Arabian Journal of Geosciences (2021) 14: 1943 https://doi.org/10.1007/s12517-021-08337-z ORIGINAL PAPER Validation of an analytical technique, distribution, and risk assessment of aliphatic and polycyclic aromatic hydrocarbons in surface sediments of the coastal and selected estuaries of Sarawak Ebenezer Aquisman Asare1,2 & Zaini Bin Assim1 & Rafeah Wahi1 Received: 7 March 2021 /Accepted: 26 August 2021 / Published online: 4 September 2021 # Saudi Society for Geosciences 2021 Abstract This study explains a validation of an analytical technique, monitoring, and risk evaluation of hydrocarbons in surface sediments of the coastal and selected estuaries of Sarawak, Malaysia. The performance of an analytical methodology was validated for the evaluation of hydrocarbons in coastal and estuaries sediment samples. After the clean-up and separation process, GC-FID and GC-MS were used to quantify aliphatic and polycyclic aromatic hydrocarbon extracts, respectively. The suggested methodology is able to measure aliphatic and polycyclic aromatic hydrocarbons in samples at lower concentrations for example 10 ng/g. The precision of the technique was satisfactory as compared to 15% for most of the analytes. This method gives information concerning the distribution and characteristics of hydrocarbon contaminants in the coastal environment. In regard to monitoring and risk assessment, total n-alkane concentrations (C10–C33) varied from 96.63 to 367.28 ng/g dw. The lowest and highest n- alkane content is observed at Santubong estuary (CZ10) and the coastal site CZ2, respectively. Simultaneously, the contents of ∑PAHs varied from 12.54 to 21.20 ng/g dw. The highest ∑PAH content is reported in the sediments of coastal site CZ8 (21.20 ng/g dw), whereas the lowest content is recorded in the sediments of coastal site CZ3 (12.54 ng/g dw). The outcome of the risk assessment suggested that there is no risk in all the studied locations. The findings from this study will help to understand the sources and possible risks of hydrocarbons in the coastal and estuary settings, and provide information for safeguarding human health and aquatic bodies in the studied area. Keywords Validation . Sediments . Petroleum hydrocarbons . Toxic equivalency factor . BaP equivalent Introduction contaminants and the projection of the possible long-term ef- fect of spilled oils on the environment. Over thousands of On account of the extensive distribution of oil contamination organic compounds can be found in petroleum. The develop- in the environment, the determination of petroleum-related ment of feasible and reasonable analytical methods for consti- environmental samples is remarkably significant. Petroleum tutional analysis by gas chromatography–flame ionization contaminants cause wide harm to the estuary and coastal life, (GC-FID) and GC–mass spectrometry detection (MS) in the natural resources, and human health. Its make-up study per- determination of petroleum hydrocarbons is of great concern mits the understanding of the fate and characteristics of (Ramos et al. 2000; Wang et al. 2002; Hartmann et al. 2004; Basheer et al. 2005). These analytical methods permit the assessment and their relative pattern of each petroleum hydro- Responsible Editor: Amjad Kallel carbon in compounds of a complex mixture (Damas et al. 2009). Various steps are required for organic traces in com- * Ebenezer Aquisman Asare plex matrices analysis. Fundamentally, the extract was clean- aquisman1989@gmail.com up and fractionated after extraction, summing it all, chroma- tography procedures are employed in the separation of the 1 Faculty of Resource Science and Technology, Universiti Malaysia analytes. According to Song et al. (2002), using Soxhlet, me- Sarawak, Kota Samarahan, Malaysia chanical shaking or stirring, and ultrasonic extraction serve as 2 Department of Nuclear Science and Applications, Graduate School the basis by which petroleum contaminants are extracted from of Nuclear and Allied Sciences, University of Ghana, AE1, Atomic, solid samples in the environment. Numerous techniques have Accra, Ghana 1943 Page 2 of 19 Arab J Geosci (2021) 14: 1943 been documented in the literature for the pre-separation or Malaysia, where the existence of fast urban development and fractionation of crude oil. These techniques include supercrit- setting up of various industrial areas is taking place, hydrocar- ical fluid chromatography separation (Campbell and Lee 1986; bon contamination is introduced in every part of pointed and Nishioka et al. 1986; Omorinoye et al. 2020); high-performance non-point sources. Aside from that, the Malaysian Marine liquid chromatography separation (Lucke et al. 1985; Guo et al. Department published 127 oil spill occurrences since 1976 be- 2011); classical adsorption chromatography on different adsor- cause of heavy oil tanker traffic in the Straits of Malacca bents, including alumina (Grossi et al. 2002), silica gel (Zakaria (Malaysian Marine Department 2003). It was regarded as true et al. 2000), and combination of silica and alumina (Hostettler et al. that the Malaysian environment is under a heightening menace 1999; Grossi et al. 2002); solid-phase extraction (SPE) (Theobald of petroleum pollution (Zakaria and Takada 2003), even though 1988); and florisil (El Nemr and Abd-Allah 2003). This study it is not well-written and recorded. concentrates on the validation of gas chromatography–flame ion- For these reasons, surface sediments were collected from the ization (GC-FID) and GC–mass spectrometry (MS) for the quan- coastal and selected estuaries of the Kuching Division of Sarawak titative investigation of petroleum hydrocarbons in coastal sedi- to predict the source and monitor and assess the potential risk of ment. Analytes considered are aliphatic (AHs) and polycyclic ar- aliphatic and polycyclic aromatic hydrocarbons. omatic hydrocarbons (PAHs). The technique validated was used on real samples to characterize the chemical constituent of petro- leum remains in coastal and selected estuaries sediment samples. Material and methods The accumulation of aliphatic and polycyclic hydrocarbons in the aquatic system is inversely proportionated to the possi- Reagents and chemicals bility and capacity of petroleum compounds tometabolize them biologically or chemically. Determining the origin of AHs and Germany (i.e., Merch, Darmstadt) is where toluene, n-hexane, PAHs contamination is a serious interest for researchers all over cyclohexane, and dichloromethane (DCM) were bought and the globe. In the 1970s, numerous scientists began to identify they were analytical-grade. Spain (i.e., Sharlau, Barcelona) is the sources of petroleum contamination in the aquatic system. where anhydrous potassium sulfate was purchased. Baking of In Southeast Asia, studies on particular organic compounds in K2SO4 at 250 °C for 5 h was used to clean the glassware before the aquatic environment started by a rigorous survey in the use. Silica gel was purchased from Merck, Darmstadt, Strait of Malacca (Zakaria et al., 1999; 2000; 2001; 2002; Germany. To remove the sulfur during the extraction, 10% 2006) and also research carried out by Boonyatumanond et al. HCl was used to activate the copper powder for 60 s; Milli-Q (2006, 2007) in the Gulf of Thailand. Intending to identify the water and acetone were used as a cleaning agent. Switzerland origin of petroleum hydrocarbons contamination in the ecolog- (i.e., Fuka, Steinheim) is where AHs and PAHs standards were ical system, there are several approaches to use, for instance, the bought. use of isomer pair ratios (Yunker et al., 2002), biomarkers (Wang and Fingas 1995), and individual compound ratios Sample collections and preparation (Zakaira et al. 2000; Aly Salem et al. 2014). Malaysia, which is found in Southeast Asia, has a distinctive tropical ecosystem. The protocol for surface sediments sampling and preparation was It is circumambient by the South China Sea in the west of adapted by Omorinoye et al. (2020). Surface sediments were col- Peninsular Malaysia and the Straits of Malacca in the west. lected from 10 stations distributed at the coastal and selected estu- Apart from the rapid development of Peninsular Malaysia, the aries sites in the Kuching Division of Sarawak, Malaysia (Fig. 1). eastern part of Malaysia is also undergoing some sort of devel- Sampling was carried out in September 2020. Pre-cleaned alumi- opment throughout the last half-century. On the contrary, the num bags were used to store the samples and kept at 15 °C until strategic area of this nation has earned Malaysia one of the further analysis. Sediment samples were defrosted, dried at room busiest shipping routes in the globe because of the high demand temperature overnight, and passed through a 2000-μm sieve to for petroleum from the Middle East to China and Japan. While remove debris and gravel. The ten sediment samples were marked Malaysia is undergoing remarkable population and economic as CZ1 (N01° 41′ 37.7″ E110° 08′ 24.5″), CZ2 (N01° 44′ 46.8″ growth, it is as well developing rapidly in urbanization, indus- E110° 08′ 45.4″), CZ3 (N01° 46′ 22.6″ E110° 08′ 37.8″), CZ4 trialization, and motorization in the last 25 years. As a conse- (N01° 44′ 46.8″E110° 08′ 45.4″), CZ5 (N01° 45′ 50.4″E110° 11′ quence of this development, the natural world of this nation is 30.2″), CZ6 (N01° 47′ 23.5″ E110° 10′ 39.7″), CZ7 (N01° 40′ earning several threats and hazards particularly from the funda- 41.1″ E110° 16′ 59.2″), CZ8 (N01° 42′ 45.7″ E110° 27′ 63.1″), mental energy source which is petroleum. The status and CZ9 (N01° 44′ 49.6″E110° 29′ 72.3″), and CZ10 (N01° 42′ 32.6″ sources of petroleum contamination in Malaysia differ depend- E110° 19′ 02.3″). CZ1 stands for the location of the estuary of river ing on locations, for example, in the eastern part, the contami- Rambungan, CZ4 represents the estuary of river Sibu, nation usually comes from the urban and fewer industries due to CZ7 represents the estuary of river Salak, and CZ10 is low industrial developments. In regard to western Peninsular the estuary of river Santubong. Arab J Geosci (2021) 14: 1943 Page 3 of 19 1943 Fig. 1 Map of Sarawak depicting the sampling locations. km N 0 100 200 LEGEND East Malaysia CZ6CZ3 CZ9 CZ5 Border of Sarawak CZ2 CZ8 CZ10 CZ4 Border of study area CZ1 CZ7 Kuching Division National park and wetlands Sampling stations 110°E Spiking procedure Extraction technique, extract clean-up, and fractionation process The protocol for the spiking of sediment samples was adapted by Damas et al. (2009) with little modification. The Soxhlet extraction method used for extraction, clean-up, and Spiked samples were used to validate the analytical pro- fractionation of AHs and PAHs from sediment samples was tocol. For this reason, sediments were collected from adapted from the United States Environmental Protection uncontaminated coastal sites. This coastal sediment Agency, EPA 3540 modified method as cited in Ugwu and contained AHs from the biogenic origin without PAH Ukoha (2016). About 25.0-g dried sediment samples in a cellulose included. Before the extraction, AHs and PAHs standard thimble were placed in a Soxhlet extractor and extracted with 200 mixtures were used to spike each sample, and concen- mL of dichloromethane for 10 h. To get rid of elemental sulfur tration for each analyte was increased between 20 and present in the sample, about 5.0 g of activated powder was added 100 ng/g and 10 and 50 ng/g, respectively. This was to extraction balloons. The crude extract was dried using rotary then extracted and underwent a clean-up process. vapor to get a volume of about 2.0 mL. The solvent utilized for Comparisons were made between spiked and non- extraction was substituted into cyclohexane and the eluted volume spiked samples. The recovery tests were used to assess was fairly reduced by a logical stream of ultra-pure nitrogen up to the matrix effect. 1.0mL. The extract had to undergo a clean-up process to eliminate unwanted substances that were co-extracted for instance lipids and 1943 Page 4 of 19 Arab J Geosci (2021) 14: 1943 pigments, and biogenic macromolecules which may impede the compounds under chromatography conditions were assessed final assessment and measurement of the compounds of concern. in pairs (see Fig. 3). The concentration ranges were relevant The clean-up process of extract helps to achieve the separations of when compared to the levels normally observed in environ- analytes in groups into respective fractions for analysis. The effec- mental materials. For the measurement of the total AHs and tive height and internal diameter of the chromatography columns PAHs, calibration curves obeyed by certified reference mix- used were 55.0 cm and 1.0 cm, respectively. The columns were ture were ascertained. Considering this technique of quantifi- packed with cotton wool at the bottom and filled with 6.0 g of cation, all standard eluting between C10 and C33 was pre- silica gel and 2.0 cm of potassium sulfate was added at top of the sumed to be a mixture of several cyclic, branched-chain, and column. The column was conditioned with 10 mL of n-hexane normal-chain hydrocarbons. Regarding aromatic hydrocar- before the addition of the extract. Approximately 400 μL of the bons, the eluting of all standards between naphthalene and crude extract was transferred to the top of the column. Thirty benzo[ghi]perylene was accepted to be a combination of var- microliters of n-hexane was added and the 1st fraction (aliphatic ied non-alkylated and alkylated aromatics, comprised of 2–6 compounds) eluted. The 2nd fraction (polycyclic aromatic hydro- aromatic rings, and cycloalkanes-aromatic composite patterns. carbons) was eluted with a 30-mL mixture of DCM and hexane In Fig. 2 and Fig. 3, the X is interpreted as the total concen- (50:50, v/v). Both fractionswere then gently evaporated to dryness trations of individual hydrocarbons, whereas Y is expressed as using purified nitrogen gas and kept in a dark place at 4 °C tem- the total of the peak areas of individual hydrocarbons. perature until further analysis. GC-FID was used to analyze ali- Calibration curves based on five (5) points were established phatic hydrocarbon (AH) fractions, while GC-MS was used to with the linearity ranges 20–100 ng/mL and 100–500 ng/mL analyze polycyclic aromatic hydrocarbon (PAH) fractions. for n-alkanes while that of PAHs were in the ranges of 10–50 A procedure blank was periodically analyzed for each sam- ng/mL and 50–250 ng/mL from the regression analysis of the ple in a batch of 10. The blank was prepared by applying all peak areas versus injected concentrations (see Supplementary the analytical techniques including the same solvents and re- Table S1). F-statistic (P ˂ 0.05) was applied to examine the agents used for extracting the samples. The analytical blank fitness of experimental data to a linear model. At higher con- aims to examine no contamination by impeding compounds, centration values is where linear ranges begin for some com- which may lead to errors during measurements. pounds. The regression coefficients for GC-FID and GC-MS are higher than 0.99 for all analytes. In analyzing the concen- Quantification of AHs and PAHs in the sample tration of the analyte in standard solution, the instrumental limit of detection (LOD) in ng/mL was evaluated as a The quantity of AHs and PAHs was determined by using an signal-noise ratio (S/N) of 3. Table S1 shows the summarized external standard. The external standard is a compound-like results (see Supplementary Table S1). internal standard that shows similar behaviors to the analyte Recoveries were computed from the increase in the content but is not added to the unknown sample. The quantity of the of n-alkanes of PAHs between the spiked and non-spiked analyte could be obtained by comparing the responses of AHs samples and assessed the accuracy of the entire method. The and PAHs standard obtained from GC (DB-5 column) to that extraction and clean-up protocol was carried out over five (5) of the targeted analyte using a calibration curve. The peak area replicates for each spiked level. Fig. 4 shows the recoveries of of the unknown compounds was compared to the peak area of the added compounds at the 100-ng/mL spiked level of n- AHs and PAHs standard (known compound). The presence of alkanes and 50-ng/mL spiked level of PAHs. Lower recovery AH and PAH compounds in the sample was identified by the values correspond to the n-alkanes were observed at C9H20 to retention time. About twenty-three (23) AHs and sixteen (16) C33H26 while the lower recovery values of PAHs were ob- targeted PAHs were quantified using the peak area, concen- served at naphthalene to acenaphthene. These compounds tration, and response factor related to the respective calibration are incompletely lost in the course of evaporation of the sol- curve based on five (5) points for each compound. vent extract in the nitrogen stream due to their volatility be- havior. For n-alkanes, recoveries that varied from 54.2 to 104.1 % were obtained from the range between C9H20 and Results and discussion C33H68, and recoveries that varied from 52.4 to 94.0 % were obtained for PAHs ranged between naphthalene and Validation of GC-FID and GC-MS for quantitative as- benzo[ghi]perylene. Analytical procedure precision was rep- sessment of AHs and PAHs, respectively resented as relative standard deviations (RSD), and for n-al- kanes, it varied from 4.9 to 19.1 in the elution ranges between External standard multipoint calibration was used to construct C9H20 and C33H68. That of PAHs varied from 4.1 to 16.6 in the calibration curves for each PAH and n-alkane. The linear- t h e e l u t i o n r a n g e s b e twe e n n aph t h a l e n e a nd ity range of the calibration curves was achieved by the evalu- benzo[ghi]perylene. Higher RSD values were observed in ation of the analyzed compounds. Unresolved PAH the volatile analytes C9H20 (19.1), C10H22 (14.9), naphthalene Arab J Geosci (2021) 14: 1943 Page 5 of 19 1943 Fig. 2 GC-FID chromatogram of aliphatic standard solutions. X- axis represents retention time/min, while y-axis denotes peak area. (15.4), and acenaphthylene (16.6) which could be attributed to The detection limit (LOD) is the minimum quantity of tar- more significant losses in the course of spiking, extraction, get analyte that generates a chromatographic peak with a and evaporation processes. The results obtained from preci- signal/noise ratio (S/N) of 3. On the contrary, the quantifica- sion and extraction efficiency with this protocol were tion limit (LOQ) is considered as the lowest concentration of similar to results that have been reported for determin- an analyte in a sample that can produce a chromatographic ing PAHs in coastal sediment using Soxhlet extraction peak with a signal/noise ratio (S/N) of 10 under the stated (Jaouen-Madoulet et al. 2000). The reproducibility of conditions of the test. Before and after the analyte retention the extraction and pre-separation steps was acceptable, time, the baseline peak-to-peak noise (N) was assessed on the suggesting that the method is good for the assessment chromatogram of a blank sample handled by the analytical of aliphatic hydrocarbons and polycyclic aromatic hy- technique for a stipulated period. Detection and quantification drocarbons in marine coastal sediments, at a concentra- limits were computed by gradually lessening the concentra- tion interval below 500 ng/g. tion of the analyte in the spiked sample (Omorinoye et al. Fig. 3 GC-MS chromatogram of PAHs standard solutions. X-axis represents retention time/min, while y-axis denotes peak area. 1943 Page 6 of 19 Arab J Geosci (2021) 14: 1943 Fig. 4 n-Alkanes (GC-FID analysis) and PAHs (GC-MS analysis) recoveries from fortified coastal sediment (spiked concen- tration: n-alkanes (100 ng/mL) and PAH (50 ng/mL)). Vertical bars stand for the standard deviation. 2019a), in a way that GC-FID or GC-MS signals were dis- such a manner that supplies the data needed to generate a tinctly detected at the last lowest level of concentration with a value of the uncertainty of a measurement. The recovery study signal/noise ratio of three and ten, respectively. Table S2 de- concentration range obtained was used. Equations S1–S5 are picts the summarized results obtained (see Supplementary the fundamental equations used for uncertainty evaluation Table S2). The values of LOD varied from 16.2 to 26.6 ng/g (see Supplementary Equation S1–S5). In connection with for n-alkanes, and from 17.9 to 26.4 ng/g for PAHs. In regard spiked compounds which were native congeners in the sedi- to LOQ, the values for n-alkanes ranged from 22.9 to 38.2 ng/ ments, Equation S1 is used to determine the uncertainty in theg, while that of PAHs varied from 26.4 to 35.8 ng/g. 2recovery u R . Contrarily, Equation S2 is used if the stan- Evaporation losses are the main cause of higher values that dard was added to blank sediments. The uncertainty in the correspond to analytes. concentration of the spike added to the samples [u(Cspike(i))] The uncertainty of a measurement is the doubt that exists is evaluated by taking into consideration all the spotted effects about the results of any measurement, which defines the dis- operating on these concentration values. The uncertainty ob- tribution of the values that could fairly be ascribed to the tained from the concentration of the native analyte u(Cnative) is quantity intended to be measured (measurand) (Quantifying calculated as s.d (standard deviation) of these compounds’ the Uncertainty in Analytical Measurement, EURACHEM/ concentration. The combined uncertainty for each spiked level CITAC Guide 2000; Asare et al. 2019a; Asare et al. 2019b). is computed from the s.d of the concentration of the analyteThe measurement of uncertainty was made as stated by the 2 (SCobs) and u R using Equations S3 and S4. Hence, con-protocol recommended in the literature (Barwick and Ellinson 1999, 2000). The accuracy and recovery investigations initi- structed graphs for (Uc) considered in the concentrations in ated for the validation were organized and accomplished in sediments investigated by the analytical technique are Arab J Geosci (2021) 14: 1943 Page 7 of 19 1943 Fig. 5 The link between combined uncertainty (Uc) and concentration for C20 and C30 depicted in Fig. 5 and Fig. 6. Besides, the expanded uncertain- quantity of the total aliphatic hydrocarbons. The polycyclic ty (U), was quantified impacting the Uc by a coverage factor aromatic hydrocarbon compounds detected from station CZ5 (k) as stated in Equation S5 (see supplementary material). This are Naph, Acthy, Ace, Fl, Phe, and BaP benzo[a], whereas limiting factor defines an interval that is anticipated to include PAH compounds detected from sample station CZ8 include a large fraction of the distribution of values fairly accountable Naph, Acthy, Ace, Fl, Phe, Ant, BaA, Chry, and BaP. The to the measurand (ISO/TS 21748: 2004). preponderance of the compounds available in this portion is molecules that cannot be resolved by GC capillary columns Nature of GC chromatograms detected from selected and are named unresolved complex mixture (UCM) (Damas real sediment samples et al. 2009). Fig. 7 and Fig. 8 explain the appearance of the unresolved complex mixture in the gas chromatography trace Analysis of coastal and estuaries sediments proceeded once as a hump region between the solvent baseline and the curve the analytical technique was defined and validated. Fig. 7 and characterizing the base of resolvable peaks. It is made up of a Fig. 8 are typical chromatograms of the aliphatic hydrocarbon composite mixture of branched alicyclic hydrocarbons analyzed by GC-FID and GC-MS chromatogram of polycy- concerning GC-FID chromatogram (Fig. 7) and other aromat- clic aromatic hydrocarbon compounds extracted from the ic compounds in regard to GC-MS chromatogram (Fig. 8) coastal sediment sample at stations CZ5 and CZ8, respective- (Peters et al. 2005) and has a widely known linkage to ly. The most important resolved constituents were character- biodegraded petroleum remains (Grossi et al. 2002; Wang ized by the homologous series of n-alkanes varying in the and Fingas 1995; Wang et al . 1998). An 85-m/z number of carbon from nC14 to nC33 for station CZ5 and fragmentogram was used to come up with upstanding and nC10 to nC33 for station CZ8 and correlate with only a small comprehensive compositional information concerning n- 1943 Page 8 of 19 Arab J Geosci (2021) 14: 1943 Fig. 6 The link between combined uncertainty (Uc) and concentration for naphthalene, and chrysene. alkanes constituents with minimal intrusion from other ali- the GC-MS and the full scan analyses were insufficient for a phatic hydrocarbons. The n-alkanes with lower molecular comprehensive assessment. Because of that, few individual weight were absent in some of the sample stations. The rep- polycyclic aromatic compounds were able to evaluate. resentative sediment sample’s quantitative results analyzed are shown in Table 1. The possible motive is that organic Assessment and characterization of aliphatic compounds with LMW are more willingly volatilized to the hydrocarbons (AHs) atmosphere, while on the contrary, the HMW constituents can be anticipated to partition onto the phase of the particulate and Table 1 shows the concentration of n-alkanes evaluated in undergo sedimentation. However, due to further losses in the representative coastal and selected estuaries sediment samples course of the evaporation process, volatile analytes can lessen of Sarawak while Table 2 depicts the other related parameters. their concentration to non-detected levels. The concentration Total aliphatic hydrocarbon concentrations (C9–C33) of each n-alkane was taken into consideration when quantify- ranged from 96.63 to 367.28 ng/g dw (see Table 1). The sta- ing the total n-alkane concentration in samples. Fig. 8 tion with the highest total n-alkane concentration was record- (CZ5PAH and CZ8PAH) depicts the profiles of chromato- ed at the coastal location CZ2, whereas the lowest total n- grams of polycyclic aromatic fractions that emerge as an en- alkanes content was observed at the coastal station CZ10. In velope with limited resolved peaks which is representative of regard to the estuaries, an estuary station CZ1 recorded higher aromatic fractions attributed to highly weathered sources total aliphatic hydrocarbon concentrations as compared to es- (Charrie-Duhaut et al. 2000; Damas et al. 2009). The 2–3 tuary stations CZ4, CZ7, and CZ10. LMW and HMW n- aromatic ring compounds were under these highly weathered alkane which are used as a source identifier and other related conditions and the remaining composition was at a level that parameters are shown in Table 2. LMW and HMW ranged Arab J Geosci (2021) 14: 1943 Page 9 of 19 1943 Fig. 7 Characteristic gas chromatogram of aliphatic hydrocarbon (n-alkanes) fractions extracted from coastal sediments CZ5 in locations CZ5 and CZ8. X-axis represents retention time/min, while y-axis denotes peak area. CZ8 from 29.90 to 87.69 ng/g dw and 45.10 to 291.80 ng/g dw, which is exhibited in Fig. 7, there is a vivid resolution of all respectively. Sample station CZ1 recorded the highest value aliphatic hydrocarbons and enrichment of longer chain normal of LMW (i.e., 87.69 ng/g dw), while the lowest value of LMW alkanes (LHC, C25 to C33) than the shorter chain normal al- was reported at station CZ5 (i.e., 29.90 ng/g dw). Besides, the kanes (SHC, C10–C24). highest value of HMW was observed at station CZ2 (i.e., Figure 9 shows the sum of hydrocarbons of the two ranges 291.80 ng/g dw) whereas station CZ10 recorded the lowest (∑LHC and∑SHC). In regard to∑SHC, station CZ2 recorded value of HMW (i.e., 45.10 ng/g dw). The low molecular the highest value (179.18 ng/g dw), whereas the lowest∑SHC weight to high molecular weight ratios (LMW/HMW) varied value was observed at station CZ9 (64.9 ng/g dw). The order from 0.26 to 1.14 at stations CZ2 and CZ10, respectively. of increasing∑SHC value is as follows: CZ9 ˂CZ5 ˂CZ10 ˂ Slightly higher LMW/HMW ratio at station CZ10 (1.14), CZ8 ˂ CZ7 ˂ CZ6 ˂ CZ4 ˂ CZ3 ˂ CZ1 ˂ CZ2. Considering CZ6 (0.94), CZ7 (0.85), CZ8 (0.81), CZ9 (0.72), CZ1 ∑LHC, the highest value was recorded at station CZ2 (188.1 (0.67), and CZ1 (0.67) could be as a result of fresh oil inputs, ng/g dw), while station CZ10 recorded the lowest value of whereas low LMW/HMW ratio at CZ2 (0.26), CZ4 (0.38), 21.05 ng/g. The order of increasing∑LHC value is as follows: and CZ5 (0.31) could be influenced by sedimentary bacteria, CZ10 ˂CZ8 ˂ CZ9 ˂CZ7 ˂CZ5 ˂ CZ6 ˂CZ3 ˂CZ1 ˂CZ4 higher plants, and marine animals inputs (Sakari et al. 2008). ˂ CZ2. To evaluate the dominant higher plant and/or Thus, the differences in normal alkane concentration may re- phytoplankton-derived macrophyte-derived organic matter in late to the natural inputs for example emergent terrestrial the sediments, the LHC/SHC ratios were computed and had plants, submerged/floating macrophytes, and microbial activ- values varying from 0.28 to 1.08 (see Table 2) (El Nemr et al. ity; and anthropogenic sources such as shipping activities, 2013). The ratios obtained suggested that the stations are dom- industrial discharges, and sewage (El Nermr et al. 2013). In inated by higher plants and/or macrophyte waxes the GC-FID chromatograms, a representative example of (Commendatore et al. 2000). Petroleum may be the 1943 Page 10 of 19 Arab J Geosci (2021) 14: 1943 Fig. 8 Characteristic gas chromatogram of polycyclic aromatic hydrocarbon fractions extracted from coastal sediments CZ5 in locations CZ5 and CZ8. X-axis represents retention time/min, while y-axis denotes peak area. CZ8 anthropogenic source, also recycled organic matter of several vascular plants. Inputs from recycled organic matter, petro- sources for example discharges from treatment plants, erosion leum, and/or microorganisms give CPI values close to unity of soil organic matter by rains, and sewage may be a contrib- (Kennicutt et al. 1987; Aly Salem et al. 2014). In this present uting factor. Bacteria, algae, plankton, marine animals, and study, there were no significant differences between stations terrestrial vascular plants which are an example of biogenic in terms of CPI values for all stations. The CPI values ranged sources may also be the reason (Commendatore et al. 2000). from 0.80 to 1.54 which throwbacks that all sediment samples The source identification of pollution caused by aliphatic hy- are likely polluted with petrogenic hydrocarbons dependent drocarbon was determined using the ratio of odd to even car- on CPI values less than 3 suggesting oiled sediments (Aly bon which is mostly referred to as the Carbon Preference Salem et al. 2014). When the ratio of natural n-alkanes Index (CPI). Odd number carbon is usually associated with (NAR) is close to zero then the source of the hydrocarbon is natural origins, while even number carbon is accredited to obtained from petroleum and crude oils and close to unity anthropogenic origins. Jeng (2006) opined that CPI values means the source is from marine plants or higher terrestrial of 5–10 are attributed to terrestrial higher plant waxes. plants. The values of natural n-alkanes ratios of the current According to Hedges and Prahl (1993), higher values of CPI study varied from −0.35 to 0.23. The ratio of terrigenous to found in soil or sediment indicate a greater influence on aquatic (TAR) values ranged from 0.25 to 1.96. The highest Arab J Geosci (2021) 14: 1943 Page 11 of 19 1943 Table 1 Content of n-alkanes determined in representative coastal and selected estuaries sediment samples. n-Alkane compounds Sample CZ1 CZ2 CZ3 CZ4 CZ5 CZ6 CZ7 CZ8 CZ9 CZ10 ng/g dw C10H22 n.dx n.d n.d n.d n.d n.d n.d 0.15 0.47 n.d C11H24 n.d n.d n.d n.d n.d n.d n.d 0.58 0.14 n.d C12H26 n.d n.d n.d n.d n.d n.d n.d 1.03 0.62 n.d C13H28 3.12 n.d 7.21 1.36 n.d 5.01 n.d 2.75 1.51 n.d C14H30 2.49 4.22 0.87 2.33 0.15 4.90 n.d 2.05 2.08 1.52 C15H32 5.32 3.96 10.2 3.71 1.32 7.36 6.20 4.24 2.32 1.96 C16H34 12.12 9.07 6.41 8.01 1.02 2.91 7.74 6.02 3.06 3.61 C17H36 17.03 13.2 9.71 7.87 4.11 9.36 20.4 8.08 4.08 2.81 C18H38 19.88 17.7 9.98 11.3 9.05 16.5 10.2 19.2 13.1 16.2 C19H40 24.02 23.9 17.6 14.8 13.1 15.2 13.7 11.5 16.4 16.4 C20H42 3.71 3.43 5.14 4.05 1.15 14.9 5.19 2.06 2.04 9.03 C21H44 18.15 36.1 21.2 10.9 4.01 8.13 16.2 5.33 1.17 13.0 C22H46 14.62 27.9 13.1 7.11 7.81 3.06 1.04 14.9 6.76 2.34 C23H48 9.43 16.6 3.51 12.4 16.9 0.54 2.81 3.22 2.11 7.18 C24H50 7.19 23.1 8.98 9.03 7.94 1.89 5.53 6.03 9.04 1.53 C25H52 8.06 17.9 2.05 5.21 3.07 6.23 6.01 4.51 11.0 6.41 C26H54 11.23 10.1 7.36 7.83 16.9 9.04 3.63 3.48 3.06 3.03 C27H56 24.62 37.2 12.0 18.4 6.03 4.59 6.24 6.11 6.14 1.03 C28H58 12.20 13.0 16.4 6.27 2.11 10.2 10.4 4.90 5.10 0.81 C29H60 6.61 15.7 22.6 19.6 5.51 2.78 6.02 7.03 3.24 0.23 C30H62 14.01 31.0 6.31 11.7 7.32 8.31 7.21 4.51 4.08 2.71 C31H64 5.66 27.4 4.21 9.26 8.03 10.4 3.17 2.11 4.25 4.02 C32H66 n.d 25.7 7.81 13.1 5.23 9.11 5.05 6.04 5.01 1.34 C33H68 n.d 10.1 2.75 9.01 4.71 7.03 1.35 3.10 3.16 1.47 ySum of C9 to C33 219.47 367.28 195.40 193.25 125.47 157.45 138.09 128.93 109.94 96.63 x n.d, non-detected y Sum of concentration of n-alkanes from C9 to C33 TAR value (1.96) was recorded at station CZ2 and according system (Aly Salem et al. 2014). Colombo et al. (1989) opined to Jeng and Huh (2006), this could be influenced by n-alkanes that biogenic samples contain higher (> 50) values of n-al- with short-chain which are more susceptible to degradation as kanes/nC16 ratio, whereas petrogenic samples contain lower compared to longer-chain types. Another parameter to esti- (˂ 15) n-alkanes/nC16 ratio. From Table 2, the values of the n- mate the sources of aliphatic hydrocarbons is an n-alkane alkanes/nC16 ratio suggested a mixture of origins comprising proxy (Paq). From Table 4, the Paq varied from 0.21 to petrogenic and biogenic. 0.73 and on the report of Ficken et al. (2000), Paq values between 0.01 and 0.23 are ascribed to waxes from the terres- Assessment and characterization of polycyclic trial plant, while Paq values between 0.48 and 0.94 are attrib- aromatic hydrocarbons (PAHs) uted to submerged/floating species of macrophytes. Overall, the outcomes obtained from the current study indicated the The contents of polycyclic aromatic hydrocarbon and other contribution of both phytoplankton-derived organic carbon associated parameters are headlined in Table 3. There were and higher plant/macrophyte waxes derived (EL Nemr and no significant differences among the studied locations of the Abd-Allah 2003; El Nemr et al. 2013). The important param- concentrations of ∑PAHs in surface sediments. The contents eter for the identification of environmental variations for a of total PAHs were in the range of 12.34–21.20 ng/g dw, with particulate ecosystem is the average carbon chain length an average value of 16.10 ± 2.06 ng/g dw. Samples from (ACL). A continual value for average carbon chain length station CZ8 reported the highest concentration of ∑PAHs suggests that little ecological variations are happening in the (21.20 ng/g dw), whereas the lowest concentration of 1943 Page 12 of 19 Arab J Geosci (2021) 14: 1943 Table 2 Concentrations of n-alkanes (ng/g) and computed distribution indexes in surface sediments of coastal and selected estuaries of Sarawak. Station LMWa HMWb %LMW %HMW LMW/ CPId NAR TAR Paq CPISHC CPILHC LHC/ ACLLHC n-Alkanes/ HMWc SHC C16 CZ1 87.69 131.78 39.96 60.04 0.67 1.11 0.21 0.80 0.59 1.29 1.20 0.63 27.44 18.12 CZ2 75.48 291.80 20.55 79.45 0.26 1.21 0.13 1.96 0.45 1.16 1.36 1.05 28.53 40.49 CZ3 67.12 128.28 34.35 65.65 0.52 1.04 0.12 1.04 0.21 1.43 1.15 0.72 29.11 30.48 CZ4 53.43 139.82 27.65 72.35 0.38 1.43 0.21 1.79 0.38 1.26 1.58 1.08 28.95 24.13 CZ5 29.90 95.57 23.83 76.17 0.31 0.78 0.08 1.06 0.60 1.46 0.87 0.86 29.39 123.01 CZ6 76.14 81.31 48.36 51.64 0.94 0.83 -0.35 0.56 0.34 1.03 0.85 0.75 29.48 54.11 CZ7 63.43 74.66 45.93 54.07 0.85 0.80 0.18 0.38 0.49 2.00 0.87 0.55 27.91 17.84 CZ8 57.66 71.27 44.72 54.90 0.81 1.07 0.09 0.64 0.49 0.67 1.21 0.48 28.40 21.42 CZ9 45.82 64.12 41.68 53.32 0.72 1.34 0.12 0.60 0.56 0.77 1.61 0.69 27.74 35.93 CZ10 51.53 45.10 53.33 46.67 1.14 1.54 0.23 0.25 0.73 1.26 1.67 0.28 27.95 26.77 a Sum of low molecular weight hydrocarbon from C10 to C20 b Sum of high molecular weight from aliphatic hydrocarbons C21 to C33 c Ratio of LMW alkanes to HMW alkanes  d Carbon Preference Index (CPI) ¼ 1 nC25þnC27þnC29þnC31þnC33 þ nC25þnC27þnC29þnC31þnC332 nC24þnC26þnC28þnC30þnC32 nC24þnC26þnC28þnC30þnC32 e Average Carbon Length of LHC (ACLLHC) ¼ ð25ðnC25Þ þ27ðnC27Þ þ29ðnC29Þ þ31ðnC þ33ðnC33Þ31Þ nC25þnC27þnC29þnC31þnC33Þ f Natural n-alkanes ratio ðNARÞ ¼ ½∑n−alkanesðC19−C32Þ −2∑even n−alkanesðC20−C32Þ∑n−alkanesðC19−C32Þ g Terrigenous / Aquatic ratio ðTARÞ ¼ nC27þnC29þnC31nC15þnC17þnC19 g Ficken et al. (2002) formulated n-alkane proxy (Paq): Paq ¼ ðC23þC25Þ ðC23 þ C25 þ C29 þ C31Þ ∑PAHswas observed in sediments collected from station CZ3 rivers. The total PAH concentrations of the coastal and select- (12.34 ng/g dw). The order of increasing ∑PAH contents ed estuaries detected in this study were comparatively smaller among researched stations is as follows: CZ3 ˂ CZ2 ˂ CZ6 than the selected areas of the world. For instance, in a study of ˂ CZ1 ˂ CZ7 ˂ CZ4 ˂ CZ9 ˂ CZ10 ˂ CZ5 ˂ CZ8. The PAH contents in sediments collected from the Red Sea, Egypt, discrepancy in PAH status along the experimented sediments by Aly Salem et al. (2014), the total contents of PAH range could be attributed to the different origins of discharged wa- from 0.74 to 436.91 ng/g with a mean value of 93.49 ng/g. ters, fuel combustion emissions, and closeness to human ac- Also, research conducted by Omorinoye et al. (2019b) to de- tivities. Furthermore, Table 4 depicts some published studies termine PAH concentrations in surface sediments from reporting PAHs in sediments collected from other seas or Sadong River, Sarawak, Malaysia, indicated higher PAH Fig. 9 sum of n-alkanes of the two ranges (∑LHC and∑SHC) at all sample stations Arab J Geosci (2021) 14: 1943 Page 13 of 19 1943 Table 3 Concentration of polycyclic aromatic hydrocarbons (ng/g dw) assessed in representative coastal and selected estuaries sediment samples of Sarawak PAHs Station CZ1 CZ2 CZ3 CZ4 CZ5 CZ6 CZ7 CZ8 CZ9 CZ10 Naph 2.79 0.77 1.43 0.94 3.44 1.06 2.06 1.04 3.03 1.19 Acthy 1.43 2.91 0.73 n.d n.d 1.93 3.49 3.91 2.16 0.84 Ace 2.21 n.d 1.21 4.01 1.06 3.41 n.d 1.28 1.48 2.04 Fl n.d n.d 2.17 0.11 3.21 0.64 4.33 3.96 n.d 1.31 Phe 2.05 1.57 1.04 3.42 1.26 2.82 n.d 2.71 n.d 0.51 Ant n.d 1.04 1.22 n.d 3.37 n.d n.d 1.06 1.04 n.d Flu n.d 3.21 n.d n.d n.d n.d 2.51 n.d n.d n.d Pyr 2.61 n.d n.d 1.28 n.d n.d n.d n.d 2.09 n.d BaA n.d 1.66 1.02 1.15 4.01 1.22 2.68 3.03 1.41 1.52 Chry 3.31 n.d 2.51 2.09 0.63 0.88 0.42 2.46 n.d 2.21 BbF n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d BkF n.d n.d n.d n.d n.d n.d n.d n.d 3.31 3.26 BaP 1.03 2.07 1.21 3.96 1.22 1.56 n.d 1.72 n.d 4.66 InP n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d DBA n.d n.d n.d n.d n.d n.d n.d n.d 2.35 n.d BghiP n.d n.d n.d n.d n.d n.d n.d n.d n.d n.d ∑PAHs 15.43 13.23 12.54 16.96 18.20 13.52 15.49 21.20 16.87 17.54 ∑PAHCARC 4.24 3.73 4.74 7.20 5.86 3.66 3.10 7.21 4.72 11.65 % CARC 27.45 28.19 37.80 42.45 32.20 27.07 20.01 34.01 27.98 66.42 TEQCARC 1.03331 2.2360 1.3145 4.0771 1.6216 1.6829 0.2684 2.0255 2.8220 5.1402 BaPE 1.03 2.17 1.27 4.03 1.46 1.63 0.16 1.90 0.46 4.98 concentrations (i.e., 18.21–184.25 ug/g) as compared to this 1, which suggest that they are from pyrogenic origins, while current study (see Table 4 for more details). Nevertheless, the stations CZ2, CZ3, CZ4, CZ5, CZ6, CZ7, and CZ8 ∑LPAH/ relative contamination level of PAHs has been classified into ∑HPAH ratios were > 1, which indicate that they were obtain- four groups by Baumard et al. (1998a): (i) low, 0–100 ng/g; ed from petrogenic origins (see Supplementary Table S3, Fig. (ii) moderate, 100–1000 ng/g; (iii) high, 1000–5000 ng/g; and 10 and Table 6). (iv) very high, more than 5000 ng/g. Based on the above The main ratios to investigate the pyrogenic or petrogenic classification, all the levels of PAHs in all stations studied sources of polycyclic aromatic hydrocarbons in sediments are were low. (i) Phe/Ant ratio by Aly Salem et al. (2014) or according to Table 5 shows the total of individual PAH compounds Baumard et al. (1998a, b), Soclo et al. (2000), Magi et al. analyzed in all locations and their number of aromatic rings, (2002), Qiao et al. (2006), and Aly Salem et al. (2014), Ant/ while Table S3 (see Supplementary Table S3) and Fig. 10 (Phe + Ant), ratios disclose whether the sediment is primarily depict the percentage distribution of PAHs in all stations de- polluted by inputs of petrogenic or pyrogenic. The thermody- pending on the number of aromatic rings. namically more stable behavior of Phe and its preponderance Stout et al. (2004) opined that PAH primary sources in the over Ant suggests that the PAHs in sediment samples were aquatic environment originate primarily from the sources of primarily attributable to the activities of petrogenesis. The pyrolytic or petrogenic. Baumard et al. (1998a) and Aly Salem value of the Phe/Ant ratio is normally high for petroleum et al. (2014) reported that pyrolytic PAHs obtained from com- products. Baumard et al. (1998a) and Qiao et al. (2006) re- bustion have four or more rings, whereas petrogenic PAHs ported that if the ratio of Phe and Ant is greater than 10 or Ant/ obtained from petroleum have less than four aromatic rings. (Phe + Ant) is higher than 0.1, it generally shows that the To differentiate between pyrolytic and petrogenic PAH source of the PAH is from pyrolytic inputs. It can be observed sources, the estimated ratio of 2–3 rings to 4–6 rings is used from Table 6 that the Phe/Ant and Ant/(Phe + Ant) ratios in all in this study (De Luca et al. 2005). Regarding studied settings, investigated stations were less than 10 and greater than 0.1, stations CZ2, CZ9, and CZ10 ∑LPAH/∑HPAH ratios were ˂ respectively. Based on the study by Chen and Chen (2011), 1943 Page 14 of 19 Arab J Geosci (2021) 14: 1943 Table 4 Comparison of PAH contents in sediments from the coastal and selected estuaries of Sarawakwith those from different coastal and estuaries of the world. Location Range Mean References Coastal (CZ2, 3, 5, 6, 8, and 9), Rambungan 12.34–21.20 ng/g 16.10 ± 2.06 ng/g This study estuary (CZ1), Sibu estuary (CZ4), Salak estuary (CZ7), Santubong estuary (CZ10), Sarawak, Malaysia Africa Red sea, Egypt 0.74–436.91 ng/g 93.49 ng/g Aly Salem et al. 2014 Suef Gulf, Egypt 18.99–97.19 ng/g 45.51 ng/g Aqaba Gulf, Egypt 6.86–100.05 ng/g 40.998 ng/g Buffalo river estuary, South Africa 1107–22,310 μg/L Adeniji et al. 2019b Algoa Bay, South Africa 1.17–10.47 mg/kg Adeniji et al. 2019a Lake Victoria, Uganda 44.2–80.2 ng/g Kerebba et al. 2017 River Sasa, Nigeria 777.68–2431.39ng/g Adekunle et al. 2020 Asia Sadong River, Sarawak, Malaysia 18.21–184.25 ug/g Omorinoye et al. 2019b Langkawi Island, Malaysia 869–1637 ng/g 1167 ng/g Nasher et al. 2013 Zhanjiang Bay, China 41.96–933.90 ng/g 315.98 ng/g Huang et al. 2012 Zhanjiang Bay, China 22.65–79.76 ng/g Zhu 2007 Deep Bay, China 184.1–581 ng/g 353.8 ng/g Qiu et al. 2007 Kyeonggi Bay, Korea 9.1–1400 ng/g 120 ng/g Kim et al. 1999 Hsin-ta Harbour, Taiwan 1156–3382 ng/g Fang et al. 2003 Europe Santander Bay, Spain 20–344,600 ng/g 49079.40 ng/g Viguri et al. 2002 Aquitaine Bay, France 3.5–853 ng/g 256 ng/g Soclo et al. 2000 Coast of Porto Region, Portugal 51.98–54.79 μg/kg dw Rocha et al. 2011 Douro River estuary, Portugal 58.98-156.45 μg/kg dw Rocha et al. 2011 America Narragansett Bay, USA 569–216,000 ng/g 21100 ng/g Hartmann et al.2004 Todos Santos Bay, Mexico 7.6–813 ng/g 96 ng/g Macias-Zamora et al. 2002 Boston Harbour, USA 7266–358,092 ng/g Wang et al. 2001 Table 5 Sum of individual PAH compounds analyzed in all Compounds Abbreviations Number of cycles ∑ % stations with its abbreviation and number of aromatic rings Naphthalene Naph C2 17.75 11.00 Acenaphthylene Acthy C2 17.40 10.80 Acenaphthene Ace C2 16.70 10.40 Fluorene Fl C2 15.73 9.77 Phenanthrene Phe C3 15.38 9.55 Anthracene Ant C3 7.73 4.80 Fluorathene Flu C3 5.72 3.55 Pyrene Pyr C4 5.98 3.70 Benzo(a)anthracene BaA C4 17.70 11.00 Chrysene Chr C4 14.51 9.01 Benzo(b)fluoranthene BbF C4 0 0 Benzo(k)fluoranthene BkF C4 6.57 4.08 Benzo(a)pyrene BaP C5 17.43 10.80 Indeno[1,2,3-cd]pyrene InP C5 0 0 Dibenzo[a,h]anthracene DBA C5 2.35 1.46 Benzo(ghi)perylene BghiP C6 0 0 Arab J Geosci (2021) 14: 1943 Page 15 of 19 1943 To examine the biological impacts of PAHs of coastal and selected estuaries of Sarawak, the effect range-medium (ERM) and effect range-low (ERL) were compared to the mean concentration of PAH (Li et al. 2012; Aly Salem et al. 2014). These two values describe three concentration ranges for a specific chemical. When the PAH content ˂ ERL, it suggests that biological effects are unusual, when the PAH concentration ≥ ERL but ˂ ERM, it suggests that adverse biological impacts would happen sometimes, while PAH con- centration ≥ ERM indicates that adverse biological effects would occur frequently. In regard to Fig. S1 (see Supplementary Fig. S1), the green-colored graph represents Fig. 10 Polycyclic aromatic hydrocarbons source characterization in the mean concentration of PAH detected in this current study, sediment the blue-colored graph denotes effect range-low (ERL), and the red-colored graph signifies the effect range-medium this indicates that the PAH source could be attributed to the (ERM). From Table 7 and Fig. S1, the three ranges of chem- activities of combustion and the sediment is primarily polluted ical concentrations, unfavorable biological impacts were an- by petrogenic inputs. In regard to the studies conducted byGuinan ticipated rarely in all stations because the levels of PAH et al. (2001) and Li et al. (2006), other important indicators for chemicals detected were below effect range-low. assessing the source of PAH contamination in sediments are the Qiao et al. (2006) reported that some PAHs possessed car- Flu/Pyr and Flu/(Flu + Pyr) ratios. Surprisingly, all the studied cinogenicity characteristic and their availability in the envi- stations showed no detection of either Flu or Pyr or both; therefore, ronment are of high concern. In regard to the study by Wang the evaluation of Flu/Pyr and Flu/(Flu + Pyr) ratios was not suc- et al. (2009), to quantitatively evaluate the potential health risk cessful. Besides, BaA/(BaA +Phe) ratio was performed and it was of PAH, the BaP equivalent (BaPE) is used. Thus, the BaPE found that the values of all the studied stations were ˂ 1 indicating was derived using equation 1 (Liu et al. 2009a): that the source is from petroleum. The sum of major combustion- specific compounds (∑COMB) varied from 3.66 to 11.65 ng/g BaPE ¼ 0:06ðBaAÞ þ 0:07ðBbFÞ þ 0:07ðBkFÞ þ BaP dw, and ratios of∑COMB to the sumof PAHsvaried from0.27 to 0.66. El Nemr et al. (2013) reported that an extensive combustion þ 0:06ðDBAÞ þ 0:08ðInPÞ ð1Þ activity affected the content of PAHs in the studied settings when the ∑COMB/∑PAH values are higher. From Table 3, the calculated values of BaPE for all sediment As headlined in Table 6, ∑COMB/∑PAH values were samples ranged from 0.16 to 4.98 ng/g dw. The maximum higher indicating extensive combustion activities. value of BaPE was reported at Santubong estuary (CZ10), Table 6 PAHs isomeric ratio in sediment from the coastal and selected estuaries of Sarawak Station TH ∑COMBa ∑COMB/ ∑LPAHb ∑HPAHc ∑LPAH/ Phe/ Ant/ Flu/ Flu/ BaA/(BaA Flu/ ∑PAH ∑HPAH Ant (Phe+Ant) Pyr (Flu+Pyr) +Phe) (Flu+Phe) CZ1 234.90 6.95 0.45 8.48 6.95 1.22 - - - - - - CZ2 380.51 6.94 0.53 6.29 6.94 0.90 1.51 0.40 - - 0.51 0.67 CZ3 207.94 4.74 0.38 7.80 4.74 1.65 0.85 0.54 - - 0.50 - CZ4 210.21 8.48 0.50 8.48 8.48 1.00 - - - - 0.25 - CZ5 143.67 5.88 0.32 12.32 5.88 2.10 0.37 0.73 - - 0.76 - CZ6 170.97 3.66 0.27 9.86 3.66 2.69 - - - - 0.30 - CZ7 153.58 5.61 0.36 9.88 5.61 1.76 - - - - - - CZ8 150.13 7.21 0.34 13.99 7.21 1.94 2.56 0.28 - - 0.53 - CZ9 126.81 6.81 0.40 7.71 9.16 0.84 - - - - - - CZ10 114.17 11.65 0.66 5.89 11.65 0.51 - - - - 0.75 - a∑COMB = Flu + Chry + Pyr + BaA + BbF + BaP + BkF + InP + BghiP b∑LPAHb = Naph + Acthy + Ace + Fl + Phe + Ant c∑HPAH = Flu + Pyr + BaA + Chry + BbF + BkF + BaP + InP + DBA + BghiP 1943 Page 16 of 19 Arab J Geosci (2021) 14: 1943 Table 7 Guidelines values (i.e., ERL and ERM) of PAHs in Effect range-low Effect range-medium Present study surface sediments (ng/g dw) (Long et al. 1995; Liu et al., Mean Minimum Maximum >ERL ˂ERM 2009a, b, c; Aly Salem et al. 2014). Naph 160.00 2100.00 1.78 0.77 3.03 - - Acthy 16.00 500.00 2.18 0 3.91 - - Ace 44.00 640.00 2.09 0 4.01 - - Fl 19.00 540.00 2.25 0 3.96 - - Phe 240.00 1500.00 1.71 0 3.42 - - Ant 853.00 1100.00 1.55 0 3.37 - - Flu 600.00 5100.00 2.86 0 3.21 - - Pyr 665.00 2600.00 1.99 0 2.61 - - BaA 261.00 1600.00 1.97 0 3.03 - - Chry 384.00 2800.00 1.81 0 3.31 - - BbF 320.00 1880.00 - 0 - - - BkF 280.00 1620.00 3.29 0 - - - BaP 430.00 1600.00 2.18 0 4.66 - - InP - - - 0 - - - DBA 63.40 260.00 2.35 0 2.35 - - BghiP 230.00 1600.00 - 0 0 - - suggesting that PAHs in this station exhibited relatively high petroleum hydrocarbons in surface sediments of the toxicity as compared to other studied stations (Zhang et al. coastal and selected estuaries of Sarawak, Malaysia. 2012). Out of ∑PAH (i.e., 160.98 nd/g dw), 36.80% represents The suggested technique is able to quantify the avail- ∑PAHCARC and the highest percentage of ∑PAHCARC was able n-alkanes and polycyclic aromatic hydrocarbons reported at Santubong estuary (66.42%) (Table 3). (PAHs) in sediment samples at lower concentrations To quantitatively evaluate the possible toxicological impacts for instance as small as 10 ng/g, with better precision of PAHs on human health, toxic equivalency factors of seven as compared to 15% for most of the analytes. The an- carcinogenic PAHs (PAHsCARC) were used (Table 3). Out of the alytical technique was used to assess petroleum hydro- seven PAHsCARC, the one having adequate toxicological data for carbons from sediments collected from the coastal and the derivation of a carcinogenic factor is BaP (Aly Salem et al. selected estuaries of Sarawak. The total n-alkane con- 2014). On the report of the UNEP (1995), the toxic equivalent centrations (C10–C33) varied from 96.63 to 367.28 ng/g factor for BkF, BaA, BaP, BbF, DBA, Chry, and InP are 0.1, 0.1, dw. The lowest and highest n-alkane content was ob- 1.0, 0.1, 1.0, 0.001, and 0.1, respectively. The toxic equivalents served at Santubong estuary (CZ10) and the coastal site (TEQs) or total toxicity of seven PAHsCARC was established by labeled CZ2, respectively. Thus, the difference in con- equation 2 (Gesine and Erika 1999; Guo et al. 2011): centration of n-alkanes could be attributed to the anthro- ¼  ð Þ pogenic sources and inputs from natural processes. AtTEQs TEFi ΣConc:i 2 the same time, the contents of ∑PAHs varied from where TEF stands for a toxic equivalent factor of individual 12.54 to 21.20 ng/g dw. The highest total PAH contenti PAH compound and Conc. stands for the concentration of each was reported in the sediment of coastal site CZ8 (21.20i PAH compound. From Table 3, the values of total TEQ in ng/g dw), whereas the lowest content was reported inCARC sediments samples ranged from 0.2684 to 5.1402 ngTEQ/g. the sediment of coastal site CZ3 (12.54 ng/g dw). In The estuary of Santubong River (CZ10) recorded the higher regard to the studied sites, the ratios of most stations total value of TEQ (i.e., 5.1402 ngTEQ/g). were > 1, suggesting their petrogenic inputs except sta-CARC tions CZ2, CZ9, and CZ10 which ratios were ˂ 1, which could be ascribed to pyrogenic sources. The av- erage PAH concentrations were compared to ERL and Conclusion ERM values and found that the result of all the studied sites suggested no adverse biological effect. Risk assess- The present study describes the validation of an analyt- ment of PAHs was assessed using BaP equivalent ical technique, monitoring, and risk evaluation of values technique, and the outcomes indicated no risks Arab J Geosci (2021) 14: 1943 Page 17 of 19 1943 in all studied locations. The information obtained from Barwick VJ, Ellinson SLR (1999)Measurement un-certainty: approaches this study can lead to understanding the distribution, to the evaluation of uncertainties associated with recovery. Analyst 124:981–990 sources, and potential risk of aliphatic and polycyclic Barwick VJ, Ellinson SRL (2000) Protocol for uncertainty evaluation aromatic hydrocarbons in coastal and river bodies. from validation data; VAM Project 3.2.1, development and harmonisation of measurement uncertainty principles. Part D. Baumard P, Budzinski H, Garrigues P (1998a) Polycyclic aromatic hy- Supplementary Information The online version contains supplementary drocarbons in sediments and mussels of the western Mediterranean material available at https://doi.org/10.1007/s12517-021-08337-z. Sea. Environ Toxicol Chem 17:765–776 Baumard P, Budzinski H, Michon Q, Garrigues P, Burgeot T, Bellocq J Acknowledgements The authors acknowledge the contribution of col- (1998b) Origin and bioavailability of PAHs in the Mediterranean leagues from the Faculty of Resource Science and Technology (FRST) Sea from mussel and sediment records. Estuar Coast Shelf Sci. 47: Analytical Laboratory, Universiti Malaysia Sarawak. 77–90 Basheer C, Obbard JP, Lee HK (2005) Analysis of persistent organic Availability of data and material Not applicable. pollutants in marine sediments using a novel microwave assisted solvent extraction and liquid-phase microextraction technique. J chromatogr A 1068(2):221–228 Author contribution EAA, ZBA, and RW conceived of the study and carried out the design of the experiment. EAA carried out the sample Boonyatumanond R, Wattayakorn G, Amano A, Inouchi Y, Takada H preparation and analysis, EAA assessed the data, and EAA, ZBA, and (2007) Reconstruction of pollution history of organic contaminants RW helped to draft and edited the manuscript. The author(s) read and in the upper Gulf of Thailand by using sediment cores: first report approved the final manuscript. from Tropical Asia Core (TACO) project. Mar Pollut Bull 54:554– 565 Boonyatumanond R, Wattayakom G, Togo A, Takada H (2006) Funding The consumables and field trip cost of the entire research were Distribution and origins of polycyclic aromatic hydrocarbons in es- financially supported by Universiti Malaysia Sarawak, Postgraduate tuarine, rivers and marine sediments in Thailand. Mar Pollut Bull Research Grant, with Grant Code: F07/PGRG/1896/2019. 52:942–956 Campbell RM, Lee ML (1986) Supercritical fluid fractionation of Declarations petroleum- and coal-derived mixtures. 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