RESEARCH ARTICLE

Levels, distribution profile, and risk assessmentof polychlorinated biphenyls (PCBs) in water and sedimentfrom two tributaries of the River Chenab, Pakistan

Adeel Mahmood & Riffat Naseem Malik & Jun Li &Gan Zhang

Received: 5 December 2013 /Accepted: 27 January 2014 /Published online: 19 March 2014# Springer-Verlag Berlin Heidelberg 2014

Abstract The first study aimed to investigate thepolychlorinated biphenyl (PCB) concentration level, spatialdistribution pattern, and ecological risk assessment of waterand sediment samples from two tributaries (Nullah Aik andPalkhu) of the River Chenab, Punjab Province, Pakistan. Atotal of 32 PCB congeners were analyzed, and PCB concen-tration in sediment and water samples ranged between 0.80and 60 ng/g and 0.20 and 28 ng/L, respectively, where tetra-CBs and tri-CBs dominated over other studied PCB homo-logs. Dioxin toxicity equivalency (TEQ) was calculated andPCB-126 and PCB-169 showed the higher TEQ values com-pared with the WHO guidelines, and sediment samples weremore toxic than the water samples. The results of the presentstudy should be considered seriously by government author-ities to take a proper action against unchecked discharge ofcontaminants in ecological integrities; otherwise, there may bedrastic results in the near future.

Keywords PCBs . Distribution pattern . Risk assessment .

NullahAik and Palkhu . Pakistan

Introduction

Polychlorinated biphenyls (PCBs) are synthetic chemicalsprepared commercially for various applications (Wright andWelbourn 2002). PCBs, a group of 209 congeners, are impor-tant for anxiety due to the magnification and bioaccumulationin the food chain (Morrison et al. 2002). PCBs were listed aspersistent organic pollutants (POPs) by StockholmConvention of May 2001 (Ranjendran et al. 2005; Eqaniet al. 2012b). Considering the best dielectric properties, ther-mal stability, and resistance to oxidation, PCBs are used ascooling fluids in capacitors, transformers, and other electricalproducts. PCBs are also used in manufacturing of transmis-sion fluids, plastics, lubricants, adhesives, pigments/paints,and other metal coating compounds (EPA 2004; Park 2000).Open burning sites, improper dumping of nonfunctional trans-formers, leakage of transformer oil, open transformerrepairing workshops, waste incineration, and vaporization ofPCBs from contaminated products are the main sources ofPCBs transmission to the environment (EPA 2004; Breiviket al. 2002). Contamination of PCB in different environmentalmatrices has been reported by various countries all over theglobe, even from Antarctica and the Arctic zone (Ranjendranet al. 2005). POPs are very toxic and resistant to degradationin nature, so production of such compounds is banned in manycountries. However, in many regions, production and usage ofPCB are still practiced. The PCB level in ecological integritiesis still high which made them pervasive (Bozlaker et al. 2008).

Industrial and urban areas donate the PCBs to aquaticenvironment, atmosphere, and ultimately to other environ-mental matrices from discharge of industrial wastewater toriver-linked tributaries and unattended municipal and

Responsible editor: Leif Kronberg

Electronic supplementary material The online version of this article(doi:10.1007/s11356-014-2730-1) contains supplementary material,which is available to authorized users.

A. MahmoodEnvironmental Biology and Ecotoxicology Laboratory, Departmentof Plant Sciences, Faculty of Biological Sciences, Quaid-I-AzamUniversity, Islamabad, PO 45320, Pakistane-mail: adilqau5@gmail.com

R. N. Malik (*)Environmental Biology and Ecotoxicology Laboratory, Departmentof Environmental Sciences, Faculty of Biological Sciences,Quaid-I-Azam University, Islamabad, PO 45320, Pakistane-mail: r_n_malik2000@yahoo.co.uk

J. Li :G. ZhangState Key Laboratory of Organic Geochemistry, Guangzhou Instituteof Geochemistry, Chinese Academy of Sciences,Guangzhou 510640, China

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industrial waste dumping sites (Khawaja 2003). PCB conge-ners have a strong affinity to bind with suspended matterparticulates in the aquatic environment and eventually, sinkand accumulate in the sediments (Eqani et al. 2012a; Maliket al. 2011). A variety of human health issues includingneurological, immunological, and reproductive problemshave been reported due to PCB exposure. Long-term exposuremay affect the liver functioning and mutation in DNA leadingto developmental defects and cancer. PCBs are considered as“endocrine disrupting” chemicals, and their exposure maycause thyroid hormone dysfunctioning by reducing serumconcentration (Wei et al. 2008).

Pakistan is a signatory member of the StockholmConvention, but unfortunately, there is no proper regulatorymechanism to monitor the PCB level in various ecologicalmatrices. The production and usage of PCBs are not con-trolled here, also these chemicals are not listed in theNational Environmental Quality Standard as chemicals ofmajor concern (Eqani et al. 2012b). It is important to note thatthere are various obsolete pesticides dumping sites located inbig cities of Pakistan, and the level of POPs from 18 pesticidedumping sites is reported recently with high POPs concentra-tion (Ahad et al. 2009). Two obsolete pesticide dumping sitesare located in the study area, Gujranwala division (Simbrialand Wazirabad), Punjab province (Ahad et al. 2009). Twotributaries (Nullah Aik and Nullah Palkhu) of the RiverChenab pass from Sialkot, Simbrial, and Wazirabad, whichreceive a huge efflux of industrial and urban wastewater alongwith the runoff of chemicals from pesticide dumping sites.The stretch of about 175 km along these tributaries is purelyagricultural belt, where wheat and rice is cultivated at largescale and traded to the other parts of the country. These foodcrops are irrigated with the wastewater of these tributariesalong the whole agricultural belt across these Nullahs. Tothe best of our knowledge, there is no reported study to assessthe level, distribution, and risk of PCB from water and sedi-ments of these Nullahs. Based on these observations, thepresent study aimed to assess the level and distribution profileof PCBs congeners from water and sediment of two tributes(Nullah Aik and Nullah Palkhu) of the River Chenab and toinvestigate the dioxin toxicity equivalency level along withthe risk assessment of PCB.

Materials and methods

Sampling strategy

Water and sediment samples were collected from 14 samplingsites located across the River Chenab and its two tributaries,namely Nullah Aik and Nullah Palkhu. Samples were collect-ed from about 170 km stretch during January–March 2013.Twelve sites were located on Nullah Aik and Palkhu and two

were on the River Chenab. The study area was divided intothree zones, namely upstream (S8, S9, S10, and S11), mid-stream (S6, S7, S12, and S13), and downstream zones (S1, S2,S3, S4, S5, and S14). Figure 1 describes the details of each siteof the allocated zone of the study area. The zonation wasbased on the origin of Nullahs and its gradual stream towardsthe river Chenab. Upstream zone comprises purely rural andagricultural areas; here, Nullahs receive rural sewage/wastewater. Midstream zone comprises the urban and indus-trial areas of Sialkot district, and here, Nullahs receive a hugeefflux municipal, industrial, and urban wastewater.Downstream zone is located in urban and peri-urban areas.Two obsolete pesticide dumping sites are also located near themidstream and downstream of Nullahs.

Water sampling

Water samples were collected (n=28) from 14 selected sites oftwo tributaries of the River Chenab during January–March2013. Each sample was the composite (over 500 m stretch) offive subsamples, collected from a depth of about 2–3 m belowthe top surface of water in 5 L pre-cleaned (washed withorganic solvent) sampling jars. After collection, samples wereplaced in ice-containing cooler and transferred immediately tothe Environmental Biology and Ecotoxicology Laboratory,Quaid-I-Azam University, Islamabad, Pakistan. In laboratorywater, samples were filtered with glass wool to remove debrisand other small particles and finally stored in −8 °C untilfurther analysis.

Sediment sampling

Sediment samples were collected from the bottom of streamsof each site. A composite sediment sample of five to sevensubsamples were collected over a stretch of 500 m across bothbanks of streams and stored in a polythene bags. Sampleswere transported to the Environmental Biology andEcotoxicology Laboratory, QAU, where sediment sampleswere freeze dried, sieved with 2 mm sieve, and furthertransported to the State Keys Laboratories, GuangzhouInstitute of Geochemistry, Guangzhou, China where storedin freezer until further analysis.

Extraction of sediment samples

About 20 g of sediment was Soxhlet extracted for 24 h withdichloro methane (DCM). A mixture of decechlorobiphenyl(PCB 209) and 2,4,5,6-tetrachloro-m-xylene (TCmX) wasadded as surrogate standard in each sample prior to extraction.For the removal of elemental sulfur, activated copper granuleswere added in the collection flasks. The extract was concen-trated and the solvent phase was changed from DCM tohexane through rotary evaporator.

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Extraction of water samples

Water samples were extracted through liquid–liquid extractionin separating funnel. Before extraction, water was filtered viaWhatman 42 filterpaer to remove the suspending particles orsmall debries. One liter of filtered water was mixed with the25- to 35-mL of DCM and shacked thoroughly for 2 min andstayed for 10 min to obtain two layers. A lower transparentlayer of organic solvent containing chlorinated pollutants wascollected on anhydrous Na2SO4, and a mixture ofdecechlorobiphenyl (PCB 209) and TCmX was added assurrogate standard in each sample. The extract was concen-trated, and the solvent phase was changed from DCM tohexane through rotary evaporator.

Clean-up procedure

Sediment samples were washed with H2SO4 prior to columnclean up. For column clean-up, silica alumina column wasused. Silica gel, anhydrous Na2SO4 and alumina were Soxhletextracted with DCM for 48 h and finally backed at 450 °C for6 h before using. The volume of the sample fraction wasreduced to 0.2 mL under the gentle nitrogen (high purified)stream after adding 30 μL of iso-octane as solvent keeper.PCB-54 was added as an internal standard in each sampleprior to GC-MS analysis.

Chromatographic analysis

Thirty-two PCB congeners, specifically PCB-8, PCB-28,PCB-37, PCB-44, PCB-49, PCB- 52, PCB-60, PCB-66,PCB-70, PCB-74, PCB-77, PCB-82, PCB-87, PCB-99,PCB-101, PCB-105, PCB-114, PCB- 118, PCB-126, PCB-128, PCB-138, PCB-153, PCB-156, PCB-158, PCB-166,PCB-169, PCB-170, PCB-179, PCB-180, PCB-183, PCB-187, and PCB-189 were analyzed by GC-EI-MS. Varian,CP-Sil 8 CB; 50-m, 0.25-mm, and 0.25-μm columns wereused. Temperature of the injector was 250 °C. Initially, tem-perature of the oven was set as 150 °C for 3 min, and then thetemperature was raised up to 290 °C at the rate of 4 °C/minand held for 10 min. The congeners of PCB were identifiedwith three fragment ions with electron impact spectrometry inthe selected ion monitoring mode. MSD source temperaturewas 230 °C, and quadruple temperature was 150 °C.

Quality control and quality assurance

Quality control procedure was strictly followed for the entiresample to ensure the quality of results. Calibration standardswere used daily for instrument calibration. All the chemicalsused during the experimentation were of analytical grade andpurchased from Merck (Germany). Standers for PCBs werepurchased from Dr. Ehrenstorpher GmbH, Germany. Field,

Fig. 1 Map showing the location of the study area from Pakistan

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procedural, and solvent blanks were analyzed by the similarmethodology, adapted for original samples. Glassware wasdouble washed with distilled water and baked at 450 °C formore than 6 h. Agilent MSD Productivity Chemstation soft-ware was used for data processing and acquirement. Detectionlimits were estimated at three times the standard deviation ofthe blank. Surrogate recoveries in all samples for TCmXranged between 52 and 70 %, and average recovery forPCB-30, PCB-198, and PCB-209 was 82, 77, and 85 %,respectively. Standard of 5, 10, 20, 50, 100, and 200 μg/Lwere used to quantify the calibration curves.

Results and discussion

Descriptive statistical values of 32 PCB congener concentra-tion, toxicity equivalency (TEQ) values for dioxin-like PCBs,and detailed concentration of PCB in sediment and water arepresented in Tables 1 and 2 and SI Table 1, respectively. Datafor sediment and water are expressed as nanograms per gram(dry weight (dw)) and nanograms per liter, respectively.Spatial distribution pattern of PCB from each site of the studyarea is shown in Fig. 2, whereas PCB level from each zone ispresented in Fig. 3.

PCB congener profile

Level of PCB in sediment

When we look at the PCBs level in sediment, tetra-CBsdominated over other PCBs followed by the tri-CBs, di-CBs, and penta-CBs. The concentration of ∑PCB in sedi-ments ranged between 0.82 and 60 mg/g with a mean valueof 13.9±18 ng/g. Among congeners, PCB-28 dominated with18 % of the total PCBs followed by the PCB-169 (12 %),PCB-8 (9 %), PCB-37, and PCB-49 (5 %). Dioxin-like PCBcongeners were also detected in all sediment samples with amean concentration of 4.7±0.5 ng/g (sum of non- and mono-ortho dioxin-like PCBs). Among dioxin-like PCBs, PCB-169(non-ortho) was the dominated one, which also dominated theoverall PCB congeners. Non-ortho dioxins like PCB are ofgreat concern in terms of toxicity because of their carcinogen-ic properties which closely resembles with the tetrachlorodienzo-p-dioxin (Zhao et al. 2006). Concentration of ∑PCBswas lower as compared with the reported concentration ofsediments from River Chenabwhich was 23.8 ng/g and rangedbetween 9.33 and 129.45 ng/g (Eqani et al. 2012a, b). Thereason may be perhaps, Eqani et al. (2012a, b) studied thesediment samples of the River Chenab, and its study stretchwas the downstream of Punjab province, whereas the presentstudy was conducted on two major tributaries and study areawas along the upstream of the River Chenab in Punjab. Whenwe compare these results with previously published reports of

China, Bengal, and India, these concentrations are in the rangeor a little bit lower than these countries (Ranjendran et al. 2005;He et al. 2006; Shen et al. 2006). The PCB concentrations ofthe current study are lower than previous studies of MinjiangRiver, southeast China and Pearl River estuary, China (Zhanget al. 2003; Kang et al. 2000). PCB levels in sediments ofprevious published reports from the USA, Egypt, and Italywere found higher than the present reported levels (Barakatet al. 2002; Hartmann et al. 2004; Sprovieri et al. 2007).

Level of PCB in water

Tetra-CBs dominated over other studied PCB congeners inwater, followed by the tri-CBs, di-CBs, penta-CBs, and hexa-CBs. The mean concentration of ∑PCB was 5.7±9 ng/L thatranged between 0.2 and 27.5 ng/L. Among individual PCB,PCB-37 was the dominant with 21 % of total PCB followedby the PCB-28 (12 %), PCB-08 (100 %), and PCB-49 (7 %).Dioxin-like PCB also exhibited considerable concentrationand found 10 % of the total PCB. PCB-114 was the dominantamong dioxins like PCB. Level of PCB presently reported islower than the previously published report from Pakistan(Eqani et al. 2012a, b). Compared with the previously pub-lished data from China (Daya Bay China, Xiamen Harbor,China, Minjiang River, China), India, and Russia, (BaikalLake), PCB were found slightly lower in the current report(Iwata et al. 1995; Zhang et al. 2003; Zhou and Maskaoui2003; Ranjendran et al. 2005). The reported concentrations ofPCB were in the range of permissible limits of USEPA.According to the EPA, the level of PCB in water should belower than the 14-ng/L limit, and the present study followedthis permissible limit (http://www.epa.gov/waterscience/criteria/wqcriteria.html).

PCB homologs in sediment and water

Seven PCB homologs (di-CBs, tri-CBs, tetra-CBs, penta-CBs, hexa-CBs, hepta CBs, and dioxin-like PCBs) were ana-lyzed. In sediment samples, tetra-CBs and tri-CBs were thedominating ones over other PCB homologs with a proportionof 25 and 23 %, respectively, of total PCBs. The trend of PCBhomologs for sediments appeared as tetra-CBs>tri-CBs>di-CBs>penta-CBs>hexa-CBs>hepta-CBs. Dioxin-like CBs al-so exhibited the higher levels in sediment samples that ac-count for 25% of the total CBs. The PCB homologs pattern ofthe present study was not consistent with the reported PCBhomologs pattern in a previous study from sediment samplesfrom Pakistan (Eqani et al. 2012a, b). Eqani et al. 2012a, breported the higher level of hepta-CBs and penta-CBs in riversediment samples, whereas in the present study, tetra and tri-CBs were more dominant and tetra-CBs were at the third rankin the previous published report. Tetra-CBs and tri-CBs werethe dominant homologs with 36 and 33 %, respectively,

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among PCB homologs fromwater sample, followed by the di-CBs (10 %), penta-CBs (06 %), and penta-CBs and hexa-CBs(3 %).

Spatial distribution pattern and sources of PCBs

PCB level was found highest in sediment and water samplesfrom midstream zone followed by the downstream zone andupstream zone (SI Table 1). Figure 2 represents the spatialdistribution pattern of PCB levels from each site of the allo-cated zone of the study area, whereas levels of PCB homologsfrom each zone is presented in Fig. 3. There is a significant

difference (p>0.05) between the PCB levels from each zoneof the study area, and midstream was the most contaminatedzone. Midstream of Nullahs was passing from industrial andurban areas of the study area where a huge efflux of industrialwastewater is discharged into Nullah Aik and Palkhu. Anumber of industrial units are located in the urban and peri-urban areas of Sialkot district which discharge PCB and othercontaminants into the rivulet water system. Downstream zonealso exhibited higher concentration of PCB, which may bedue to the running wastewater draining from midstream.Despite these reasons, two dumping sites are located in thestudy area located near the midstream and downstream zones.

Table 1 Descriptive statistics of PCBs congeners in sediment (nanograms per gram) and water (nanograms per liter)

PCB congeners Sediment (ng/g) Water (ng/L)

Mean SD Min Max Mean SD Min Max

PCB-8 1.30 1.57 0.13 4.96 0.57 0.99 0.05 3.24

PCB-28 2.43 3.00 0.21 11.2 0.68 0.83 0.01 2.69

PCB-37 0.75 0.92 0.03 3.04 1.23 1.95 0.03 5.69

PCB-44 0.31 0.29 0.01 0.99 0.28 0.46 0.03 1.46

PCB-49 0.69 0.71 0.10 2.13 0.40 0.34 0.03 1.17

PCB-52 0.53 0.59 0.09 1.8 0.28 0.49 0.01 1.55

PCB-60 0.48 0.56 0.02 1.87 0.39 0.65 0.01 1.99

PCB-66 0.46 0.58 0.03 2.17 0.22 0.37 0.011 1.15

PCB-70 0.57 0.59 0.03 1.93 0.31 0.49 0.01 1.33

PCB-74 0.43 0.45 0.04 1.43 0.23 0.37 0.01 1.20

PCB-82 0.15 0.27 0.01 1.06 0.05 0.07 0.002 0.20

PCB-87 0.26 0.44 0.014 1.53 0.07 0.13 0.0006 0.39

PCB-99 0.36 0.58 0.016 1.99 0.08 0.14 0.002 0.44

PCB-101 0.42 0.57 0.03 1.98 0.13 0.22 0.001 0.69

PCB-128 0.12 0.26 ND 0.98 0.02 0.02 ND 0.08

PCB-138 0.20 0.32 0.01 0.96 0.06 0.11 0.0003 0.32

PCB-153 0.41 0.59 0.01 1.92 0.09 0.14 0.001 0.42

PCB-158 0.08 0.20 ND 0.74 0.01 0.01 ND 0.02

PCB-166 0.04 0.08 0.0003 0.29 0.003 0.004 ND 0.01

PCB-179 0.11 0.19 ND 0.67 0.006 0.005 ND 0.02

PCB-183 0.16 0.28 0.0005 0.91 0.006 0.005 ND 0.02

PCB-187 0.35 0.58 0.01 1.7 0.15 0.33 ND 1.03

PCB-77 0.28 0.44 0.0065 1.37 0.08 0.14 ND 0.42

PCB-105 0.04 0.07 0.0002 0.24 0.007 0.01 ND 0.03

PCB-114 0.43 0.65 0.02 2.28 0.25 0.46 0.005 1.39

PCB-118 0.04 0.05 ND 0.18 0.01 0.02 ND 0.05

PCB-126 0.07 0.11 0.0005 0.31 0.01 0.02 ND 0.04

PCB-156 0.20 0.25 0.005 0.74 0.06 0.11 0.0002 0.31

PCB-169 1.64 1.70 0.016 4.66 0.02 0.03 ND 0.09

PCB-170 0.38 0.69 0.01 2.25 0.01 0.003 0.0006 0.01

PCB-180 0.17 0.28 0.001 1.07 0.03 0.031 0.0005 0.10

PCB-189 0.02 0.02 0.002 0.07 0.003 0.004 ND 0.01

∑PCBs 13.9 17.9 0.83 59.4 5.72 8.96 0.21 27.5

ND not detected

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The runoff of PCB from these pesticides dumping sites andthe deposition of atmospheric PCB may be the reason for the

high PCB levels in the downstream zone. It is important tonote that sediment samples exhibited higher concentration as

Table 2 TEQ values of dioxin-like PCBs

Congeners Sediment (ng/kg) Water (ng/L)

Mean Min Max TEF(1998) TEF(2005) Mean Min Max TEF(1998) TEF(2005)

PCB-77 0.286 0.0065 1.37 0.0000286 2.86E−09 0.075 0.00 0.42 0.0000075 7.5E−10PCB-126 0.070 0.0005 0.31 0.007 0.0007 0.01 0.00 0.04 0.001 0.0001

PCB-169 1.636 0.0161 4.66 0.01636 0.0004908 0.023 0.00 0.09 0.00023 0.0000069

PCB-105 0.041 0.0002 0.24 0.0000041 1.23E−09 0.007 0.00 0.03 0.0000007 2.1E−10PCB-114 0.427 0.0057 2.28 0.0002135 6.405E−08 0.25 0.00499 1.39 0.000125 3.75E−08PCB-118 0.038 0.00 0.18 0.0000038 1.14E−09 0.006 0.00 0.05 0.0000006 1.8E−10PCB-156 0.199 0.0049 0.74 0.0000995 2.985E−08 0.063 0.00028 0.31 0.0000315 9.45E−09PCB-189 0.017 0.0023 0.07 0.0000017 5.1E−10 0.003 0.00 0.01 0.0000003 9E−11

Fig. 2 Spatial distribution ofPCB in sediment and water fromeach site of the study area

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compared with the water samples. This is perhaps due to thereason that water flows continuously towards the river bydonating its contaminants to the river and the leaching ofcontaminants into sediments which reduced the contaminantlevels in water.

Highest PCB concentration was found from industrial andurban sites including S6, S7, S12, S13, and S14, whichcontributed more than 40 % of the total PCB for sedimentand water samples from the study area. Previously publishedreports concluded the same results, as the industrial and urbansites were much polluted compared with the peri-urban andrural sites (Ren et al. 2007). Huang et al. (1992) concludedthat soil of urban and industrial area of Taiwan was highlypolluted by pesticides. The main source of PCBs emissionwas the combustion of electric equipment and PVS, vehiclefuel, and other chemical processes, and there were many ofsuch sources in the urban sites of the study area. Previouspublished reports also reflected the same urban fraction asthose in the present report (Fu et al. 2003; Breivik et al. 2007).PCB sources in the urban areas include off-gassing from oldequipment, transformers (contain large quantities of PCB),repairing workshops, and polyvinyl chloride burning andmanufacturing units (Breivik et al. 2002). These resultsreflected that urban sources influenced PCB pollution. Thus,it is necessary for government officials to take a proper actionfor appropriate treatment of these sources as regards properdisposal of industrial wastes, and there should be a propercheck on the open burning of these industrial and urbanwastes.

Results of cluster analysis also verified the PCB contami-nation sources and distribution pattern. Rural and agriculturalsites (S8, S9, and S10) are located in the same region (Fig. 4),whereas industrial and urban sites are also located in similarregion or closer to the urban fractions. Results of clusteranalysis classify the study sites in four regions, and eachregion occupies the similar type of sites and zonation pattern

with the same sources of contaminants. It is important to notethat these results also reflected the zonation differentiation ofstudy sites. Each site of a particular zone is grouped in similaror related regions of the cluster.

Dioxin toxicity equivalency

TEQs were calculated for PCBs having dioxin-like propertiesby TEF described in detail by Van den Berg et al. (1998, 2006)for sediment and water samples as higher amount (25 %) ofdioxin-like PCBs was exhibited by the sediment samples.Among PCB congeners, PCB-77, PCB-126, and PCB-169exhibit non-ortho dioxin-like properties, PCB-105, PCB-114, PCB-118, PCB-156, and PCB-189 exhibit mono-orthodioxin-like properties, and PCB-170 and PCB-180 exhibit di-ortho dioxin-like properties. The World Health Organization(WHO) reported the TEQ value that ranged between 0 and3 pg/m. TEF value calculated byVan den Berg et al. (1998) forsediment and water ranged between 0.0000017 and 0.016 ng/kg and 0.0000003 and 0.001 ng/L, respectively, whereas TEFvalue calculated byVan den Berg et al. (2006) ranged between0.0007 and 5.1E−10 and 0.0001−9E-11, respectively. TEFvalue for PCB-126 and PCB-169 was higher compared withthe other congeners, and these are more than the WHO guide-lines. Other dioxin-like PCBs showed TEQ values within therange of WHO permissible limits. The presented TEQ valuesare also lower than the published TEQ values of other coun-tries (Wang et al. 2008; Fu et al. 2009). Improper discharge ofwastes into riverine system and discharge of wastewater maybe the possible source of dioxin-like PCBs in the studiedmatrices. Investigation showed that the TEQs are higher insediments as compared with the water, sinking down andleaching of PCB into bottom of Nullahs seems the reason ofthis higher concentration. The lower value of WHO-TEQ inthis study may be due to the atmosphere water ambienttemperature conditions.

Fig. 3 Distribution of PCBshomologs among each zone of thestudy area

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Ecological risk assessment

To assess the risk from ecotoxicological aspects of PCB insediments and water, data were counter checked and com-pared with the Canadian Council of Ministers of Environment(CCME 1999), USEPA, and WHO guidelines. It is reportedthat 22.7 ng/g (dw) is a low effect range of PCB in river/riverine ecosystem that may be toxic on aquatic life, whereasthe value of 180 ng/g (dw) is the higher possible PCB con-centration that have a severe toxic effects on aquatic life (Longet al. 1995). Canadian Sediment Quality Guidelines suggestedthat 227 ng/g is a probable effect level of PCB that has toxiceffects on aquatic organism, and the threshold effect level is34.1 ng/g (Long et al. 1995). According to EPA, the level ofPCB in water should be lower than the 14 ng/L, and thepresent study follows this permissible limit (http://www.epa.gov/waterscience/criteria/wqcriteria.html). In our study, the∑PCB concentration in sediments and water was in therange of the permissible limits. Sites from midstream zoneexhibited high levels of PCB that were in accordance to theallowable limits of WHO and other environmental protectionorganizations. Sediments were more threatened to the POPscontamination. It is important to note that TEQ values ofsediments were also considerably few of the congeners,showing higher TEQ values compared with the WHOpermissible limits. At the present overall, PCB level isalmost free from risk. However, this risk will be hazardousto humans and animals in the near future, and contaminationlevel should be higher as, improper, unchecked discharge ofindustrial wastewater is continued. As reflected by theseresults, considerable TEQs for water and sediment samplesmay affect the aquatic life of the River Chenab, as well asstudied river tributaries. In a previously published report,

Qadir et al. (2008) have analyzed the heavy metals concen-tration in fish and water samples from these tributaries andfound a hazardous impact of heavy metals on fish populationand other aquatic lives. Consequently, the toxicity of PCBs inwater and sediments may definitely affect the aquatic integ-rities including fish population of Nullh Aik and Palkhu,tributaries of the River Chenab. It is important to note thatalong the banks of these streams, a number of fields were usedto cultivate rice and wheat that is consumed and traded at thelarge scale in Pakistan. Hundreds of pumps were used to suckthe PCB-contaminated water from Nullah Aik and NullahPalkhu to irrigate the wheat and rice crops. This practicedirectly expose the food crops with PCBs, which have greattendency to bioaccumulate with cereal grain due to the pres-ence of fatty tissue that in turn consumed by humans.

Conclusions

The first systematic study was conducted on PCB level,profile, distribution, and risk assessment in sediment andwater from Nullah Aik and Palkhu, tributaries of the RiverChenab. The results reflect that PCB contamination in thestudy area should consider a serious environmental matteras, uncontrolled PCBs are practiced in industrial areas.Compared with the other regions of the globe, pattern ofPCN contamination levels was similar but slightly lower thanpublished reports from those areas. Tetra and tri-CBs domi-nated over other chlorinated biphenyls, and urban/industrialsites were more polluted followed by the peri-urban and rural/agricultural sites. Dioxin-like PCB also account a consider-able amount in studying samples, sediments exhibited higherlevel of dioxin-like PCB than water. TEQ values of dioxin-

Fig. 4 Cluster analysis based on the PCB concentration from each site

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like PCB for sediment samples were high and consistent withthe EPA andWHO permissible safety limits. It is recommend-ed that government authorities should take a serious action tocontrol the open discharge of contaminants to riverine systemas water is a major source of POPs contamination to the foodchain. There should be proper disposal of obsolete pesticidechemicals from unchecked dumping sites located in populatedareas of the study area.

Acknowledgments The authors would like to acknowledge the HigherEducation Commission of Pakistan for providing support under theInternational Research Support Initiative Program. The authors also ex-press their thanks to Guangzhou Institute of Geochemistry, ChineseAcademy of Sciences, China and to Prof. Dr. Xiandong Li (PolytechnicUniversity, Hong Kong) for providing assistance for sample transporta-tion to Guangzhou Institute of Geochemistry, Guangzhou, China. Finally,the authors acknowledge Mr. Irfan Ali Ch, who served as a guide duringsample collection from far areas.

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