Oil Exploration Activities Research Articles

The Impact of Oil Exploration Activities on Soil, Water and Shrimps of Maa-Or Gbor in Korokoro Community, Rivers State, Nigeria

Crude oil exploration and its associated spillage pose a major threat to the environment in Nigeria and if not checked and managed properly, could lead to total annihilation of the ecosystem especially in the Niger Delta Region. Therefore, this study examines the impact of oil spill on soil, water and shrimps from Maa-or gbor. Water and soil samples were collected in the upstream, midstream and downstream, while shrimps from the river were also collected. They were digested with nitric acid. The heavy metal components were analyzed using atomic absorption spectrophotometer while physiochemical parameters were determined using different analytical methods. The result of the metals concentration in the soil showed that the values of some of the metals analyzed were within the acceptable limit of FAO/WHO except for Cu, Mn and Fe values. The result of water quality showed that pH values of the stations were in the range of 6.08-6.20 and a mean value of 6.15± 0.05 for the three stations, which is lower than the limit (6.5- 8.5) recommended for drinking water. Also the result showed that Station C had the highest conductivity value when compared with other stations, and significantly differs when compared with station B. However, the values of the electrical conductivity in all the stations were lower than that of FEPA acceptable limit of 250, while the mean value for the stations was 60.9± 3.42. Trace metals concentration in shrimps was below FAO/WHO acceptable limit. The result obtained for water quality index was147. This value is above the recommended standard for drinking water, thus indicates poor quality water status of Maa-or gbor and unfit for human consumption.

Entrepreneurial activity in the Albertine Graben region of Uganda: the role of infrastructure development and entrepreneurial orientation

PurposeThe purpose of this paper is twofold (1) to establish the relationship between infrastructure development and entrepreneurial orientation (EO) on the entrepreneurial activities in the Albertine Graben region of Uganda and (2) to establish whether entrepreneurial orientation mediates the relationship between infrastructure development and entrepreneurial activity.Design/methodology/approachQuantitative data were collected from a sample of 118 enterprises, mainly small businesses. The authors sent out 118 self-administered questionnaires of which 93 useable questionnaires were returned, giving a response rate of 79%. Quantitative data were processed and analyzed using SPSS version 21. Analyses such as correlation, hierarchical regression and mediation were carried out to understand (1) the relationship between the variables, (2) the prediction potential of the independent variables to entrepreneurial activity and (3) the mediation role of EO on the relationship between infrastructure activity and business performance.FindingsThe authors found out that infrastructure developments are a significant predictor of entrepreneurial activity (ß = 0.432**, p < 0.01), explaining 21.6% of entrepreneurial activity in the region. EO was found to have a significant positive relationship with entrepreneurial activity (r = 0.580**, p < 0.01). The results of a hierarchical regression indicate that both infrastructure development and EO explain 42% of the entrepreneurial activity in the Albertine region. Mediation analysis indicated that EO is a partial mediator in the relationship between infrastructure development and entrepreneurial activity.Research limitations/implicationsThe results are based on self-report statistics. The model explains 42% of entrepreneurial activity thus there is need to examine the influence of other factors which contribute the 58% to entrepreneurial activity. The study was also limited to public infrastructure, with much attention on transportation (roads) and energy (electricity). Future studies can consider looking at private infrastructure as well.Practical implicationsUnderstanding the role of infrastructure development and EO helps government and other development partners to know the type, quantity and quality of the infrastructure required as well as how to grow the EO of entrepreneurs to boost entrepreneurial activity in the region.Originality/valueThis paper provides insights into our understanding of the relationship between infrastructure development, entrepreneurial orientation and entrepreneurial activity using evidence from Uganda’s oil rich region. The originality of this paper further lies in the discovery of the partial mediation of entrepreneurial orientation in the relationship between infrastructure development and entrepreneurial activity. This is the first time such a study is conducted in an African developing country such as Uganda whose oil exploration activities are still in their infancy.

Influence of oil and gas exploration activities on the macrobenthic community structure of the Krishna-Godavari basin (Ravva coast), Western Bay of Bengal

The influence of oil and gas exploration activities on the macrobenthic community of an offshore oil and gas drilling site was investigated along the Krishna-Godavari basin (KG), Western Bay of Bengal. In the oil well sites, the enrichment factor of most of the metals (Cu, Zn, Pb, Cr) showed relatively higher values (EF > 10), indicating their anthropogenic origin. The macrobenthic community exhibited a conspicuous reduction in biomass (av. 33.5%), density (av. 20.9%) and diversity (av. 6.7%) in and around the oil well platforms. Polychaetes abundance increased towards the oil well platforms and decreased away from the wells, whereas cumaceans dominated at the coastal stations. The lower density of Ampelisca sp. in the oil well platforms and higher density at the locations away from the oil wells indicates the adverse effects of exploration activities. Along with the environmental variables such as depth, sediment texture and composition, trace metal concentration also had a prominent influence on the macrobenthic fauna. The biotic indices (H’ index and AMBI) exhibiting slightly disturbed condition at the oil well sites; and M-AMBI exhibiting moderate-good–high condition, reveals the distinct distribution pattern of benthic communities in the region. Slightly disturbed conditions at a distance of 1–1.5 km from the oil wells compared to the undisturbed conditions at regions 3–4 km away from the platforms reveals the impacts of oil and gas exploration activities on the benthic habitat quality.

The utilization of Surfactant on enhanced oil recovery chemical injection to maintain energy in Indonesia

The needs of oil in the world for the transportation, industry, power plant and other fields drive us to be more consumptive in the utilization. Oil needs in Indonesia that keeps on increasing along the years is unequal with the number of oil exploration activity, which further create a scarcity on fossil energy fuel source availability. If Indonesia is unable to discover new oil sources as soon as possible, Indonesia is predicted to become oil importer in 2025. Oil production is known to be practiced through three steps which are primary recovery, secondary recovery, and tertiary recovery. At this moment, several oil wells in Indonesia have reached final stages of secondary recovery. If the production activity on these wells is continued, the recovered oil will never be able to reach optimum result and will unable to cover the production cost. Because of that, oil development and production management projects will never be able to run. The offered solution to fulfill this energy needs is by conducting tertiary recovery method known as Enhanced Oil Recovery (EOR). EOR method is known to be able to optimize oil recovery as much as 30% of total remaining reserve on an oil or gas field. One of EOR method that will be the focus in this research is chemical injection or chemical flooding, where a certain chemical compound is injected into the reservoir with an objective of reservoir physical or chemical manipulation to facilitate oil production to the surface. The material required for chemical flooding are surfactant, alkali, and polymer. On the previously conducted research at EOR Laboratory Universitas Trisakti is aimed to observe the impact of surfactant concentration on water formation salinity on phase and interfacial tension (IFT) tests to improve surfactant performance on EOR process to optimize recovery factor (RF) or oil production. Chemical ingredients used in this research are anionic surfactants which are Alpha Olein Sulfonate (AOS) and paraffin oil. The utilization of surfactant solution concentration is 0.5%, 1%, 1.5% and 2%. Meanwhile formation salinities are at 10,000 ppm, 15,000 ppm, and 20,000 ppm. The emulsion formed from the phase test is an upper phase. The factor of emulsion phase formation is high interfacial tension and the utilized surfactant basic ingredient is a petroleum based ingredient. The result of IFT measurement on surfactant solution possess a value range of 16 dyne/m to 41 dyne/m. Based on the research result and conducted analysis, the utilized AOS surfactant in this research is proven to be able to lower significant IFT of water and oil on emulsion percentage formed and stable at 18.75% on 1.5% concentration with water salinity of 15,000 ppm.

Land Procurement for Upstream Oil and Gas Business Activities in Indonesia

This paper aims to provide an understanding and insight regarding land procurement for oil and gas exploration activities as well as the development of regulations or legal and policy breakthroughs that have so far not been or very little exposed. Land procurement has always been a serious obstacle or obstacle to oil and gas exploration activities in Indonesia. Land procurement for oil and gas exploration using a business to business (B to B) mechanism makes it very difficult for SKK Migas and the contractor. In recent years, the government has made legal breakthroughs to simplify and accelerate the land procurement mechanism for exploration activities. This study uses a normative juridical method supported by in-depth interviews with legal experts, land acquisition committees and landowners and has produced conclusions: First, the business to business (B to B) mechanism often faces obstacles and obstacles, such as; 1) refusal from the landowner; 2) inconsistency with the spatial layout; 3) there is a land dispute with other parties; 4) it is difficult for oil and gas contractors to process land certification. Second, the discretion which is considered as a legal breakthrough or new policy that is ideal in helping to smooth and accelerate the process of oil and gas production in Indonesia.

STRATEGIES FOR MANAGING OIL SPILL RELATED CONFLICTS IN THE NIGER DELTA: A CASE STUDY OF BAYELSA STATE

The discovery of crude oil in Oloibiri-a town in the present Bayelsa state, Niger-Delta region of Nigeria) in 1956 and the subsequent exploration activities have over the years impacted tremendously not only on the ecosystem and livelihood pattern of the Niger Delta but on the pattern of conflicts that has trended.. While resources accruable to Nigeria from sale of crude oil are shared by all, the impacts of oil spill an offshoot of crude oil exploration activities are borne solely by the Niger Delta region. Oil spill appears to have found a permanent abode in Bayelsa state; from Southern Ijaw to Sagbama local governments, Olodiama to Azuzuama communities. Local communities are faced with the problem of continuous oil spill. This in turn has brought about conflicts between oil bearing communities and oil companies. These conflicts in some instances led to shut down of operations of oil companies, vandalism, and reduction of Nigeria’s crude export. In view of the illustrated background, this study examined the strategies for management of oil spill related conflicts in Bayelsa state regarding that oil spill is a key impact of crude oil exploration activity. Findings revealed that the strategies deployed in the management of oil spill in the state can be categorised into three: community strategies, regulators and non-governmental organisations strategies.

Exact and heuristic algorithms for the fleet composition and periodic routing problem of offshore supply vessels with berth allocation decisions

This paper presents a branch-and-cut algorithm and an adaptive large neighborhood search (ALNS) heuristic for the periodic supply vessel planning problem (PSVPP) arising in the upstream offshore petroleum logistics chain. Platform supply vessels support the offshore oil and gas exploration and production activities by transporting all the necessary material and equipment back and forth between offshore units and an onshore supply base according to a delivery schedule. The PSVPP consists of solving a periodic vehicle routing problem and simultaneously determining an optimal fleet size and mix of heterogeneous offshore supply vessels, their weekly routes and schedules for servicing the offshore oil and gas installations, and the berth allocations at the supply base. The branch-and-cut algorithm considers a reduced formulation for the problem which performs much better than the complete one, and easily finds optimal solutions for the smaller and most of the clustered instances. The ALNS heuristic contains new features which include multiple starts and spaced local searches. These algorithms were tested on instances with up to 79 offshore units, providing better results than the best available.

Laboratory Study of Copper Nanoparticle Effect on Scale and Corrosion Rate in the Oil Field

The occurrence of corrosion and scale on production equipment is an obstacle that often occurs in oil and gas exploration activities. Physical and chemical properties of formation water that come out with oil from production wells are the main variables causing corrosion and scale. In recent years, developing nanotechnology provides many benefits in various industrial activities. One product that is becoming widely known is Copper Nano Particles (CuNPs) which have anti-biotic, anti-microbial, and anti-fungal agents which are soluble in water and can be used to protect / coat metals (superficial conductive coatings of metal and non-ferrous metal). The use of nanoparticles in oil and gas exploration activities is still very limited. Specifically, the CuNPs material, its anti-bacterial and anti-fungal properties have never been researched on the possible use in the oil field. In this study, it was observed the influence of the presence of CuNPs in formation water on the potential for scale formation and corrosion. Formation water obtained from production wells in the Wonocolo region, Cepu, Central Java, is used as a sample to test the effect of CuNPs on the scale and corrosion trends. Observations have shown that the CuNPs content test at various concentrations did not have a significant effect on formation water for its tendency to form scales. While the corrosivity of water seems to be quite influenced by the presence of CuNPs, where the addition of nanoparticle material is optimal at 0.01 ppm which can reduce corrosion rates up to 95%.

Health and Well-being Challenges of Workers on the Upstream Sector in the Oil and Gas Industry

Introduction: Occupational nature, strenuous physical activity, shift work, spatial and geographical location, as well as support facilities and equipment, pose greater risks to individuals in the oil and gas industry, especially those engaged in offshore oil exploration and production activities. The purpose of this article is to explain the issue of health and well-being of oil and gas industry workers with regard to accidents in this industry, which can be better and more effective by managing safety, health and environment (HSE) by modeling events in other countries. Methods: This review article analyzes the health problems of oil and gas workers. The research question is what issues and challenges the upstream part of the oil and gas industry has in the field of employee welfare. Physical, chemical, biological and ergonomic risk factors have been investigated. It has also pushed the specific problems of the drilling industry (restrictions on offshore work, psychological hazards, stresses from frequent relocations, and sleep quality to choose from). Results: Physical, chemical and biological hazards have been identified as the most important hazards. In addition, psychological hazards have a very serious effect on health and safety. Conclusion: Systematic assessment of health risks, personnel health, training programs, accident analysis, is an effective method of HSE management.

Fouling of polyelectrolyte multilayer based nanofiltration membranes during produced water treatment: The role of surfactant size and chemistry

Large volumes of water become contaminated with hydrocarbons, surfactants, salts and other chemical agents during Oil & Gas exploration activities, resulting in a complex wastewater stream known as produced water (PW). Nanofiltration (NF) membranes are a promising alternative for the treatment of PW to facilitate its re-use. Unfortunately, membrane fouling still represents a major obstacle. In the present work, we investigate the effect of surface chemistry on fouling of NF membranes based on polyelectrolyte multilayers (PEM), during the treatment of artificial produced water. To this end, oil-in-water (O/W) emulsions stabilized with four different surfactants (anionic, cationic, zwitterionic and non-ionic) were treated with PEM-based NF membranes having the same multilayer, but different top layer polymer chemistry: crosslinked poly(allylamine hydrochloride) (PAH, nearly uncharged), poly(sodium 4-styrene sulfonate) (PSS, strongly negative), poly(sulfobetaine methacrylate-co-acrylic acid) (PSBMA-co-AA, zwitterionic) and Nafion (negative and hydrophobic). First, we study the adsorption of the four surfactants for the four different surfaces on model interfaces. Second, we study fouling by artificial produced water stabilized by the same surfactants on PEM-based hollow fiber NF membranes characterized by the same multilayer of our model surfaces. Third, we study fouling of the same surfactants solution but without oil. Very high oil retention (>99%) was observed when filtering all the O/W emulsions, while the physicochemical interactions between the multilayer and the surfactants determined the extent of fouling as well as the surfactant retention. Unexpectedly, our results show that fouling of PEM-based NF membranes, during PW treatment, is mainly due to membrane active layer fouling caused by surfactant uptake inside of the PEM coating, rather than due to cake layer formation. Indeed, it is not the surface chemistry of the membrane that determines the extent of fouling, but the surfactant interaction with the bulk of the PEM. A denser multilayer, that would stop these molecules, would benefit PW treatment by decreasing fouling issues, as would the use of slightly more bulky surfactants that cannot penetrate the PEM.

Polycyclic aromatic hydrocarbons in sediments and fish species from the White Nile, East Africa: Bioaccumulation potential, source apportionment, ecological and health risk assessment.

The impact of oil exploration and production activities on the environment of sub-saharan African countries is not well studied. This study aimed at determining concentrations, sources, and bioaccumulation of 13 polycyclic aromatic hydrocarbons (PAHs) in sediments and fish from the White Nile near Melut oil fields, South Sudan. The study also assessed the ecological and human health risk associated with PAHs in this aquatic system. Total (∑13) PAH concentrations ranged from 566 to 674ng g-1dry weight (dw) in sediments, while those in fish were 191-1143ngg-1 wet weight (ww). ∑13PAH concentrations were significantly higher in C.gariepinus than in other fish species. Low molecular weight PAHs (LPAHs) dominated the profile of PAHs in sediments (constituted 95% of ∑13PAHs) and fish (97% of ∑13PAHs). Compared to Sediment Quality Guidelines of the United States Oceanic and Atmospheric Administration, the levels of LPAHs in this study were all above the threshold effect limits, but below the probable effect level, while those of high molecular weight PAHs (HPAHs) were all below the lowest effect levels. The carcinogenic potency equivalent concentrations of PAHs in L.niloticus and C.gariepinus were above the US EPA screening level; suggesting consumption of these species could adversely affect human health. Biota-sediment accumulation factor values (range: 0.006-3.816g OC g-1 lipid) for PAHs showed high bioaccumulation of LPAHs in fish muscle, and that bioaccumulation decreased with increase in hydrophobicity of the compounds. This is possibly because LPAHs have higher aqueous solubilities which increases their bioavailability through water-gill transfers compared to HPAHs. Profiles of PAHs in the White Nile environment indicate predominant contribution from petrogenic sources, which could be attributed to presence of crude oil reservoirs and oil production operations. More research into the levels of other environmental pollutants in the oil-rich area is recommended.

Cetacean habitat modelling to inform conservation management, marine spatial planning, and as a basis for anthropogenic threat mitigation in Indonesia

Indonesia harbours a high diversity of cetaceans, yet effective conservation is hampered by a lack of knowledge about cetacean spatial distribution and habitat preferences. This study aimed to address this knowledge gap at an adequate resolution to support national cetacean conservation and management planning. Maximum Entropy (Maxent) modelling was used to map the distribution of 15 selected cetacean species in seven areas within Indonesian waters using recent cetacean presence datasets as well as environmental predictors (topographic and oceanographic variables). We then combined the individual species suitable habitat maps and overlaid them with provincial marine spatial planning (MSP) jurisdictions, marine protected areas (MPAs), oil and gas contract areas, and marine traffic density. Our results reflect a great heterogeneity in distribution among species and within species among different locations. This heterogeneity reflects an interrelated influence of topographic variables and oceanographic processes on the distribution of cetacean species. Bathymetry, distance to- coast and the −200m isobaths, and chlorophyll-a concentration and sea surface temperature were important variables influencing distribution of most species in many regions. Areas rich in species were mainly related to coastal areas or insular-reef complexity, representing high productivity and upwelling-modified waters. Although some important suitable habitats currently fall within MPAs, other areas are not and overlap with oil and gas exploration activities and marine traffic, indicating potentially high risk areas for cetaceans. The results of this study can support national cetacean conservation and management planning, and be used to reduce or avoid adverse anthropogenic threats. We advise to consider currently unprotected suitable cetacean habitats in MPA and MSP development.

Impact of gas flaring on communities in Delta region of Nigeria, narrative review part 1: environmental health perspective

<p class="abstract">Gas flaring is the combustion of associated gas from crude-oil exploitation and exploration operations and occurs in refineries, oil wells, oil rigs by fiery of the gas. Nigeria is one of the main producers of gas in the world and oil exploration activities have occasioned high rate of gas flaring because of poor enforcement of anti-gas flaring laws by the regulatory authorities. Gas flaring comes with serious environmental concern because it is a major source of air pollution with adverse public health consequences particularly in the gas flaring communities. The objective of this narrative review is to identify the risks associated with gas flaring in relation to the environment. Literatures from diverse databases including peer reviewed journals as well as governmental and organizational papers were searched to develop the narrative. Over the years, several laws have been enacted in Nigeria with stipulated dates to end gas flaring, but the targets have not been met. The Federal government of Nigeria updated the legal framework titled flare gas (prevention of waste and pollution) regulations, 2018 to facilitate financial profits through utilization and commercialization of associated gas, with a view to reduce or exterminate flaring. This effort appears ineffective due to weak enforcement and poor monitoring mechanism. The statutory government institution entrusted to enforce anti-gas law may benefit from some sort of motivation to ensure oil operators comply to combat environmental health risks from gas flaring.</p>

Pollution Studies on Soils from Crude Oil Producing Areas of Rivers State, Niger Delta Region, Nigeria

Soil pollution assessment was carried out in seven oil producing areas in Rivers State, and also in Nnamdi Azikiwe University, Awka which served as the control area. Five composite soil samples from five different locations were randomly collected in each local government area (L.G.A.) with oil deposits, at a depth of 1 metre using soil auger. The samples were air-dried, ground, sieved and analyzed for pH, electrical conductivity, moisture content and heavy metals (cadmium, chromium, lead and nickel), using standard procedures. The data were subjected to statistical analysis using mean and bar graphs, and the results obtained were compared with those from the control area and DPR Standard. One way analysis of variance (ANOVA) was also done to establish the statistical difference between the study areas and the control area at 0.05 confidence level. The mean values of the parameters analyzed ranged as follows; pH: 4.25 - 6.48, electrical conductivity: 2.45 - 10.60 μS/cm, moisture: 0.60% - 0.90%, cadmium: 0.08 - 0.58 mg/kg, chromium: 2.86 - 7.91 mg/kg, lead: 0.22 - 9.79 mg/kg and nickel: 0.44 - 5.08 mg/kg. The control values were; pH: 6.04, electrical conductivity: 92.00 μS/cm, moisture: 0.80%, cadmium: 0.09 mg/kg, chromium: 8.72 mg/kg, lead: 1.04 mg/kg and nickel: 0.89 mg/kg. The results revealed that the pH levels of the soils were acidic and most of the values were within the DPR limit. Electrical conductivity and moisture contents of the soils were low and also below the control value and DPR standard. Heavy metal concentrations in the soils exceeded the control values but were below DPR limit. ANOVA results showed that there was a significant difference (p < 0.05) between chromium concentration in the assessed soils and the control soil. The results obtained revealed that the examined areas in Rivers State were not yet adversely polluted in terms of oil exploration and exploitation activities. Therefore, periodic monitoring of the project areas is strongly recommended to prevent the buildup of these contaminants beyond limits of maximum tolerance.

Chemical Fractionation of Copper and Zinc After Addition of Conocarpous Waste Biochar to A Drill Cutting

Background: Drill Cutting (DC) are large amount of waste generated in gas and oil exploration and production activities that contains toxic substances, especially heavy metals. This study aimed to use Conocarpus Waste (CW) biochar to investigate its effects on changes in chemical forms and stabilization and distribution of Cu and Zn in DC samples of Ahvaz oil field at different incubation times. Methods: In order to study the effects of CW biochar at different rates (0, 2, 5, and 10% w/w) and four incubation times (1, 2, 4, and 8 weeks) for adsorption and chemical fractionation of Copper (Cu) and Zinc (Zn) in DC of Ahvaz oil field in southwestern Iran. An experiment was conducted as a factorial in a completely randomized designing in three replication. Sequential extraction procedure of Tessier was applied for the determination of heavy metals fraction. Results: Application of biochar significantly (p &lt;0.05) increased the pH, soil organic carbon (SOC), electrical conductivity (EC), and cation exchange capacity (CEC) especially at the 10% application rate. After the addition of CW biochar, the exchangeable (EX) and carbonate (CAR) fractions of Cu and Zn, respectively decreased (P≤0.05) significantly while organic matter (OM) bound, oxides (OX) bound, and residual (RES) fraction were increased. Conclusion: The CW biochar can be a low-cost and effective amendment in immobilizing the Cu and Zn, and also effectively to reducing their mobility in DC.

Application of NSO compounds in the research of hydrocarbon migration direction in the Wangjiagang area of the Dongying sagin the Bohai Bay Basin

The determination of hydrocarbon migration direction is an important part in the study of petroleum accumulation in petroliferous basins, and plays an important role in guiding oil and gas exploration activity. Despite their relatively low content in petroleum, the polar nitrogen-, sulphur-and oxygen- containing compounds (collectively referred to as NSO compounds) have great potential in characterizing the hydrocarbon migration process. A series of crude oils along hydrocarbon migration pathway were selected and analysed using GC×GC/TOFMS and GC-MS in the Wangjiagang area of the Dongying sag. Total concentration of NSO compounds and other related parameters are determined to verify the role of different parameters in indicating hydrocarbon migration. Our research result shows that the total amount of NSO compounds, 1-/3-MC ratio, 1,8-/2,7-DMC ratio, 4-/1-MDBF ratio and 2,4-/1,4-DMDBT ratio changes grandully with the increase of migration distances. Thus, these parameters can be applied as effective migration direction indicators in study area. Some other parameters may not be suitable for the identification of hydrocarbon migration direction in the study area.

Ecological Impact Analysis of Dispersants and Dispersed Oil: An Overview

Soaring oil demand, as a result of industrial development, boosts oil exploration and production activities at sea, even into deeper and icier waters. The transportation of the oils, as well as the potential spill accidents and associated pollutions are thus increased. There is an urgent call for contingency planning with effective and eco-friendly oil spill cleanup responses. Dispersant applications can facilitate the breaking up of oil slicks into small oil droplets, allowing their rapid dispersion, dissolution, dilution and biodegradation in the water column. Dispersants have been recognized as effective oil treating agents and well adopted. Nearly 7 million liters of chemical dispersants, mostly Corexit® 9500A, were used after the Deepwater Horizon oil spill incident. However, debates over dispersants continued with major concerns about their environmental impacts and the ecological toxicity, which need to be well reviewed and tackled. Therefore, this study summarized the recent lab- and meso-scale studies and field trials on the ecological impact analysis of dispersants and the chemically dispersed oils. By providing an up-to-date review of the ecological toxicity and environmental impact assessment, this study would help to bridge the knowledge gaps in the field and facilitate future dispersant applications.

Interpretation of Gravity Anomalies over the Continental Rise of Sri Lanka

Seven profiles of intense negative gravity anomaly over the South Western, Southern and South Eastern parts of the continental rise of Sri Lanka have been interpreted two dimensionally. Results of the interpretation of profiles were interpolated and a map of sediment thickness has been compiled. As revealed by the interpretation and the map compiled there are three noticeable sediment distributions with thickness varying from approximately 2.5 km to 3.5 km. Sediment thickness map in this study closely agree with that compiled using seismic studies by previous workers. Results of this study may have applications in the oil and gas exploration activities over the region.

Phytosociology and antioxidant profile study for selecting potent herbs for phytoremediation of crude oil-contaminated soils.

Crude oil exploration activities affect the surrounding vegetation. The present investigation deals with the study of phytosociology and biochemical profiles of the herbaceous community in the active and abandoned oil drilling sites of crude oil-explored area. For comparison, a similar investigation was also carried out in control sites where oil exploration activities were not evident. At first, a phytosociological investigation was carried out and based on the results obtained antioxidant enzyme profiles of dominant herbs were studied tounderstand their defense mechanism to crude oil-associated stress. A total of 69 plant species belonging to 20 families were recorded in the studied sites and the family Cyperaceae was the most dominant in the crude oil-contaminated sites. The results revealed that the plants growing near the oil-explored-contaminated sites exhibit a higher level of DPPH and H2O2 radical scavenging activities as compared to control plant samples. For DPPH assay, the lowest IC50 value was exhibited by Cyperus rotundus which was recorded to be 31.49 and 55.31 respectively for the samples of contaminated and control sites. Again, in the case of H2O2 scavenging activity assay, Parthenium hysterophorus showed the lowest IC50 values of 27.48 and 63.07 for the samples of contaminated and control sites respectively. As a whole, the findings confirm the superior defense mechanism of some dominant herbs of the contaminated sites that include Torenia flava, Croton bonplandianus, Eclipta alba, Cyperus rotundus, Cyperus brevifolius, and Parthenium hysterophorus and their suitability for use in phytomanagement practices.

Groundwater quality monitoring of a popular Niger Delta university town in Nigeria

This study provides a detailed scientific data on the quality of groundwater in Oleh. It aimed at helping to facilitate the planning of potable water supply scheme for the community. Water samples from boreholes (BHs) and hand-dug wells (HDWs) in the community were obtained for the determination of biological and physicochemical parameters, from December 10, 2016 to March 10, 2017 for dry season and May 01, 2017 to August 01, 2017 for wet season. Structured interviews were also organized for households for the estimation of degree of access to safe drinking water, quality perception and awareness of domestic treatment techniques. But for pH being lower in some locations, results arrived at reveal that the physicochemical parameters were within the World Health Organization (WHO) and Standard Organization of Nigeria (SON) limits. Cd and Pb in the BHs and HDWs were generally, slightly higher than the maximum limits of the WHO and SON. Though total coliform (TC) bacteria and Escherichia coli were found in the samples, HDWs had higher values. The small elevated values of Pb and Cd could be linked to crude oil exploration and processing activities in the sub-region. While most of the HDW samples (>72%) were found to be in the category of “low risk (FC, >11-100 cfu/100 mL), result of the survey showed that over <30% of households sourced their drinking water from hand-dug wells and had no working knowledge of domestic water treatment.