Petroleum Industry Activities Research Articles

The impact of exploration/appraisal activities on the recovery per well in North Perth Basin

The North Perth Basin (NPB) in Western Australia has experienced significant petroleum industry activity over the past 3 years (2021–2023), marked by the drilling of exploration and appraisal wells by various operators, along with notable merger and acquisition transactions. This flurry of drilling activity, coupled with the acquisition of new seismic data, have enhanced our understanding of the variability within the primary petroleum play levels – namely, the Permian ‘Kingia’ and High Cliff reservoirs. This understanding is crucial for assessing the future potential of domestic gas supply in Western Australia. This paper aims to elucidate how recent drilling efforts have narrowed the basin-wide portfolio of available gas prospects relative to the situation in early 2021, and how the landscape of undiscovered gas resources has evolved. This shift is attributed to both unsuccessful exploration attempts and revised estimates of well deliverability. Furthermore, an updated long-term production forecast for the NPB – considering existing gas pools and the newly assessed undiscovered resources – emphasises the urgent need to re-evaluate the narrative concerning gas availability for the domestic market. The Permian gas plays within the NPB have proven to be more intricate and unpredictable than previously believed. Nonetheless, their significance to the Western Australian economy is anticipated to be substantial for many years ahead.

Evaluation of heavy metal contamination using cokriging geostatistical method (case study of Abteymour oilfield in southern Iran)

One of the most significant sources of soil contamination is the industries involved in the discovery, extraction, and use of petroleum and gas resources. One of the largest oil fields in Iran is the Abteymour oilfield, which is situated in the agricultural areas and Karun river flood plain. This study was carried out to analyze and monitor soil contamination by heavy metals and to create a map of the spread of contamination in the vicinity of the Abteymour oilfield, taking into account the significance of soil pollution in such a region. Thirty-three samples from the local surface soils were used in this study, and in addition to testing the ICP-MASS device's ability to detect the presence of heavy metals and other key elements, some of the soil's physical and chemical characteristics were also determined. After drawing the variograms and determining the appropriate fitting model, the cokriging method was used to study the spatial distribution of Al, Ti, Sr, Cr, Ni, V, Cu, Li, and Pb heavy metals and Na and S elements. The results of the heavy metals distribution in the studied area showed that the distribution of the studied elements is affected by geological conditions and human activities, including the petroleum industry and agriculture activities.

Tween-80 enhanced biodegradation of naphthalene by Klebsiella quasipneumoniae.

Accidental spillage of petroleum products and industrial activities result in various hydrocarbons in the environment. While the n-hydrocarbons are readily degraded, the polycyclic aromatic hydrocarbons (PAHs) are recalcitrant to natural degradation, toxic to aquatic life and are responsible for diverse health challenges in terrestrial animals; suggesting the need for faster and more eco-friendly ways of removing PAHs from the environment. In this study, the surfactant tween-80 was used to enhance a bacterium's intrinsic naphthalene biodegradation activity. Eight bacteria isolated from oil-contaminated soils were characterised using morphological and biochemical methods. The most effective strain was identified as Klebsiella quasipneumoniae using 16S rRNA gene analysis. High-Performance Liquid Chromatography (HPLC) analyses showed that the detectable concentration of naphthalene was decreased from 500 to 157.18μg/mL (67.4%) after 7 d in the absence of tween-80, while 99.4% removal was achieved in 3 d in the presence of tween-80 at 60μg/mL concentration. The peaks observed in the Fourier Transform Infra-Red Spectroscopy (FTIR) spectrum of control (naphthalene), which were absent in that of the metabolites, further established naphthalene degradation. Furthermore, Gas Chromatography-Mass Spectrometer (GCMS) revealed metabolites of single aromatic ring, such as 3,4-dihydroxybenzoic acid 4-hydroxylmethylphenol, which confirmed that the removal of naphthalene is by biodegradation. Tyrosinase induction and laccase activities suggested the involvement of these enzymes in naphthalene biodegradation by the bacterium. Conclusively, a strain of K. quasipneumoniae that can effectively remove naphthalene from contaminated environments has been isolated, and its biodegradation rate was doubled in the presence of non-ionic surfactant, tween-80.

Isolation of indole biodegrading bacterial species from petroleum contaminated site of northeast India: Growth kinetics and crude oil biodegradation assessment

Petroleum industrial activities such as crude oil spillage, sludge generation, and effluent wastewater adversely affects the surrounding ecosystem. Several biological processes have been developed so far to remediate the petroleum contaminants. This article is focused on the remediation of petroleum waste using novel bacterial isolates from petroleum-contaminated sites. The indole biodegradation was studied in bioreactor wherein 84.86 % COD removal was observed using consortium of Alcaligenes faecalis RB-10, Pseudomonas guariconensis RB-12 and Pseudomonas monteilii RB-29. The residual analysis of biodegraded samples were performed using various analytical techniques. The maximum specific growth rate (μmax) and half-saturation rate constant (ks) were evaluated individually for Alcaligenes faecalis RB-10, Pseudomonas guariconensis RB-12 and Pseudomonas monteilii RB-29 species using Monod model. The crude oil degrading potential of isolated bacterial consortium was also investigated.

Circular economy potential and contributions of petroleum industry sludge utilization to environmental sustainability through engineered processes - A review

The petroleum industry activities unavoidably generate a large quantity of sludge named Petroleum industry sludge (PIS). The generation rate has been increasing because of the ascending energy demand. It is a potential energy resource. PIS has been shown to contain hazardous constituents that may have negative consequences on the environment and public health. Thus, the treatment and disposal of this waste is a global issue. Numerous treatment methods have been demonstrated to reduce sludge volume and toxicity and recover petroleum components. The sludge qualities affect how effective they are. These treatment strategies can reduce the toxic substances in sludge and reduce their detrimental effects on human health and the environment. However, because of the sludge's tenacious character, only a few technologies can meet strict environmental laws while using a sizable amount of water, electricity, and chemicals. PIS treatment methods that are both waste-free and cost-effective are currently unavailable. In terms of environmental engineering significance, this study adopted the systematic review to discuss the waste to resource potential applications of PIS for reusability in sustainable construction, wastewater treatment applications, and gas generation. PIS application ineffective microorganism biofertilizer production, levan production, rubber tires manufacturing, metal catalysts synthesis, carbon–clay composites for use in sensors and electronic devices were also discussed. That is not enough, this review also found that the adoption of the circular economy that represents a new direction to create value and prosperity by elongating product lifespan and moving the waste from the end of the supply chain to the outset is very important. Thus, the circular economy potential of PIS to achieve self-cycle operation through the concept of “wastes-treat-wastes” in the petroleum industry was extensively discussed.

Technology Focus: Reserves Management (December 2021)

The year 2021 has seen improvement in the market fundamentals for the petroleum industry, and merger and acquisition activity has increased. Market volatility and project investment caution, however, are expected to continue as the world adjusts to the “new normal” of the societal, environmental, and economic effects of living with COVID-19 and the climate challenge. Pressure to address environmental, social, and governance (ESG) issues increasingly affects the commercial viability of projects and their corresponding chance of development. Further, entities face reputational, financial, and litigation risk from not maintaining high ESG standards. The papers selected highlight some of these considerations and the importance of using all the tools provided by the industry resource classification systems to navigate projects through to viable and sustainable development reasonably and transparently for all stakeholders. Paper SPE 203422 provides a systematic approach to gathering data consistently and benchmarking projects based on reservoir performance that allows efficient data mining to help identify opportunities. It also highlights the importance of appropriate analogs to underpin recovery potential and field development planning. Paper SPE 206104 highlights the deterministic incremental method for resource evaluation, specifically that it is often difficult to reconcile the incremental method with the deterministic scenario method with forecasts for a different range of uncertainty and commercial projections for the same project. These differences should be mitigated by clearly defining the project that under-pins the evaluation and applying principles from the SPE Petroleum Resources Management System (PRMS). Paper SPE 206322 illustrates the challenges faced when combining reserves and resources management systems in a merger scenario that involves classified or evaluated projects in different ways. Pleasingly, it highlights the use of subclasses, recommended by the PRMS and other global classification systems and increasingly a standard practice. Caution should be taken to ensure consistency and alignment with the PRMS subclasses. Governments globally are announcing net-zero targets and other initiatives for reaching sustainable development goals. Two recommended reading papers focus on the effect of carbon pricing and stream-lining reporting. Paper SPE 205847 describes the new Petroleum Resource Specifications and Guidelines (PRSG) published as supporting documentation for the United Nations Framework Classification (UNFC). The UNFC system is unique in considering technical feasibility separately from economic, environmental, and social viability to provide greater transparency. The UNFC framework and PRSG can be used independently or in conjunction with other classification systems for individual projects and for comparisons between petroleum and other emerging energy projects. Recommended additional reading at OnePetro: www.onepetro.org. SPE 202458 - What Does a Carbon Price Do to Your Reserves and Development Plans? by Daniel Lorng Wong, Gaffney Cline, et al. SPE 203182 - Intelligent Annual Reservoir Performance Reporting System i-ARPR— A Fascinating Journey From a Concept to Reality by Muhammad Navaid Khan, ADNOC, et al. SPE 205847 - Development of the Petroleum Resource Specifications and Guidelines (PRSG)—A Petroleum Classification System for the Energy Transition by Barbara Pribyl, Independent, et al.

Behavioral and hypothalamic transcriptome analyses reveal sex-specific responses to phenanthrene exposure in the fathead minnow (Pimephales promelas)

Environmental concentrations of the polycyclic aromatic hydrocarbon phenanthrene can become elevated with petroleum processing, industrial activities, and urban run-off into waterbodies. However, mechanisms related to its neurotoxicity in fish are not fully described. Here, we exposed adult fathead minnows (FHM) to an average measured concentration of 202 μg phenanthrene/L over a 47-d period. Behaviors of male and female FHM were assessed using a novel aquarium test. Phenanthrene exposed females displayed equilibrium loss, while phenanthrene exposed males spent less time in the aquarium bottom, suggesting phenanthrene reduced anxiety-related behavior. To elucidate putative mechanisms underlying behaviors, we determined the hypothalamic transcriptome profile, a critical integration centre for the regulation of behaviors. There were 1075 hypothalamic transcripts differentially expressed between males and females (sex-specific) while 15 transcripts were phenanthrene-specific. Thus, sex of the animal was more pervasive at influencing the transcriptome compared to phenanthrene and this may partially explain the divergent behavioral responses between sexes. Transcripts altered by phenanthrene included palmitoylated 3 membrane protein, plectin 1,ATP synthase membrane subunit c, and mitochondrial ribosomal protein S11. Gene set enrichment analysis revealed less than 5% of the gene networks perturbed by phenanthrene were shared between males and females, thus phenanthrene altered the hypothalamic transcriptome in a sex-specific manner. Gene networks shared between both sexes and associated with phenanthrene-induced neurotoxicity included processes related to mitochondrial respiratory chain dysfunction, epinephrine/norepinephrine release, and glutamate biosynthesis pathways. Such energy deficits and neurotransmitter disruptions are hypothesized to lead to behavioral deficits in fish. This study provides mechanistic insights into phenanthrene-induced neurotoxicity and how it may relate to changes in fish behaviors.

Utilização de combustíveis fósseis no Brasil e suas consequências ambientais

Este trabalho tem o objetivo de analisar os impactos ambientais de atividades de exploração e produção de petróleo e de discutir também o risco da atividade para as populações e ecossistemas sensíveis na área de influência direta. Partindo do entendimento das atividades da indústria do petróleo em suas diversas etapas, este se fundamenta numa pesquisa bibliográfica. Aborda os principais pontos da história, a composição do petróleo, extração, produção, enfim, todas as fases de seus processos de obtenção de derivados. O presente artigo tem como perspectiva ampliar o conhecimento a respeito dos impactos que o refino de petróleo causa ao meio ambiente, pois, para se obter os produtos finais do petróleo são necessários diversos processos para que sejam retirados os seus derivados. Tais processos geram diversos danos aos recursos naturais em especial os hídricos; aumentando também os danos ao ecossistema.

Bioremediation of oily sludge polluted soil employing a novel strain of Pseudomonas aeruginosa and phytotoxicity of petroleum hydrocarbons for seed germination

Agricultural land pollution is key a problem globally, which is linked with growth of industries. Petroleum industrial sector is one of the major industrial sectors and the activities of petroleum industry lead to the agricultural land pollution. Oily sludge is a type of solid and hazardous waste generated from petroleum industrial activities. Hence, there is an urgent need to find remediation methods of the oily sludge contaminated agricultural land. Thus, the aim of this work was to study bioremediation of oily sludge polluted soil employing a novel strain of Pseudomonas aeruginosa and evaluation of phytotoxicity on germination of Vigna radiata seed in pots. Five different approaches were adopted for the bioremediation studies, which included Bioaugmentation + Biostimulation, bioaugmentation, biostimulation, natural attenuation and abiotic factors. Simultaneous application of P. aeruginosa NCIM 5514 and nutrients in microcosm showed 92.97 ± 0.92% decrease in oily sludge with good hydrocarbon utilizing bacterial count and decreased nutrient level in 56 days. Pot experiments on seed germination of mung beans (Vigna radiata) seeds was performed by pot experiments. 80.95% germination in five days in treated soil. From the results it was concluded that simultaneous use of oily sludge degraders and nutrient supplement could revive seed germination ability of oily sludge polluted soil effectively. This is first report of comparing five techniques to bioremediate oily sludge polluted soil using Pseudomonas aeruginosa, followed by pot study using V. radiata seeds, showing that P. aeruginosa can be an efficient bioremediation agent and can be effectively used for remediation of oily sludge contaminated soil.

NEW APPROACH TO FLARE GAS RECOVERY SYSTEM USING INTEGRATED RECIPROCATING COMPRESSORS FOR SOLVING ENVIRONMENTAL ISSUE BY MONETIZING GAS

Flare gas is light hydrocarbon gas, by product of any petroleum industry activities, that is flared; and it could not pass into production facilities due its to low pressure. The gas flare volume frequently is significant, causing greenhouse gas emissions which gives serious environmental issue. Aims: The purpose of this research is to utilize flare gas in oil and gas fields to reduce environmental issue. Methodology and Results: Flare gas in an oil producing field is compressed to produce higher pressure gas flow, by using three one-stage Integrated Reciprocating Compressors to enter the production trunk line. The gas is flown to CO2 Removal Plant, as the gas would be gas sales. The subject field in West Java, the production wells experiences pressure decline; resulting the wellhead flowing pressure becomes low, so the gas is being flared. The gas flare recovery system is economically profitable both for purchase and rental scenarios. Renting the equipment is more profitable and has lower technical risk, because all risks is burdened to rental service provider. Conclusion, significance and impact study: Monetizing flare gas will reduce environmental issue, and it is utilized for own use or gas sales. The best Economics Scenario is rental scenario.

Soil Microcosm Study for Bioremediation by a Crude Oil Degrading Pseudomonas aeruginosa NCIM 5514

AbstractAgricultural land pollution is a big threat globally, which is associated with petroleum industry activities. Hence, the exploration of remedial methods for the treatment of polluted agricu...

Optimization and Performance Test of Oil Spill Dispersant at Bioremediation of Contaminated Soil with Heavy Oil by Bioslurry Technique

Petroleum industry activities produce waste such as petroleum hydrocarbons which damage to the soil environment due to changes in soil physical, chemical and biological properties. Oil Spill Dispersant (OSD) is a product that can break down waste of oil into small parts so that it can be dispersed naturally. Laboratory experiments aimed to find out optimize and performance test of OSD in the process of bioremediation with using bio-slurry technique on contaminated soil with heavy oil was carried out at Laboratory of Surfactant and Bio-energy Research Center (SBRC), Research and Community Service Institute of Bogor Agricultural University on January - August 2018 using contaminated soil with heavy oil. The experiment used Response Surface Method (RSM) with two factors, namely the incubation time factor (X1) and the Dispersant to oil ratio (DOR) (X2). The observed variables were soil Total Petroleum Hydrocarbons (TPH), pH, total microbes, and Chemical Oxygen Demand (COD) at soil solution. The results showed that the treatment of incubation time and its combination with DOR significantly reduced soil TPH, increased soil acidity, and increased soil total B. megaterium, but did not significantly affect on COD in soil solutions. Optimization of OSD with RSM showed that the higher DOR of OSD and the longer the incubation time, the higher also the rate of biodegradation of TPH. The optimum conditions were reached at DOR of 1.16:1 and incubation time of 7 days which were able to degrade soil TPH of 54.30%. The optimum conditions of soil pH (8.825) was reached at DOR of 1:1 and incubation time of 5 days, as well as the optimum conditions of B. megaterium (8.35 log CFU g-1) was reached at DOR of 0.86:1 and incubation time of 7 days. Oil spill dispersant (OSD) increased COD in soil solution in both uncontaminated and contaminated soils with heavy oil.

Characterization of naphthenic acids in crude oils and refined petroleum products

Naphthenic acids (NAs) or naphthenic acid fraction compounds (NAFCs) are generally recognized as a family of cycloaliphatic carboxylic acids naturally occurring in petroleum. These acid extractable organics (AEOs) from petroleum industry activities including oil sands produced waters (OSPW) have led to increasing environmental concern in recent years due to their potential release into the environment. This study presents a characterization of naphthenic acids in a number of crude oils and refined petroleum products from various sources. NAs with unsaturated degree of z −2 to z −24 and carbon number ranging from 6 to 60 were determined by liquid chromatography-high resolution Orbitrap mass spectrometry (LC-HRMS). NA profiles generally vary from oil to oil. Conventional light crude oils generally contain low concentrations of NAs, while heavier crudes and oil sands bitumen contain significant levels of NAs. NAs in Federated and Alaska North Slope crude oils are relatively low with O2-NA concentrations of 139 µg/g and 419 µg/g, respectively, while their abundances are as high as 7994 µg/g in Venezuelan Orinoco bitumen. The ratio of even to odd (E/O) carbon number NAs in all petroleum oils studied is close to 1.0 for z −2 to z −24 NAs. NA series z 0 to z −12 in bitumen account for about 90% of the total determined NAs, and z −14 to z −24 NAs make up the remaining ∼10%. Moreover, z −2∼−6 (1- to 3-ring) NAs are the most predominant in all oil samples. In terms of distribution according to carbon number, C6 to C21 NAs (α-group) make up about 44.2% of the total NAs in an Alberta oil sands bitumen. Caustic extraction of oil sands bitumen mostly transports the more toxic low-molecular weight portion of NAs into OSPW, in which α-group NAs constitute about 90% of the total NAs. Evaporation (up to 23.6% by weight) weathering slightly enriched the NAs but likely did not affect the distribution profile of NAs in a diluted bitumen (dilbit).

Recent advances in remote sensing technologies for hydrocarbon exploration and environmental evaluation

Remote sensing detects and monitors the physical and spatial characteristics of the earth's oceans, surface, and atmosphere by measuring the reflected or scattered downwelling or emitted upwelling electromagnetic radiation or acoustic signal using passive or active sensors at a distance. It plays an important role in today's energy and environmental sustainability efforts. Remote sensing from spaceborne, airborne, terrestrial, and marine platforms has long been used in hydrocarbon exploration to map surface geology, topography, and hydrocarbon seepages, as well as to evaluate environments that relate to petroleum industry activities. Since the mid-2000s, remote sensing technologies have undergone substantial advances in data acquisition, processing, and interpretation. In the last decade, rapid advances in satellite systems, unmanned autonomous vehicles (UAVs), sensors, and scale of surveys have further expanded applications.

Influence of abiotic factors, natural attenuation, bioaugmentation and nutrient supplementation on bioremediation of petroleum crude contaminated agricultural soil

Contamination of agricultural land(s) is a major problem worldwide which is associated with activities of petroleum industry. Due to these exploration activities remedial techniques for clean-up of contaminated agricultural soil(s) has become an alarming research topic. Hydrocarbon utilizing bacterial consortium (HUBC), isolated from petroleum crude (petroleum industry waste water and soil) contaminated sites, India has been used for soil microcosm study. The aim of present study was to compare potency of five different techniques to remediate petroleum hydrocarbons contaminated agricultural soil by employing soil microcosm study. To the best of our knowledge this is the first report for comparison of five different techniques (abiotic control, natural attenuation, biostimulation, bioaugmentation and simultaneous bioaugmentation & biostimulation) for bioremediation of agricultural soil using consortium of hydrocarbon utilizers by employing soil microcosms. Concurrent application of bioaugmentation (with HUBC) and biostimulation (with nutrient amendments) in the soil microcosm resulted in 93.67 ± 1.80% hydrocarbons degradation in 45 days of experiment and hydrocarbon utilizing bacterial count was recorded 4.11 ± 0.11 × 108 CFU/g. In the bioaugmented and biostimulated soil microcosm organic carbon was reduced from 3.49 ± 0.08% to 0.62 ± 0.11% with simultaneous decrease of other nutrients. The consortium could survive in artificially crude oil contaminated and nutrients amended agricultural soil microcosm and could degrade petroleum hydrocarbons effectively in soil microcosm conditions. This suggests its application as a potential bioremediation agent for farmland restoration i.e. management of soil environment.

Transformed Territories of Gendered Care Work in Ecuador's Petroleum Circuit

This article explores the transformation of indigenous women's care work in the Ecuadorian Amazon, as their communities are increasingly integrated into petroleum industry activities. Care work activities–not only for social reproduction, but also to sustain cycles of fertility, growth and waste interdependent with nature–constitute affective ecologies. In development sites of Ecuador's petroleum circuit, such activities are domesticated and devalued, and the territories produced by women's care work are progressively delimited. Once aimed at social and natural reproduction, their care practices now focus on household and familial reproduction. This article is based on two years of ethnographic and qualitative research in indigenous communities of the Amazonian provinces of Sucumbíos and Pastaza. We bring feminist economic approaches to the study of affective ecologies to show how fundamental changes in inhabitants' historically shaped relationships to, and conservation of, nature both depend on and produce gendered ecological and socioeconomic relations.

Valorisation of Waste Chicken Feathers: Green Oil Sorbent

The threat of oil pollution increases with the development of large-scale off-shore petroleum industrial activities. Recently, reducing waste materials through reuse has contributed to sustainable manufacturing in many industries. With development of large-scale poultry farming industries, the disposal of large amounts of waste chicken feathers has become a huge problem. Thus, sustainable methods for valorisation of this waste are needed. This paper examines beneficiation of waste chicken feathers via conversion into sorbents for clean-up of oil spills in water bodies to replace conventionally used synthetic adsorbents that are costly. Chicken feathers have a very high capacity for adsorption of liquid oils (up to 16.21 g of oil/g of chicken feather) at fast uptake time (10 min). The removal efficiency of oils in spills increases with increment in contact time with the sorbent. Untreated waste chicken feathers exhibited slow sorption rate for oil due to the presence of grease and other impurities on the surface of feathers. More than 85% of the oil adsorbed by chicken feathers can be recovered. Thus, waste chicken feathers show very attractive and promising adsorption/absorption properties for oil spill clean-up applications to replace polymer-based adsorbents due to their high oil absorption capacities. Both untreated and treated chicken feathers show promising potential for use as oil absorbents.

Comprehensive review on toxicity of persistent organic pollutants from petroleum refinery waste and their degradation by microorganisms

Control and prevention of environmental pollution has become a worldwide issue of concern. Aromatic hydrocarbons including benzene, toluene, ethyl benzene, xylene (BTEX) and polyaromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs), released into the environment mainly by exploration activities of petroleum industry. These pollutants are mutagenic, carcinogenic, immunotoxic and teratogenic to lower and higher forms of life i.e. microorganisms to humans. According to the International Agency for Research on Cancer (IARC) and United States Environmental Protection Agency (U.S. EPA), Benzo[a]pyrene (BaP) is carcinogenic in laboratory animals and humans. Aromatic hydrocarbons are highly lipid soluble and thus readily absorbed from environment in gastrointestinal tract of mammals. Treatment and remediation of petroleum refinery waste have been shown either to reduce or to eliminate genotoxicity of these pollutants. Bioremediation by using microorganisms to treat this waste is showing a promising technology as it is safe and cost-effective option among various technologies tested. The main aim of this review is to provide contemporary information on variety of aromatic hydrocarbons present in crude oil (with special focus to mono- and poly-aromatic hydrocarbons), exposure routes and their adverse effects on humans. This review also provides a synthesis of scientific literature on remediation technologies available for aromatic hydrocarbons, knowledge gaps and future research developments in this field.

Effects of low crude oil chronic exposure on the northern krill (Meganyctiphanes norvegica)

Chronic oil pollution related to gas and oil drilling activities is increasing in the sea due to the rising offshore petroleum industry activity. Among marine organisms, zooplankton play a crucial role in the marine ecosystem and therefore understanding the effects of crude oil chronic exposure on zooplankton is needed to determine the impact of oil in marine environments. The present study reports on the effect of crude oil on adult northern krill, Meganyctiphanes norvegica, collected during three seasons. Their sensitivity to oil was examined with oil concentration of 0.01 versus 0.1mgoilL−1 and photo-modified oil in flowing seawater maintained in the dark for 2weeks at in situ temperature. Oil (polycyclic aromatic hydrocarbons, PAHs) entered the krill (on average, 350 and 4400μg·kg−1 wet weight in low and medium oil treatments respectively) and a larger fraction of the krill exhibited digestive gland pathologies (enhanced apoptosis and pathology of digestive tubules) in oil treatments (27–80%) compared to a significantly lower fraction (7–13%) in treatments that received no oil. However, 2-week oil exposure at these concentrations did not significantly decrease survivorship or impair basic functioning such as feeding and respiration rates. Similarly, there were only limited changes in the transcription of 7 selected genes from head tissue. Additionally, although there was significant seasonal variation in krill total lipid content and fatty acid composition, there was no treatment effect on both these parameters, which suggests limited oxidative stress under experimental conditions. Furthermore, there was no significant treatment effect on two direct measures of oxidative stress (MDA: malondialdehyde and AOPP: advanced oxidation protein products) in any of the seasons. Nevertheless, histology clearly revealed enhanced digestive gland pathologies in krill even at low concentrations. Although krill with such pathologies continue to survive, their accumulation of PAHs may be transferred up the food chain, impacting their predators and the wider ecosystem.

Congener Specific Determination of Polychlorinated Biphenyls (PCBs) in Human Milk

Eighteen congeners Polychlorinated biphenyls (PCBs) congeners were analyzed in 38 human milk samples collected from different ages living in Eastern and Central provinces in Saudi Arabia. The PCB profile was dominated by higher chlorinated congeners. Non-ortho PCB congeners which have the highest Toxic Equivalency Factor (TEF) values were detected in all of individual samples. PCB-81 and PCB-153, the most dominating PCB congeners, which might therefore be used as an indicator for sum PCBs. Toxic Equivalents Factor (TEF) for mono-ortho substituted PCB congeners indicated higher exposure to toxic PCBs in Eastern province rather the Central due to main petroleum industry activities, but estimated daily intakes for both provinces indicate that infants consuFming mother’s milk are not at risk of adverse effects caused by PCBs. Our study builds the first database in Saudi Arabia research of human milk samples.