PHYSICO-CHEMICAL ANALYSIS OF SOILS PROXIMATE TO ARTISANAL REFINING PLANTS IN SOUTHERN NIGERIA

Abstract

The physico-chemical analysis of the impacted soil in Bodo community was carried out due to severe degradation of the environment and the aesthetic destruction of the terrestrial environment, the need to access the effect of non-conventional refining plants on the physico-chemical parameters of the soil. The pH, conductivity, total nitrogen, phosphate, cation exchange capacity and so on were analyzed using the standard method. From the result, it was observed that the impacted soil recorded mean and standard error as 54.1258 and 24.162 respectively while the non-impacted soil recorded 18.4176 and 6.323 respectively. Amongst the physical parameters, soil textural analysis revealed that the soil is mainly sandy loamy and small percentage of clay loamy. This therefore requires appropriate remediation measures to avoid infiltration into the groundwater.

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PHYSICO-CHEMICAL ANALYSIS OF SOILS PROXIMATE TO ARTISANAL
REFINING PLANTS IN SOUTHERN NIGERIA
Tochukwu E. Ebe
Dept. of Environmental Technology, Federal University of Technology, Owerri, Nigeria.
John D. Njoku
Dept. of Urban and Regional Planning, Federal University of Technology, Owerri, Nigeria.
Akachukwu O. Enem
Dept. of Environmental Technology, Federal University of Technology, Owerri, Nigeria.
ABSTRACT: The physico-chemical analysis of the impacted soil in Bodo community was
carried out due to severe degradation of the environment and the aesthetic destruction of the
terrestrial environment, the need to access the effect of non-conventional refining plants on the
physico-chemical parameters of the soil. The pH, conductivity, total nitrogen, phosphate,
cation exchange capacity and so on were analyzed using the standard method. From the result,
it was observed that the impacted soil recorded mean and standard error as 54.1258 and
24.162 respectively while the non-impacted soil recorded 18.4176 and 6.323 respectively.
Amongst the physical parameters, soil textural analysis revealed that the soil is mainly sandy
loamy and small percentage of clay loamy. This therefore requires appropriate remediation
measures to avoid infiltration into the groundwater.
KEYWORDS: Impacted, physico-chemical, artisanal
INTRODUCTION
Refining of petroleum is hardly an environmental friendly operation. This is due to the release
of different greenhouse gases into the atmosphere resulting to substantial air pollution (Carla,
2002). Aside air pollution impacts; there are also waste water concern, risk of industrial
accidents such as fire and explosion (Adeniyi and Afolabi, 2002).A non-conventional refining
plant is not concerned with the chemical changes in crude oil rather it involves the physical
changes found in simple distillation. It has been reported that petroleum refining contributes to
solid, liquid and gaseous wastes in the environment (Nwankwo and Irrechukwu, 1998).
Soil quality is an account of soil’s ability to provide ecosystem and social services through its
capacity to perform its function under changing conditions (Doran and Parkin, 1994). The
concept of soil quality expressed by this function allows practical applications with regards to
targeted social or ecosystem services. Targeted application maybe linked to special soil
functions like in the case of soil productivity ranking, evaluation of carbon sequestration
potential in accounting peat stock etc. The simplest case of soil quality evaluation therefore is
to assess the performing potential of soil by single function. On higher levels of aggregation
soil quality can express the sum capabilities (Arshad and Martin, 2002).
The non conventional refining plant has more devastating effects because of the absence of
process control and waste treatment facilities found in conventional refining plants to mitigate

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and minimize environmental hazards. This non conventional refining plants has degraded the
terrestrial environment of the study area.
MATERIALS AND METHODS
Delimitations and Description Of Study Area
Bodo community lies on the coastal low land of the Niger Delta, and in the Southern part of
Gokana Local Government Area of Rivers State. The community is about 56 kilometers by
road from Port Harcourt, the capital of Rivers State. It is located between latitude 40361N and
longitude 70211E of the equator. Bodo is bounded on the North by K-Dere and B-Dere (both in
Gokana) on the East by the Andoni people, on the West by the Bolo people of Okirika kingdom
and on the South by the Bonny people and the Atlantic ocean. Bodo occupies an approximate
area of about one hundred thousand hectares of land, with a considerable population which
spread over major 36 villages and numerous fishing settlements (RIVGIS, 2010). According
to the 1991 National population Commission, Bodo had a population figure of 14,000 people
establishing it as the largest settlement in Ogoni Division. From 1991 to 2006, the figure rose
30,000 (Oguntoyinbo, 2008). The major occupations of the people are fishing and farming.
Figure 3.1 Schematic drawing of parts of Rivers State showing the study site,Bodo
In Gokana Local Government Area Rivers state.
Railway
line
Minor
Roads
Major
Roads
Rivers
Study
Location
Creeks
N
KEY

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Determination of Soil Conductivity
10 g of the crushed soil sample was put in a sterile container and mixed thoroughly with 5 ml
of distilled water and allowed to settle. Then the conductivity meter was used to take the
reading.Furthermore, walkey-black method was used to determine the total organic carbon and
total organic matter while Dumas method was used for nitrogen.
Determination of Nitrate and Nitrite
About 1.0g of soil sample was taken in a 25ml beaker and extracted with 3ml portion of 0.5%
sodium carbonate solution.
The extract was filtered through whatman no. 41 filter paper.
Then the filtrate was then collected and diluted to 25ml and appropriate aliquots of 1-2ml of
the solution was transferred into 10ml calibrated flask and analyzed.
More also, flame photometer was used to determine K, Na, P, Ca, Mg and Mn.
RESULTS AND DISCUSSION
Magnesium, Calcium, Sodium and Potassium varies from 0.32 to 14.89, 0.03 to 2.02, 0.20 to
5.33 and 0.20 to 3.27 respectively. Magnesium has the highest range of 14.57 followed by
sodium with 5.13, potassium 3.07 and 1.99 for calcium.Exchangeable aluminum and
exchangeable acidity varies from 0.19 to 2.21 and 0.32 to 1.75. They had a range of 2.02 and
1.43 respectively. Cations Exchange Capacity (CEC) varies from 2.52 to 18.33 with range of
4.328. Also, some of the physiochemical parameters measured exerted significant influences
on the hydrocarbons. Furthermore, at p˂0.05, PAH correlated positively with nitrate (r=0.593)
and phosphate (r=0.630) while TPH correlated positively with nitrate (r=0.534). Nitrite
correlated positively with PAH (r=0.7550 and TPH (r=0.712) at p˂0.01.
A comparison of the levels of the physiochemical parameters in the impacted and non-impacted
(control) locations revealed significant difference (sig.t=0.04) at p˂0.05 (Table 3.1). Results
also revealed significant correlation (sig.r=0.00) between the two locations.
However, the impacted locations recorded mean value of 54.12 (+ 24.16) while the non-
impacted location (control) recorded a mean value of 18.41 (± 6.32).
Table 3.1:Comparison of the Physicochemical Parameters in Impacted and Control Locations
using the Student t-test of Significance (p˂0.05)
Pair
Mean
SE
r
Sig.r
t
Sig.t
Impacted
54.125820
0.713
0.000
1.772
0.041
Non Impacted
18.4176
24.162
6.323

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The results from this study revealed that there were different concentration of hydrocarbons
and physiochemical parameters within the impacted and control stations at different depths (0-
15 and 15-30cm). The concentration of polynuclear aromatic hydrocarbon (PAH) and total
petroleum hydrocarbons (TPH) showed that PAH recorded maximum concentration of
6899.4287ppm at station III at the depth of 0-15cm and minimum concentration of 37.6942ppm
at control station at the depth of 15-30cm. TPH recorded maximum concentration of
21873.1149ppm in station III at the depth of 0-15cm and a minimum concentration of
83.1469ppm at the control station at the depth of 15-30cm. These figures represent high
concentration of hydrocarbons when compared with the control station.
A review of the existing data on Niger Delta Environmental Survey NDES (1999),Osuji et al.,
(2006) and UNEP (2011) affirms that such high concentration of hydrocarbons shows severe
hydrocarbon contamination. BTEX were below detectable limit and it might be as a result of
high volatility. It is suspected that BTEX compounds might have volatilized during the
destruction of the refining plants.The results also showed that the whole area under
investigation recorded highest pH value of 5.99 in control station at the depth of 0-15cm while
minimum value of 4.12 was recorded at the depth of 0-15cm in sampling station III. This
revealed that the soil of the study area were slightly acidic.
Results for conductivity measurement were quite high with values ranging from 118.00 to
361.00µs/cm with range of 234.00µs/cm. This may be due to the increase in the concentration
of some soluble salts in the soil. It is also worthy to note that maximum level of conductivity
occurred at station I at the depth of 15-30cm. Particle size composition showed that the soil
composition of the soil is mainly sandy. Sand ranges from 48% to 81% and a range of 33%.
Clay ranges from 12% to 33% with range of 21% while silt ranges from 5% to 19%. The sandy
nature of the soil of the study area aids infiltration of contaminants and increases the pollution
pathway for contaminants. The texture also allows for free drainage and ease of mobility of
ions within the soil.
Total organic carbon content appears very low with minimum value of 0.16% and maximum
value of 2.19% with range of 2.03. Total nitrogen, nitrate, nitrite, ammonia and phosphate
recorded low values as was shown in Table 3.2. Magnesium recorded higher levels in all
stations including control station than the other nutrient elements. The fact that there was lower
EC values in station II,III,IV and VI confirms that organic compounds like crude oil cannot
conduct electrical current very well Osuji et al., (2006)

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Table 3.2 Descriptive Statistics of the physicochemical Parameters of Impacted
Soils in Bodo Community
Parameters
Minimum
Maximum
Range
Mean
SE
PAH
TPH
pH
Conductivity
Sand
Silt
Clay
TOC
Total Nitrogen
Nitrate
Nitrite
Phosphate
Ammonia
TOM
Magnesium
Calcium
Sodium
Potassium
Ex. Al
Ex. Acidity
CEC
37.6942
83.1469
4.12
118.00
48.00
5.00
12.00
0.16
0.069
2.02
2.10
1.17
0.03
1.20
0.32
0.03
0.20
0.20
0.19
0.32
2.52
6899.4287
21872.1149
5.99
361.00
81.00
19.00
33.00
2.19
1.500
4.40
3.01
2.67
0.17
3.70
14.89
2.02
5.33
3.27
2.21
1.75
18.33
6861.7345
21788.9680
1.87
234.00
33.00
14.00
21.00
2.03
1.431
2.38
0.91
1.50
0.14
2.50
14.57
1.99
5.13
3.07
2.02
1.43
15.81
1844.8400
5913.381529
5.1179
213.7857
68.2857
10.7143
20.7143
1.3036
0.29500
2.9450
2.5657
2.0729
0.1157
2.2314
7.2671
0.2857
1.0029
0.5093
0.4736
1.0107
10.5492
534.9329
1.71662003
0.13987
19.31866
2.21491
1.01866
1.64560
0.14509
0.106846
0.17358
0.07619
0.10569
0.00906
0.20359
0.91359
0.13686
0.43531
0.21318
0.13843
0.11518
1.15331
Ex. Al= Exchangeable Aluminum, Ex acidity= Exchangeable acidity, T/N= Total Nitrogen, CEC=
Cation Exchange Capacity, and TOM= Total Organic Matter, SE= Standard error
Table 3.3: Correlation (r) matrix between the physiochemical parameters and Hydrocarbons
Parameters
PAH TPH
pH
EC
Sand
Silt
Clay
TOC
Total Nitrogen
Nitrate
Nitrite
Phosphate
Ammonia
TOM
Magnesium
Calcium
Sodium
Potassium
Ex. Al
Ex. Acidity
CEC
-0.654*
-0.438
-0.427
0.525
0.286
-0.418
-0.240
0.593*
0.755**
0.630*
-0.349
-0.694**
0.747**
-0.103
-0.333
-0.195
-0.050
-0.033
0.409
-0.614
-0.483
0.425
0.465
0.323
-0.430
-0.219
0.534*
0.712**
0.639
-0.317
-0.712**
0.768**
-0.090
-0336
-0.190
-0.031
0.096
0.0442
*=significance at p˂0.05, **=significance at p˂0.01, EC= Electrical conductivity
TOC=Total organic carbon, TOM=Total organic matter, EX. Al=Exchangeable Aluminum
Ex=Exchangeable

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Figure 3.1:Spatial variations in levels of sand, silt and clay compositions of impacted and
control soils of Bodo community.
Figure 3.2: Spatial variations in levels of total organic carbon (TOC), total nitrogen and total
organic matter (TOM) of impacted control soils of Bodo community
0
10
20
30
40
50
60
70
80
90
SS I SS II SS III SS IV SS V SS VI Control
Compositions (%)
Sampling stations
Sand (0-15cm) Sand (15-30cm)
Silt (0-15cm) Silt (15-30cm)
Clay (0-15cm) Clay (15-30cm)
0
0.5
1
1.5
2
2.5
3
3.5
4
SS I SS II SS III SS IV SS V SS VI Control
Concentrations (%)
Sampling stations
TOC (0-15cm) TOC (15-30cm) T.Nitrogen (0-15cm)
T.Nitrogen (15-30cm) TOM (0-15cm) TOM (15-30cm)

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Figure 3.3: Spatial variations in levels of potassium ions, exchangeable aluminum and acidity
of impacted soils of Bodo community
Plate 3.1: Non-conventional refining plant 1 at Bodo Community Gokana Local Government
Area
0
0.5
1
1.5
2
2.5
3
3.5
SS I SS II SS III SS IV SS V SS VI Control
Concentrations (meq/100g)
Sampling stations
K (0-15cm) K (15-30cm)
Exch.Al (15-30cm) Exch.Acid (0-15cm)
Exch.Acid (15-30cm)

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Plate 3.2: Non-Conventional Refining Plant II at Bodo Community in Gokana
Local Government Area
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