Quantitative Oil Source Fingerprinting and Diagnostic Ratios Application for Identification of Soil Residual Hydrocarbon (SRH) in Waste Dump Areas within Oil Well Clusters

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

Quantitative Oil Source Fingerprinting and

Diagnostic Ratios: Application for

Identification of Soil Residual Hydrocarbon

(SRH) in Waste Dump Areas within Oil Well

Clusters

Ayobami Omozemoje Aigberua

Received: 20/02/2019

Accepted: 29/04/2019

Published: 01/06/2019

Department of Chemical Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria.

Abstract

The elucidation of soil residual hydrocarbon (SRH) in oil-impacted dumpsite soils is aimed at distinguishing the

principal source (municipal waste dumpsite or oil well-head clusters) of petroleum and polycyclic aromatic hydrocarbons in

the mangrove environment receiving mineral oil loading form mixed anthropogenic influences. Chemical fingerprints of soil

specimen were obtained on determination by gas chromatographic – flame ionization detection (GC-FID) technique using an

HP 5890 series II instrument. Flt/Pyr ratios revealed the presence of petrogenic hydrocarbons while carbon preference index

(CPI) showed soils composed mainly of degraded material and fossil fuels, apart from location E-2 which was loaded with

non-biodegraded biological materials using Ph/nC₁₈data. Elucidation of Pr/nC17 ratios showed that the retention of non-

biodegraded hydrocarbon was decimated at locations E-4 and E-6 due to reduced microbial degradation in comparison to the

other field areas. Overall, the soil was insignificantly impacted by terrestrial sources, as greater magnitude came from

surrounding oil well clusters. Therefore, soil toxicants are likely to be bio-accumulated in crops growing along proximate

farmlands, especially nypa palm fruits which are commonly consumed. It is imperative to avoid ingesting herbage or other

nutriments from this area until residual oil seepages are effectively controlled and hydrocarbons have been monitored for

substantial degradation.

Keywords: Soil residual hydrocarbon, Carbon preference index, Total petroleum hydrocarbon, Polycyclic aromatic

hydrocarbon, Eagle Island

water (4). Correlations have been established between

Introduction

PAH levels and anthropogenic input into waste dumps.

PAH levels in waste dumps were often higher than in

pristine soils. Also, levels of PAHs have been reported to

exceed 0.02 g/g as stipulated in the guidelines of

Canadian Environmental Quality (5).

The release of petroleum and aromatic hydrocarbons

into the immediate and surrounding environment of the

Eagle Island is not limited to the anthropogenic inputs

emanating from waste dumps alone. The area is

characterized by the presence of crude oil equipment

Like most urban cities across Nigeria, Port Harcourt

metropolis is characterized by series of open waste

dumpsites. These dumpsites have been known to

contaminate surface waters that are within close

proximity (1). They have also been known to moderately

contaminate air mainly from fossil fuel burning and

vehicular exhausts, especially around industrial zones

(

2). Soils within the vicinity of auto-mechanic work areas

depicted spiked levels of petroleum hydrocarbons in

relation to those from cultivated farmlands, thereby

suggesting direct impact of anthropic releases (3). Most

dumpsites within Port Harcourt have been observed to

consist of discarded household electronics, plastic and

food waste. Mechanic waste dumps have been reported

(such as oil well heads). In the event of equipment failure

or seepages from worn-out metal joints, the proximity of

the study area to nearby creeks can make the soil and

aquatic resources vulnerable to crude oil contamination,

creeks receives domestic, municipal and industrial wastes

due to human activities from settlements, commerce and

industries within its vicinity, this in turn alters soil

chemistry and decimates plants population (6-8). Crude

oil is a complex mixture containing several hydrocarbon

compounds (such as aliphatic, volatile and semi-volatile

aromatics, as well as the organometallic heavy metal

complexes) which can be fractionally separated into sub-

products such as: kerosene, jet and diesel fuel, heating

to represent

potential source of hydrocarbon

contamination of soils, sediment, surface and ground

Correspoinding author: Ayobami Omozemoje

Aigberua, Department of Chemical Sciences, Faculty of

Science, Niger Delta University, Wilberforce Island,

Bayelsa State, Nigeria. E-mail:ozedee101@gmail.com.

Contact: +234 8032765181.

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

oil, etc. Crude oil transportation lines linking oil well

heads are susceptible to acts of vandalism or self-rupture.

The presence of hydrocarbon in soil, whether from

municipal or oil wastes can result in variation of

microbial population, negative physicochemical changes

in the environment, release of cancer-causing aromatic

complexes, consequent loss of food, herbage, water and

other resources (6-14).

Materials and Methods

.1 Study area

Eagle Island is located within the Rumueme -

Oroakwo axis of Port Harcourt. Its geographical

coordinates lie within the different latitudes and

longitudes: E1 (N4º 47.223’, E6º 58.134’), E2 (N4º

(

7.223’, E6º 58.134’), E3 (N4º 47.327’, E6º 58.573’), E4

N4º 47.326’, E6º 58.574’), E5 (N4º 47.327’, E6º

8.574’), E6-control (N4º 47.204’, E6º 58.336’) (Plate

Total petroleum hydrocarbons (TPHs) in the form of

^a^l^k^aⁿ^e^s^aⁿ^dⁱ^s^o^p^r^eⁿ^oⁱ^d^s⁽ⁿ^C8 to nC ) can be used to

1). The waste dump environment is located within the

mangrove/nypa palm forest zones of Eagle Island in Port

Harcourt city local government area. It is bound by

surrounding creeks and river tributaries. The common

occupation of settlement dwellers within the area is fish

farming and crop production. The soil environment is

susceptible to hydrocarbon (petrogenic, pyrogenic or

biogenic) contamination emanating from either or both of

the municipal waste dumps and oil well heads.

trace the source of an oil spill (whether emanating from

source rock or secondary anthropogenic sources) (15-17).

Similarly, polycyclic aromatic hydrocarbons (PAHs) can

be classified as petrogenic (petroleum) or pyrogenic

(

combustion) origins; they can be further classified as

resulting from natural and anthropogenic sources (11, 18-

0). Examples of anthropogenic sources of PAHs in the

environment include: burning of refuse waste dumps (5),

burnt remnants and soot samples (21), indiscriminate

deposition of mechanic wastes (4), urbanized municipal

waste effluents (19) and from oil spillage (11, 22). PAHs

tend to move across soil regions while being slow to

biodegradation, especially by indigenous microorganisms

.2 Field Sampling and pre-treatment

Five (5) samples of soil were randomly collected

from areas most visibly impacted by waste dumps at

depths of 0 – 15 cm using soil auger. One (1) was

collected about 1 meter away from impacted area (as

control). However, the field area was within close

proximity of oil equipment and well heads. Samples were

transferred into pre-cleaned aluminum foil packs and

preserved with ice in cold-storage box prior to laboratory

delivery.

(

20). On the other hand, alkanes and isoprenoids showing

ⁿ^C8 ^t^oⁿ^C40 petroleum hydrocarbon compounds have

been used as diagnostic tools for the identification of oil

sources in soil (16), ambient air (23), crude oil (15, 17,

4) and shellfish (25), etc.

Oil source fingerprinting is an environmental

forensics technique that uses analytical chemistry to

determine the origin of oil residues in environmental

samples by comparing to a known or suspected source of

oil (22). Even though PAHs have been major constituents

of hydrocarbon contaminated environmental media, its

distribution and source identification has been carried out

by the application of diagnostic PAH ratios (11, 18-20,

.3 Statistical analysis

In order to determine field sample areas of close

association (or mutual dependence) and those of mutual

independence, the hierarchical cluster analysis was

carried out using Euclidean distance based on average

linkage between groups. Only one variable (sample

location) across the waste dump soil was statistically

evaluated. Clustering techniques are used to separate

objects related with a specific cluster; such objects

should be quite alike (or homogenous). Hydrocarbons of

mutual dependence show similarities or closeness in

features while those of mutual independence mirror

diverging attributes. Principal component analysis (PCA)

is a multivariate analysis technique used in transforming

original sample composition data into new, smaller and

uncorrelated variables called principal components. The

hypothesis is based on expressing the total variance of

the variables with two factors, accounting for the

maximum variance of the variables (17, 29).

6) which is a fingerprinting technique used for the type

and source identification of hydrocarbons in the

environment. For the alkanes and isoprenoids, typical

diagnostic ratios are: pristane/phytane (Pr/Ph),

^p^rⁱ^s^t^aⁿ^e^/ⁿ^C¹7

(Pr/nC ),

^p^h^y^t^aⁿ^e^/ⁿ^C18

(Ph/nC ),

nC /nC , carbon preference index (CPI), (Pr

nC )/(Ph + nC ), have been applied by (15-17, 24-25)

to determine the extent of biodegradation (Ph/nC ), level

of oil maturation (CPI), determination of oil source

Pr/Ph), etc. Whereas, PAH ratios such as:

phenanthrene/anthracene (Ph/anth), benzo (a)

anthracene/chrysene (BaA/Ch) and fluoranthene/pyrene

Flt/Pyr) have been applied by (17), other mixed PAH

(

isomeric ratios such as: (Ant/Ant + Ph), (Flt/Flt + Pyr),

BaA/(BaA + Ch) and benzo (a) pyrene/(benzo (a) pyrene

.4 Sample Preparation, Quality Control Procedure and

chrysene) (BaP/BaP + Ch) have been used to

Analytical Data Validation

distinguish between petrogenic and pyrogenic sources

Soil samples were refrigerated at 4 C and analyzed

within the first 3 days from time of sample collection.

Glass wares were acid-washed, rinsed under tap water

and, further rinsed with distilled water. Washed glass

wares were oven-dried at 105 C for 30 minutes and

cooled in a desiccator.

(

11, 18, 27-28).

The need to specify the prevalent source of

hydrocarbons within the Eagle Island environment was

necessary, this is due to the presence of various waste

streams (primarily consisting of waste dumps and oil

well-heads) which represent human burden within the

area of study. The diagnosis of aliphatic and aromatic

hydrocarbon sources is concurrently aimed at identifying

the nature of residual mineral oil and its effect on

biodegradability over time. Also, the scarcity of literature

in chemical fingerprinting of soils receiving multiple

waste streams such as is typical of this study location

makes this work quite unique.

.4.1 TPH extraction

Exactly 5 grams wet-weight soil was mixed with two

spatulas-full of anhydrous Sodium Sulphate (as drying

agent), depending on the moisture level of the sample.

Also, a volatile surrogate (2-bromobenzofluoride) was

mixed with sample prior to extraction. A 16 hour soxhlet

extraction was applied for TPH extraction using 95% n-

hexane solvent (11).

1:1 mix ratio of n-

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

hexane/dichloromethane solvents was used to extract

PAHs by the cold-extraction method adopted by (11, 18).

Gas chromatography with flame ionization detection was

the method of analysis. Helium gas (at flow rate of 14.81

psi) was streamed as mobile phase, while an Agilent HP-

less mode) which are often observed in trace amounts.

When the target analyte concentrations (in this case,

volatile or semi-volatile aromatics) are so low that

splitting the sample in the injection port will not allow an

adequate signal from the detector, the spit-less mode is

usually a preferred option.

GC capillary column, with 100% 1,3-dimethylsiloxane

stationary phase material, length (30 m), internal

diameter (0.320 mm), and film diameter (0.25 µm) with

temperature range (-60 C to 325 C), was used for the

separation of vapor constituents of different hydrocarbon

fractions. Hydrogen and air (at flow rates of 30 psi)

served as ignition gases (10).

2.4.3 Instrument Calibration

A three (3) point linear calibration curve was

prepared from working solutions of 25, 50 and 250 µg/ml

stock of hydrocarbon window defining standard solution

of TPH (500 µg/ml). Another series of working solutions

(25, 50 and 250 µg/ml) were prepared from 1,000 µg/ml

.4.2 Instrument Conditions

Table 1 shows the instrument conditions. The split

of the proposed DEP(MA) – PAH mix and used for

instrument calibration of the polycyclic aromatic

components. All standard solutions were purchased from

AccuStandard-USA. The aliphatic and aromatic

hydrocarbons were determined with an HP5890 series II

Gas chromatograph-Flame ionization detector (GC-FID),

manufactured in USA (10).

and split-less injection techniques were used for this

analysis. Hence, the samples were introduced into the

heated injection port as solvent-dissolved extracts. The

inlet vent was purged at a split ratio of 10:1 for aliphatic

hydrocarbons. This is because of their typically high

concentrations when compared to the aromatics (split-

Plate 1: Map of study area

Table 1: GC-FID operating conditions

TPH

Parameters

Initial oven temperature ( C)

Final oven temperature ( C)

PAH

290

310

Column flow rate (ml/min)

0.8

275

320

1.2

275

310

Injector temperature ( C)

Detector temperature ( C)

Inlet condition

Split ratio (10:1)

Split-less

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

.4.4 Instrument Blank (IB)

Immediately after instrument calibration, method

0.50 ml respectively, into sample vials. Each volume was

made up to the 1.0 ml mark using a 500 µl micro syringe.

PAH standards were prepared in a similar manner.

blanks were analyzed as quality control at the start and

end of run of each fractional species. A solvent blank

was injected into the GC system using the injection

solvent (95% n-hexane) to establish the chromatographic

baseline and to ensure its suitability. The resulting TPH

and PAH concentrations for the IB were below the

reported detection limit (0.01 µg/g). The two IB

concentrations generated at the start and end of sample

analysis were averaged and subtracted from

corresponding sample concentrations.

Results and Discussion

.1 Hydrocarbon source diagnostics in soil environment

Table 2 shows the levels of petroleum (aliphatic) and

polycyclic (aromatic) hydrocarbons in soil, the amounts

are compared against the regulatory limit of DPR. Apart

from soils of E6 (control) all other field areas depicted

TPH values exceeding stipulated limit. On the other

hand, PAHs were least in the control area even though

samples of E1, E2 and E3 were mostly impacted with

residual oil. Results reflect a spike in contaminant levels

of oil-contaminated soils in relation to the less

contaminated control zones. This corroborated the

findings of (10) where oil spill affected soils showed

increased elevation in hydrocarbon contamination as

against soils from proximate farmlands.

The level of total petroleum hydrocarbon in soil

ranged from 26.57 to 348.08 mg/kg. Reported values

were compared against the DPR limit of 50 mg/kg. Apart

from samples of control location E-6 that depicted the

least concentration (which was within DPR limit),

residual petroleum hydrocarbon exceeded regulatory

comparison for all other sample locations (E-1 to E-5)

.4.5 Calibration Authentication Standard (CAS)

Mid-concentration standards for TPH (100 µg/ml)

and PAH (200 µg/ml) prepared from stock solution was

analyzed before and after sample injection. The average

concentrations, TPH (89.7 µg/ml) and PAH (192.5

µg/ml) obtained was within the acceptance criteria of ±

0% of target value.

.4.6 Sample Duplicates

A second aliquot of one (1) of the six (6) test soil

samples was weighed for each of the TPH/PAH

extraction as “sample check”. The duplicate sample was

subjected to all sample preparation steps applied earlier.

(

Table 2). Similarly, the least concentration of total

.4.7 Surrogate Compounds

volatile surrogate

polycyclic aromatic hydrocarbon was observed for the

control location. Overall, total PAHs ranged from 0.162

to 1.581 mg/kg. Samples of point E-4 and E-5 also

depicted values slightly below DPR limit for PAHs in a

standard soil (1.0 mg/kg) [30]. For this study, samples

were collected during the dry season month of

November, 2018. Results obtained compared with (11)

that reported mean values of 148.9 mg/kg total

hydrocarbon content (THC) and 0.99 mg/kg PAHs for oil

spill contaminated soils of Rumuolukwu during the

month of November, 2013. Results of the different

isomeric ratios applied for TPH and PAH across the

different field locations are recorded in Table 3.

compound

(2-

bromobenzofluoride) was added to each sample in 95%

n-hexane solution prior to extraction. Percentage

recovery was calculated as 94.2%.

.5 Reagents and Chemicals

The following analytical grade reagents and

chemicals were used: 95% n-hexane (Riedel-de Haen,

Germany), dichloromethane (BDH, Poole-England), 99%

sodium sulphate anhydrous, AR (JHD Guangdong

Guanghua Sci-Tech Co., Ltd.). Working solutions of 25,

0 and 250 mg/l concentrations were prepared from a

TPH stock solution of 500 mg/l in n-hexane. This was

done by transferring aliquot volumes of 0.05, 0.10 and

Table 2: Concentration of total petroleum and polycyclic aromatic hydrocarbons in soil

Total TPHs

mg/kg)

Sample Identity

Total PAHs

(mg/kg)

1.174

1.581

1.039

0.744

0.704

0.162

(

E-1

E-2

E-3

E-4

E-5

E-6

234.06

348.08

208.28

132.60

123.50

26.57

DPR Limit for standard soil

Table 3: Calculated diagnostic ratios of aliphatic and aromatic hydrocarbon fractions in soil

E-1 E-2 E-3 E-4 E-5

Diagnostic Ratios

Pr/Ph

Pr/nC17

Ph/nC18

nC25/nC18

CPI

E-6

0.81

1.26

2.21

0.40

1.16

1.00

0.46

29.66

20.87

2.45

1.54

0.93

8.57

2.74

1.95

2.81

0.95

0.04

0.91

0.68

1.71

2.06

1.29

1.42

3.16

1.01

2.33

2.11

4.70

1.44

3.43

0.79

1.51

5.64

0.91

0.86

0.35

0.62

4.33

9.11

0.67

0.80

1.26

3.97

2.82

0.92

3.82

3.48

55.80

1.33

0.91

1.29

0.08

0.16

(Pr+nC17)/(Ph+nC18)

Ph/anth

BaA/Ch

Flt/Pyr

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

Figures: (1) TPH fingerprint of location E-2 (point of highest CPI and lowest oil maturation), (2) TPH fingerprint of location E-5 (point of

lowest CPI and highest oil maturation), (3) PAH fingerprint of location E-1 (point of highest Flt/Pyr ratio and most petrogenic source), (4)

PAH fingerprint of location E-2 (point of lowest Flt/Pyr ratio and least petrogenic source).

The diagnostic ratios depicted the following ranges:

Pr/Ph (0.35 - 2.45); Pr/nC₁₇(0.62 - 4.70); Ph/nC₁₈(0.93 -

in China. Only soil from location E-2 reflected non-

biodegradation as Ph/nC₁₈was observed below 1.0.

All other sample locations suggested that samples

were being biodegraded. Ph/nC₁₈ratio from this study

reportedly exceeded levels reported by (17) where values

ranged from 0.14 to 0.99 for Agbada-1 oil spill impacted

sites in the Niger Delta. The nC /nC ratio revealed the

.33); nC /nC (0.40 - 55.80); CPI (0.67 - 2.74); (Pr +

25 18

nC )/(Ph + nC ) (0.80 - 1.95); Ph/anth (0.46 - 5.64);

BaA/Ch (0.08 - 29.66); Flt/Pyr (0.04 - 20.87) (Table 3).

Some light hydrocarbon fractions (C - C ) (Figures 1 -

) were not observed probably because of evaporative

loss during sample processing and weathering of oil spill

samples after the incident (15, 17).

The chemical composition of aliphatic components

had not undergone significant alteration. The low Pr/Ph

ratio for the soils at locations E-1 (0.81), E-3 (0.91), E-5

shortest weathering process for soil E-1 (0.40) and the

longest for control soil E-6 (55.80), while (E-3 (2.06) &

E-4(3.43)) with (E-2 (8.57) & E-5 (9.11)) showed similar

weathering processes. Results from this study partially

agreed with (17) where nC /nC ratio reportedly ranged

(0.35) and E-6 (0.92) suggests that the residual oil in soil

from 0.93 to 3.52.

is not derived from source rock with insignificant

terrestrial contribution. On the other hand, the high Pr/Ph

ratio for soils at locations E-2 (2.45) and E-4 (2.11)

reflects significant terrestrial contribution and is an

indication that the source of residual oil in soil is crude

oil or petroleum; this may have emanated due to the

presence of oil well heads in the vicinity of the waste

dumpsite. [31] revealed Pr/Ph ratios of crude oil

contaminated soils to decrease from 2.358 to 1.626 on

amendment with oil degrading pseudomonas consortium.

Also, (15) recorded Pr/Ph ratios to depict ranges from

Apart from location E-2 that depicted oils of low

maturation with CPI value of 2.74, all other sample

locations depicted CPI<1.5 thereby reflecting oils of high

maturation. Crude oils from Umutu/Bomu fields in the

Niger Delta had been reported to be of high maturation

levels even though they lacked a specific maturity trend

(15). Similarly, (17) had reported oils of high maturation

in soils of Agbada-1 oil spill impacted sites in the Niger

Delta. Also, (33) had reported CPI>5 to reflect

significant contributions due to recent biological material

while CPI≈1 reflected significant contributions from

degraded material and fossil fuel compounds.

Consequently, residual oil in soils of location E-2 with

CPI 2.74 reflects the presence of biological materials

most likely from municipal waste dump source while

other locations may reflect a mixed combination of

degraded biological material and fossil fuels.

.78 to 32.27 for crude oils from Umutu/Bomu fields in

the Niger Delta.

The application of the Pr/nC₁₇ratio in this study

reveals that soils from locations E-4 (4.70) and E-6

(

3.80) are depicted by weak microbial activity and

tendency for a slower rate of bio-degradation while all

other sampling points may require relatively less time to

be decomposed. (32) applied pristine isomerization ratio,

reporting values between 0.42 and 0.97 to reflect

increased thermal maturity in coal rocks of river Junggar

Flt/Pyr ratio greater than unity (>1) is indicative of a

petrogenic source of PAHs (11, 15, 17). Similar to the

CPI ratios, location E-2 depicted the lowest Flt/Pyr ratio

and the least petrogenicity with value of 0.04. Other

points of low petrogenic inputs were locations E-4 (0.86)

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

and E-6 (0.16). Location E-1 (20.87) represented the area

of most petrogenic contribution while E-3 (2.33) and E-5

PAH sources for oil contaminated soils of Agbada-1 oil

spill sites. Oil impacted soils of Rumuolukwu

community had earlier been reported to consist

predominantly of pyrogenic hydrocarbons (11).

(2.82) also indicated petrogenic sources of residual PAHs

in soil. Results from this study partially compares to (17)

with Flt/Pyr ratio (>1) and an indication of petrogenic

Figures: (5) Hierarchical dendograms of sample locations, (6) Hierarchical dendograms of diagnostic TPH/PAH ratios.

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

Statistical analysis like the hierarchical cluster

analysis (HCA) carried out across the geospatially

varying sample locations revealed the closest association

or mutual dependence for samples of locations E-3 and

E-4. Similarly, locations E-2 and E-5 showed close

association, while samples of locations E-1 and E-6

reflected the greatest mutual independence, hence,

showing no similarities with other sampling points

recommendation for future studies and regulation for

soils receiving hydrocarbon waste from multiple point

sources. PCA relationship in this study is similar to (17)

where there was observed relationship between locations

PC1 and PC2, with only point PC3 depicting divergent

characteristics with TPH isomeric ratios.

Conclusion

Typical of the study area is the availability of mixed

(Figure 5). The close interlink between most of the

sampling points is a reflection of strong similarities

between sources of residual oil in soils of the

environment. Sample locations belonging to the same

cluster or group are likely to have originated from a

common source. The high level of similarity between

interlinked sample locations is strong conformation of a

common source of spilled oil and residual oil from waste

dumps. In conclusion, both the aliphatic and aromatic

hydrocarbons in the study area depict an anthropogenic

organic source which may have emanated from the

numerous human influences within the environment.

Similarly, (17) had reported a common source for spilled

oil in soils of Agbada-1 oil impacted field area, high

levels of similarity (98%) were observed from results of

cluster analysis. HCA of TPH and PAH diagnostic ratios

revealed close associations for the following groups of

sources of anthropogenic inputs. Results of chemical

fingerprinting for soils of the area revealed an equal

amount of low and high petrogenic hydrocarbons based

on Flt/Pyr ratio. CPI revealed soils of location E-2 to be

composed mainly of biological materials while other

sample points reflected soils with residual oil resulting

from degraded material and fossil fuel sources.

Consequently, all other sample locations reflected

biodegraded soils apart from location E-2 which

composed mainly of non-biodegraded hydrocarbons

based on Ph/nC₁₈ratio. Apart from soils of locations E-4

and E-6 (control) which reflected Pr/nC₁₇ratios greater

than 1.0 indicating poor microbial utilization of mineral

oil, all other areas showed maturation of organic

material. Generally, soil residual hydrocarbons (SRH)

depicted insignificant terrestrial contribution with higher

levels emanating from crude oil or petroleum sources.

The HCA applied to locations of sample collection

showed close interlinks and strong associations except

for location E-6; this indicates a common source of spilt

oil. Using PCA, discrete locations of the sites indicated

dissimilarities in the source diagnostic ratios applied due

to variability in hydrocarbon sources across the study

site. The numerous anthropogenic influences such as

waste dumps, oil wells, amongst others are responsible

for the presence of oil in soil, but oil seepages are most

liable. This may impact negatively on nypa palm fruits

which are found growing in this area and commonly

consumed by the indigenous inhabitants who farm along

the near coastal stretch of the creek.

variables (Pr/Ph and (Pr+nC )/(Ph+nC )), (Pr/nC and

Ph/anth) and (BaA/Ch and Flt/Pyr) while the variable of

highest mutual independence was (nC /nC and CPI)

(Figure 6).

CP( PrP r IP+ hn C17)/(Ph+nC18)

Ph/anth

Pr/nC17

Ph/nC18

E E2 3

nC25/nC18 E6

Flt/Pyr

Acknowledgement

The author acknowledges the immense technical

support of Anal Concept Laboratories, Port Harcourt,

Nigeria.

BaA/Ch

Competing interests

64 -48 -32 -16

The author declares that there is no conflict of

interest that would prejudice the impartiality of this

scientific work.

Component 1

Figure 7: Scatter diagram principal component analysis

The study also found that variables such as Ph/anth,

Authors Profile

Pr/nC , Ph/nC , Pr/Ph, (Pr+nC )/(Ph+nC ) and CPI

Ayobami Omozemoje Aigberua is a Ph.D research

student of the department of chemical sciences in the

Niger Delta University, Wilberforce Island, Amassoma,

Bayelsa State, Nigeria. His research interests extend

across environmental topics that are relevant within sub-

Saharan Africa, while partly sharing the passion to

research food and herbal drugs toxicity. He is also an

environmental laboratory expert, with over 12 years of

experience carrying out operations and maintenance of

specialized laboratory equipment such as Flame atomic

absorption spectrophotometer, Gas chromatograph-flame

ionization detector, Gas chromatograph-mass selective

detector, amongst others. He has published several

research articles in the area of oil spill pollution studies.

He is currently working on the use of chemical

accounted for the locational separation of sites E-2, E-3,

E-4 and E-5 while Flt/Pyr and BaA/Ch accounted for the

distinction of location E-1. Also, nC /nC accounted for

the locational distinction of site E-6 in the PCA (Figure

). The inter-relationships between locations E-2 to E-5

may have resulted due to similar characteristics of the

soil and the related degradable and non-biodegradable

toxicants that persist in the environment. Contrastingly,

the dissimilarities in samples of E-1 and E-6 may have

been due to their locational distance from the most

impacted areas which are directly receiving municipal

waste leachates and oil spill seepages (Plate 1). This

finding reflects the soil residual hydrocarbon sources in

the contaminated soils around dumpsites of the Eagle

Island at the time of this study and serves as

Journal of Environmental Treatment Techniques

2019, Volume 7, Issue 2, Pages: 220-228

fingerprinting techniques to identify sources of residual

hydrocarbons in environments that are prone to

anthropogenic influences.

in Niger Delta, Nigeria. Archives of Applied Science

Research, 2012, 4(1): p. 246-253.

15. Rushdi, A. I., et al., Occurrence and sources of

aliphatic hydrocarbons in surface soils from Riyadh

city, Saudi Arabia. Journal of the Saudi Society of

Agricultural Sciences, 2012, 12: p. 9-18.

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