Organochlorine Pesticide Residues in the Major Rivers of Southern Thailand
Abd Naser Haji Samoh a and Md Sani Ibrahim b
a Faculty of Science and Technology, Yala Rajabhat University, Yala 95000, Thailand
b School of Chemical Sciences, University Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia
Received 20 August 2008; Accepted 28 September 2008
Abstract
Environmental contaminations by organochlorine pesticides (OCPs) of inland water have been a global issue, since most of these compounds are very persistent, bioaccumulative and toxic compounds. Due to the widespread use of DDT for malaria vector eradication programs in the past and no comprehensive works have been conducted to assess trace organic pollutants in river waters, this work is the first effort to assess the contamination levels of OCPs in the major rivers of Southern Thailand. The objectives of this study were to determine the concentration levels of OCPs and oil and grease in the 3 major rivers and to compare the present results with surrounding regions for further assessment of OCPs contamination status in inland waters of Southern Thailand. The water samples were collected along the 3 major rivers (Saiburi, Patani and Tiba River) during June 2007-February 2008. Water samples were solid phase extracted with Supelco C-18 cartridge (1g/6 mL) and quantified by gas chromatograph (GC-ECD). The concentration of oil and grease was determined by gravimetric method and reported as hexane extractable material (HEM) and silica gel treated hexane extractable material (SGT-HEM). Several parameters of waters such as total suspended solid, pH, turbidity, and conductivity were measured. The commonly found OCP residues in these rivers were β-HCH, γ-HCH, heptachlor epoxide, endosulfan 1, p,p’- DDE and endrin aldehyde. The overall results showed that Saiburi River was more polluted with OCPs than Patani and Tiba River, especially p, p’-DDE which was detected in the wide range concentration of 9.6 to 203.1 ng/mL. For oil and grease contamination, Tiba River waters were found to be more polluted than either Patani or Saiburi River. The experimental procedures and analytical results together with the possible sources of OCPs and its environmental impacts are presented.
Keywords: organochlorine pesticides; solid phase extraction; oil and grease; river water; southern Thailand
* corresponding author : Dr. Abdulnaser Hajisamoh