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  • 1 Aqaba Special Economic Zone Authority (ASEZA), Ben Hayyan — Aqaba International Laboratories, Aqaba 77110, Jordan
  • 2 The University of Jordan, Amman, Jordan
  • 3 Mote Marine Laboratory — Mote Aquaculture Research Park, Sarasota, FL 34240, USA
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The levels of persistent organic pollutants (POPs) from industrial by-products were determined in beach sand and marine sediments from different sites along the Jordanian coast of the Gulf of Aqaba. Seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) compounds were identified. Automatic Soxhlet (Soxtec) extraction method was used for PCDD/Fs extractions using toluene as a solvent. Pre-washed multilayer silica gel column was used for cleanup step. Samples were analyzed using high-resolution gas chromatography and mass spectroscopy detector (HRGC–MS). Low levels of POPs were found in all sand and sediment samples. Concentrations of PCDD/Fs ranged between 3.91 and 8.91 ng kg−1 dw with an average of 6.49 ng kg−1 dw for beach sand samples and between 6.560 and 45.95 ng kg−1 dw with an average of 28.70 ng kg−1 dw for marine sediment samples. Concentrations of PCDD/Fs for soil and sediment were mostly less than other sites worldwide. PCDD/Fs concentrations measured in this study can be considered as a baseline for future monitoring and control of PCDD/Fs as requested by Stockholm Convention.

Abstract

The levels of persistent organic pollutants (POPs) from industrial by-products were determined in beach sand and marine sediments from different sites along the Jordanian coast of the Gulf of Aqaba. Seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) compounds were identified. Automatic Soxhlet (Soxtec) extraction method was used for PCDD/Fs extractions using toluene as a solvent. Pre-washed multilayer silica gel column was used for cleanup step. Samples were analyzed using high-resolution gas chromatography and mass spectroscopy detector (HRGC–MS). Low levels of POPs were found in all sand and sediment samples. Concentrations of PCDD/Fs ranged between 3.91 and 8.91 ng kg−1 dw with an average of 6.49 ng kg−1 dw for beach sand samples and between 6.560 and 45.95 ng kg−1 dw with an average of 28.70 ng kg−1 dw for marine sediment samples. Concentrations of PCDD/Fs for soil and sediment were mostly less than other sites worldwide. PCDD/Fs concentrations measured in this study can be considered as a baseline for future monitoring and control of PCDD/Fs as requested by Stockholm Convention.

1. Introduction

Chemical contaminants released from industrial processes have been documented to adversely affect environmental and public health [1]. One group of these contaminants is the persistent organic pollutants (POPs) which encompass some pesticides, polychlorinated biphenyl (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) [2].

PCDDs and PCDFs, shortened here as PCDD/Fs, are highly toxic substances. They are considered as by-products of some industrial processes such as manufacturing of pesticides, phenoxy herbicides, chlorophenols, combustion processes such as waste incineration, cement production, chlorine bleaching of paper pulp, and smelting [2].

PCDD/Fs bind to cell aryl hydrocarbon receptors (AhRs) causing toxic effects [3]. This binding changes the expression of genes that are mediated by AhR and may affect cell growth and differentiation, result in hormonal disturbances, and alter cell function [4]. PCDD/Fs are strongly hydrophobic and insoluble in water. Therefore, in the aquatic environment, they accumulate in sediment, providing a potential means of exposure to aquatic organisms [4]. Likewise, they bioaccumulate and biomagnify because of their resistance to metabolism [57].

International concern for global pollution of PCDD/Fs is progressively increasing; throughout the world, many agreements and conventions have been signed to decrease their impacts. For example, the Stockholm Convention [2] classified twelve contaminant group species of POPs into three categories in order to limit their impacts: category A, compounds or groups to be eliminated such as organochlorine pesticides and polychlorinated biphenyl (PCB); category B, compounds to be restricted like 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT); and category C, compounds or groups which are unintentionally produced like polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

No previous studies have investigated the levels of PCDD/Fs in the coastal sediments of the Gulf of Aqaba and Red Sea despite the presence of some potential sources for PCDD/Fs in the region. This study was aimed to estimate the PCDD/Fs concentration levels in beach sand and marine sediment in different sites along the Jordanian Coast of Gulf of Aqaba to establish baselines for these compounds.

2. Materials and Methods

2.1 Sample Collection

The study sites (Figure 1) included the most important activities related to the PCDD/Fs according to the categorization of United Nation Industrial Development Organization (UNIDO) [8]. Six sites were examined along the Jordanian coast of the Gulf of Aqaba, including (1) industrial sites; Industrial Complex (IC), Aqaba Old Thermal Power Plant (OTP), and Aqaba New Thermal Power Plant (NTP); (2) tourist sites, including Hotel Area (HA) and Marine Park; and (3) the Marine Science Station, which is a reserved area that functions as a reference site. Surface sediment and beach sand samples were collected between March and May 2015 from these sites. Surface sediment samples (top 10 cm layer) were collected at a water depth of 7 to 10 m by diving. Beach sand samples were collected from 10 to 20 m away from the tidal zone. Samples were homogenized in the laboratory, dried (at room temperature on trays), sieved using a 250 μm mesh size sieve [7], and stored at −20 oC until analysis.

Figure 1.
Figure 1.

Sampling locations along the Jordanian coast of the Gulf of Aqaba

Citation: Acta Chromatographica Acta Chromatographica 30, 1; 10.1556/1326.2017.00238

2.2 Analysis

Because the concentrations of PCDDs/PCDFs were expected to be very low, the analytical methods differ from those for other organochlorine compounds [9]. The levels of the seventeen PCDD/Fs were determined based on the method of United States Environmental Protection Agency (US EPA) [10, 11] and International Council for the Exploration of the Sea ICES [9].

2.2.1 Solvents and reagents

All solvents, glass wool, and filter paper used were of pesticide residue analysis grade. Anhydrous sodium sulfate (Merck, NJ, USA) was heated at 500 °C for 24 h, cooled, and stored in a closed container. Neutral silica gel (Sharlau, Barcelona, Spain) was baked at 500 °C for at least 10 h, cooled to room temperature, then activated at 150 °C for 2 h, and stored in a tightly closed bottle. An appropriate amount of neutral silica gel was mixed until uniform with 1 mol L−1 sodium hydroxide (Sharlau, Barcelona, Spain) to give 33% basic silica gel. Neutral silica gel was also mixed with concentrated sulfuric acid (Sharlau, Barcelona, Spain) to yield a 44% acidic silica gel. Lastly, neutral silica gel was mixed with 28% silver nitrate (Merck, NJ, USA) until uniform. All mixtures were stored in amber bottles.

2.2.2 Standards

Labeled primary standard mixture, primary standard for cleanup, and internal standard were purchased from Cerilliant analytical reference standards (Texas, USA). Reference standards for native PCDD/F compounds were purchased from Wellington laboratories (Canada). A solution of each standard was prepared to give concentrations of 2/4 ng mL−1 for labeled compounds and 2/4/8 and 1/2/4 ng mL−1 for native compounds. Cleanup and internal standards were prepared directly from the primary stock with fixed volume for each one (0.1 mL of cleanup and 10 μL of internal standard). Internal standards (recovery standard) and concentrations of 200 ng mL−1 of 13C-1,2,3,7,8,9-HxCDD and 13C-1,2,3,4-TCDD mixture were used to aid in qualitative and quantitative interpretation of the results. All stocks and dilutions were stored at −4 °C.

2.2.3 Apparatus

A Soxtec extraction system (FOSS, model 2050, Sweden), mechanical shaker (Universal Table, shaker 709, Italy), and rotary evaporator (Strike, Steroglass, Italy) were used for extraction. A high-resolution gas chromatograph and mass spectrometer (HRGC–HRMS) (Waters, model P710, United Kingdom), and a fused silica Restex Rtx-Dioxin2 (60.0 m × 250 μm i.d. × 0.25 μm film thickness) were used for sample analysis [10].

2.2.4 Sample extraction and cleanup

Ten grams of dry weight (dw) base was mixed with 10 g anhydrous sodium sulfate in 30 × 80 mm cellulose extraction thimbles and then extracted with 70 mL toluene (Merck, NJ, USA) for 3 h using the Soxtec extraction system (FOSS, 2050, Sweden). The extract was then concentrated to 2–3 mL by rotary evaporator (Strike, Steroglass, Italy). The concentrated extract was cleaned up using pesticide grade n-hexane (Merck, NJ, USA) and a 30 cm × 15 mm ID pre-washed multi-layer silica gel column arranged in the following order: glass wool, 1 g anhydrous sodium sulfate, 3 g neutral silica gel, 4 g 33% basic silica gel, 1 g neutral silica gel, 10 g 44% acidic silica gel, 1 g neutral silica gel, and 3g silica gel treated with silver nitrate. The column was pre-washed with 120 mL hexane. PCDD/Fs were eluted using 170 mL n-hexane. The solvent was concentrated to 1–2 mL using a rotary evaporator. The extract was transferred to 50 mL V-shape bottomed tubes (Agilent, USA) and washed several times with 1 mL portions of concentrated sulfuric acid until the acidic layer became clear. The extract was then washed several times with 1 mL portions of deionized water to eliminate the acid. Afterwards, the extract was passed over anhydrous sodium sulfate to remove remaining water and collected in a 300 μL clear V-shape bottomed vial insert. Extracts were evaporated until dry using 99% purity nitrogen gas flow. Ten microliters of 99% purity n-nonane solvent (pesticide grade, Chemical service, PA, USA) was added, and 10 μL of internal standard was added just prior to analysis. The efficiency of the cleanup process was estimated by adding 0.1 mL of 200 ng mL−1 37Cl4-labeled 2,3,7,8-TCDD cleanup standard to the extract prior to clean-up and eluted with the sample extract as described before. HRGC–HRMS analysis gave a recovery of 90–97% of the cleanup standard.

2.2.5 Qualitative and quantitative analysis

Qualitative determination was performed for target (native) and labeled compounds. The compounds were identified according to their characteristic mass-to-charge ratio (m/z), such that each labeled compound was used as a quantification standard to identify the retention time (RT) and concentration of the corresponding native congener.

The quantification methods used in this study were optimized following the method described in US EPA [10]. Quantitative determination was carried out based on the relative peak area and the relative concentration.

2.2.6 Detection limits

Signal-to-noise ratio method (3:1) was used to calculate the detection limits [12]; values were as follows: 2378-TCDD (0.05 ng kg−1), 2378-TCDF (0.04 ng kg−1), 12378-PeCDD (0.03 ng kg−1), 12378-PeCDF (0.03 ng kg−1), 23478-PeCDF (0.03 ng kg−1), 123478-HxCDD (0.42 ng kg−1), 123678-HxCDD (0.07 ng kg−1), 123789-HxCDD (0.10 ng kg−1), 123478-HxCDF (0.06 ng kg−1), 123678-HxCDF (0.09 ng kg−1), 234678-HxCDF (0.07 ng kg−1), 123789-HxCDF (0.02 ng kg−1), 1234678-HpCDD (0.02 ng kg−1), 1234678-HpCDF (0.08 ng kg−1), 1234789-HpCDF (0.05 ng kg−1), OCDD (0.11 ng kg−1), and OCDF (0.05 ng kg−1).

2.2.7 Evaluation of total analytical procedures

The percent recovery of the compounds being investigated was determined using matrix spiking techniques of a thermally cleaned sand sample mixed with reference standards of the target compounds (native) and with 13C-labeled compounds as internal standards.

The recovery percent was 92–110% for all compounds, except for OCDF which was 75%.

3. Results and Discussion

3.1 PCDD/Fs Levels in Sediment and Sand

The concentrations of the 17 PCDD/Fs congeners detected in the beach and sediment samples are given in Tables 1 and 2, respectively, expressed in ng kg−1 dry weight. Example chromatograms for marine sediment at New Thermal Plant for total ion current and hexa-CDD/Fs are shown in Figures 2 and 3, respectively.

Table 1.

PCDD/Fs concentrations for beach sand samples expressed in ng kg−1 dry weight in Old Thermal Power Plant (OTP), Marine Science Station (MSS), Marine Park (MP), New Thermal Power plant (NTP), and Industrial Complex Jetty (ICJ)

No.CongenerOTPMSSMPNTPICJ
12378-TCDD
22378-TCDF0.10
312378-PeCDD
412378-PeCDF0.080.06
523478-PeCDF0.110.07
6123478-HxCDD
7123678-HxCDD
8123789-HxCDD
9123478-HxCDF0.260.081.62
10123678-HxCDF
11234678-HxCDF0.140.140.230.14
12123789-HxCDF0.030.03
131234678-HpCDD1.371.230.921.080.56
141234678-HpCDF0.240.640.120.510.37
151234789-HpCDF
16OCDD5.646.482.504.352.93
17OCDF0.140.130.19
Sum7.538.913.918.144.00

The PCDD/Fs at HA site was not estimated in the sand because analytical output had no sufficient resolution.

Table 2.

PCDD/Fs concentrations for sediment samples expressed in ng kg−1 dry weight in Hotel Area (HA), Old Thermal Power Plant (OTP), Marine Science Station (MSS), Marine Park (MP), New Thermal Power plant (NTP), and Industrial Complex Jetty (ICJ)

No.CongenerHAOTPMSSMPNTPICJ
12378-TCDD0.054.42
22378-TCDF0.270.090.194.40
312378-PeCDD0.070.410.681.241.082.19
412378-PeCDF0.200.220.800.340.892.98
523478-PeCDF0.240.450.841.210.922.12
6123478-HxCDD1.050.813.082.22
7123678-HxCDD0.304.871.061.062.462.51
8123789-HxCDD0.491.181.080.982.242.08
9123478-HxCDF0.301.021.800.882.333.12
10123678-HxCDF0.261.171.290.842.172.81
11234678-HxCDF0.171.141.390.982.502.52
12123789-HxCDF0.211.070.980.872.212.18
131234678-HpCDD0.762.473.302.113.372.11
141234678-HpCDF0.321.323.671.272.541.71
151234789-HpCDF0.191.380.981.032.251.37
16OCDD1.967.5312.227.528.355.42
17OCDF0.672.553.770.080.111.81
Sum6.4627.8334.6723.5833.6145.97
Figure 2.
Figure 2.

Chromatogram of the New Thermal Plant sediment PCDD/Fs (total ion current)

Citation: Acta Chromatographica Acta Chromatographica 30, 1; 10.1556/1326.2017.00238

Figure 3.
Figure 3.

Chromatogram of the New Thermal Plant sediment (Hexa CDD/Fs)

Citation: Acta Chromatographica Acta Chromatographica 30, 1; 10.1556/1326.2017.00238

PCCD/Fs for beach sand samples with relatively low masses like tetra- and penta-CDD/Fs were below the method detection limits (MDLs) for most sites. The high volatility of these compounds causes rapid evaporation from sand and results in their low concentrations. However, the PCCD/Fs with relatively high masses were quantifiable for all sites. For marine sediments, the target congeners were detectable for all sites. Moreover, sum of the PCDD/Fs in marine sediment was generally 3 times higher than that of the sand samples for all locations (Figure 4). PCDD/Fs accumulate in sediment as a result of their hydrophobic nature. This may explain their high concentrations in sediment compared to sand.

Figure 4.
Figure 4.

Sum of the PCDD/Fs concentrations (ng kg−1 dw) in beach sand and marine sediment

Citation: Acta Chromatographica Acta Chromatographica 30, 1; 10.1556/1326.2017.00238

3.2 Comparison with Previous Studies

The toxicity equivalent quantities (TEQs) are usually used to express the toxicity of the sum of the PCDD/Fs [9]. Table 3 provides a comparison of the results of this study, as the sum of all compounds (TEQ) calculated according to the US EPA [10] (1994), with some regional and international investigations worldwide. Studies conducted in industrial countries and crowded cities show higher levels of PCDD/Fs as compared to the sited examined in this study, which can be attributed to the higher amount of PCDD/Fs produced from heavy industrial and transportation activities. The large distance of Aqaba city from industrial countries is likely the main factor protecting Aqaba from high levels of PCDD/Fs. The closest location to Aqaba that has been examined for PCDD/F concentrations is Temsah Lake in Egypt which has sediment levels of PCDD/Fs comparable to our study. These locations have similar environmental and industrial conditions [7, 13]. The results of a similar study in Cairo, a crowded city, demonstrated 40 times the PCDD/F concentrations compared with Aqaba. As for the PCDD/F contamination of sand, only the concentrations found in Italy by Fiedler [14] are comparable with those of this study. The levels of PCDD/Fs in sand estimated by other studies are higher than observed in this study (Table 3).

Table 3.

Comparison of PCDD/Fs levels (ng TEQ/kg dw) in beach sand and sediment of this study with different studies worldwide

CountryBeach sand/soilReferencesMarine sedimentReferences
MinMaxMinMax
Germany0.142[14]1273[14]
Italy0.0570.12[14]0.0710[14]
Netherlands255[14]110[14]
Luxembourg1.820[14]2.416[14]
Spain0.638.4[14]0.257[14]
UK0.7887[14]2123[14]
USA0.122.9[15]102302[16]
USA –urban0.1186
Canada77[17]160620[18]
Turkey0.44.72[19]0.45255[20]
Egypt–Cairo240775[7]
Egypt–Temsah Lake0.37811.2[13]
Antarctic2.4373.28[21]
Jordan–Aqaba0.030.23This study0.6513.53This study

4. Conclusion

In conclusion, this study provides evidence that relatively low concentrations of PCDD/Fs exist in some coastal soil and sediment environments at the Jordanian Coast of the Gulf of Aqaba. Concentrations of PCDD/Fs for beach sand and marine sediment were mostly less than the concentrations reported by previous studies worldwide. In principal, PCDD/Fs concentrations measured in this study can be utilized as a baseline for future monitoring and control of PCDD/Fs.

Acknowledgment

The authors would like to thank Aqaba Special Economic Zone Authority (ASEZA), colleagues at Aqaba International Laboratories — Ben Hayyan, the University of Jordan and Marine Science Station in Aqaba for their help and support. Thanks are due to Dr. Richard Pierce and Dr. Rayan Schlosser for their valuable revision. This work was analyzed and written during a Sabbatical Fellow from the University of Jordan to Mohammed Rasheed to be spent at the Mote Marine Laboratory in Florida USA. Fulbright scholarship was also awarded to Mohammed Rasheed during this period.

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  • 1.

    Le Van, A. Unpublished Master Dissertation , Sweden , 2011 .

  • 2.

    Stockholm Convention on Persistent Organic Pollutants , Geneva ,Secretariat of the Stockholm Convention (http://chm.pops.int), 2009 .

    • Search Google Scholar
    • Export Citation
  • 3.

    Kojima, H.; Takeuchi, S.; Iida, M.; Nakayama, S. F.; Shiozaki, T. Environ. Sci. Poll. Res. 1 12 , DOI: .

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    Hurst, M. R.; Balaam, J.; Chan-Man, Y. L.; Thain, J. E.; Thomas, K. V. Mar. Poll. Bull. 2004 ,49 , 648 658 .

  • 5.

    Klanova, J.; Matykiewiczova, N.; Zdenek Macka, Z.; Prosek, P.; Lask, K.; Petr Klan, P. Sci. Direct Environ. Pollut. 2007 , 152 , 1 8 .

    • Search Google Scholar
    • Export Citation
  • 6.

    Minh, N.H.; Someya, M.; Minh, B.; Kunisue, T.; Iwata, H.; Watanabe, M.; Tanabe, S.; Viet, P. H.; Tuyen, B. C. Environ. Pollut. 2004 , 129 , 431 441 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7.

    El-Kady, A. A.; Abdel-Wahhab, M. A.; Henkelmann, B.; Belal, M. H.; Khairy, M.; Morsi, S.; Galal, S. M.; Schramm, K. Chemosph. 2007 , 68 , 1660 1668 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8.

    UNIDO , Promotion of strategies to reduce unintentional production of POPs in the Red Sea and Gulf of Aden (PERSGA) coastal zone , 2011 .

    • Search Google Scholar
    • Export Citation
  • 9.

    ICES , Determination of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenylsin biota and sediment . ICES TIMES No. 50, 2012 .

    • Search Google Scholar
    • Export Citation
  • 10.

    US EPA , Tetra- through octachlorinated dioxins and furans by isotope dilution HRGC/HRMS . US. Environmental Protection Agency Office of Water Engineering and Analysis Division , Washington DC , US EPA method 1613 Rev. B, 1994 .

    • Search Google Scholar
    • Export Citation
  • 11.

    US EPA , Polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) by High Resolution Gas Chromatography and High Resolution Mass Spectrometry (HRGS/HRMS) , US EPA method 8290 Rev., 1998 .

    • Search Google Scholar
    • Export Citation
  • 12.

    Skoog, D. A.; Holler, F. J.; Crouch, S. R. Principles of Instrumental Analysis , 6th edn, Thomson Brooks/Cole Publishers , USA , 2007 .

    • Search Google Scholar
    • Export Citation
  • 13.

    Tundo, P.; Raccanelli, S.; Reda, L. A.; Ahmed, M. T. Chem. Ecol. 2004 , 20 , 257 265 .

  • 14.

    Fiedler, H. Dioxins and Furans (PCDD/PCDF). In: H. Fiedler (Ed), The Handbook of Environmental Chemistry . Vol. 3 , Part O Persistent Organic Pollutants , Springer-Verlag, Berlin, Heidelberg , 2003 , pp. 133 135 .

    • Search Google Scholar
    • Export Citation
  • 15.

    Urban, J. D.; Wikoff, D. S.; Bunch, A. T.; Harris, M. A.; Haws, L. C. Sci. Total Env. 2014 ,466 , 586 597 .

  • 16.

    Wenning, R.; Von Burg, A.; Martello, L.; Pekala, J.; Maier, M.; Luksemburg, W. Organohalogen Compd. 2004 ,66 , 1482 .

  • 17.

    Birmingham, B .Chemosphere 1990 ,20 , 807 814 .

  • 18.

    Burniston, D. A.; Klawunn, P.; Hill, B.; Marvin, C. H. Chemosphere 2015 , 123 , 71 78 .

  • 19.

    Bakoglu, M.; Karademir, A.; Durmusoglu, E. Chemosphere 2005 ,59 , 1373 1385 .

  • 20.

    Karademir, A.; Ergül, H. A.; Telli, B.; Kılavuz, S. A.; Terzi, M. Env. Sci. Poll. Res. 2013 , 20 ,6611 6619 .

  • 21.

    Jia, S.; Wang, Q.; Li, L.; Fang, A.; Shi, Y.; Xu, W.; Hu, J. Sci. Total Env. 2014 , 497 , 353 359 .

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