Imo Shale Research Articles

Investigation of the Transfer Influence and Health Threat from the Intake of Maize and Exposure to Soil in Different Geological Formations in Akwa Ibom State, Nigeria

The consumption of maize contaminated by radionuclides may pose certain health challenges to the body. This research was conducted to investigate the possible danger radionuclides could cause. Soil and maize samples were obtained from different geological formations. They were analyzed using a Sodium Iodide-Thalium (NaI(TI)) detector. The activity concentration results from the soil samples show the highest values of 238U, 232Th and 40K as 14.74±0.26 Bqkg-1, 40.34±0.73 Bqkg-1 and 444.89±8.12 Bqkg-1 respectively which correspond to Ogwashi-Asaba, Ogwashi-Asaba and Imo shale geological formations. The findings from maize samples indicate the maximum values of 238U, 232Th and 40K as 16.46±0.25 Bqkg-1, 18.12±0.46 Bqkg-1 and 435.17±7.89 Bqkg-1 respectively which correspond to Benin, Ogwashi-Asaba and Ogwashi-Asaba geological formations. The outcome of mean transfer factor of 238U, 232Th and 40K corresponds to 0.942, 0.460 and 1.002. The absorbed dose rate ranges from 28.91 nGyh-1 to 36.08 nGyh-1. Radium equivalent varies from 49.40 Bqkg-1 to 98.75 Bqkg-1. Almost equal value (0.15×10-3) was assessed for the mean excess lifetime cancer risk. Although the activity concentration noted from maize is high, the evidence obtained shows that there is no geological formation with health risk problem as the external, internal and radioactivity hazard indices are less than unity.

Investigation of the Transfer Influence and Health Threat from the Intake of Maize and Exposure to Soil in Different Geological Formations in Akwa Ibom State, Nigeria

The consumption of maize contaminated by radionuclides may pose certain health challenges to the body. This research was conducted to investigate the possible danger radionuclides could cause. Soil and maize samples were obtained from different geological formations. They were analyzed using a Sodium Iodide-Thalium (NaI(TI)) detector. The activity concentration results from the soil samples show the highest values of 238U, 232Th and 40K as 14.74±0.26 Bqkg-1, 40.34±0.73 Bqkg-1 and 444.89±8.12 Bqkg-1 respectively which correspond to Ogwashi-Asaba, Ogwashi-Asaba and Imo shale geological formations. The findings from maize samples indicate the maximum values of 238U, 232Th and 40K as 16.46±0.25 Bqkg-1, 18.12±0.46 Bqkg-1 and 435.17±7.89 Bqkg-1 respectively which correspond to Benin, Ogwashi-Asaba and Ogwashi-Asaba geological formations. The outcome of mean transfer factor of 238U, 232Th and 40K corresponds to 0.942, 0.460 and 1.002. The absorbed dose rate ranges from 28.91 nGyh-1 to 36.08 nGyh-1. Radium equivalent varies from 49.40 Bqkg-1 to 98.75 Bqkg-1. Almost equal value (0.15×10-3) was assessed for the mean excess lifetime cancer risk. Although the activity concentration noted from maize is high, the evidence obtained shows that there is no geological formation with health risk problem as the external, internal and radioactivity hazard indices are less than unity.

The Assessment of Groundwater Availability in Sedimentary Environments Using the Electrical Resistivity Method: A Case of Ekpoma and Its Environs, Southern Nigeria

Groundwater resources are an ephemeral aspect of the ecosystem, especially in the university town of Ekpoma, where the issue of severe water shortages brought on by failed or unproductive boreholes has lingered over time. This study makes an effort to thoroughly define the groundwater-bearing zones and estimate their thicknesses and depths in order to identify the cause(s) of groundwater scarcity in Ekpoma and its peri-urban area. In order to accomplish the objectives of the work, fifteen (15) Vertical Electrical Soundings (VES) were conducted across the study location, leveraging Schlumberger electrode array, with current electrode spacing varying from 5.00 to 550.00 m. The results show there were five distinct geoelectrical strata identified: top soil, clayey sandstone, sand, consolidated sandstone, and unconsolidated sandstone. The unconsolidated sandstone layer constituted the aquifer units in the area, whose depth ranges between 103.00 m and 258.00 m. Besides, this study showed that there is strong indication/evidence of saturation of the aquifer identified in the Imo Shale Formation surrounding Irrua with highly porous and permeable materials atop it, justifying the region's highly productive wells and boreholes. The aquifers delineated in and around the Ekpoma community, on the other hand, have relatively high resistive values (3404.20–5303.00 ?m), indicating less saturation, and are equally overlain by less porous and permeable materials, establishing why Ekpoma (located within the Bende-Ameki and Ogwashi Asaba Formations) has a perennial groundwater shortage. The shallow aquifer units in the area of study were discovered to be rather thin, with the majority having a thickness of less than 30 m, making them less sustainable for long-term groundwater abstraction and resulting in failed boreholes in most portions of Ekpoma town. The study indicates that the groundwater prospects of Ekpoma and its environs are poor, and deep boreholes reaching a minimum depth of 250.00 m should be drilled since it is sustainable due to its significant thickness to serve the Ekpoma community and its environs. The present investigation findings can aid in improving knowledge of underlying geological conditions, evaluating the feasibility of the researched area for predicted urban and economic development, and sustaining water supply for connected activities.

Evaluating the Potentials of Drilling Mud Production from Clayey Solis Derived from Imo Shale Formation in Okada, Near Benin, South Western Nigeria

Samples from Okada area in the Southwestern, Nigeria were collected to evaluate their likely potentials in drilling mud production with comparison with some commercial bentonite. In order to carry out this evaluation mineralogical, geotechnical and geochemical analysis were used to assess these drilling mud potential. The geotechnical analysis involving the determination of moisture content, specific gravity, particle size analysis, atterberg/ consistency limits test was combined with geochemical analysis of Xray Fluorescence (XRF) and Xray Diffraction (XRD) to determine the qualitative, (types of clays) and quantitative (compositions of each mineral in clay component) and the mineralogy percentages in the clay. The geotechnical results showed particles size of < 60% with very high plasticity (88-140%) having clay activity of <1.25%. Geochemical analysis shows significant amount of Silicate (SiO2), Alumina (Al2O3), Iron (Fe2O3), Magnesium (MgO), Calcium oxide (CaO), Titanium oxide (TiO2) and Manganese oxide (MnO). In CEC, Ca, K, Na (in order of decrease) oxides in Okada and high LOI (38%). The Okada clay revealed the dominance of montmorillonite (30-35.1%) and Kaolinite (2-20.1%) with Quartz (2-24%), Calcite (7-91%) and a very unique occurrence of Palygorskite (2-33%) in the study area which has never been seen in Nigeria. The attributes of the Okada clay were compared with the natural commercial bentonite of Wyoming and Moscow and it was observed to meet the requirement as drilling mud except in the plasticity and swelling potentials which would have to be taken into consideration in beneficiation of the okada clays.

Freundlich, Langmuir and Temkin isotherm studies of silicon sorption on soils derived from three parent materials in Edo State, Nigeria

The study was conducted to assess Freundlich, Langmuir, and Temkin isotherm studies of silicon sorption of soils derived from three parent materials in Edo State, Nigeria. A completely randomized design was used to collect fifteen soil samples from five depths in three replications at three locations namely, NIFOR, Uhomora, and Ososo which are developed on Coastal Plain Sand, Imo Shale, and Basement complex rock parent materials respectively. Some soil physical and chemical properties were determined according to standard procedure, in the Faculty of Agriculture laboratory, University of Benin. Samples were equilibrated in 50 ml distilled water containing various amounts of Si as Calcium-Magnesium silicate (CaMgSiO2) to give 50, 100, 200, 400, and 800 mg Si L-1 for 30 min., allowed to stand overnight, equilibrated again for 30 minutes, filtered and Si read colorimetrically. Data obtained were fitted to Freundlich, Langmuir, and Temkin adsorption models. Results showed that the Temkin model expressed Si sorption capacity better considering the R2 values of 0.733, 0.296, and 0.288 for coastal plain sand, Imo shale, and Basement complex rock soils, respectively. The soils formed on Basement complex rock adsorbed more Si than soils formed on Coastal plain sand and Imo shale parent materials, considering the mean Temkin BT (retention capacity of adsorbed Si) values. The Temkin model could be relied upon as a suitable model to determine Si sorption in soils of the study area.

Late maastrichtian- early eocene dinoflagellate cyst biostratigraphy and aleoenvironmental study of sediments in Akukwa-1 well in the Anambra Basin

Dinoflagellate cyst biostratigraphy and palaeoenvironment of deposition of sediments penetrated by Akukwa-1 Well was carried out with a total of 253ditch cuttings using the conventional maceration technique for recovering of acid insoluble organic-walled microfossils from sediments. Sedimentological description delineated five (5) lithological units within the well, which included those of Nkporo Shale, Mamu Formation, Ajali Sandstone, Nsukka Formation and Imo Shale. A total of 14 genera and 35 species of dinoflagellate cyst were identified. The recovered dinocysts were used to establish palaeoenvironment which ranged from marginal to shallow marine, the forms were also used to propose four (4) informal dinoflagellate cyst zonations labelled (A-D) based on the first and last occurrences of two or more species. They included Zone A (Apectodinium paniculatum zone), occurring at 7990ft(Maastrichtian), zone B(Paleocystodinium australinium zone) occurring between 7990ft -4000ft (Upper Maastrichtian), zone C(Apectodinium homomorphum zone) occurring between 4000ft -2550ft (Upper Maastrichtian), and zone D(Homotryblum palladium zone) occurring between 5550ft-1520ft(Paleocene- Early Eocene). The erected dinocyst zones were correlated with the existing biozones in tropical areas of Africa and northern South America.

EFFECT OF CALIFORNIA BEARING RATIO OF SOILS USED AS SUBGRADE MATERIALS ON THE BENIN-AKURE ROAD, NIGERIA

An investigation was carried out to assess the suitability of soils brought in for use as subgrade materials for the Benin- Sobe axis of the Benin – Akure road by testing the bearing capacity using the California Bearing Ratio (CBR)test. The road passes through four soil parent materials: - Coastal Plain Sand- CPS, Imo-Shale (IS), BendeAmaki (BA) and the False Bedded or Basement Complex (FB).Soil samples were collected from four profile pits based on the parent materials. Soil samples were also collected about 50 cm from the tarred road representing materials brought in for the subgrade. The soils were analyzed for physicochemical properties and the California Bearing Ratio. Analyses were carried out on soils collected from each section of the parent materials.Results obtained showed that there were more road failures in the Imo Shale,BendeAmeki and to a less extent in the Coastal Plains segment of the road, and least in the False Bedded parent material section.CBR for unsoaked soils showed BendeAmaki having highest values (14.6 and 16.18) for the 2.5 and 5 mm penetration test; however values were not significantly different from the other parent material sections ( p> 0.05).The Imo Shale soils were poorly drained and are seasonally floodedand had the least CBR values (4.64, 5.2 for the 2.5 and 5 mm readings for the top and bottom penetration test. Coastal Plain Sands and BendeAmeki values were not significantly different from the Imo shale but values were higher.Soaking the soil did not significantly affect the soil strength for the False Bedded segment of the road; hence the failure rate was lowest.The False Bedded had higher CBR values for the soaked test, indicating that the parent material through which the road is built had significant effect on the failure rates

Freundlich and Langmuir Isotherm Studies of Phosphorus Sorption unto Soils Derived from Basement Complex Rock, Alluvium, Coastal Plain Sand and Shale Parent Materials

To provide information on best model to predict Phosphorus (P) Sorption unto Soils derived from Basement Complex Rock, Alluvium, Coastal Plain Sand and Imo Shale Parent Materials in 3 states of Nigeria. Completely randomized design was used to collect surface soil samples in 3 replications from 4 locations in Nigeria.
 Samples were collected from Idanre, Koko, NIFOR and Uhonmora in Ondo, Delta and Edo states Nigeria, laboratory analysis was carried out in the Central analytical laboratory of Nigerian Institute for Oil-Palm Research (NIFOR) Benin City, Nigeria between march 2016 and September 2017.
 Soil samples were equilibrated in 25 ml of 0.01 M CaCl2 containing various concentration of P as KH2PO4 to give 0, 50, 100, 150, 200 and 250 mg/L P for 24 hours (h) at room temperature 25 ± 2oC. 3 drops of CHCl3 was added to inhibit P mineralization. The suspension was shaken for 24 h on a reciprocating mechanical shaker, centrifuged at 7000 rpm After equilibration, decanted and P determined using spectrophotometer. The sorption data were fitted to linear Freundlich and Langmuir sorption isotherm.
 Considering the Freundlich model, P adsorption capacity (a) and P sorption energy (n) was highest in soils B (1400 mg kg-1) and (2.806 L kg-1) respectively. The Freundlich model fitted better to the data obtained with average root mean square error (RMSE) and R2 value of 0.69 and 0.951 respectively, as against average RMSE and R2 value of 1.60 and 0.883 respectively obtained from Langmuir model.
 The sorption data fitted well to Freundlich and Langmuir isotherms of which Freundlich Adsorption model was found to be better based on lowest RMSE (0.69) and highest regression (R2 = 0.951) value. Freundlich model should be adopted to determine P sorption characteristics of the soils studied. These predictors, however, need further works to validate reliability.

Commercially Imported Bentonite Versus Locally Derived Bentonitic Clays: A Comparative Assessment Study of Mineralogy and Geochemical properties, Anambra Basin, Southeastern Nigeria

This study aimed to investigate the mineralogy and chemical properties of the bentonites from the Imo Shale and Ameki formations, vis-a-vis commercially imported bentonite (CIC), for its suitability in formulation of drilling mud. 50 suspected bentonitic clays were studied, and properties of starting materials were utilized during screening. The CIC and four samples that met the API specification for drilling mud were subjected to X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses. XRD revealed SPL15 consists: 55% kaolinite, 20% quartz, 15% K-feldspar, and 10% hematite, suggesting kaolinite-type; and SPL6, SPL8, and SPL11 consist: 28-47% kaolinite, 26-32% quartz, and 12-20% nontronite, indicating smectite-type with significant amount of kaolinite co-existing, while the CIC consists of 12% quartz, 10% K-feldspar, 12% calcite, 41% nontronite, and 25% amorphous materials. XRF, showed Al2O3 (15.77-25.49) wt%, Fe2O3 (6.61-10.01) wt%, SiO2 (51.67-59.11) wt%, and loss on ignition (7.57-11.22) wt%, indicating variable degrees of alterations. Significant proportion of the CIC exists in an amorphous phase, suspected to be additives. Thus, comparison with the CIC revealed compositional disparity/deficits in the local clays. Consequently, treatment/beneficiations may be necessary to achieve the desired compositions. Based on these results, the primary criteria for the formulation of drilling fluid, using mineralogy and chemical compositions, are achievable.

Phosphorus Sorption in Soils Overlying Basement Complex Rock, Alluvium, Coastal Plain Sand and Imo Shale Parent Materials

This study aimed at evaluating phosphorus (P) sorption capacities in Soils overlying basement complex Rock (A), Alluvium (B), coastal plain sand (C) and Imo shale (C) parent materials.
 Completely randomized design was used to collect soil samples from 5 depths in 3 replications from Idanre, Koko, NIFOR and Uhomora in Nigeria.
 Samples collected were analyzed in the central analytical laboratory of the Nigerian Institute for Oil palm Research, Benin City, Nigeria between march 2016 and September 2017.
 60 soil samples were equilibrated in 25 ml of 0.01 M CaCl2 containing various concentration of P as KH2PO4 to give 0, 50, 100, 150, 200 and 250 mg/L P for 24 hours (h) at room temperature 25 ± 2 oC. Genstat statistical package was used to calculate Analysis of variance, correlation of Phosphorus sorption index (PSI) with soil properties, coefficient of variation, means separation and Least Significant difference (LSD).
 The rate and %P adsorption increased with increasing concentration of P added to the soils. The P sorption capacities of the soils considering Freundlich model decreased in the order of D > B > C >A. %P adsorbed was highest in D soils with value of 15.19% for 100 mg/kg P added. The PSI correlated with organic carbon r = -0.58 P ≤ .05 in C soils, r = 0.44 P ≤ .05 in D soils, it also correlated with N r = -0.58 P ≤ .05 in C Soils, K r = 0.57 P ≤ .05, r = 0.49 P ≤ .05 in C and D soils respectively.
 D soils sorbed more P than other soils hence the D soils will require more P fertilization to attain optimum P concentration in soil solution, however further study is required to determine the form of P sorbed by these parent materials.

Reassessing Groundwater Potentials and Subsurface water Hydrochemistry in a Tropical Anambra Basin, Southeastern Nigeria

This review presented a detailed re-assessment of the hydrogeology and hydrochemistry of the Tropical Anambra Basin. It identified and discussed the major geological formations and their groundwater potentials. The geological examination showed that the Ajali Formation is confined in places forming an artesian condition; the potentials of this aquifer decline in the western basin due to a decrease in thickness. The sandstone associates of the Nsukka Formation are aquiferous and have produced high-pressure artesian boreholes along the Oji River. The Imo Shale is characterized by permeability stability all over much of the intermediate unit. The Bende-Ameki aquifer has a lesser amount of groundwater when equated to other formations; the geologic characteristics do not produce favorable hydrogeological conditions for groundwater occurrence. The stratigraphical and structural framework suggested the presence of an efficient throughflow in the basin. Based on physical and chemical parameters of water quality, the basin holds water of acceptable quality. While there are considerable investigations on the hydrogeology and hydrochemistry, studies are short of analysis of the hydrogeochemical evolution of groundwater, water quality index, heavy metals pollution index as well as total hazard quotient. Suitability of groundwater based on agricultural water quality indices (e.g. SAR) is also salient. Therefore, future studies should address these owing to increasing dependence on groundwater.

Estimates of aquifer geo-hydraulic and vulnerability characteristics of Imo State and environs, Southeastern Nigeria, using electrical conductivity data.

Two hundred and twenty-six vertical electrical sounding (VES) data were acquired across the study area that has six geologic formations for the purpose of evaluating the geo-hydraulic potentials and the protective capacity of the aquifers of the study area. Schlumberger array was adopted for data acquisition using the ABEM™ Terrameter SAS 4000. Results of the study revealed four to six geo-electric layers. A variety of geo-electric curve types were identified in the study area with the KK curve type being dominant. The aquifer zones lie between the third and sixth layers with their resistivity values ranging from 101 to 8900Ωm with a mean value of 1799Ωm. Estimates of the aquifer hydraulic characteristics using the new set of model equations based on conductivity data revealed hydraulic conductivity range of 0.925 and 13.42m/day while transmissivity ranged between 16.0 and 887m2/day. These findings showed that groundwater potential is high in Benin Formation, moderate in Nsukka and Ajali Formations, and generally poor within Ogwashi and Imo Shale Formations. Aquifer vulnerability studies revealed that the values of the integrated electrical conductivity (IEC) of the study area ranged between 28.4 and 2202mS with a mean value of 403mS. Results of the IEC revealed that the aquifer protective capacity of most parts of the study area were extremely poor (86.2%) with percolation period of several months while only 1.8% of the study area are fairly good. The aquifers of the study area may therefore be vulnerable to contamination from anthropogenic sources, and adequate aquifer protective strategies are therefore recommended.

Aquifer Mapping in the Niger Delta Region: A Case Study of Edo State, Nigeria

In Nigeria, potable water is in short supply to the greater population and where available, groundwater accounts for over 90% of the supply. Oil exploration and exploitation activities are carried out in the Niger Delta region of Nigeria and this has affected the environment in this region. However, naturally occurring traces of petroleum products in strata or petroleum losses through spillages can contaminate groundwater, thus aquifer mapping in the Niger Delta Region becomes crucial. The study involves collection, collation and analysis of relevant information and data required for successful development of groundwater in Edo state. Groundwater in Edo State occurs under different conditions in the various aquifers defined by the following geological units, namely: Coastal Plain Sands of the Benin Formation, Ogwashi- Asaba, Bende- Ameki and Imo Shale Group of the Tertiary Deposits, False-bedded Sandstones and the Nkporo Shale Group of the Cretaceous deposits and the Basement Complex Rocks which only contain groundwater in the overburden, faults and joints. From the information collated, groundwater levels are deepest in the Ishan Plateau where it is about 171 metres above mean sea level at Ekpoma. Away from the pleateau, groundwater rises southwards and northwards. At Aduwawa/Ikpoba Hill (Benin City), the groundwater level is 40 metres, at Iguiye (Lagos Road, Benin City) to the west, the groundwater level is 55 metres and at Fugar to the north, the groundwater level is 95 metres. The groundwater flow direction is from the Plateau to all other areas with higher groundwater levels. Therefore, aquifer mapping in the Niger Delta region is necessary, as it will help in assessing the availability and development methods to be adopted.

Palynological Zonations and Sequence Stratigraphic Analysis of Sediments in Benin West-1, Anambra Basin, Nigeria

Palynoflora analyses from Benin west -1, Anambra Basin has unfold three palynozones based on abundance, composition of palynoflora and cluster analysis. Palynozone-1 has been dated as Late Maastrichtian age and belong to the lowermost Imo Shale, palynozone-2; Middle Eocene and palynozone -3 is dated Lutetian to Bartonian age. Sediments between depth intervals of 2649-2560 m is marked a sequence boundary, 1650-2560 m, and 970-1190 m is delineated as high stand system tract. Shaly intervals from the depth of 1644 m, and 1234 m recorded acme of palynoflora (Zonocostites ramonae, Monoporites annulatus, Verrucatosporites spinosus, Botryococcus braunii) and probably fingerprints a condensed section. The condensed section intervals (1644 m and 1234 m) may depict good source rock and exploration targets.

Source rock potential of lignite and interbedded coaly shale of the Ogwashi–Asaba Formation, Anambra basin as determined by sequential hydrous pyrolysis

Outcrops in the Anambra Basin in southern Nigeria contain Paleogene Imo Shale (marine), the Neogene paralic Ogwashi–Asaba and the continental Benin Formations, representing equivalents of the subsurface successions in the Niger Delta Basin. Thirty-three samples of lignite and the interbedded coaly shale of the Ogwashi–Asaba Formation were investigated petrologically before Rock-Eval screening. Two selected samples of lignite and coaly shale were subjected to sequential hydrous pyrolysis (HP) at 330°C for 72h and at 355°C for 72h to characterize their oil and gas potential. The lignite sample has a Rock-Eval hydrogen index (HI) of 481mg/g TOC and a mean vitrinite reflectance of 0.36% Rom. The total amount of expelled oil generated in the sequential HP experiments is 259mg/g of original total organic carbon (TOCorig). This expelled waxy oil has abundant high-molecular-weight n-alkanes and an extremely high pristane/phytane ratio of 6.5, typical of crude oils generated from coals as observed in some onshore and shallow offshore accumulations of the Niger Delta. The overlying coaly shale has a lower HI of only 191mg/g TOC. The total amount of expelled oil generated in the sequential HP experiments is only 15mg/g TOCorig. This oil is not waxy and has a pristane/phytane of 2.6, which is more typical of a marine source rock. These results are contrary to the idea that coaly shale associated with coal is the main source of oil. The greater yields of expelled oil from the coal relative to the coaly shale are attributed to the higher liptinite content in the former and the possibility that the organic matter in the latter was oxidized prior to deposition. δ13C of the methane generated at 355°C for 72h is −39.5‰ for the lignite and −35.0‰ for the coaly shale. This suggests different methane precursors in these two lithologies. The data set reveals remarkable differences in the characteristics of the two types of source rocks in the Ogwashi–Asaba Formation and their potential to contribute a mixture of hydrocarbons derived from intervals that are stratigraphically only meters apart. These results suggest that coal and coaly shale within the thermally mature stratigraphic levels of the Agbada Formation in the sub-surface are potential source rocks for liquids and gaseous hydrocarbons in the Niger Delta.

Characterization of some clays from Nigeria for their use in drilling mud

The need to source for local components of drilling mud in Nigeria has necessitated the assessment of the properties (in natural state and when beneficiated) of clays from three geological units: namely; Asu River Group (Albian), Eze Aku Group (Turonian) and Imo Shale Formation (Paleocene). Analysis on the raw clays indicates that they are predominantly smectite (notable for high plasticity and swellability) and mixed layer clay types but posses other rheological properties that fall short of the requirements for good drilling mud materials. On account of beneficiation, with 4% Na2CO3, most of the swellability and rheological parameters, such as liquid limit, plasticity index, free swell index, and viscosity improved. With 4% barite, the specific gravity of the clays increased significantly from 2.42–2.64 to 2.72–2.90. However, the improvement especially in the swellability quality is considerably low when compared with swellability data on naturally active bentonites from Wyoming and Texas, and activated clays from Manitoba and India. The quality of these referenced clays served as standard for assessing clays for oil-based drilling mud. Study suggests marginal performance of clays both in raw and beneficiated states, especially in oil-based drilling mud, as they failed to meet most specifications.

Borehole Annulus-Filling Materials and Enrichment of Heavy Metals in Eocene-Palaeocene Aquifer Systems in Awka, Southeast Nigeria

Contamination of groundwater resources is more often associated with the infiltration of pollutants from anthropogenic activities such as waste dump sites and industrial effluents. Similar to this, reported results may be limited in its accuracy by poor sampling and analytical techniques. This study is interested in the role of geologic materials. Geologic materials, whether in-situ host rock or transported materials play a massive role in determining the quality of groundwater in any geosystem. A time-lapse evaluation of groundwater quality in Awka shows a progressive deterioration as a result of increasing enrichment in heavy metals. It is noted that Vanadium, Manganese, Arsenic and Copper increased the most over the 1993 to 2013 period under consideration. Host-rock geochemistry discounts the dominant Imo Shale as a source of the contaminants. While recognising the likely infiltration of pollutants from other common sources, it is here suggested that the high concentration of heavy metals can also be the effect of weathering products and leachates that are being derived from heavy-metal-rich igneous rock aggregates that are commonly used as annulus-filling materials in borehole construction. This calls for a more indepth study to understand the pollution network in order to evolve a coordinated approach to protect the groundwater system and save the populace from looming health and environmental hazards.

Assessment of the Groundwater Quality in Parts of Imo River Basin, Southeastern Nigeria: The Case of Imo Shale and Ameki Formations

Hydro-geochemical survey is undertaken in parts of Imo River Basin, Southeastern Nigeria, particularly in the geologic formations of Imo Shale and Ameki, to assess the quality of groundwater. Eleven samples of groundwater are obtained from various boreholes in the study area and subjected to physico-chemical analysis using standard laboratory techniques. The study is aimed at the assessment of the groundwater quality indicators namely: pH, electrical conductivity (N), phosphate (PO4), sulphate (SO4), nitrate(NO3-) and total dissolved solids (TDS). The result shows that the water from boreholes in Umuahia has low pH, and is therefore acidic. The pH values range between 4.40 and 5.60, which is below the acceptable range of 6.5-8.5. The acidity probably results from carbonic acid derived from the solution of CO2 from both the atmosphere and the decomposition of plant materials in the soil zone. The acidity of the groundwater gives slight sour taste to drinking water, due to the mobilization of trace metals from the aquifer material into the groundwater system, because of the corrosive effect of acidic water. Since borehole supply is rarely treated, these trace metals end up in domestic supplies resulting in health implications and complaints. Acidic waters are typically low in buffering calcium minerals, but are high in dissolved carbon dioxide gas, which can cause the low pH or acidity. Calcite neutralizer tanks with natural crushed and screened pure calcium carbonate easily neutralize acidic water from 6.0 to 6.9. Below 6.0 a blend of calcite and Corosex is recommended. Common systems used to treat low pH: Calcite Neutralizer, calcite & Corosex Blend Neutralizer, pflow Neutralizer, Soda Ash Feed Pump Injection System.

Lithofacies characterization of sedimentary succession from Late Cretaceous-Tertiary age in Benin west-1, northern Depobelt, Anambra Basin, Nigeria

Lithofacies and their relationships, textural content, sedimentary structures were used to delineate eight facies associations in the Benin west-1. Seven lithofacies are recognized; coarse grained sandstone with granules, laminated shaley sandstone, shaley siltstone, laminated shaley siltstone with fossil fragment, laminated shale, siltstone, coarse grained sandstone and micaceous sandstone facies. Each lithofacies is interpreted to represent different or similar depositional environments. Sediments of the Ameki Formation and Imo Shale encountered in the Benin west-1 were deposited in distributary channel and prodelta to marine shelf environments

A Geotechnical Investigation on the Structural Failures of Building Projects in Parts of Awka, Southeastern Nigeria

Twelve samples of shale from different locations within the Imo Shale Formation in the Awka area (southeastern Nigeria) have been assessed to evaluate the impact of the shale formation on some geotechnical problems experienced by constructed projects in the area. Results indicate that shale samples from the formation have Atterberg limits that might be considered moderate to high; while liquid limit (LL) ranged from 32 - 78, the plasticity index (PI) ranged from 11 - 32. These relatively high LL and PI suggest presence of expansive clays, some swelling of the shale on moisture influx and high compressibility. Natural moisture content (with mean value of 17%) was also significantly high. Despite indicating fair stability as fills (Maximum dry density and soaked California bearing ratio have mean values of 1.85 mg/m 3 and 42%, respectively), the formation is likely to have low shear strength, as suggested by its low values of strength parameters (mean value of angle of internal friction is 22°, while mean cohesion is 21 kN/m 3 ). Geotechnical behaviours of the Imo Shale also give indications that the shale failed some relevant material specifications for general engineering purposes and, thus, was significantly responsible for structural failures and foundation problems of buildings that are prevalent in some parts of Awka area.