Distribution Of Petroleum Hydrocarbons Research Articles

Distribution and abundance of oil-degrading bacteria in seawater of the Yellow Sea and Bohai Sea, China

Petroleum hydrocarbons are widespread in seawater. As an important sea area in northern China, the content and distribution of petroleum hydrocarbons in seawater need our attention because of the high toxicity and lasting polluting effects on the ecological environment of the Yellow Sea and Bohai Sea. In addition, there are few reports comparing the diversity of oil-degrading bacteria before and after enrichment. Therefore, we collected surface seawater from 10 sites in the Yellow Sea and Bohai Sea in the autumn of 2020 to study the distribution characteristics of total petroleum hydrocarbons (TPH) and the diversity of oil-degrading bacteria. The concentration of TPH was 81.65 μg/L-139.55 μg/L at ten sites in the Bohai Sea and the Yellow Sea, which conformed to the China Grade II water quality standard (GB3097–1997). Moreover, the pristine/phytane (PR/PH) value of most sites was close to 1, indicating that the area was obviously polluted by exogenous petroleum hydrocarbons. We found that oil-degrading bacteria in the seawater of the Yellow Sea and the Bohai Sea had a good degradation effect on C11-C14 short chain alkanes (degradation rate of 59.19–73.22 %) and C1-C4 phenanthrene (degradation rate of 48.19–60.74 %). In terms of the diversity of oil-degrading bacteria, Gammaproteobacteria and Alphaproteobacteria dominated the enriched bacterial communities. Notably, the relative abundance of Alcanivorax changed significantly before and after enrichment. We proposed that surface seawater in the Bohai Sea and Yellow Sea could form oil-degrading bacteria mainly composed of Alcanivorax, which had great potential for oil pollution remediation.

Interaction and spatio-taxonomic patterns of the soil microbiome around oil production wells impacted by petroleum hydrocarbons

Numerous onshore oil production wells currently exist, and the petroleum hydrocarbon contamination of the surrounding soil caused by oil production wells is not well understood. Moreover, the impact of the distribution of the total petroleum hydrocarbons (TPH) in the soil on the microbiota requires further investigation. Accordingly, in this study, the distribution of petroleum hydrocarbons in the soils around oil production wells was investigated, and their alteration of the microbiota was revealed. The results revealed that in the horizontal direction, the heavily TPH-contaminated soils were mainly distributed within a circle with a radius of 200 cm centered on the oil production well; and in the vertical direction, the heavily TPH-contaminated soils were distributed within the 0–50 cm soil layer. A significant positive correlation was found between the microbial abundance and the TPH concentration in the soil with relatively low total carbon contents. Heavy TPH contamination (TPH concentration of >3000 mg/kg) significantly reduced the microbial diversity and altered the microbiota compared with the light TPH contamination (TPH concentration of around 1000 mg/kg). In the heavily TPH-contaminated soils, the relative abundances of the Proteobacteria and Bacteroides increased significantly; the network complexity among the soil microorganisms decreased; and the co-occurrence patterns were altered. In summary, the results of this study have reference value in the remediation of soils around oil production wells and provide guidance for the construction of microbial remediation systems for petroleum contamination.

Particle-size-based elution of petroleum hydrocarbon contaminated soil by surfactant mixture

Surfactants are often used to elute the contaminants from soils in order to remediate the polluted soils. However, the heterogeneity of minerals and organic matters with soil particle size may result in adsorption and precipitation of surfactants and affect the distribution of petroleum hydrocarbons (PHCs). In this work, spiked soil samples and surfactant mixture consisting of Tween 80 (TW80) and sodium dodecyl sulfate were prepared. Results showed that the silt-clay-mixture held the high retention capacity of PHCs, and 30% total petroleum hydrocarbons (TPHs) was retained in the soil fraction of ‘<125 μm’ (high concentration), while 70% TPHs (low concentration) was retained in the soil fraction of ‘>125 μm’. TW80 was highly adsorbed on the montmorillonite and aluminosilicates of the soil, and the adsorption of TW80 in surfactant mixture could be relieved at mass ratio of 1:1. This study provides a novel strategy in the elution removal of PHCs from the contaminated soils, in which with the separation of soil particles by the size of 125 μm before elution, as high as 80% PHCs could be eluted from the soil by surfactant mixture.

The analysis of impact factor on temporal and spatial distribution characteristics of petroleum pollution in surface sediments of Laizhou Bay

According to the monitoring data of five cruises in Laizhou Bay from 2013 to 2018, the content, pollution status and spatial distribution characteristics of petroleum hydrocarbons in the surface sediments were analyzed. The results showed that the content range of petroleum hydrocarbons in the sediments was from 0.00~ 377.00 mg / kg, with an average of 63.34 mg/kg, which indicated that the pollution extent was light. The obtained monitoring data were analyzed through DPS18.10 software and PRIMER 7 software. The analysis results showed that the spatial dispersion extent of inter-annual petroleum hydrocarbon content at the monitoring stations was high, the difference was not significant, the clustering similarity was low, and the grouping was not obvious. The results showed that the spatial distribution trend of petroleum hydrocarbon contents in the sediments was uniform, and there were high value areas in some areas.The spatial distribution of petroleum hydrocarbons in Laizhou Bay was dominated by the distribution of ports and the input of human activities. The inter-annual variation of petroleum hydrocarbon contents in the sediments was not obvious. The area where the decrease or increase of petroleum hydrocarbon content in each monitoring station was obvious, was in the SW-NE direction.

Evaluation of the Total Dispersion and Distribution of Petroleum Hydrocarbons in the Aya Stream, Located in Niger Delta: Implications on the Quality and Health of Aya Water Stream

Globally, oil spills are known catastrophic events with harmful consequences that tend to endanger plant, animal and human life. The dispersion and distribution of petroleum hydrocarbons levels were investigated to evaluate its effect on the quality and health of Aya stream, located in the Niger Delta sub region, south east Nigeria. Water samples were collected from the stream, which is the most available source of water in Ikot Ada Udo local community, five years after an extensive oil spillage between the months of June and November 2012. These samples were analyzed to assess the level of total petroleum hydrocarbon (TPH) and physicochemical enrichment using Spectrophotometric with 1g of Bonny Light and Bonny Medium Crude Oils dissolved in 1000 ml of tetrachloromethane were used as standards as well as insitu measurements of water temperature and dissolved oxygen. TPH concentrations ranged from 0.21mg/l in dry season (September, October, November) to a maximum level of 0.33 mg/l in wet season (June, July, August) during the study. The mean concentrations found for physicochemical parameters during wet and dry seasons respectively were: temperature (27.67±0.29 &amp; 27.83±0.290C), DO (3.47±0.65 &amp; 3.44±0.67 mg/l), Cd (0.03±0.003 &amp; 0.03±0.01mg/l), Pb (0.17±0.06 &amp; 0.18±0.04 mg/l), Ni (0.08±0.01 &amp; 0.08±0.005 mg/l), V (0.02±0.01 &amp; 0.02±0.01 mg/l).The distribution pattern of trace heavy metals in the stream water followed the sequence: Pb&gt;Ni&gt; Cd&gt;V. In all cases, Pb was the most abundant and V the least abundant metal. Elevated levels of some physicochemical parameters shown to correlate significantly (p=0.05) and associate with the oil spill infer that Aya stream has been severely polluted. Statistical analysis (t-test) of seasonal levels of TPH in water samples showed positive relationship (t=0.55, p=0.05). The implication of these results is that the concentrations of the studied parameters did not depend on seasonal influence but were connected with the incessant exposure of the site to oil seeps from the well-head. The high levels of lead above permissible limits in the studied samples poses a health threat, hence, the removal of the well-head and future situation of such structures away from the source of communal water source should be implemented to preserve the quality and health of the water source.

Distribution Characteristics of Bacterial Communities and Hydrocarbon Degradation Dynamics During the Remediation of Petroleum-Contaminated Soil by Enhancing Moisture Content.

Microorganisms are the driver of petroleum hydrocarbon degradation in soil micro-ecological systems. However, the distribution characteristics of microbial communities and hydrocarbon degradation dynamics during the remediation of petroleum-contaminated soil by enhancing moisture content are not clear. In this study, polymerase chain reaction and high-throughput sequencing of soil microbial DNA were applied to investigate the compositions of microorganisms and alpha diversity in the oil-polluted soil, and the hydrocarbon removal also being analyzed using ultrasonic extraction and gravimetric method in a laboratory simulated ex-situ experiment. Results showed the distribution of petroleum hydrocarbon degrading microorganisms in the petroleum-contaminated loessal soil mainly was Proteobacteria phylum (96.26%)-Gamma-proteobacteria class (90.03%)-Pseudomonadales order (89.98%)-Pseudomonadaceae family (89.96%)-Pseudomonas sp. (87.22%). After 15% moisture content treatment, Actinobacteria, Proteobacteria, and Firmicutes still were the predominant phyla, but their relative abundances changed greatly. Also Bacillus sp. and Promicromonospora sp. became the predominant genera. Maintaining 15% moisture content increased the relative abundance of Firmicutes phylum and Bacillus sp. As the moisture-treated time increases, the uniformity and the richness of the soil bacterial community were decreased and increased respectively; the relative abundance of Pseudomonas sp. increased. Petroleum hydrocarbon degradation by enhancing soil moisture accorded with the pseudo-first-order reaction kinetic model (correlation coefficient of 0.81; half-life of 56weeks). The richness of Firmicutes phylum and Bacillus sp. may be a main reason for promoting the removal of 18% petroleum hydrocarbons responded to 15% moisture treatment. Our results provided some beneficial microbiological information of oil-contaminated soil and will promote the exploration of remediation by changing soil moisture content for increasing petroleum hydrocarbon degradation efficiency.

Assessment of water pollution near the deep oil seep in Lake Baikal

Water purity was assessed at the site of a deep oil seepage near Cape Gorevoy Utes (Central Baikal). Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were determined in different types of oil-containing samples collected at this section of Lake Baikal. The set of studied samples included: (i) samples of water from the surface water layer; (ii) samples of water from different depths; (iii) oil on the water surface; (iv) oil from a sediment core. In the surface water layer and the water column, the total concentration of n-alkanes ranged from 0.2 to 5.3 µg/L and did not exceed the 0.1 maximum permissible concentration (MPCfish = 50 µg/L) established for hydrocarbons in water bodies of fishery importance. PAHs with carcinogenic properties were less than 0.1 ng/L. The total concentration of PAHs found in the water column did not exceed 110 ng/L; toxic equivalent (TEQ) values ranged from 0.001 to 0.110 ng/L. The distribution of petroleum hydrocarbons from the seepage site was limited, and water pollution was localised. The low level of water pollution is associated with natural mechanisms in the Baikal ecosystem. Microbiological community and phytoplankton make a decisive contribution to the purity of Baikal water, and oil fractionation during deep discharge contributes to the bioavailability of petroleum hydrocarbons.

Petroleum Hydrocarbons’ Content and Distribution in Soils of Geochemical Landscapes in Southern Sakhalin

The article reports the results from the analysis of content and distribution of petroleum hydrocarbons in the soils of geochemical landscapes in southern Sakhalin. It discusses the main types of soil formed in this region and the parameters determining the migration of petroleum hydrocarbons in the landscapes. It has been shown that the soils of transit-accumulative and accumulative landscapes are characterized by the highest content and the penetration depth of petroleum hydrocarbons into the soil profile. In the event of accidental oil spills, along with lateral migration, a significant role is played by vertical migration of petroleum hydrocarbons to the accumulative landscapes.

BP Gulf Science Data Reveals Ineffectual Subsea Dispersant Injection for the Macondo Blowout

After the Deepwater Horizon oil platform explosion, an estimated 172.2 million gallons of gas-saturated oil was discharged uncontrollably into the Gulf of Mexico, causing the largest deep-sea blowout in history. In an attempt to keep the oil submerged, massive quantities of the chemical dispersant Corexit® 9500 were deployed 1522m deep at the gushing riser pipe of the Macondo prospect’s wellhead. Understanding the effectiveness of this unprecedented Sub-Sea Dispersant Injection (SSDI) is critical because deep-water drilling is increasing worldwide. Here we use the comprehensive BP Gulf Science Data (GSD) to quantify petroleum dynamics throughout the 87-day long blowout. The spatio-temporal distribution of petroleum hydrocarbons revealed consistent higher concentrations at the sea surface and in a deep intrusion below 1000 m. The relative importance of these two layers depended on the hydrocarbon mass fractions as expected from their partitioning along temperature and pressure changes. Further, analyses of water column Polycyclic Aromatic Hydrocarbons (PAH) of GSD extensively sampled within a 10-km radius of the blowout source demonstrated that substantial amounts of oil continued to surface near the response site, with no significant effect of SSDI volume on PAH vertical distribution and concentration. The turbulent energy associated with the spewing of gas-saturated oil at the deep-sea blowout may have minimized the effectiveness of the SSDI response approach. Given the potential for toxic chemical dispersants to cause environmental damage by increasing oil bioavailability and toxicity while suppressing its biodegradation, unrestricted SSDI application in response to deep-sea blowout is highly questionable. More efforts are required to inform response plans in future oil spills.

The role of microbially-mediated exopolymeric substances (EPS) in regulating Macondo oil transport in a mesocosm experiment

Large-scale exopolymeric substances (EPS) formation was observed in contaminated surface waters of the Gulf of Mexico, after the Deepwater Horizon oil spill. The conditions under which EPS are produced can cause variations in their physico-chemical properties, affecting the fate of the oil through either emulsification or coagulation with particles, followed by aggregation and marine oil snow (MOS) sedimentation. Here, we report results from a four-day mesocosm experiment that examined EPS production, the change in the bulk chemical composition (mainly polysaccharides and proteins), as well as the partitioning into different size fractions (suspended particulate matter (SPM), colloidal fraction, and sinking MOS). The treatments included 1) natural coastal seawater (Control), 2) a water accommodated fraction of oil (WAF), 3) a chemically-enhanced WAF with addition of oil dispersant Corexit (CEWAF), and 4) a diluted CEWAF (DCEWAF). Generally, the presence of WAF stimulated more extracellular polysaccharide production, whereas the addition of Corexit promoted more protein production. Moreover, marine aggregates changed from a terrestrial signature (higher aromaticity, lower EPS content and more uniform monosaccharide distribution) in the early stages of the experiment, to a fresher autochthonous signature (less aromatic, higher EPS content and glucose-dominated monosaccharide distribution) in the later stage of the mesocosm experiment. Corexit promoted the association between oil and proteins, assisting to emulsify the oil in colloids and SPM and delay the settling of EPS and oil (MOS) for the duration of the mesocosm. Furthermore, when oil, especially Corexit-dispersed oil, was present, extracellular polysaccharides were preferentially incorporated into sinking MOS relative to proteins, as evidenced from a lower protein-C/carbohydrate-C ratio of the sinking MOS than those of SPM and colloidal fraction in WAF, CEWAF and DCEWAF, respectively. This is in contrast to a higher protein-C/carbohydrate-C ratio in the sinking marine snow than those of SPM and colloidal fraction in the control. Likely, microbially-mediated extracellular polysaccharides are the key component that anchors the mineral ballast until the aggregates become dense enough and overcome the buoyancy added to the aggregates as a result of their association with oil/Corexit. We conclude that interactions between Corexit and EPS components regulate petroleum hydrocarbon distribution between the water column and sinking MOS.

Distribution of petroleum hydrocarbons in sea water of the Aden city -Yemen

This study is to determine the concentration and distribution of petroleum hydrocarbons residual in sea water in the coast of the city of Aden, Yemen, during three seasons: the first was in the period from 11 to 14 July 2014, the second was in December 2014, and the last was during March 2015,where the use of a gas chromatography and spectroflourometer to determine the characteristics of the hydrocarbons extracted. The results confirmed the concentration of hydrocarbons levels with regard the coast of to the city of Aden. The results showed that the concentrations of petroleum hydrocarbons in water ranging from 0.688715in Gold Mohour to 15.891754 µ /L in the refineries area, with an average concentration of 6.3269 µg /L. The study revealed that the level of hydrocarbons in sea water of the coast of thecity of Aden is close to the levels of petroleum hydrocarbons in the region and other parts of the world , after comparing their results with other regions of the world, which showed that it is low/ within the range in the permissible limits.

Composition and depth distribution of hydrocarbons in Barataria Bay marsh sediments after the Deepwater Horizon oil spill

In 2010, an estimate 4.1 million barrels of oil were accidentally released into the Gulf of Mexico (GoM) during the Deepwater Horizon (DWH) Oil Spill. One and a half years after this incident, a set of subtidal and intertidal marsh sediment cores were collected from five stations in Barataria Bay, Louisiana, USA, and analyzed to determine the spatial and vertical distributions and source of hydrocarbon residues based on their chemical composition. An archived core, collected before the DWH oil spill from the same area, was also analyzed to assess the pre-spill hydrocarbon distribution in the area. Analyses of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and stable carbon isotope showed that the distribution of petroleum hydrocarbons in Barataria Bay was patchy and limited in areal extent. Significant TPH and ΣPAH concentrations (77,399 μg/g and 219,065 ng/g, respectively) were detected in the surface sediments of one core (i.e., core A) to a depth of 9 cm. Based on a sedimentation rate of 0.39 cm yr−1, determined using 137Cs, the presence of anthropogenic hydrocarbons in these sediment core deposited ca. 50 to 60 years ago. The historical background hydrocarbon concentrations increased significantly at the sediment surface and can be attributed to recent inputs. Although the oil present in the bay's sediments has undergone moderate weathering, biomarker analyses performed on core A samples likely indicated the presence of hydrocarbons from the DWH oil spill. The effects of oiling events on Barataria Bay and other marsh ecosystems in this region remain uncertain, as oil undergoes weathering changes over time.

Distribution of petroleum hydrocarbons in sediments from Dianchi Lake, China

Thirteen Dianchi Lake sediments were analyzed for parent and alkylated polycyclic aromatic hydrocarbons (PAHs), hopanes, and steranes by gas chromatography-mass spectrometry. Total PAH concentrations in the sediment ranged from 590 to 23,250 ng/g. The alkylated phenanthrene/phenanthrene and alkylated pyrene/pyrene ratios displayed a strong correlation with the total PAH concentrations, suggesting that the sediments were heavily impacted by petrogenic PAHs. This finding was consistent with the ratios and compositional features of hopanes and steranes, and confirmed the presence of mature petroleum in the sediments. The sedimentary total organic carbon contents were correlated with the organic pollutant concentrations (R2 = 0.81–0.88), suggesting that the distribution was controlled by an extensive point source and/or transport and sedimentation processes. Principal component analysis results indicated two major sources of inputs to the aquatic environment in the area: (1) discharge from the Daguanhe River, and (2) leakage of oil from motor boats in nearby harbors. A gradient of increasing parent PAH (relative to alkylated PAHs) concentrations toward the lower section of Dianchi Lake, as compared to those in the upper section, reflected the resistance of the parent PAHs to degradation and bioavailability during pollutant diffusion. The uniform composition between sedimentary steranes and hopanes was explained not by one diffuse single source but, rather, by the lack of change in the composition of oil residues after natural transport and sedimentation processes.

Characterization of Petroleum Hydrocarbons in Post-Burn Crude Oil-Spilled Soils, Gokana, Rivers State, Nigeria

In the Niger delta, crude oil spilled soils are burned as a means of decontaminating the impacted soils. Gas chromatography - flame ionization detector (GCFID) analyses were performed on oil residues extracted from burnt spilled oil soil samples to facilitate detailed chemical composition and characterization of petroleum hydrocarbons. The concentrations of aliphatic hydrocarbons (AHCs) from C 13 to C 36 were low and range from 363.4 to 439.6 mg/kg, with hydrocarbons burning ≤ C 12 and the monocyclic aromatics – BTEX not detected in all the samples. Polycyclic aromatic hydrocarbon (PAH) concentrations, which ranged from 3236.6 to 4190.0 mg/kg, were significantly high and constituted from 88.26 to 91.25% of total petroleum hydrocarbon compositions in the burnt spilled oil soil samples. Petroleum hydrocarbon distribution profiles for the AHCs and PAHs were similar for all the samples and indicated similar alteration source. The compositions of AHCs were generally low, between 1.13 and 11.18%, while compositions of PAHs varied considerably from 0.17 to 30.50%. The composition of the 5-6 ring PAHs were between 3.94 - 4.65 times more than the 2-4 ring PAHs. From these results, the burning of spilled oil soils extensively degraded the AHCs and volatile low molecular weight aromatic hydrocarbons and generated significant amounts of 5-6 ring PAHs, some of which are carcinogenic.

Pollution of the coastal waters in the Possyet Bay (Peter the Great Bay, Japan Sea) in conditions of current economic activity

Impact of economic activity on environment quality is assessed for the coastal waters of the Possyet Bay (Peter the Great Bay, Japan Sea). Total volume of the sewage water discharged from coastal sources to the bay and total amount of principal pollutants wasting this water body are calculated. Specific index of sewage for the Possyet Bay is estimated as 0.081 g/m 3 that is rather high value. Distribution of petroleum hydrocarbons in the coastal waters is considered: their concentration ranges from 0.025 to 0.065 mg/L. Following to biotesting results, the worst water quality is in the Reid Pallada Bay where the highest inhibitory effect on the byssus thread formation of mussel Crenomytilus grayanus is observed.

Effects of chemical dispersant and seasonal conditions on the fate of spilled oil – modelling of a hypothetical spill near Saint John, NB

The proposed Energy East pipeline project has raised concerns about potential oil spills in Saint John, New Brunswick. While environmental conditions could pose challenges for using mechanical recovery methods if a spill occurs, chemical dispersant could be an alternative. However, the application of chemical dispersant in shallow water and costal zones remains an issue of debate. Furthermore, the effectiveness of chemical dispersant under different seasonal conditions is yet to be determined. This study attempts to describe a modelling effort to understand the probable distribution of petroleum hydrocarbons in Port Saint John following a hypothetical release of crude oil to which dispersant is applied during different seasons. A three-dimensional model was used to simulate the transport of oil with a release of 1,000 m3 of Arabian light crude in the summer and winter. A stochastic approach took into account the uncertainties of environmental inputs. The results were a significant reduction of oil ashore, and enhanced biodegradation with dispersant application. However, these effects were accompanied by an increase of oil in the sediment and water column, which is a concern. While the results are only conclusive for the selected scenarios of summer and winter, the method could be applied to other months and seasons to support more detailed analysis regarding dispersant application.

Total petroleum hydrocarbons in sediments from the coastline and mangroves of the northern Persian Gulf

To provide baseline information for the marine ecosystem of Hormozgan province, the distribution of petroleum hydrocarbons was evaluated in 52 stations involved in the mangrove and coastline ecosystem. Coastline sampling sites included areas facing harbor, river, domestic and industrial discharge. Sediment samples were analyzed based on ultraviolet fluorescence spectroscopy. Petroleum hydrocarbons showed narrow variations ranging from non-detectable (ND) to 1.71 and from 0.2 to 0.63μg/g dry weight for coastline and mangrove sediments, respectively. The detected concentrations for total petroleum hydrocarbons were lower than guideline values for ecological risk. Furthermore, the minimum environmental risk was confirmed by background levels for the Persian Gulf, the Sea of Oman, and detected values for reference areas. The results were regarded as background data in the studied area, and, considering the rapid expansion of activities related to the petroleum industry in Hormozgan province, the continuous monitoring of pollutants is recommended.

Total petroleum hydrocarbon distribution in soils and groundwater in Songyuan oilfield, Northeast China

In order to investigate the distribution of the total petroleum hydrocarbons (TPH) in groundwater and soil, a total of 71 groundwater samples (26 unconfined groundwater samples, 37 confined groundwater samples, and 8 deeper confined groundwater samples) and 80 soil samples were collected in the Songyuan oilfield, Northeast China, and the vertical variation and spatial variability of TPH in groundwater and soil were assessed. For the groundwater from the unconfined aquifer, petroleum hydrocarbons were not detected in three samples, and for the other 23 samples, concentrations were in the range 0.01-1.74 mg/l. In the groundwater from the confined aquifer, petroleum hydrocarbons were not detected in two samples, and in the other 35 samples, the concentrations were 0.04-0.82 mg/l. The TPH concentration in unconfined aquifer may be influenced by polluted surface water and polluted soil; for confined aquifer, the injection wells leakage and left open hole wells may be mainly responsible for the pollution. For soils, the concentrations of TPH varied with sampling depth and were 0-15 cm (average concentration, 0.63 mg/g), >40-55 cm (average concentration, 0.36 mg/g), >100-115 cm (average concentration, 0.29 mg/g), and >500-515 cm (average concentration, 0.26 mg/g). The results showed that oil spillage and losses were possibly the main sources of TPH in soil. The consequences concluded here suggested that counter measures such as remediation and long-term monitoring should be commenced in the near future, and effective measures should be taken to assure that the oilfields area would not be a threat to human health.

The spatial variability of the oil contamination level in technogenic transformed podzolic soils at the northeast of Sakhalin Island

The vertical and lateral microvariability of total petroleum hydrocarbon (TPH) in technogenic soils is considered in this work. An autocorrelation and cross-correlation analysis of the TPH along a transect in the lateral direction is carried out. Statistical parameters of TPH for various industrial sites, oil spills, and natural exits are described and the normal or lognormal law of distribution of petroleum hydrocarbons in technogenic soils is confirmed. The percentage of the total spatial variability of TPH contributed by hierarchical sampling levels (10 cm, 0.25 ha, and 20 km2) is estimated. Planning the volumes of the samples that are necessary for an assessment of the average level of pollution in soils for separate sites and the entire territory of the oil field is carried out.

Distribution of petroleum hydrocarbons in soils and the underlying unsaturated subsurface at an abandoned petrochemical site, North China

AbstractContamination characteristics of petroleum hydrocarbons in soils and the underlying unsaturated subsurface were analysed by investigating and sampling at different depth of five boreholes named SH1 through SH5 at a typical petrochemical site, North China. Topsoil volatile organic gas measurement revealed that SH‐3 was the center of one pollution plume. Soil samples analysis showed that aromatic hydrocarbons and chlorinated hydrocarbons were major pollutants. Their maximum concentration was found at 6.5 and 14.6 m of SH‐2, 13 m of SH‐5, and 18.5 m of SH‐3. These pollutants are mostly accumulated on the interface between two different lithological layers, especially between the sand and silt clay layers. Denitrifying and iron reducing were main biogeochemical processes in this site. Under the influence of groundwater level fluctuation, free NAPLs passed through the boundary and dissolved into the lower groundwater. Knowledge of these associations between contaminant distributions and affecting factors could have implications for soil and groundwater pollution prevention and control. Copyright © 2013 John Wiley &amp; Sons, Ltd.