Landfill leachate as a source of polycyclic aromatic hydrocarbons (PAHs) to Malaysian waters

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Organic chemicals of environmental concern are those with known or potentially deleterious effects on natural resources and humans. These compounds are referred to as micro-organic pollutants. Polycylic aromatic hydrocarbons (PAHs) are one of the most important classes of anthropogenic micro-organic pollutants that have long been the interest of environmental chemists. This concern arises primarily from the fact that a small fraction of the PAHs generated and released to environment has been shown to be carcinogenic and mutagenic to mammals. PAHs have also been reported to disrupt endocrine system in humans. Landfilling and disposing of wastes in open dumpsites have been and is expected to remain the most common method for the disposal of municipal solid wastes in Malaysia. In 1990, there were about 230 official municipal dump sites in Malaysia. In 1994, the amount of wastes generated and collected in Kuala Lumpur was around 3 million kg/day In the year 2000, the amount of wastes generated has increased to about 7.9 million kg/day and is expected to increase to more than 11 million kg/day in 2010. This study focused on 2 landfill sites in Malaysia : Taman Beringin and Ulu Maasop landfills. The Taman Beringin landfill is located in the city of Kuala Lumpur (representing an urban area) while the Ulu Maasop landfill is located in Negeri Sembilan (representing a rural area). Taman Beringin landfill receives a mixture of municipal, commercial, agricultural, recreational, domestic and mixed industrial wastes originating from households and industrial premises while the Ulu Maasop landfill receives mostly domestic waste. Leachate from both landfills are directly discharged into the adjacent rivers. The objective of this study is to understand the composition and sources of compound-specific PAHs in the landfill leachates and to understand their transport pathways. Leachate, river water and sediment samples were collected at the landfill sites in 2003. The leachate samples were subjected to liquid-liquid extraction using a mixture of 1 : 1 toulene : methanol and re-extracted twice with hexane. Water samples were filtered and the filtrate containing particulate matter were freeze-dried and soxhlet-extracted. Sediment samples were freeze-dried and soxhlet-extracted with dichloromethane. All the extracts were purified and fractionated by a method described by Zakaria et al., 2002. PAHs were analyzed by gas chromatography mass spectrometry (GC-MS). This is the first report of compound-specific PAHs in landfill leachates in Malaysia. High concentrations of PAHs were detected in the leachate, river particulate and sediment samples for both landfills sites. Total PAHs concentrations in the Taman Beringin leachate, river particulates and sediments ranged from 9.9-575.6ng/g dry wt, 3.9-5.0ng/g, and 1.5×10^5ng/g, respectively while PAHs concentrations for the Ulu Maasop leachate, river particulates and sediments range from 11.8-2836ng/g dry wt., 3783-5904ng/g, and 1.31×10^4-3.06×10^5ng/g, respectively River-borne particulate matter is an important carrier of land-based contaminants to the ocean. Particulate matter adsorbs various organic and inorganic pollutants such as PAHs and heavy metals and carries these contaminants along with them and are finally deposited in coastal and open oceans. Landfill sites in Malaysia are normally situated near major towns and rivers. Direct discharge of leachates to these rivers will enhance the transport of organic contaminants such as PAHs to the coastal environments and open oceans. The study has demonstrated that PAHs in leachate pose potential PAH pollution in Malaysian waters. Additional inputs of PAHs from landfill leachate must therefore be controlled to preserve the coastal ecosystems in Malaysia.
東京大学の論文
2005-01-31

Landfill leachate as a source of polycyclic aromatic hydrocarbons (PAHs) to Malaysian waters

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