Evaluation of Physico-Chemical and Fungal Species Associated with Oil Contaminated Soil from Selected Automobile Garage in Sokoto Metropolis

© 2018 The Authors. This article is licensed under a Creative Commons Attribution 4.0 License Abstract. This study was conducted with a view to evaluating the physicochemical and mycological properties of different oil contaminated soils collected from three different automobile garages in Sokoto Metropolis, and uncontaminated soil from the temporary site, Usmanu Danfodiyo University, Sokoto (UDUS) was used as the control. The pH was determined using pH meter model Hanna (H1991301), quantity of mineral elements was evaluated in accordance with Murphy and Fungi were isolated from the three oil contaminated samples (A, B. and C) and the uncontaminated (sample D) as control, this was done by standard procedure using the method of P. Ren, T. Jankun & B. Leaderer. The physical, chemical, and mineral elements from the oilcontaminated soils of the three automobile garages and control. The results of particle soil analysis revealed the high content of sandy soil (96.2 to 87.3) and silt is the lowest with (2.5–0.6). Magnesium had the highest concentration of studied minerals, ranging from 193 to 649.2 mg/kg. while PH result revealed that the soil samples were pH value ranged from (16.85–16.20) in oil Contaminated samples, while the control had 15.90, and electrical conductivity ranged from 12.8–13.8 % and 28 % in control, four fungal isolates Aspergillus sp., Penicillum sp., Mucor sp. and Sporobolomyces sp. were identified based on colonial, sexual and morphological characteristics. These fungal strains can be used in bioremediation process and oil pollution reduction in aquatic ecosystems.


INTRODUCTION
Soil is the naturally occurring, unconsolidated or loose covering on the earth's surface.Soil is made up of broken rock particles that have been altered by chemical and environmental conditions, such as weathering and erosion.Soil is a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states.Soil bacteria and fungi play pivotal roles in various biogeochemical cycles (BGC) and are responsible for the cycling of organic compounds.Soil microorganisms also influence above-ground ecosystems by contributing to plant nutrition, soil structure, tex-ture and fertility [1,8,14].Pollution in the environment is the unfavourable alteration of our environment as a result of wastes from man's activities, changes in radiation levels, physicochemical characteristics and abundance of organisms in a harmful way.However, a pollutant is a substance that occurs in the environment, at least in part, as a result of human activities, and which has deleterious effect on the environment [10,19], in another words, pollution is the presence of harmful products of man activities, chemicals or other alteration of the natural soil environment.This type of contamination typically arises from the rupture of underground tanks as a result of the application of pesticides, percolation of contaminated surface water to subsurface strata, leaching of wastes on landfills or direct discharge of Industrial waste to the soil that results from accidental discharge of oil and its derivatives [25,27].With urban industrialization, social development and population increases, solid waste production are growing rapidly, making pollution a serious problem.If not properly disposed and managed the resulting environmental impact from these wastes can be disastrous [21].Some of the obvious consequence of man-made pollution includes transmission of diseases by water borne pathogens, accumulation of toxic or recalcitrant chemicals in the soil, destabilization of ecological balance and negative effects on human health [7,14,20,24].As a result of change in land use and accumulation of non-biodegradable wastes pointed out, there is need to determine the soil properties for proper management planning.These properties or parameters includes: soil pH, particles size, organic matter/carbon content, macro and micro element content among others.The collected soil data can be used to assess the soils capacity to perform its ecological functions [20].The knowledge of the soil PH will enable understanding the varying amount of plant nutrients present in the soil and give a level of microbial activities in the soil.Most arid and semi-arid soils have pH within the range of 6.0-6.8 [6,15].Soil texture is a term used to designate the proportionate distribution of the different sizes of mineral particles in a soil; it does not contain any organic matter.These mineral particles vary in size from those easily seen with the unaided eye to those below the range of a high-powered microscope [5,12,13].Soil texture is determined by the relative proportions of sand, silt, and clay found in a given soil.Author [12] stated that oil spillage on soil makes it unsatisfactory for plant growth.This is due to insufficient aeration of the soil because of the displacement of air from the space between the soil particles by petroleum byproducts.The petroleum stations and retail outlets are responsible for a number of environmental pollution resulting from accidental spills of oils and its derivatives [5].
Microbial communities exposed to hydrocarbon become adapted exhibiting selective enrichment and genetic changes resulting in increasing proportion of hydrocarbon degrading bacteria, and fungi.Bacterial plasmid encoding hydrocarbon catabolic genes and fungi makes them potential degraders of oil.For Fungi, some are opportunis-tic and affect a susceptible host while some are truly pathogenic [3,9].Automobile workshops abound within Sokoto metropolis.This has resulted in the concomitant exposure of the surrounding soils within the vicinity of these workshops to high levels of spent crankcase engine oil and lubricating oils [4,23].This study was conducted with the aim of isolating and identifying the fungal species from soils collected from three different auto mechanic workshops within Sokoto metropolis and evaluation of their physicochemical characteristics.

MATERIALS AND METHODS
Source of soil samples.The study was carried out in selected areas of Sokoto metropolis.The city is located between latitude 5°09' E and 5°18' E, Longitude 12°57' N and 13°07' N, at 308 m above sea level.The River Sokoto partially surrounds the metropolis on the northwest axis.The three different automobile garages which are the Buzaye Auto mechanic Workshop, Sahara Automobile Engineering workshop and Tashar Illela garage are located at different sites of the Sokoto Metropolis.Automotive repairs and maintenance are the main activities going on in the automobile garages.This involves the indiscriminate disposal of various petroleum oils on the soil surfaces in substantial amounts.Identification of Fungal Isolates.Fungi were isolated from the three oil contaminated samples (A, B and C) and the uncontaminated (sample D) as control.This was done by standard procedure using the method of [11,26].Physicochemical Evaluation and Analysis.The three oil contaminated soil samples (A, B, and, C), and the uncontaminated soil (sample D) were physically and chemically evaluated to determine moisture, texture, pH.As well as cation exchange capacity (C.E. C).The quantity of mineral elements such as Nitrogcn (N), Magnesium (M), Calcium (Ca), Phosphorus (P), Sodium (Na), Potassium (K), Organic carbon and Organic matter content were also measured using the methods of [17] in accordance with [18,28].The pH was determined using pH meter model Hanna (H1991301) [16].The Potassium, Nitrogen, and Phosphorus were determined using Flame photometer machine.Statistical Analysis was conducted using SPSS statistical package software version 20.0 using Dunnett tests to treat one group as a control, and compare all other groups against it [30].

RESULTS AND DISCUSSION
Results of physiochemical parameters are presented in Table 1.Evaluated soil samples in the study had pH and electrical conductivity ranging from 6.95 to 7.0 and 12.8 to 28% respectively.The highest level of organic carbon was observed in sample A (0.96 %), followed by C (0.6 8%) then D with (0.20) and B with (0.08), organic matter was also recorded high in A (1.68 %) followed by D (0.34 %) then B with 0.14 % and lastly C with (0.045 %).For moisture results demonstrated 39.92-41.12%; A having the highest and C with the lowest while uncontaminated soil had 57.25 %.
Organic matter 0.1-0.6 % while control was 0.34 %.This results is in line with other previous findings as in [14,20,22,23].The results of particle soil analysis revealed high content of sandy soil (95.1 to 87.3).
Clay have the highest with 4.5 %, followed by 4.3 % then 4.0 while control had 2.0 % and finally.
Silt with B having 0.11 % then C had 0.8 followed by 0.6 and control had 2.5 %.
pH is an important soil property, having great effects on solute concentration and absorption in soil [2].Soils with acidic pH levels tend to have an increased micronutrient solubility and mobility as well as increased heavy metal concentration.The levels of exchangeable cations (Na+, K+, Ca2+, Mg2+) is a reflection of soil condition with regards to the agricultural potential of soil at the study sites.Nitrogen is an important constituent of protein and nucleic acid and most microorganisms and plants take up inorganic nitrogen as nitrate (NO3-) or ammonium (NH4+) ions [2,29].
Four genera of fungi were isolated from the oil contaminated soil samples and the control sample.The types of meld identified from the four samples include Penicillium sp. which was predominant.Table 2 shows the type of mycoflora isolated from the three samples of oil contaminated soil and the control.[14,16,22].

CONCLUSIONS
Soil is basically the primary recipient of daily generated wastes at different places been it industries, markets and automobiles waste from mechanics, the quality of soil is always remains with its chemical and biological components.The occurrence of the four fungal species among the soil samples in the selected automobile garage, Sokoto Metropolis, indicates the capacity of the fungal species to adapt in oil contaminated soils.
This suggests that they are potential hydrocarbon degraders and therefore can be used for the remediation of petroleum sites which happen to be polluted.The effect of these wastes on the soil ecosystem is not surprising considering the tendency for pollutants to alter soil quality.Therefore, informing the public of the dangers inherent in improper management of soil environment should be considered as an important aspect of scientific research and awareness.
It is therefore recommended that more investigation should be carried out into the biochemical pathways employed by these isolates in the breakdown of petroleum by-products for their possible application to ensure extensive clear of petroleum by-products contaminated sites.

Table 1 -
Physicochemical Properties of Oil Contaminated and Uncontaminated Soils

Table 2 -
Fungal Species Isolated from Oil Contaminated and uncontaminated Soil Samples Apergillus sp. was found in two locations C (Illela garage) and D (control) while it was not detected in the remaining two locations, Mucor sp. was found in location C only and not detected in the remaining locations including control, Penecillium sp. was found in all the locations except C, and finally, Sporobolomyces sp. was detected in two locations namely; B and D while the two other locations it was not detected, this could be traced in similar research as in Notes: Samples A -Buzaye, B -Sahara, C -lllela garage, Sample D -Oil uncontaminated soil (temporary site)