Hydrocarbon accumulation and orderly distribution of whole petroleum system in marine carbonate rocks of Sichuan Basin,SW China

Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.

Contents and Distribution of Petroleum Hydrocarbons (PHC) in Jiaozhou Bay Waters

Based on data from the investigation in Jiaozhou bay waters in 1979, the distribution, pollution source and seasonal variation of PHC in Jiaozhou Bay are analyzed. It is showed that in Jiaozhou bay PHC contents arrived the national Category Ⅱof the water quality standard during this year. In summer in the bay the pollution of PHC was heavy, while relatively light in spring. In the coastal waters in the east and the northeast of the bay, the PHC contents in spring surpassed the national Category Ⅱ, and surpassed the national Category Ⅲ. In the coastal waters, in the northeast of the bay, the change of the PHC contents formed the grads: the contents presented the falling trend from the big one to the small, which unveiled that the PHC souce in the bay mainly came from the discharge of the industrial waste water and living sewage.

Petroleum geology features and research developments of hydrocarbon accumulation in deep petroliferous basins

As petroleum exploration advances and as most of the oil-gas reservoirs in shallow layers have been explored, petroleum exploration starts to move toward deep basins, which has become an inevitable choice. In this paper, the petroleum geology features and research progress on oil-gas reservoirs in deep petroliferous basins across the world are characterized by using the latest results of worldwide deep petroleum exploration. Research has demonstrated that the deep petroleum shows ten major geological features. （1） While oil-gas reservoirs have been discovered in many different types of deep petroliferous basins, most have been discovered in low heat flux deep basins. （2） Many types of petroliferous traps are developed in deep basins, and tight oil-gas reservoirs in deep basin traps are arousing increasing attention. （3） Deep petroleum normally has more natural gas than liquid oil, and the natural gas ratio increases with the burial depth. （4） The residual organic matter in deep source rocks reduces but the hydrocarbon expulsion rate and efficiency increase with the burial depth. （5） There are many types of rocks in deep hydrocarbon reservoirs, and most are clastic rocks and carbonates. （6） The age of deep hydrocarbon reservoirs is widely different, but those recently discovered are pre- dominantly Paleogene and Upper Paleozoic. （7） The porosity and permeability of deep hydrocarbon reservoirs differ widely, but they vary in a regular way with lithology and burial depth. （8） The temperatures of deep oil-gas reservoirs are widely different, but they typically vary with the burial depth and basin geothermal gradient. （9） The pressures of deep oil-gas reservoirs differ significantly, but they typically vary with burial depth, genesis, and evolu- tion period. （10） Deep oil-gas reservoirs may exist with or without a cap, and those without a cap are typically of unconventional genesis. Over the past decade, six major steps have been made in the understanding of deep hydrocarbon reservoir formation. （1） Deep petroleum in petroliferous basins has multiple sources and many dif- ferent genetic mechanisms. （2） There are high-porosity, high-permeability reservoirs in deep basins, the formation of which is associated with tectonic events and subsurface fluid movement. （3） Capillary pressure differences inside and outside the target reservoir are the principal driving force of hydrocarbon enrichment in deep basins. （4） There are three dynamic boundaries for deep oil-gas reservoirs; a buoyancy-controlled threshold, hydrocarbon accumulation limits, and the upper limit of hydrocarbon generation. （5） The formation and distribution of deep hydrocarbon res- ervoirs are controlled by free, limited, and bound fluid dynamic fields. And （6） tight conventional, tight deep, tight superimposed, and related reconstructed hydrocarbon reservoirs formed in deep-limited fluid dynamic fields have great resource potential and vast scope for exploration. Compared with middle-shallow strata, the petroleum geology and accumulation in deep basins are more complex, which overlap the feature of basin evolution in different stages. We recommend that further study should pay more attention to four aspects： （1） identification of deep petroleum sources and evaluation of their relative contributions; （2） preservation conditions and genetic mechanisms of deep high-quality reservoirs with high permeability and high porosity; （3） facies feature and transformation of deep petroleum and their potential distribution; and （4） economic feasibility evaluation of deep tight petroleum exploration and development.

Influences of Cu or Cd on the neurotoxicity induced by petroleum hydrocarbons in ragworm Perinereis aibuhitensis

The ecotoxicological effects of heavy metals and petroleum hydrocarbons （PHCs） on ragworms are still vague. The relationships between toxicological indices （mortality and acetylcholinesterase （ACHE） activity） and concentrations of toxicants （Cu, Cd, and PHCs） were examined in the estuary keystone species Perinereis aibuhitensis in laboratory conditions. The results of single toxicant indicated that three toxicants had potentially physiological toxicity to P. aibuhitensis. The estimated 4-d and 10-d LC50 for Cu, Cd, and PHCs was derived from the relationships between mortality and toxicants concentrations. Notable changes in the morphological signs and symptoms of P. aibuhitensis exposed to PHCs were observed. The ACHE activity of P. aibuhitensis was more sensitive to the toxicity of PHCs than the others. The results of combined toxicants implied that the combined toxicity of Cu or Cd and PHCs to P. aibuhitensis was related to the concentration combination of toxicants. Compared to single PHCs treatment, the addition of Cu or Cd significantly mitigated the neurotoxicity of PHCs to ACHE activity in P. aibuhitensis, which showed an antagonistic effect.

Relationship between petroleum hydrocarbon and plankton in a mesocosm experiment

A mesocosm experiment was carried out from May 26 to June 1, 1998 at the location of 30'52'N, 122'36'E, the Changjiang Estuary, in order to measure the influence of petroleum hydrocar- bon to the ecosystem, furthermore, to estimate the environmental capacity. In the experiment, it is found that the petroleum hydrocarbon can, in some degree, enhance the growth of diatom, but inhibit the growth of dinoflagellate. In general, the petroleum hydrocarbon can inhibit the growth of both Phytoplankton and zooplankton, and can the inhibit the growth of total plankton (including phytoplankton and zooplankton) as well. A kinetic model was presented to estimate the uptake/release rate constants of petroleum hydrocarbon by plankton, and thereafter, the uptake and release rate constants (k1, k2), bioconcentration factor (BCF) as well as the petroleum bydrocarbon influenced influenced uptake and release rate constants of nutrients by phytoplankton (kup, krel) were obtained. The results imply that the bioconcentration of petroleum hydrocarbon by plankton is fairly large and petroleum hydrocarbon caused no significant influence on the uptake of N- NO3, but significant influence on that of P -PO4. In addition, the application of kinetic model for the bioconcentration of volatile organic toxic compound by organism suggests that the uptake of petroleum hydrocarbon by plankton was an important process for the environmental capacity of petroleum hydrocarbon.

Single and joint effects of petroleum hydrocarbons and cadmium on the polychaete Perinereis aibuhitensis Grube

Using the concentration gradient and combined pollutant exposure method, the single and joint effects of petroleum hydrocarbons （PHCs） and cadmium （Cd） on polychaete Perinereis aibuhitensis Grube, an ecologically keystone species in estuarine and coastal environment, have been investigated. The results indicate that the toxicity of PHCs to P. aibuhitensis is stronger than that of Cd to the organism. There are positive correlations between the mortality of worms and the exposed concentration of single Cd or PHCs in solution. Similarly, the accumulation of Cd or PHCs in worms increased with increasing Cd- or PHC-exposed concentrations. All the correlation relationships can be described using unitary quadratic equations （Y or Z = aX^2 ＋ bX ＋ c）. It is calculated, on the basis of these expressions, that the median lethal dose （LC50） ofP aibuhitensis exposed to a single Cd or PHCs is 793.4-13567.3 and 28.0-119.9 μg/L, respectively. The exposed time has some stimulative effect on the two pollutants and on the mortality of the worms. Thus, even a low concentration of a single Cd or PHCs may have strong toxic effects on the worms when the exposed time becomes longer. The accumulation of Cd or PHCs in worms differs with an increase in exposure time at the given exposed concentration of a single Cd or PHCs. Noticeably, the accumulation of PHCs in worms decreases with an increase in exposure time at the given high concentration of PHCs in solution. The joint effect of PHCs and Cd on P. aibuhitensis is very complicated and changes with the exposed concentrations of the two pollutants. At the given concentration of PHCs, the joint toxicity of the two pollutants on the worms changes from synergism to antagonism with an increase in Cd concentration. The accumulation of Cd in the worms significantly decreases with the addition of PHCs to exposure solution.

Microbial changes in rhizospheric soils contaminated with petroleum hydrocarbons after bioremediation

Effects of bioremediation on microbial communities in soils contaminated with petroleum hydrocarbons are a scientific problem to be solved. Changes in dominate microbial species and the total amount of microorganisms including bacteria and fungi in rhizospheric soils after bioremediation were thus evaluated using field bioremediation experiments. The results showed that there were changed dominant microorganisms including 11 bacterial strains which are mostly Gram positive bacteria and 6 fungal species which were identified. The total amount of microorganisms including bacteria and fungi increased after bioremediation of microbial agents combined with planting maize. On the contrary, fungi in rhizospheric soils were inhibited by adding microbial agents combined with planting soybean.

Hydrocarbon test in lower-layer atmosphere to predict deep-sea petroleum or hydrate in the Okinawa Trough: an example

Light hydrocarbon (methane, ethane, propane, butane and CO2) test and C isotopic analysis of CO are conducted for over 100 lower-layer atmospheric samples from the East China Sea slope and the Okinawa Trough. The results show that the lower-layer atmosphere mainly consists of CO2 and then of CH4, and the CO2 concentrations are calculated to have a high average value of 0.87 omega/10(-2) about three times that of the regional background (0-3 omega/10(-2)). The result also shows that the average value of C isotope - 20.8 x 10(-3) is given to the CO2, inferring that it is inorganic gas. Thus, for the future 's work in the Okinawa Trough, special attention should be paid to CO2 hydrate, which is very possibly an important hydrate type.

Petroleum Hydrocarbon Degradation Potential of Soil Bacteria Native to the Yellow River Delta

The bioremediation potential of bacteria indigenous to soils of the Yellow River Delta in China was evaluated as a treatment option for soil remediation. Petroleum hydrocarbon degraders were isolated from contaminated soil samples from the Yellow River Delta. Four microbial communities and eight isolates were obtained. The optimal temperature, salinity, pH, and the ratios of C, N, and P (C:N:P) for the maximum biodegradation of diesel oil, crude oil, n-alkanes, and polyaromatic hydrocarbons by indigenous bacteria were determined, and the kinetics changes in microbial communities were monitored. In general, the mixed microbial consortia demonstrated wider catabolic versatility and faster overall rate of hydrocarbon degradation than individual isolates. Our experimental results demonstrated the feasibility of biodegradation of petroleum hydrocarbon by indigenous bacteria for soil remediation in the Yellow River Delta.

Effects of Temperature, Acetate and Nitrate on Methane Generation from Petroleum Hydrocarbons

In this study, the effects of temperature, acetate and nitrate on methane gas production from biodegradation of petroleum hydrocarbons were investigated. The results indicated that methane gas production at 35 ℃ was higher than that obtained at 55 ℃. The acetate addition significant enhanced the methane production at 35 ℃, however, at 55 ℃ the nitrate addition could largely promote the methane production. The microbial community structures were revealed by PCR-DGGE. The Actinobacteria, Clostridia, Clostridiales, Syntrophus, Pseudomonas, and Proteobacteria-like bacteria and Methanocellales, Methanosaeta, Methanomicrobiales, Methanolinea, Thermoprotei-like archaea had been enriched at 35 ℃ in the acetate addition test. The Thermoprotei, Proteobacterium, Thermodesulfovibrio-like bacteria and Methanocellales-like archaea had been enriched at 55 ℃ in the nitrate addition test. The results may shed light on the bio-utilization of marginal oil reservoirs for enhancing energy recovery.

Petroleum geological framework and hydrocarbon potential in the Yellow Sea

Sedimentary basins in the Yellow Sea can be grouped tectonically into the North Yellow Sea Basin (NYSB), the northern basin of the South Yellow Sea (SYSNB) and the southern basin of the South Yellow Sea (SYSSB). The NYSB is connected to Anju Basin to the east. The SYSSB extends to Subei Basin to the west. The acoustic basement of basins in the North Yellow Sea and South Yellow Sea is disparate, having different stratigraphic evolution and oil accumulation features, even though they have been under the same stress regime since the Late Triassic. The acoustic basement of the NYSB features China-Korea Platform crystalline rocks, whereas those in the SYSNB and SYSSB are of the Paleozoic Yangtze Platform sedimentary layers or metamorphic rocks. Since the Late Mesozoic terrestrial strata in the eastern of the NYSB (West Korea Bay Basin) were discovered having industrial hydrocarbon accumulation, the oil potential in the Mesozoic strata in the west depression of the basin could be promising, although the petroleum exploration in the South Yellow Sea has made no break-through yet. New deep reflection data and several drilling wells have indicated the source rock of the Mesozoic in the basins of South Yellow Sea, and the Paleozoic platform marine facies in the SYSSB and Central Rise could be the other hosts of oil or natural gas. The Mesozoic hydrocarbon could be found in the Mesozoic of the foredeep basin in the SYSNB that bears potential hydrocarbon in thick Cretaceous strata, and so does the SYSSB where the same petroleum system exists to that of oil-bearing Subei Basin.

Environmental Capacity of Petroleum Hydrocarbon Pollutants in Jiaozhou Bay, China: Modeling and Calculation

An environmental capacity model for the petroleum hydrocarbon pollutions （PHs） in Jiaozhou Bay is constructed based on field surveys, mesocosm, and parallel laboratory experiments. Simulated results of PHs seasonal successions in 2003 match the field surveys of Jiaozhou Bay resaonably well with a highest value in July. The Monte Carlo analysis confirms that the variation of PHs concentration significantly correlates with the river input. The water body in the bay is reasonably subjected to self-purification processes, such as volatilization to the atmosphere, biodegradation by microorganism, and transport to the Yellow Sea by water exchange. The environmental capacity of PHs in Jiaozhou Bay is 1500 tons per year IF the seawater quality criterion （Grade Ⅰ/Ⅱ, 0.05 mgLl） in the region is to be satisfied. The contribution to self-purification by volatilization, biodegradation, and transport to the Yellow Sea accounts for 48%, 28%, and 23%, respectively, which make these three processes the main ways of PHs purification in Jiaozhou Bay.

Petroleum Hydrocarbon Distribution Features in Water and Sediment off Fujian Shore

This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the research period, petroleum hydrocarbon concentrations in water varied from 5.77 μg/L to 37.28 μg/L, averaged 14.48 μg/L; was lower in the wet season than in the dry season; and was highest in the Minjiang Estuary and Jiulong Estuary in both seasons. The petroleum hydrocarbon concentrations in shore sediment varied from 14.48 mg/kg to 784.36 mg/kg, averaged 133.3 mg/kg, and was closely related to sediment types (granularity).

Pollution Condition of Petroleum Hydrocarbon Pollutant and Estimation of Its Environmental Capacities in Summer in the Bohai Sea

The pollution condition of petroleum hydrocarbon (PH) was summarized in the Bohai Sea in this paper. The results showed that the mean concentration of PH was (25.7±13.6) mg/m3, varying from 4.4 to 64.8 mg/m3 in the survey sea area. Laizhou Bay and Bohai Bay have been contaminated badly inshore. The dynamic model for distribution of marine PH among multiphase environments in the Bohai Sea has been established. The environmental capacities (ECO) and surplus environmental capacities (SECO) of PH have been estimated in the Bohai Sea according to the dynamic model. The results showed that the ECo separately were about 29 169 t/a, 177 306 t/a and 298 446 t/a under the first, second and third, fourth class seawater quality standards requirement. And the ECO of Bohai Bay, Liaodong Bay, Laizhou Bay and Central Bohai Sea were about 5 255 t/a, 8 869 t/a, 4889 t/a and 10 156 t/a respectively under the first and second class seawater quality standards requirement.

Comparative Bioremediation of Petroleum Hydrocarbon-Contaminated Soil by Biostimulation, Bioaugmentation and Surfactant Addition

A bench-scale biopiling experiment was conducted to hydrocarbon bioremediation in a chronically contaminated soil compare the ability of different techniques to enhance petroleum After 195 days, 10%-32% removal of TPHs （total petroleum hydrocarbons） occurred in unamended soil （control）. Biostimulation by inorganic nutrient addition enhanced TPH removal （49%） confirming that bioremediation was nutrient limited and the soil contained a well-adapted hydrocarbonoclastic microbial community. The addition of organic amendments including green waste at 25% and 50% （w/w） and a commercial product called DaramendTM had a further biostimulatory effect （50%-66%, 34%-59% and 69%-80% TPH removal respectively）. Bioaugmentation using two commercially available petroleum hydrocarbon degrading microbial cultures with nutrients enhanced TPH removal in the case of RemActivTM （60%-69%）, but had a marginal effect using Recycler 102 （49%-55%）. The effect of a non-ionic surfactant in green waste amended soil was variable （52%-72% TPH reduction）, but its potential to enhance biodegradation presumably by promoting contaminant bioavailability was demonstrated. High degradation of artificially added polycyclic aromatic hydrocarbons （PAHs） occurred after 106 days （75%-84%）, but significant differences between the control and treatments were unapparent, suggesting that spiked soils do not reflect the behavior of contaminants in genuinely polluted and weathered soil.

Geochemical insights into contribution of petroleum hydrocarbons to the formation of hydrates in the Taixinan Basin, the South China Sea

Methane hydrate in the South China Sea (SCS) has extensively been considered to be biogenic on the basis of its δ13C andδD values.Although previous efforts have greatly been made,the contribution of thermogenic oil/gas has still been underestimated.In this study,biomarkers and porewater geochemical parameters in hydrate-free and hydrate-bearing sediments in the Taixinan Basin,the SCS have been measured for evaluating the contribution of petroleum hydrocarbons to the formation of hydrate deposits via a comparative study of their source inputs of organic matters,environmental conditions,and microbial activities.The results reveal the occurrence of C_(14)–C_(16) branched saturated fatty acids (bSFAs) with relatively high concentrations from sulfate-reducing bacteria(SRBs) in hydrate-bearing sediments in comparison with hydrate-free sediments,which is in accord with the positive δ^(13)C values of dissolved inorganic carbon (DIC),increasing methane concentrations,decreasing alkalinity,and concentration fluctuation of ions (Cl^(-),Br^(-),SO_(4)^(2-),Ca^(2+),and Mg^(2+)).These data indicate the relatively active microbial activities in hydrate-bearing sediments and coincident variations of environmental conditions.Carbon isotope compositions of b SFAs (-34.0‰to -21.2‰),n-alkanes (-34.5‰to-29.3‰),and methane(-70.7‰to -69.9‰) jointly demonstrate that SRBs might thrive on a different type of organic carbon rather than methane.Combining with numerous gas/oil reservoirs and hydrocarbon migration channels in the SCS,the occurrence of unresolved complex mixtures (UCMs),odd-even predominance (OEP) values (about 1.0),and biomarker patterns suggest that petroleum hydrocarbons from deep oil/gas reservoirs are the most probable carbon source.Our new results provide significant evidence that the deep oil/gas reservoirs may make a contribution to the formation of methane hydrate deposits in the SCS.

Petroleum Source-Rock Evaluation and Hydrocarbon Potential in Montney Formation Unconventional Reservoir, Northeastern British Columbia, Canada

Source-rock characteristics of Lower Triassic Montney Formation presented in this study shows the total organic carbon (TOC) richness, thermal maturity, hydrocarbon generation, geographical distribution of TOC and thermal maturity (Tmax) in Fort St. John study area (T86N, R23W and T74N, R13W) and its environs in northeastern British Columbia, Western Canada Sedimentary Basin (WCSB). TOC richness in Montney Formation within the study area is grouped into three categories: low TOC ( 3.5 wt%), and high TOC (>3.5 wt% %). Thermal maturity of the Montney Formation source-rock indicates that >90% of the analyzed samples are thermally mature, and mainly within gas generating window (wet gas, condensate gas, and dry gas), and comprises mixed Type II/III (oil/gas prone kerogen), and Type IV kerogen (gas prone). Analyses of Rock-Eval parameters (TOC, S2, Tmax, HI, OI and PI) obtained from 81 samples in 11 wells that penetrated the Montney Formation in the subsurface of northeastern British Columbia were used to map source rock quality across the study area. Based on total organic carbon (TOC) content mapping, geographical distribution of thermal maturity (Tmax) data mapping, including evaluation and interpretation of Rock-Eval parameters in the study area, the Montney Formation kerogen is indicative of a pervasively matured petroleum system in the study area.

The Impact Of Oil Spill To The Total Petroleum Hydrocarbon(Tph)Concentration In Fishes At North Coastal Of Karawang Regency,West Java Province

The coastal area is one of the areas that is quite vulnerable to the threat of pollution caused by human activities,including pollution caused by oil spills(hydrocarbons)in the sea.The incident can be caused by several factors including the explosion,leakage of petroleum pipelines on the seabed,leakage of tanks or petroleum tankers at sea and disposal of waste petroleum products into the environment.Oil spills continuously can cause environmental contamination and pollution both aquatic and terrestrial.If the petroleum hydrocarbons enter sea waters,some of them will be absorbed by aquatic organisms because the nature of the petroleum hydrocarbons is difficult to decompose in waters.The intentional and unintentional entry of hazardous and toxic substances into marine ecosystems such as petroleum hydrocarbons and chemical solvents resulting from industrial wastes has become a serious problem for human health and the environment.The purpose of this study was to determine the concentration of Total Petroleum Hydrocarbon(TPH)contained in fish in coastal waters of Karawang Regency,West Java Province.This research was conducted in September-November 2019 by taking several fish samples at Ciparage Jaya Fish Auction Place,Betok Mati and Sungai Buntu Rive with a total sample of 24 fish,and taking seawater samples in the three study sites.TPH analysis was carried out at the Integrated Chemistry Laboratory,Bogor Agricultural University.TPH values in fish at Ciparage-1,Ciparage-2,Betok Mati and Sungai Buntu stations,in general,have different mean values but are almost uniform,each at 6.82;6.82;7.45 and 5.12 mg/kg.Based on the average TPH concentration in fish,it can be said that the average TPH in fish at Betok Mati station is relatively higher compared to other stations.TPH values in all fish samples exceed the safe threshold,which is a maximum of 0.002 mg/kg.Based on the results of the Bioaccumulation factor(BAF)analysis showed that the average TPH in fish was 6.55 mg/kg and the average TPH in the waters was 11.23 mg/l,so the BAF value was 58.35 which means that the absorption rate of TPH by fish organisms against the concentration of TPH in the waters of 58.35%.The analysis shows that the value of Ecological Hazard Assessment(EHA)is 3743.33 which means that the level of influence of the hazard on ecosystems and organisms is 3743.33.This value exceeds the recommended threshold according to the European Union,which is a maximum of 0.002 mg/l.

CAPILLARY GAS CHROMATOGRAPHIC ANALYSES OF THE PETROLEUM HYDROCARBONS IN COASTAL SEAWATER

This study of the petroleum hydrocarbons in coastal seawater, using dichloromethane extraction withO-terphenyl and n-C20 as internal standards, and gas chromatography with silica-capillary-column showedthat the recovery of petroleum hydrocarbons reaches 87.8% and that the lowest detection limit is 0.96μg.This method is reproducible, highly accurate, and applicable for determining the petroleum hydrocarbonsin coastal seawater.

Petroleum Hydrocarbon Transport through Saturated-unsaturated Media: A Numerical Model and Practice

The mathematical model of migration of total petroleum hydrocarbons in unsaturated media was described,including convection,molecular diffusion,mechanical dispersion and adsorption,and chemical reactions.By finite element method,a numerical model of evaluating petroleum hydrocarbon migration through contaminated soils was created and applied to the environmental investigations of a relocated mechanical factory in Shanghai.The model consisted of three compacted soil layers:plain fill,sandy silt and silty clay.The results showed that pollutants in the sandy silt traveled faster than that in the plain fill and silty clay.The same decreasing trend of migration velocity was observed in all of the three soil layers.After 180 d,the concentrations of pollutants in the sandy silt can be as low as 40% of the original maximum,while its counterpart in the silty clay is 64%.