EDXRF analysis and risks assessment of potentially toxic elements in sand fraction (tailing) of Nigerian oil sands

Abstract

Elemental composition of sand fraction of Nigerian oil sand was determined with a view to assessing the human and ecological risks to the sand fractions. Soxhlet extraction of bitumen from the oil sand was done using toluene as the extracting solvent. Elemental analysis was done using energy-dispersive X-ray fluorescence spectrophotometry and risks calculated using elemental concentrations as variables. Fe had the highest mean concentration (9453 ± 1477.72 µg/g), while As had the least mean concentration (81.75 ± 17.91 µg/g) in the sand fractions. It was observed that the elemental concentrations in this study were comparatively higher than those of Nigerian oil sands and bitumen, indicating that the larger percentages of the elements were extracted into the sand fraction which is part of the tailings (including water) that will be discarded as wastes during the recovery of bitumen from the oil sands. Close inter-element clustering existed between the elements (Fe and V) and (Cu, As, Nb, Sc, Ga, Rb, Ca, Se, V, Mn, Zn, K, Ti, Ni, Sr and Zr), indicating chemical affinity and/or similar sources. Contamination factor results indicated varying degrees of contamination by the elements, while modified degree of contamination (mCd > 32) indicated an ultra-high degree of contamination of the sand fractions by the elements. Pollution load index (PLI > 1) indicated deterioration of site quality, while potential ecological risk index and modified ecological risk index results indicated very high ecological risks by the elements. Study concluded that the elemental levels were high enough to degrade the environment and cause ill-heath to humans upon long exposure if the sand fraction (tailing) is disposed indiscriminately. Therefore, regular environmental monitoring assessment should be carried out to screen uncritical disposal of tailings during the development of the natural resource.

Keywords

EDXRF / Element / Oil sand / Risk assessment / Sand fraction

References

[1] Abey JA, Adebiyi FM, Asubiojo OI, Tchokossa P. Assessment of radioactivity and polycyclic aromatic hydrocarbon levels in ground waters within the bitumen deposit area of Ondo State, Nigeria. Energy Sources Part A Recovery Util Environ Effects, 2017, 39(13): 1443-1451

[2] Abrahim GMS (2005) Holocene sediments of Tamaki Estuary: characterization and impact of recent human activity on an urban estuary in Auckland, New Zealand, PhD Thesis University of Auckland, Auckland (New Zealand), p 361

[3] Abrahim GMS, Parker PJ. Assessment of heavy metal enrichment factors and the degree of contamination in marine sediments from Tamaki Estuary, Auckland, New Zealand. Environ Monit Assess, 2008, 136(1-3): 227-238

[4] Adebiyi FM, Obiajunwa EI, Akpan I. Mineralogy of Nigerian bituminous sands using particle induced X-ray emission (PIXE) spectrometry. J Sustain Energy Eng, 2013, 1(1): 1-13

[5] Adebiyi FM, Akinola AS, Santoro A, Mastrolitti S. Chemical analysis of resin fraction of Nigerian bitumen for organic and trace metal compositions. Pet Sci Technol, 2017, 35(13): 1370-1380

[6] Akinlua A, Ajayi TR, Adeleke BB. Organic and inorganic geochemistry of Northwestern Niger delta oils. Geochem J, 2007, 41: 271-281

[7] Akinnifesi JO, Adebiyi FM, Olafisan KF. Structural characterization of asphaltenes derived from nigerian bitumen using X-ray diffraction technique. Pet Sci Technol, 2017, 35(16): 1667-1670

[8] Al-Marshed A, Hart A, Leeke G, Greaves M, Wood J. Effectiveness of different transition metal dispersed catalysts for in situ heavy oil upgrading. Ind Eng Chem Res, 2015, 54(43): 10645-10655

[9] Barbieri M. The importance of enrichment factor (EF) and geoaccumulation index (I _geo) to evaluate the soil contamination. J Geol Geophys, 2016, 5: 237

[10] Basta NT, Ryan JA, Chaney RL. Trace element chemistry in residual-treated soil: key concepts and metal bioavailability. J Environ Qual, 2005, 34(1): 49-63

[11] Buccolieri A, Buccolieri G, Cardellicchio N. Heavy metals in marine sediments of taranto gulf (Ionian Sea, Southern Italy). Mar Chem, 2006, 99: 227-235

[12] Coker SJL. Bitumen saturation and reserve estimation of Okitipupa oil sand Nigeria. J Min Geol, 1988, 38: 1-2

[13] Douay F, Pelfrêne A, Planque J, Fourrier H, Richard A, Roussel H, Girondelot B. Assessment of potential health risk for inhabitants living near a former lead smelter, Part 1: metal concentrations in soils, agricultural crops, and home- grown vegetables. Environ Monit Assess, 2013, 185: 3665-3680

[14] Duodu GO, Goonetilleke A, Ayoko GA. Comparison of pollution indices for the assessment of heavy metal in Brisbane River sediment. Environ Pollut, 2016, 219: 1077-1091

[15] Enu EI. Textural characteristic of the Nigerian tar sands. Sed Geol, 1985, 44: 65-81

[16] Esteves AM. Mining and social development: refocusing community investment using multi-criteria decision analysis. Resource Policy, 2008, 32: 39-47

[17] Hakanson L. An ecological risk index for aquatic pollution control: a sedimentological approach. Water Res, 1980, 14: 975-1001

[18] International Atomic Energy Agency, IAEA (1996) Quantitative X-ray analysis system (QXAZ) Users Manual. Ip, C.C.M

[19] Ipinmoroti KO, Aiyesanmi AF. Trace metals in the bituminous sands of Ondo State, Nigeria. Nig J Sci, 2001, 35: 63-68

[20] IUGS/IAGC (2007) Annual report for the International Union of Geological Sciences (IUGS)/International Association of Geochemistry (IAGC) task group on global geochemical baselines. Retrieved on October 9, 2008 from the World Wide Web: http://www.ugs.org/PDF/AR07_IG_GGB.pdf

[21] Landis MS, Pancras JP, Graney JR, Stevens RK, Percy KE, Krupa S. Percy K. Receptor modeling of epiphytic lichens to elucidate the sources and spatial distribution of inorganic air pollution in the Athabasca Oil Sands Region. Alberta oil sands: energy, industry and the environment, 2012 Oxford Elsevier 427-467

[22] Madu AN, Njoku PC, Iwuoha GA. Extent of heavy metals in oil samples in Escravous, Abiteye and Malu platforms in Delta state, Nigeria. J Agric Environ Stud, 2011, 2(2): 41-44

[23] Meyer R, Attanasi E, Freeman P. Heavy oil and natural bitumen resources in geological basins of the World. US Geol Surv Open-File Rep, 2007, 2007–1084: 336

[24] Ogunsuyi HO, Ajayi OO, Ipinmoroti KO, Oladipo MOA. Neutron activation analysis of some Nigerian bitumen samples and their components. Orient J Chem, 2012, 28(1): 333-342

[25] Oluwole AF, Hannan AHMA, Kehinde LO, Borishade AB, Adegoke OS. Trace elements in Nigerian oil sands and extracted bitumens. J Radioanal Nucl Chem Art, 1987, 110(1): 275-282

[26] Onojake MC, Osuji LC, Ndubuka CO. Characterization of bitumen samples from four deposits in southwest, Nigeria using trace metals. Egypt J Pet, 2017, 26(2): 547-552

[27] Onuoha J. The state and economic reforms in Nigeria. An explanatory note on the capture theory of politics, 2008 Nsukka Great AP Publishers

[28] Paetz A, Crobmann G. Market B. Problems and results in the development of international standards sampling and pretreatment of soils. Sampling of environmental materials for trace analysis, 1994 Weinheim VCH

[29] Porter ME, Kramer MR. Strategy and society: the link between competitive advantage and corporate social responsibility. Harvard Bus Rev, 2006, 84: 78-92

[30] Singh A, Sharma RK, Agrawal M, Marshall FM. Health risk assessment of heavy metals via dietary intake of foodstuffs from the wastewater irrigated site of a dry tropical area of India. Food Chem Toxicol, 2010, 48: 611-619

[31] Sucharovà J, Suchara I, Hola M, Marikova S, Reimann C, Boyd R, Filzmoser P, Englmaier P. Top-/bottom-soil ratios and enrichment factors: What do they really show?. Appl Geochem, 2012, 27: 138-145

[32] Suzuki Y, Fujii N, Yano H, Ohkita T, Ichikawa A, Nishiyama K. Effects of the inhalation of manganese dioxide dust on monkey lungs. Tokushima J Exp Med, 1978, 25: 119-125

[33] Thornton I. Environmental geochemistry and health in the 1990 s: a global perspective. Appl Geochem, 1993, 2: 203-210

[34] Tomlinson DL, Wilson JG, Harris CR, Jeffrey DW. Problem in the assessment of heavy metals levels in estuaries and the formation of a pollution index. Helgoländer Meeresuntersuchungen, 1980, 33: 566-575

[35] Wang L, Zachariah A, Yang S, Prasad V, de Klerk A. Visbreaking oilsands-derived bitumen in the temperature range of 340–400 C. Energy Fuels, 2014, 28(8): 5014-5022

[36] Wilhelm SM, Liang L, Kirchgesser D. Identification and properties of mercury species in crude oil. Energy Fuels, 2006, 20: 180-186

[37] Zhang HQ, Sarica C, Pereyra E. Review of high-viscosity oil multiphase pipe flow. Energy Fuel, 2012