Distribution, characterization and origins of Polycyclic Aromatic Hydrocarbons (PAHs)in surficial sediment of Penang, Malaysia: the presence of fresh and toxic substances

Petroleum hydrocarbon pollution is one of the most serious problems facing by many developing countries including Malaysia. One class of petroleum hydrocarbon is Polycyclic Aromatic Hydrocarbons (PAHs). PAHs are made up of large group of compounds but semi volatile comprising of 2 to 7 rings are considered toxic to human health. There are 16 semi-volatile PAHs classified as priority pollutants by USEPA some of which have been shown to disrupt endocrine systems in human. Twenty surface sediments were collected along South and North of Penang Bridge (Prai Straits) covering industrial, urban, shipping lane, tourism attraction and fishing grounds. The samples were dried with anhydrous sodium sulfate and extracted with Soxhlet extraction, treated by activated copper to remove the elemental sulfur, then purified and fractionated with 2-steps column chromatography. PAHs fraction were collected and subsequently injected into Gas Chromatography - Mass Spectrometry (GC-MS) using selected ion monitoring mode. Compound-specific PAHs were qualified by comparing the retention times of native standard previously run in the same machine with identical conditions. PAHs were quantified and recovery-corrected using a known concentration of internal injection standard spiked just before the GC-MS analysis. Total concentration of PAHs in the sediment ranged from 391 to 554204 ng/g dry weight. The ratio of the sum methylphenanthrenes to Phenantherene (MP/P), an index for sources of PAHs, shows that 16 stations have MP/P values of less than 1 indicating pyrogenic origin. These results indicate that the area receives pyrogenic PAHs from long range atmospheric input. This study found that the trend of previous petrogenic input into the environmental compartment of Peninsular Malaysia is changed possibly due to strict environmental regulations on the release of petroleum products in Penang the source has been moved to the pyrogenic

Tracing the untraceable: fingerprinting pollutants through environmental forensics

Investigation of source, distribution and transport pathways of compound-specific petroleum hydrocarbon pollution is not well documented in Malaysia. In the beginning, research on petroleum hydrocarbon pollution was bulk analysis in nature. Bulk analysis of petroleum hydrocarbons gives a broad spectrum of total petroleum hydrocarbon pollution that may also include non-toxic biogenic (natural) sources. Since petroleum hydrocarbon consists of many classes of hydrocarbons and each of them has different characteristics and toxicities, compound-specific analysis of the pollutants is necessary. Therefore, in the late 1990’s, intense research by our group on compound-specific petroleum hydrocarbon opened a new phase in Malaysia using environmental forensics and fingerprinting techniques. Intensive research on the source, distribution and transport pathways of compound-specific petroleum hydrocarbon pollution was conducted in terrestrial, atmospheric and aquatic environments in Malaysia. It was found that sediments from Malaysian rivers and estuaries are contaminated with petrogenic polycyclic aromatic hydrocarbons. Furthermore, Malaysian rivers and estuaries were found to be contaminated with PAHs originated from landfill leachates. Major contributor of land-based petroleum hydrocarbon pollution was that of the used-crank case oil. Malaysian coastal beaches were also contaminated with tar balls pollution originated from previous offshore oil spills by foreign oil tankers and domestic oil spillages. PAHs were also found in coastal marine organisms including fishes in aquaculture cages. Atmospheric transport of pyrogenic PAHs in Malaysia was influenced by mobile sources such as motor vehicles and biomass burning. Monitoring of PAHs using our techniques was applied to Asian countries and results showed that petroleum hydrocarbon pollution is widespread and pose significant human health threat. Our research covers land, atmospheric and sea-based sources of petroleum hydrocarbon pollution. Our research style and techniques are now applied to other contaminants of human concern such as pharmaceutical and personal care products (PCPPs), sewage pollution, PFOA and PFOS, PBDE, and heavy metals, among others. This lecture will take a closer look at the research and our major contribution to knowledge for scientific and general communities at large