treatments influenced the structure of prokaryotic communities associated with plant species that colonized the soils and to assess the interactions between the rhizospheric and endophytic communities of the colonizing vegetation 20 years after the experiment was established. Metataxonomic analysis performed using 16S rRNA gene sequencing revealed that the original type of contaminated soil and phytoremediation strategy influenced the structure of both rhizospheric and endophytic communities of colonizing plants, even 20 years after the treatments were applied and following the disappearance of the originally planted grasses. Our findings demonstrate that the choice of initial phytoremediation strategy drove the succession of microorganisms associated with the colonizing vegetation. The outcome of this study provides new insight into the establishment of plant-associated microbial communities during secondary succession of subarctic areas previously contaminated by PHCs and indicates that the strategies for restoring these ecosystems influence the plant-associated microbiota in the long term. IMPORTANCE Subarctic ecosystems provide key services to local communities, yet they are threatened by pollution caused by spills and disposal of petroleum waste. Finding solutions for the remediation and restoration of subarctic soils is valuable for reasons related to human and ecosystem health, as well as environmental justice. This study provides novel insight into the long-term succession of soil and plant-associated microbiota in subarctic soils that had been historically contaminated with different sources of PHCs and subjected to distinct phytoremediation strategies. We provide evidence that even after the successful removal of PHCs and the occurrence of secondary succession, the fingerprint of the original source of contamination and the initial choice of remediation strategy can be detected as a microbial legacy in the rhizosphere, roots, and shoots of volunteer vegetation even 2 decades after the contamination had occurred. Such information needs to be borne in mind when designing and applying restoration approaches for PHC-contaminated soils in subarctic ecosystems.

Review of Determination of Heavy Metals and Total Petroleum Hydrocarbon Concentrations in Remediated Crude Oil Contaminated Soil

The discharge of crude oil products to the environment (soil, water and air) has great negative impacts on the organisms living therein. Most of these effects are from heavy metals, total petroleum hydrocarbons (TPH), polyaromatic hydrocarbons (PAH) among others. This research adopts an extensive review of literatures such as conference papers, journal articles, internet sources, books to find out the amount of total metal concentrations and the total petroleum hydrocarbons (TPH) that are likely to be found on crude oil contaminated soil even after remediation or cleanup activities have been carried out. The driving force behind this research is the fact that the people living in most petroleum-contaminated areas such as the Niger Delta Region of Nigeria still experience some negative effects (such as health and agricultural effects) associated with the crude oil pollutants even after remediation. The study concludes that even though heavy metals were still present in the remediated soil, they are not bioavailable for plants uptake; hence their presence is negligible harmless. On the other hand, the total petroleum hydrocarbons (TPH) that remains after cleanup is still well above the background level. As such, it would impose negative impacts on the inhabitants of such areas. The study further recommends that more effective methods of remediation should be carried out, or a combination of more than one method should be adopted in other to obtain absolute cleanup of the polluted area..

Germination Capacity of Helianthus annuus Less Seeds on Soil Media Contaminated by Waste

Used oil waste is often dumped on the ground around the workshop, causing soil pollution which can reduce the function of the soil. The most difficult contaminants in used oil waste to decompose are hydrocarbon compounds, which are highly toxic, polycyclic aromatic hydrocarbons (PAHs). The concentration of oil hydrocarbon contaminants in a sample is determined by measuring the total petroleum hydrocarbon (TPH) concentration. This study was conducted to determine the germination ability of Helianthus anuus, Less seeds on soil media contaminated with waste oil at different concentrations of Total Petroleum Hydrocarbon (TPH). The results showed that the concentration of TPH in the media could inhibit the speed of seed germination. Treatment with low concentration of TPH 2.7% in the media increased % germination, shoot and root length and sprout biomass compared to the medium/intermediate (8.00%) and high (12.26%) TPH treatments and controls. However, there was no significant difference between all treatments regarding germination time and shoot length, although in the low TPH treatment (2.70%) there was a tendency for germination time to be faster than the other treatments, as well as to shoot length which was longer than the other treatments. The higher TPH concentration in the media can inhibit germination time, germination percentage, shoot and root length and biomass. Morphological observations of the growth of sprouts showed an inhibition of root hair formation along with the high TPH content in the media, but all treatments did not affect the growth of the shoots.

Investigation of Petroleum Hydrocarbons in Soil from Auto-mobile Mechanic Workshops within Ikot Akpaden, Mkpat Enin L.G.A Akwa Ibom State Nigeria

This study investigates the concentrations of total petroleum hydrocarbon (TPH) and total hydrocarbon content (THC) in soil samples from auto-mobile mechanic workshop in Ikot Akpaden, Mkpat Enin. Soil samples were collected in triplicate at different points within the vicinity of auto-mobile mechanic workshop at Ikot Akpaden represented as site A and control samples were obtained within the frontage of Chemistry Department, AKSU represented as site C. Soxhlet extraction and shaking methods were used for the extraction of the total petroleum hydrocarbons and total hydrocarbon content respectively. Each of the sample extracts were purified using column chromatography to remove moisture, polar hydrocarbons, colour interferences and any impurities before GC analysis. Total petroleum hydrocarbons and THC were analyzed using Gas Chromatography (GC-FID) and UV-VISIBLE spectrophotometer respectively. The results obtained from TPH analysis indicates that; 15,223.4 mg/kg was recorded from the auto-mobile mechanic workshop and 808.507 mg/kg was recorded from the control samples. The results from the two stations were higher than the department of petroleum resources (DPR) permissible limit of 50 mg/Kg for soils. There was significant difference in the concentration of total hydrocarbon content, the result obtained showed that, the three sampling point at the mechanic workshop has THC level in the order; A1>A3>A2. The concentration of THC obtained in the three points were greater than the 0.6 mg/Kg limit of total hydrocarbons content allowed by the DPR. The study revealed that the soils were polluted as a result of indiscriminate disposal of waste petroleum products (used engine oil, petrol, diesel and other lubricants) directly on the soil, as well as dumping and burning of waste at the auto-mobile mechanic workshops. Hence, there is need for a holistic and sustainable monitoring and remediation of the environment for a cleaner and healthier environment.

Shift of combined ecotoxicity index in petroleum polluted soils during a bacterial remediation

Introduction: Bioremediation has been shown to be an effective strategy for removing toxic pollutants from the environment, particularly organic chemicals such as petroleum hydrocarbons. This paper investigates the changes in toxicity of petroleum-contaminated soil as a result of microbial remediation processes.Methods: Changes in the ecotoxicity of the contaminated soil were examined using a plant, earthworm, enzyme activity and luminescent bacteria toxicity tests.Results: The results showed that bioremediation could effectively degrade petroleum hydrocarbon (C10–C40) pollutants. After 42 days of remediation, the petroleum hydrocarbon (C10–C40) content of Group A (bioaugmented polluted wetland soil) decreased from 1.66 g/kg to 1.00 g/kg, and the degradation rate was 40.6%. The petroleum hydrocarbon (C10–C40) content of Group B (bioaugmented polluted farmland soil decreased from 4.00 g/kg to 1.94 g/kg, and the degradation rate was 51.6%. During the microbial remediation progress, the ecological toxicity of petroleum-contaminated soil first increased and then decreased. The photosynthetic pigment content index in the higher plant toxicity test, the earthworm survival index and the soil catalase activity all showed good agreement with the relative luminescence index of extracted DCM/DMSO in the luminescent bacterial toxicity test. The soil toxicity decreased significantly after remediation. Specifically, the photosynthetic pigment content of wheat were inhibited in the soil during the whole process (remediation for 42 days), and decreased to the minimum on remediation day 21. The 7-day and 14-day survival rate of earthworms in Group A and Group B gradually decreased in the soil remediation process, and then gradually increased, survival rate at the end of remediation was higher than at the beginning. Soil catalase activity was significantly negatively correlated with petroleum hydrocarbon (C10–C40) content (−0.988, −0.989). The ecological toxicity of contaminated soil reached to the maximum on the 21st day of remediation, relative luminosity of luminescent bacteria in dichloromethane/dimethyl sulfoxide extracts from Group A and Group B were 26.3% and 16.3%, respectively.Conclusion: Bioremediation could effectively degrade petroleum hydrocarbon (C10–C40) pollutants. Wheat photosynthetic pigment content, earthworm survival rate, soil catalase activity and relative luminescence of luminescent bacteria can better indicate the ecological toxicity of petroleum-contaminated soil in bioremediation process.

Thermal treatment of petroleum-contaminated marine sediment according to oxygen availability and temperature: Product quality as a potential plant-growth medium

The sustainable management of dredged sediment from contaminated sites needs to consider the end-use of the treated sediment. In this regard, modifying conventional sediment treatment techniques to generate a product that is suitable for a range of terrestrial uses is necessary. In the present study, we evaluated the product quality of treated sediment as a potential plant-growth medium following the thermal treatment of marine sediment contaminated by petroleum. The contaminated sediment was subject to thermal treatment at temperatures of 300, 400, or 500 °C, and no, low, or moderate oxygen availability, and the resulting treated sediment was analyzed in terms of its bulk properties, spectroscopic properties, organic contaminants, water-soluble salts and organic matter, and the leachability and extractability of heavy metals. All operational combinations for the treatment process reduced the total petroleum hydrocarbon content of the sediment from 4922 mg kg−1 to lower than 50 mg kg−1. The thermal treatment process stabilized the heavy metals in the sediment, reducing the zinc and copper concentration by up to 58.9% and 89.6%, respectively, in the leachate from the toxicity characteristic leaching procedure. The hydrophilic organic and/or sulfate salt byproducts of the treatment were phytotoxic, but these can easily be removed by washing the sediment with water. By combining the sediment analysis results with experimental data from barley germination and early-growth tests, the end product was found to be of higher quality when higher temperatures and lower oxygen availability were employed in the treatment process. These findings demonstrate that it is possible to retain the natural organic resources of the original sediment by optimizing the thermal treatment, thus ensuring a suitably high product quality for use as a plant-growth medium.

OPTIMIZATION OF BIOSTIMULANTS REQUIREMENTS FOR ENHANCED BIOREMEDIATION OF CRUDE OIL SLUDGE POLLUTED SOILS

The study was aimed at investigating the optimal requirement of biostimulants in the bioremediation of crude oil sludge polluted soils. The contaminated environment was simulatedwith 1.0kg crude oil sludge on 2.0kg soil and uniformly homogenized. The polluted soils were then simulated with NPK, Cowdung and Moringaleaf powder based on total biostimulant to soil ratio of 0:1 to 0.75:1. These biostimulants were applied individually and in varying combinations to the polluted soils in three distinct segments (1, 2, 3) corresponding to the total biostimulant to soil ratios 0.25:1, 0.50:1 and 0.75:1 respectively while the control experiment which proceeded on natural attenuation was 0:1. Results of the experiments which lasted for 92 days showed marked reduction in Total Petroleum Hydrocarbon (TPH) content in the biostimulated experiments, E1 to E30. The control experiment, E31, which was non-biostimulated showed minimal reduction in TPH throughout the experiment due to the absence of added nutrients. In the single biostimulant application, moringa leaf powder (MLP) was found to give the best degradative performance at an optimal biostimulant to soil ratio of 2.04:1corresponding to 99.9957% bioremediation of the polluted soil being investigated. This result justifies the introduction of MLP as a suitable biostimulant for bioremediation studies and a possible substitute for NPK which is very expensive and not readily available for use. In the double biostimulant combination category, NPK + mlp mixing resulted in the best degradation efficiency. The optimum extent of degradation was 100% at optimum biostimulant to soil ratio of 2.04:1. The optimum extent of remediation for combination of all three biostimulants (NPK + CD + MLP) were found to be 99.15% at optimal biostimulant to soil ratio of 2.04:1.

Using Sweet Sorghum Varieties for the Phytoremediation of Petroleum-Contaminated Salinized Soil: A Preliminary Study Based on Pot Experiments

Using energy plants to repair salinized soils polluted by petroleum is an efficient way to solve the problem of farmland reduction and prevent pollutants from entering the food chain simultaneously. In this study, pot experiments were conducted for the purposes of preliminarily discussing the potential of using an energy plant, sweet sorghum (Sorghum bicolor (L.) Moench), to repair petroleum-polluted salinized soils and obtain associated varieties with excellent remediation performance. The emergence rate, plant height and biomass of different varieties were measured to explore the performance of plants under petroleum pollution, and the removal of petroleum hydrocarbons in soil with candidate varieties was also studied. The results showed that the emergence rate of 24 of the 28 varieties were not reduced by the addition of 1.0 × 104 mg/kg petroleum in soils with a salinity of 0.31%. After a 40-day treatment in salinized soil with petroleum additions of 1.0 × 104 mg/kg, 4 potential well-performed varieties including Zhong Ketian No. 438, Ke Tian No. 24, Ke Tian No. 21 (KT21) and Ke Tian No. 6 with a plant height of >40 cm and dry weight of >4 g were screened. Obvious removal of petroleum hydrocarbons in the salinized soils planted with the four varieties were observed. Compared with the treatment without plants, the residual petroleum hydrocarbon concentrations in soils planted with KT21 decreased by 69.3%, 46.3%, 56.5%, 50.9% and 41.4%, for the additions of 0, 0.5 × 104, 1.0 × 104, 1.5 × 104 and 2.0 × 104 mg/kg, respectively. In general, KT21 had the best performance and application potential to remediate petroleum-polluted salinized soil.

Bioventing revisited: efficacy of enhanced biodegradation for sites with mobile LNAPL

Bioventing is a remediation technology that enhances aerobic biodegradation of petroleum-affected soil in the vadose zone by introducing oxygen to the subsurface. Bioventing was historically considered effective for decreasing petroleum hydrocarbons concentrations in soil but discounted for sites where mobile light non-aqueous phase liquid (LNAPL) accumulated in wells. While the science behind bioventing has not changed, the conceptual understanding of LNAPL depletion processes and framework for evaluating the efficacy of LNAPL remediation technologies has changed markedly since the 1990s. This shift leads to a new perspective on the utility and effectiveness of bioventing compared to other LNAPL remedial alternatives. A case study is used to illustrate that mass depletion by bioventing often outperforms hydraulic recovery over time. Biodegradation processes enhanced by bioventing deplete LNAPL constituents in mobile and residual LNAPL in the LNAPL smear zone, which means that bioventing can address a larger mass of LNAPL and may induce a beneficial composition change. Hydraulic LNAPL recovery technologies only access the mobile LNAPL and do not induce a composition change. Furthermore, for low LNAPL recoverability (transmissivity), bioventing typically uses less energy and produces less waste per unit mass of hydrocarbon removed than hydraulic recovery, making bioventing a more sustainable remedial technology.

Bioaccumulation Potential of Cynodon dactylon Linn. in Crude Oil Contaminated Soil.

A greenhouse experiment was conducted to investigate the growth of Cynodon dactylon Linn. in soils contaminated by various concentrations of crude oil with a view to assessing its phytoremediating potential. The crude oil prepared at different concentrations of 0.0, 2.5, 5.0, 7.5, 10.0 and 12.5 (w/v) acted as contaminants on 3kg each of air-dried soil collected from the Obafemi Awolowo University Biological garden which is rich in organic matter. Each treatment was replicated 10 times in complete randomized design. Significantly (p<0.05) highest residual total petroleum hydrocarbon content (THC) uptake (39.26 ppm) was obtained in the plant at 12.5 ml contamination with the least residual total petroleum hydrocarbon content uptake (12.79 ppm) obtained at 2.5 ml contamination. With increased contamination, there was positive correlation with residual total petroleum hydrocarbon content uptake in the plants. No detectable amount of petroleum hydrocarbon content was found in the soil at the end of the experiment. The study concluded that C. dactylon plant could be effectively used in the phytoremediation of crude oil contaminated soil without addition of soil amendment.

Impacts of Contaminants on Groundwater Quality in Rukpokwu, Delta Region of Nigeria

This study investigated the characterization of borehole sediment and the impact of contaminants on groundwater quality in the Rukpokwu Community in the delta of Nigeria. The investigation supported by spatial data supported by GIS techniques provides a data baseline for the monitoring of organo-contaminants in groundwater quality in Rukpokwu. This low pH of the groundwater and irritation of the throat and mouth became a concern to the residents. This study is necessary because of the limited data on the level of organic contamination in groundwater in this section of the delta of Niger in Nigeria. So, there was a need to track the source of contamination in this part of the delta of Niger in Nigeria. These previous studies have suggested a highly permeable open aquifer in similar deltaic terrain. Ten (10) samples of borehole sediment and water collected at 30 m depth were being analyzed for textural and physicochemical characteristics. The parameters analyzed include Iron (Fe), Total Petroleum Hydrocarbon &Total Hydrocarbon Content (i.e., TPH and THC respectively) of borehole sediment in association with groundwater quality. Ten (10) sediment samples collected at a depth of 30m and were being analyzed for mean, sorting, skewness and kurtosis, using standard laboratory procedures. Coarse silt, poorly sorted and negatively skewed were the characteristics of the borehole silt. The Kurtosis suggested the leptokurtic and platykurtic nature of the sediment. The TPH and THC range from 0.58 to 0.85 mg/L and 1.26 to 2.84 mg/L respectively. The Fe and pH range in the sediment were 0.85 to 2.46 mg/L and 4.43 to 6.02 respectively. However, Fe in the groundwater ranges from 0.12 to 0.21 mg/L. The results were above the World Health Organization's acceptable contaminant level. Based on the piece of evidence provided by spatial data mapping and textural parameters, the characteristics of the borehole sediment significantly controlled the ingress of contaminants into the groundwater. The source of groundwater contamination is the abnormal concentrations of organic contaminants. These results significantly impact human health in the food chain. This study provides information to the environmental agency for a clean-up process.

Newly isolated halotolerant Aspergillus sp. showed high diesel degradation efficiency under high salinity environment aided with hematite

The contamination of saline soil with hazardous petroleum hydrocarbons is a common problem across coastal areas globally. Bioaugmentation combined with chemical treatment is an emerging remediation technique, but it currently shows low efficiency under high saline environments. In this study, we screened and used a novel halotolerant lipolytic fungal consortium (HLFC) combined with hematite (Fe2O3) for the bioremediation of diesel contaminated saline soils. The changes in total petroleum hydrocarbons (TPH) concentrations, enzyme activity, and microbial diversity were compared among different treatments (HLFC, hematite, hematite-HLFC, and control). The results showed that TPH degradation was significantly (P<0.05) enhanced in hematite-HLFC (47.59-88.01%) and HLFC (24.26-72.04%) amended microcosms across all salinity levels, compared to the treatments of hematite (23.71-66.26%) and control (6.39-55.20%). TPH degradation was positively correlated with lipase and laccase enzyme activities, electrical conductivity, and the water holding capacity of the soil. Analyses of the microbial community structure showed that microbial richness decreased, while evenness increased in HLFC and hematite-HLFC treatments. The relative abundances of Alicyclobacillus, Sediminibacillus, Alcanivorax, Penicillium, Aspergillus, and Candida genera were significantly high in hematite-HLFC and HLFC amended microcosms. Our findings provide a promising new microbial-based technique, which can degrade TPH efficiently in saline soil.

Lagena Inferocostata – An Opportunistic Index Species of Hydrocarbon Pollutants in Gokana and Khana Local Government Areas of River State, Nigeria

Thirty shallow cores ranging from 0.0 – 1.0m and composited into upper and lower section, was studied to determine relationship between petroleum hydrocarbon pollutants and benthic foraminiferal species in order to determine an index for environmental monitoring in the study area. The core samples were taken from Gokana and Khana Local Government Areas of Rivers State, Nigeria. The cores were treated with Rose Bengal solution to distinguish between then acoenose and biocoenosis benthonic foraminiferal. The cores were analyzed for sedimentology, petroleum hydrocarbon concentrations and micropaleontology. Sedimentological descriptions of the cores indicated inhibited free flow of fluids based on the rock textures which mostly consists of clays and peaty clays. Petroleum hydrocarbons analysis consisted of Total Petroleum Hydrocarbon (TPH) and Polycyclic Aromatic Hydrocarbon (PAH). The results in concentrations of the petroleum hydrocarbons indicated higher concentrations in the upper composited sections. Total Petroleum Hydrocarbon (TPH) and Polycyclic Aromatic Hydrocarbon (PAH) ranged between (20612mg/kg – 37.09mg/kg and 9.55mg/kg – &lt;0.01mg/kg respectively) in the upper composited section and between (14731mg/kg – 14.67mg/kg and 5.71mg/kg – &lt;0.01mg/kg respectively) in the lower composited section. Occurrence of benthonic foraminiferal in the study samples is very low to barren among very low diversity. Three benthonic foraminiferal diversities were identified in the study samples and included Lagenainferocostata, Anomalinoidesspp and Ammodiscus spp. Benthonic foraminifera showed negative correlation with TPH/PAH in the presence of carcinogenic Polycyclic Aromatic Hydrocarbon (PAH) congeners except for Lagenainferocostata which increased consistently and significantly with increasing TPH/PAH in the two composited sections. This suggested Lagenainferocostata as an Index opportunistic species for the hydrocarbon polluted study area.

Approaches to the development of environmental standards for the content of petroleum hydrocarbons and Pb, Cr, Cu, Ni in soils of Greatest Caucasus

&lt;p&gt;The development of tourism and leisure infrastructure results in a continuous increase of anthropogenic impact on soils of wet and dry subtropics of the Greatest Caucasus. It is very important for the region to preserve the sustainable functions of soils and ecosystems, maintain a comfortable life and recreation environment create environmentally friendly agricultural products. It is conducted studies to determine the limits of resistance of soils in wet and dry sub-tropics to priority pollutants, especially petroleum hydrocarbons and heavy metals (Pb, Cr, Cu, Ni). It was found that the soils of wet and dry subtropics for resistance by Pb, Cr, Cu, and Ni are located as follows: south-ern chernozem &amp;gt; typical sod-carbonate soil ≥ brown typical soil ≥ brown carbonate soil = brown leached soil ≥ leached sod-carbonate soil = yellow soil &amp;gt;acid brown forest soil ≥ acid brown forest podzolized soil. In terms of the degree of resistance to oil pollution, studied soils create certain series: brown carbonate ≥ brown typical = sod-carbonate leached ≥ sod-carbonate typical &amp;gt; southern chernozem ≥ yellow soil ≥ brown leached soil &amp;gt; acid brown forest soil = acid brown forest podzolized soil. Heavy metals by ecotoxicity to the soils of wet and dry subtropics from the following series: Cr&amp;gt; Cu ≥ Ni = Pb. Based on the degradation of ecological functions of soils, we offer regional standards of the maximum permissible content of Pb, Cr, Cu, and Ni for the main soils of wet and dry subtropics.&lt;/p&gt;

Genotoxic Effects of Exposure to Water-Soluble Fraction of Diesel Fuel in Sand Dollar Scaphechinus mirabilis Gametes.

Pollution of marine areas with oil and oil products is steadily growing. As part of this connection, the study of the impact of petroleum hydrocarbons on marine hydrobionts is an urgent issue of modern ecotoxicology. In our study, the genotoxic effect of the water-soluble fraction of diesel fuel at different concentrations on the gametes of the sand dollar Scaphechinus mirabilis was evaluated. It was shown that during the incubation of sperm and eggs of a sand dollar in WAF with an oil hydrocarbon content of 1.32; 2.64; 5.37; 7.92 mg/L caused the destruction of the DNA molecule to varying degrees in both types of gametes. In addition, it has been shown that with an increase in the concentration of petroleum hydrocarbons in WAF, a large number of cells with a high level of DNA damage appear. The success of fertilization after exposure of gametes to a water-soluble extract of petroleum hydrocarbons was also evaluated. The relationship between an increase in the concentration of hydrocarbons in the tested solutions and a decrease in the level of fertilization is shown.

Physico-Chemical and Entomofauna Biodiversity Assessment of Pollution Status of Taabaa Streams, Nigeria

Taabaa streams situated at Taabaa-Okwale and East-West roads, Taabaa were investigated using physico-chemical and entomofauna biodiversity indicators to ascertain their pollution status, following series of human activities; bathing/laundry services, cars/motorcycles washing, run-offs from agricultural farms that occur at the streams. The discharge from the run-offs and other sources into the streams may cause increase in the hydro-carbon concentration and phosphates of the water bodies and consequently changes the pH, available dissolved oxygen, and biodiversity composition of the streams, making it unsuitable for its inhabitants and humans that use the water for drinking. This study was conducted to determine the physico-chemical concentrations and entomofauna diversity of the streams. The pH quality meter was used in-situ to obtain readings of pH and dissolved oxygen values. Water samples used for the analysis of chemical variables were collected from the surface water using 250 ml plastic bottles, and taken to the Laboratory where they were measured spectrophotometrically. A rectangular frame dipnet and a kicknet (500 um mesh size) was used to collect insect samples randomly and taken to the Laboratory for sorting and identification. The results indicated a low pH, and available dissolved oxygen of 6.4 and 3.7 mg/l at the station (Taabaa-Okwale Rd) of the stream. It also shows an increase in the concentrations of phosphates (5.8 mg/l) and Total Petroleum Hydrocarbon (3.47 mg/l) which were higher than WHO permissible limits. The entomofauna indicators comprising species richness and abundance, species sensitivity, and species dominance results showed that station 1 recorded 90 and station 2 (East-West Rd) 149 individual insects. The abundance of Hemiptera and Diptera were higher at station 1 and species that belong to Ephemeroptera, Plecoptera and Trichoptera (EPT) were sensitive to the contaminants and were absent at station 1 but occurred at station 2. The bioindicator species encountered at station 1 were Cybister sp., Gyrinus sp., Gerris sp., Corixa sp., and Chironomus sp. and that of station 2 were in addition to EPT species; Pelocoris sp. and Dytiscus sp. Hemiptera was the dominant insect order representing 19.66% and Chironomus sp. the dominant single species collected during the study. The results indicates that the pollution status of station 1 was relatively higher

Response of Bacteria Isolated from Spent Engine Oil Contaminated Soil to Hydrocarbons, Metals and Antibiotics

ABSTRACT Automobile Mechanic Workshops (AMWs) in Low- and Middle-Income Countries (LMIC) contribute to the problem of soil contamination with petroleum hydrocarbons and toxic heavy metals as a result of indiscriminate disposal of spent engine oil (SEO). Such contaminated soil ecosystems can serve as reservoirs of bacteria harboring adaptive tolerance to metals and hydrocarbons as well as resistance to antibiotics. This study investigated the growth response of bacteria isolated from spent engine oil contaminated soils collected from AMWs in South-West, Nigeria to different concentrations of petroleum hydrocarbons, heavy metals (Cu, Zn, Pb and their mixture) and clinically relevant antibiotics. Sixty percent of the bacterial isolates (n = 192) from the hydrocarbon contaminated soil samples possess the unique ability to metabolize various hydrocarbons, tolerate heavy metals and resist at least one of the tested antibiotics. The isolates were identified as members of the Genera Pseudomonas, Bacillus, Enterobacter, Burkholderia, Micrococcus, Staphylococcus, Actinomycetes, Citrobacter and Serratia. Significant correlation (p < .05) was observed between hydrocarbon utilization and antibiotic resistance. Results showed SEO contamination plays a role in the development and spread of antibiotic resistance in the soil ecosystem. Thus, it is necessary to enforce stricter regulations on the disposal of SEO and other petroleum hydrocarbons to limit their human and environment associated hazards.

Dynamics of Chernozem’s self-cleaning from oil pollution over two years

ABSTRACT This work investigates the natural self-cleaning capacity of Chernozem soil in the face of oil pollution. A field experiment in 2019–21 on heavy loam Haplic Chernozem confirmed that after oil pollution up to 1.6 l/m2, Chernozem can clean itself to an acceptable level in 2 years. With contamination of 6.4 and 25.6 l/m2, petroleum hydrocarbon content decreased by more than half by the 24th month, but not enough to support rye and mustard for bioremediation. The oil also caused water repellence and a decrease in water-holding capacity, nitrification, and available phosphorus. Lack of available nitrogen limits the rate of petroleum biodegradation; therefore, application of nitrogen fertilisers should be part of the bioremediation.

Hydrocarbons removal and microbial community succession in petroleum-contaminated soil under hydrogen peroxide treatment.

Chemical oxidation as a pretreatment step coupled with bioremediation for petroleum-contaminated soil may pose serious impacts on indigenous microorganisms and the available nutrients. Petroleum-contaminated soil were treated by hydrogen peroxide (H2O2) at initial concentrations of 105mM (HH), 21mM (HL), and 105mM in three equal amounts (HT) without adding any external catalyst. The contents of total petroleum hydrocarbons (TPH) and dissolved nutrients (total organic compounds, nitrogen, and phosphate), and the indigenous bacteria community succession (analyzed by high-throughput sequencing of 16S rDNA) were investigated over 50days. Compared to the control treatment without H2O2 addition, H2O2 treatments for the petroleum-contaminated soil significantly promoted the TPH removal especially in the first 4days and impacted the contents of dissolved nutrients. Both of chemical oxidation and nutrients contributed to microbial community structure changes in alpha diversity. Although the soil microbial community structure had undergone significant changes after different chemical oxidation pretreatments, Firmicutes, Proteobacteria, Gemmatimonadetes, and Actinobacteria were the main bacterial phyla. Compared with adding H2O2 at one time, H2O2 added in stepwise was beneficial to indigenous bacterial diversity recovery and TPH removal. H2O2 oxidation treatments showed a great influence on the microbial community structures in the start-up stage, while recovery time rather than the oxidation treatments presented greater effects on the composition of the microbial community structure with the incubation time extended. Therefore, adding H2O2 as pretreatment for petroleum-contaminated soil showed little effect on the structure of soil indigenous microbial community from a long-term scale, and was conducive to the continuous removal of TPH by indigenous microorganisms.

Spatial distribution, composition, and source analysis of petroleum pollutants in soil from the Changqing Oilfield, Northwest China

Petroleum contamination surrounding oilfields has attracted more concerns. However, the levels, distribution and source of petroleum of Changqing Oilfield soil still remain lots of knowns, which is important for local environmental protection. Given soil contamination issues in Changqiong Oilfield were investigated. The maximum concentrations of total petroleum hydrocarbons (TPHs), N-alkanes (TNAs) and polycyclic aromatic hydrocarbons (PAHs) were determined to be 1960.29, 96.13 and 0.82 mg/kg, respectively. TPHs were higher in the north than the south of the study area. TPHs decreased in the horizontal and vertical distribution as soil depth and distance from oil wells increased. Source analysis showed that TNAs mainly originated from petroleum, PAHs were controlled by petroleum spills, combustion and traffic. Correlation analysis implied that TPHs residues had an effect on soil environmental quality. This study have important implications for understanding the environmental behavior of petroleum and can provide support for petroleum remediation and risk control.