Polycyclic aromatic hydrocarbons (PAHs) in a large South American industrial coastal area (Santos Estuary, Southeastern Brazil): Sources and depositional history

Marine Pollution Bulletin 63 (2011) 452–458

Contents lists available at ScienceDirect

Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul

Polycyclic aromatic hydrocarbons (PAHs) in a large South American industrial coastal area (Santos Estuary, Southeastern Brazil): Sources and depositional history César C. Martins a,b,⇑, Márcia C. Bícego b, Michel M. Mahiques b, Rubens C.L. Figueira b, Moyses G. Tessler b, Rosalinda C. Montone b a b

Centro de Estudos do Mar da Universidade Federal do Paraná, Caixa Postal 50.002, 83255-000 Pontal do Sul, Pontal do Paraná – PR, Brazil Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, 05508-900 São Paulo – SP, Brazil

a r t i c l e

i n f o

Keywords: Polycyclic aromatic hydrocarbons Sediments Oil combustion Santos Estuary

a b s t r a c t Located in southeastern Brazil, the Santos Estuary has the most important industrial and urban population area of South America. Since the 1950’s, increased urbanization and industrialization near the estuary margins has caused the degradation of mangroves and has increased the discharge of sewage and industrial effluents. The main objectives of this work were to determine the concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) in sediment cores in order to investigate the input of these substances in the last 50 years. The PAHs analyses indicated multiple sources of these compounds (oil and pyrolitic origin), basically anthropogenic contributions from biomass, coal and fossil fuels combustion. The distribution of PAHs in the cores was associated with the formation and development of Cubatão industrial complex and the Santos harbour, waste disposal, world oil crisis and the pollution control program, which results in the decrease of organic pollutants input in this area. Ó 2011 Elsevier Ltd. All rights reserved.

1. Introduction The Santos Estuary, located on the Southeastern Brazilian coast, lies off one of the most metropolitan and economically important areas in South America (Fig. 1). The largest commercial harbour in Latin America and the most important metallurgical and petrochemical industrial centre in Brazil, which has more than 1100 industries, are also established in, and adjacent to, this estuary. The intensity of industrialization and urbanization began to increase around the estuary 60 years ago, when the Cubatão Industrial Complex was built and the Santos Harbour was enlarged. These events resulted in an increased input of industrial effluents and the discharge of solids and domestic sewage (Hortellani et al., 2008). During the early 1980s, the region became known as one of the worst polluted in the world, as a result of the high levels of organic contaminants in the air and water (Blacksmith Institute, 2006). A large quantity of solid waste from the domestic activities has been disposed in an area located on the margins of the estuary. Drainage from this area after successive rainfalls results in a major input of pollutants into the Santos Estuary (Martins et al., 2007). Several organic contaminants (e.g. petroleum hydrocarbons, polychlorinated biphenyls and pesticides) have been introduced ⇑ Corresponding author at: Centro de Estudos do Mar da Universidade Federal do Paraná, Caixa Postal 50.002, 83255-000 Pontal do Sul, Pontal do Paraná – PR, Brazil. Tel./fax: +5541 35118637. E-mail address: [email protected] (C.C. Martins). 0025-326X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2011.03.017

into the Santos Estuary as a result of the discharge of untreated industrial effluents and domestic wastes (Medeiros and Bícego, 2004; Bícego et al., 2006). Consequently, an examination of the depositional history of molecular markers related to industrial waste could be used to describe historical events concerning organic contaminant discharge into this environment. Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants prevalent in the sediments of marine and freshwater environments. PAHs are mainly derived from anthropogenic sources including the combustion of fossil fuels, sewage, vehicular emissions and spillages of petroleum and its by-products containing complex mixtures of petrogenic PAHs (Yunker and Macdonald, 2003; Tolosa et al., 2009). In particular, the higher molecular weight PAHs (MW P 202) with 4–6 aromatic rings are frequently related to combustion processes (Yunker et al., 2002), and are highly toxic to organisms due to their carcinogenic and mutagenic potential (Sverdrup et al., 2002; Yang et al., 2008). As PAHs lack functional groups, they are among the most stable organic indicators and their distribution in sediment cores has accurately recorded the historical input of these organic contaminants into estuarine systems (Yunker and Macdonald, 2003; Pietzsch et al., 2010). Few data are available describing the input of PAHs into the study area (Medeiros and Bícego, 2004; Bícego et al., 2006) and the existing data only characterise upper surficial sediments. Therefore, the main objective of this work was to examine the changes in sources, concentration and composition of PAHs in

C.C. Martins et al. / Marine Pollution Bulletin 63 (2011) 452–458

453

Fig. 1. Map of the study area showing the sediment sampling sites (CQ1, LSR and LCN) in the Santos Estuary and (a) location in Brazil, (b) the Southeastern Brazilian coast, and (c) Baixada Santista.

sediment cores from Santos Estuary in order to find a relation with the urban and industrial occupation in the last 50 years. The historical record of pollution levels using dated sediment cores is essential to evaluate the trends of organic pollutant inputs which are helpful to predict future pollution tendencies (Santschi et al., 2001; Boonyatumanond et al., 2007).

for the surface sediments (0–40 cm for CQ1; 0–60 cm for LSR; 0–90 cm for LCN) and then in one sub-sample in each 20 cm section to the core bottom. The sediment samples were freeze-dried, carefully homogenized in a mortar, sieved through a stainless steel mesh (250 lm) and stored at room temperature in glass bottles (for PAHs) and plastic containers (for gamma spectrometry counting).

2. Experimental methods

2.2. Dating of the sediment cores

2.1. Sampling

Sediment samples (20 g) were counted for 90,000–120,000 s using a hyper-pure Ge detector (model GEM60190, by EGG&ORTEC). Cesium-137 activity was assayed by means of its peak at 661 keV (Figueira et al., 1998). The detector was calibrated by means of several gamma ray emitting nuclides. International Atomic Energy Agency (IAEA) reference materials were employed to determine the detector counting efficiency in the radionuclide photopeak region. The estimated age of each sediment section was theoretically based on the fact that 137Cs can be used as a time-marker and that the maximum activity of this radionuclide corresponds to the interval between the years 1963 and 1965, the period of maximum fallout in the Southern Hemisphere related to nuclear weapons tests (Zuo et al., 1991; Abril, 2003; Inomata et al., 2009).

Three vibracores (3 m long, 0.75 mm wide aluminum barrels, 10 cm i.d.) named CQ1, LSR and LCN were collected in the Santos Estuary, São Paulo, Brazil (Fig. 1) in September, 2002. The samples were collected in a shallow water column (below 1.0 m). The CQ1 core was collected at the margins of estuary, near a solid waste disposal area of the cities in the estuarine system and close to small settlements. The LSR and LCN cores were collected close to an area of intensive shipping and input of waste from metallurgical and petrochemical industries. It was located close to petroleum, kerosene and alcohol storage facilities, near a channel where loading and unloading operations are carried out by several industries in the Santos Estuary (Martins et al., 2007). The cores were then sectioned at 2 cm intervals for hydrocarbon analyses. The sediment samples were wrapped in aluminum foil (baked at 450 °C) and frozen at 20 °C until they were analyzed in the laboratory. PAHs were analyzed in every 2 cm subsection

2.3. PAHs: extraction and fractioning The analytical procedure of Martins et al. (2004) was utilised. Briefly 20.00 g of sediment were extracted over 8 h using 80 mL of

454

C.C. Martins et al. / Marine Pollution Bulletin 63 (2011) 452–458

a mixture of (1:1) dichloromethane (DCM) and n-hexanes. A mixture of deuterated surrogate standards (naphthalene-d8, acenaphthened10, phenanthrene-d10, chrysene-d12, and perylene-d12) was added before each blank and sample extraction. The DCM/n-hexanes extract was purified by column chromatography using 5% deactivated alumina (1.8 g) and silica (3.2 g). The elution was done with 10 mL of n-hexanes (fraction 1 – aliphatic hydrocarbons, not presented in this study) and 15 mL of (3:7) DCM/n-hexanes mixture (fraction 2 – PAHs). An aliquot of 1 lL of each extract was injected for gas chromatographic analysis. The PAHs analyzed were: (a) alkyl-PAHs such as methyl (2-methylnaphtalene, 1-methylnaphtalene), ethyl (2-ethyl-naphtalene), dimethyl (2,6-dimethylnaphtalene, 2,6-dimethylnaphtalene, 2,7-dimethylnaphtalene, 1,3-dimethylnaphtalene, 1,7-dimethylnaphtalene, 1,2-dimethylnaphtalene) and trimethyl (1,6,7-trimethyl-naphtalene, 1,4,6-trimethyl-naphtalene, 2,3,6-trimethyl-naphtalene, 2,3,5-trimethyl-naphtalene, 1,4, 5-trimethyl-naphtalene) naphthalenes, methyl (3-methyl-phenanthrene, 2-methyl-phenanthrene, 4-methyl-phenanthrene, 9methyl-phenanthrene, 1-methyl-phenanthrene) and dimethyl (3,6-dimethyl-phenanthrene, 2,7- dimethyl-phenanthrene, 1,8 dimethyl-phenanthrene) phenanthrenes; (b) unsubstituted PAHs (2–3 rings) such as naphthalene, phenanthrene, anthracene, fluorene, acenaphthene, acenaphthylene and biphenyl; (c) PAHs (4–6 rings) such as fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo-(b + k)fluoranthene, benzo(a + e)pyrene, indene(1,2,3-c,d)pyrene, dibenzo(a,h)anthracene and benzo(g,h,i)perylene. 2.4. PAHs: instrumental analysis and quality assurance procedures The instrumental analysis procedure adopted was described by Martins et al. (2010a). Briefly, the PAH analyses were performed with an Agilent GC model 6890 coupled to an Agilent Mass Spectrometer Detector (model 5973) and an Ultra-2 capillary fused silica column coated with 5% diphenyl/dimethylsiloxane (50 m, 0.32 mm ID and 0.17 lm film thickness). Helium was used as the carrier gas. The oven temperature was programmed from 40 °C, holding for 2 min, 40–60 °C at 20 °C min 1, then to 250 °C at 5 °C min 1 and finally to 320 °C at 6 °C min 1 where this temperature was held for 20 min. Data acquisition was undertaken in the single ion monitoring mode (SIM). Compounds were identified by matching retention times and ion mass fragments with results from standard mixtures of PAHs from the National Institute of Standards and Technology, USA (NIST 2260 – Aromatic Hydrocarbons Standard Reference Material). Procedural blanks contained a few minor contaminant peaks but these did not interfere with the analyses of target compounds. A surrogate and spiked-recovery experiment was conducted simultaneously with the extraction of the samples and the recoveries ranged from 50% to 120%. Measured concentrations of target PAHs in the IAEA-417 reference material were within 90–115% of the certified values provided by the International Atomic Energy Agency (IAEA). 3. Results and discussion 3.1.

137

Cs sediment profiles

The vertical distribution of 137Cs activity in each core is presented in Fig. S1. According to the maximum 137Cs activity, the average annual sedimentation rates (SR, in cm y 1) are: 1.47 ± 0.13 (CQ1), 1.24 ± 0.11 (LSR) and 1.29 ± 0.12 (LCN). The 210 Pb dating techniques for determining sediment accumulation rates are not reliable for the Santos Estuary due to high levels of radionuclide contamination from industry wastes (Machado et al., 2008).

3.2. Polycyclic aromatic hydrocarbons (PAHs) The concentrations of total PAHs are calculated on a dry-weight basis and their vertical profiles are shown in Fig. 2 and Tables S1 and S2. The CQ1 profile (Fig. 2) exhibit low concentrations (60.06 lg g 1 dry wt.) between 60 and 100 cm and a major increase is noted between 31 and 11 cm (0.58–3.53 lg g 1 dry wt.). Near surface layers (first 10 cm) display the maximum concentrations of total PAHs for this core (>4.00 lg g 1 dry wt.), with a major peak at 3 cm (7.55 lg g 1 dry wt.). The LSR core present the lowest total PAHs concentrations between the 100 and 51 cm (1.50 ± 0.27 lg g 1 dry wt.); then there is a predominant increase to 3.67 lg g 1 dry wt. at the 35 cm. An abrupt decrease of total PAHs at 35 cm is followed by generally consistent concentrations between 33 cm and the top of the core (3.26 ± 0.20 lg g 1 dry wt.). The LCN core profile has the highest concentrations of total PAHs of the three cores with a maximum occurring between the 55 and 51 cm (7.90 ± 0.71 lg g 1 dry wt.). Lower concentrations occur between the 140 and 89 cm (mean = 1.78 ± 0.35 lg g 1 dry wt.). Three distinct peaks or spikes occur in the LCN core profile with the following patterns of concentrations. The first peak occurs between 87 and 61 cm (6.94 lg g 1 dry wt., at 73 cm), followed by an abrupt decrease to relative constant concentrations between 69 and 61 cm, with a mean concentration of (1.84 ± 0.29) lg g 1 dry wt. Next, a progressive increase of total PAHs is noted between 59 cm (3.64 lg g 1 dry wt.) and 51 cm (8.68 lg g 1 dry wt.) when the second maximum is detected. A new major decrease occur between 47 and 35 cm (7.16–0.97 lg g 1 dry wt.) followed by an increase in the concentrations of total PAHs between 33 cm and the top core (1.14–5.93 lg g 1 dry wt.) with a third maximum at 17 cm (5.94 lg g 1 dry wt.). In general, most Santos Estuary sediments can be considered moderately contaminated as they rank between sediments in pristine regions (Antarctica) and highly contaminated regions (USA and tropical Asia). Near McMurdo Station, USA, (0.62–5.02 lg g 1 dry wt.; Kim et al., 2006) and Admiralty Bay, close to Brazilian Station (>0.45 lg g 1 dry wt.); Martins et al., 2010a) are less contaminated than Santos Estuary. In other coastal/estuarine areas, concentrations of Santos Estuary are comparable in total PAHs in sediments (0.5–10.5 lg g 1 dry wt. at Cienfuegos Bay, Cuba; Tolosa et al., 2009) and (0.13– 7.34 lg g 1 dry wt. at Yangtze River Delta China, Chen et al., 2004). Locations with higher concentrations of total PAHs in sediments include Narragansett Bay, USA (1943 lg g 1 dry wt.; Hartmann et al., 2005) and highly populated cities in tropical Asian countries (174 locations in India, Indonesia, Malaysia, Thailand, Vietnam, Cambodia, Laos, and the Philippines: mean = 11.3 ± 12.1 lg g 1 dry wt.; Saha et al., 2009). In relation to previous studies in Santos Estuary, the maximum concentration found in this study (8.68 lg g 1 dry wt.) is lower compared to results reported by Nishigima et al. (2001) (42.3 lg g 1 dry wt.), Medeiros and Bícego (2004) (15.4 lg g 1 dry wt.) and Bícego et al. (2006) (68.1 lg g 1 dry wt.). Spatial differences in the sampling sites. In relation to previous studies of sediment contamination of Santos Estuary, maximum concentrations of total PAHs from our study (8.68 lg g 1 dry wt.) are lower than those of three other previous studies: (a) 42.3 lg g 1 dry wt. (Nishigima et al., 2001); (b) 15.4 lg g 1 dry wt. (Medeiros and Bícego, 2004), and (c) 68.1 lg g 1 dry wt. (Bícego et al., 2006). The spatial differences in the sampling sites are the main reason to explain the high variability between the present study and the others cited above. Another method for evaluation of the degree of contamination is to compare contaminant concentrations with sediment quality guidelines that are based upon toxicological responses of benthic

455

C.C. Martins et al. / Marine Pollution Bulletin 63 (2011) 452–458

An / 178

Total PAHs (µg.g-1) 2.00

4.00

6.00

8.00

0.00

0.10

0.20

0.30

Fl / (Fl + Py) 0.40

0.50

0.20

0.30

0.40

BaA / 228

0.50

0.60

0.20

0.35

0.50

0.65

IP / (IP + Bghi) 0.80

0.95

0.30

0.40

0.50

0.60

0.70 2002

10

1995

III

1988

30

1982

40

1975 Sewage, Biomass & Coal Combustion

50 world oil crisis (?)

60

1968 0.50 is dominance of coal and biomass (grass and wood) burning, and; (d) IP/IP + Bghi < 0.20 is dominance of petroleum, 0.20–0.50 is dominance of petroleum combustion, and >0.50 is dominance of combustion of coal and biomass (grass and wood). Ratios were only calculated in samples where the PAH concentration exceed 0.01 lg g 1 dry wt., following Martins et al. (2010a) guidance that values close to the detection limits produce unreliable ratio data. In the evaluation of CQ1 core, the An/178 and BaA/228 isomer pair ratios show PAHs are derived primarily from combustion and not petroleum (Fig. 2). The Fl/Fl + Py isomer pair ratios show PAHs associated with the direct introduction of petroleum and derivatives between 41 and 13 cm (ca. 1975–1994), presumably as soil drainage from the solid waste disposal sites. After 1995 (in the first 10 cm of CQ1), there is a marked input of petroleum combustion-derived PAHs, which could be attributed to the burning of plastic products, disposed near the Casqueiro River. Finally, other sources of PAHs were identified as derivatives of biomass and coal combustion (IP/IP + Bghi isomer pair ratios). It is arguably the biomass combustion that occurs along the margins of the estuary where the human populations are concentrated, whilst coal combustion is associated with industrial activities, particularly metallurgical production. Combustion processes are the main sources of PAHs in LSR and LCN. It is clearly identified by An/178, BaA/228 and IP/IP + Bghi isomer pair ratios. The higher values indicate the burning of fossil fuels, extensively used as power supply by industries and shipping traffic inside the estuary. Coal combustion, indicated by IP/IP + Bghi is related exclusively to iron-metallurgical industries because hydroelectricity and petroleum are the main sources of energy for human activities in this region. The Fl/Fl + Py isomer pair ratios show multiple sources of PAHs according to depth. They are associated with the direct introduction of petroleum or its derivatives between 89 and 85 cm (