Concentrations and Sources of Polycyclic Aromatic Hydrocarbons in the Seawater around Langkawi Island, Malaysia

Hindawi Publishing Corporation Journal of Chemistry Volume 2013, Article ID 975781, 10 pages http://dx.doi.org/10.1155/2013/975781 Research Article Concentrations and Sources of Polycyclic Aromatic Hydrocarbons in the Seawater around Langkawi Island, Malaysia Essam Nasher,1 Lee Yook Heng,1,2 Zuriati Zakaria,3 and Salmijah Surif1 1 Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor, 43600 Bangi, Malaysia Southeast Asia Disaster Prevention Research Institute (SEADPRI), Universiti Kebangsaan Malaysia, Selangor, 43600 Bangi, Malaysia 3 Malaysia Japan International Institute of Technology, Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia 2 Correspondence should be addressed to Essam Nasher; essam Received 12 November 2012; Revised 28 December 2012; Accepted 10 January 2013 Academic Editor: Athanasios Katsoyiannis Copyright © 2013 Essam Nasher et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper reports the levels of polycyclic aromatic hydrocarbons (PAHs) in the water around the Island and their probable sources. Water samples were collected from four jetties and three marine fish farms around the main Langkawi Island and analysed for 18 polycyclic aromatic hydrocarbons (PAHs) in December 2010. The total PAH concentrations ranged from 6.1 ± 0.43 to 46 ± 0.42 𝜇gL−1 , which exceed the maximum admissible concentrations of PAHs (0.20 𝜇gL−1 ) for the water standard of European Union. The calculated diagnostic benzo[a]anthracene : benzo[a]anthracene + chrysene ratio of between 0.52 and 1.0 suggests that the sources of PAHs at the majority of the stations studied are derived primarily from pyrogenic sources, from incomplete fuel combustion of the boats and vehicle engines, with lesser amounts of PAHs contributed from petrogenic sources. Some stations displayed mixed sources. A significant positive correlation was found between total organic carbon (TOC) and the concentrations of the high-molecular-weight PAHs (𝑟2 = 0.86, 𝑃 < 0.05), which suggests significant secondary sources of PAHs, such as those from atmospheric deposition. 1. Introduction The Langkawi Archipelago in the Straits of Malacca, north west of Peninsular Malaysia consists of 104 Islands, the largest and most exploited of which is Langkawi Island with an area of 478.5 km2 . Targeted for ecotourism, Langkawi became a duty-free island in 1987 and is protected from industrial activity [1]. In 2006, the Island was declared a National Geopark; a year later it became an UNESCO Global Geopark [1]. In 2010, 2.4 million tourists visited Langkawi [1]. To cater for this increase in tourism-related activities, the local population swelled significantly from about 40,000 in 1991 to almost 100,000 in 2010 [2]. It is envisaged that this boost in tourism industry would significantly increase pollution in Langkawi, particularly from the boating activities which use petroleum and diesel. One of the most significant polluting components of petroleum is polycyclic aromatic hydrocarbons (PAHs). PAHs are a group of over 100 different compounds with fused benzene rings [3], prominent in smoke, soot, and exhausts resulting from the incomplete combustion of carbon compounds, such as petroleum [4]. The environmentally significant PAHs are those molecules that contain 2 to 7 benzene rings. PAHs are divided into two groups based on their physical, chemical, and biological characteristics [5]. The lower-molecular-weight PAHs, for example, the 2 to 3 rings of PAHs such as naphthalenes, fluorenes, phenanthrenes, and anthracenes, have significant acute toxicity to aquatic organisms. The high-molecular-weight (HMW) PAHs, containing 4 to 7 rings, from chrysenes to coronenes, do not cause acute toxicity but are known to be carcinogenic [6]. Sixteen PAH compounds have been identified as priority pollutants due to their toxic, mutagenic, and carcinogenic characteristics [7]. Due to their low water solubility and high lipophilicity, PAHs are easily and rapidly absorbed by organisms and can be accumulated in aquatic organism or adsorbed onto the surface of suspended matter, get deposited on the sea floor and be passed onto the marine food chain. 2 Journal of Chemistry 99∘ 50󳰀 E 99∘ 55󳰀 E 06∘ 25󳰀 N 06∘ 20󳰀 N Kuah S1 06 15 N 7∘ 6∘ 6∘ Kedah Pulau Pinang 3∘ South China Sea Malaysia St ra its of M a la 5∘ 4∘ 3∘ cc a 2∘ 100 ∘ ∘ 101 ∘ 102 ∘ 103 ∘ 104 ∘ 󳰀 06 15 N P. Ular S5 S6 0 80 (km) 2∘ S4 󳰀 7∘ P. Timun S7 ∘ 104 ∘ 8∘ 4∘ S. Melaka Langkawi Port 103 ∘ N 5∘ Pulau Langkawi 06∘ 20󳰀 N 102 ∘ Thailand 06∘ 25󳰀 N S2 Telaga S3 Harbour 101 ∘ 100 ∘ 8∘ Langkawi island 99∘ 45󳰀 E S. Ki lim 99∘ 40󳰀 E Pulan Dayang Bunting 06∘ 10󳰀 N 06∘ 10󳰀 N 99∘ 40󳰀 E 99∘ 45󳰀 E 99∘ 50󳰀 E S1 Sampling station 99∘ 55󳰀 E N 3 0 (km) Figure 1: Map showing the seven sampling stations (S1–S7) around Langkawi Island, Malaysia. Sources of PAHs can be either petrogenic, from petroleum-related activities or pyrogenic (pyrolytic), from the incomplete combustion of diesel fuel and engine oil [8], wood, coal, biomass of forest, grass fires, waste incinerators, and fossil fuels that are used in industrial operations and power plants [9–12]. PAHs are also widely used in commercial products, such as intermediaries in pharmaceuticals, agricultural products, photographic products, thermosetting plastics, and lubricating materials. In the marine environment, the pollution from PAHs can result from natural seepage or land-based sources, from river discharges, urban runoff, refineries and other industrial wastewater [6], or from sea-based sources, such as two-stroke vessel discharge, nontank vessel spills, operational discharge, gross atmospheric deposition, and aircraft dumping [13]. These possible sources of PAHs can be differentiated by their respective diagnostic ratios [14]. A phenanthrene-toanthracene ratio (Phe/Ant) of >15 indicates that the PAHs are petrogenic, whereas a ratio of <10 shows that they are pyrolytic in origin [15]. Few studies have been done on the concentration of hydrocarbons in the water and the sediment of Langkawi Island. Law and Hii [16] reported that the hydrocarbon (polycyclic compounds and PAHs) concentrations in the seawater at Pulau Payar, to the south of Langkawi Island ranged from 32 to 46 𝜇g L−1 which is lower than the contamination level of hydrocarbons (50 𝜇g L−1 ) in the tropical sea [16]. The total PAHs in sediments collected from Langkawi Island after an oil spill accident ranged from 34 to 2.7 × 102 𝜇g kg−1 [17]. Abdullah [18] reported a high level of total hydrocarbons in the sediments of Langkawi Island, up to 8.5 × 102 mg kg−1 , which is higher than the safety level (1.0 × 102 mg kg−1 ) [19]. The high level was attributed to the oil spilled by the collision between the supertanker Nagasaki Sp (...truncated)