Seasonal and spatial distribution of nonylphenol and IBP in Saemangeum Bay, Korea Donghao Li a, * , Meihua Dong a , Won Joon Shim a , Sang Hee Hong a , Jae-Ryoung Oh a , Un Hyuk Yim a , Jee Hyun Jeung a , Narayanan Kanan a , Eun Soo Kim b , Sung Rok Cho b a South Sea Institute, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje-shi, Gyungsangnamdo 656-834, Republic of Korea b Ocean Climate & Environment Research Division, Korea Ocean Research and Development Institute, Sadong 1270, Ansan City, Kyunggido 426-744, Republic of Korea Abstract In order to investigate spatial and temporal distribution of organic pollutants in the Saemangeum Bay, organophosphorus pes- ticides (10), alkylphenols (8), chlorophenols (2), bisphenol A were analyzed from the surface seawater taken in 2002–2003. Most of the analytes were not detected in all stations except nonylphenol and S-benzyl-O,O-di-isopropyl phosphorothioate (IBP). Concen- trations of nonylphenol and IBP ranged from ND to 298 ng/l and from ND to 1840 ng/l, respectively. The high levels of nonylphenol and IBP were found in the estuary areas of Mangyeong and Dongjin River. The levels of nonylphenol and IBP in surface seawater varied through seasons and the high levels of nonylphenol and IBP were in summer season (August). Based on real time monitoring of IBP and on correlation between concentrations of target compounds and contents of salinity in seawater, physical mixing and diffusion of seawater were found to be the major factors that affect the spatial distribution of IBP and nonylphenol in the Saemang- eum Bay environment. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Pesticides; Organophosphates; Alkyl phenols; Korea 1. Introduction Although organophosphorus pesticides (OPs) are cholinesterase inhibitors on living organisms (Jamal, 1997; Ray, 1998), it has been widely used in agriculture for crop production in the world due to its excellent insecticidal activity and its relatively low persistence in the environment (Pehkonen and Zhang, 2002; Medina et al., 1999). During the last several decades, it was de- tected in various matrices such as river (Zhang et al., 2002), seawater (Yu et al., 2001), sediment samples (Liess et al., 1999) and organisms (Sapozhnikova et al., 2004). During the last 14 years, approximately 250 tons of pesticides were used each year in South Korea, in which OPs account for about 60% (Agricul- tural Chemicals Industrial Association, 2001). Yu et al. (2001) reported that most estuaries were contaminated with moderate levels of OPs in warmer season in Korea. Nonylphenol is a degradation product of nonylphe- nol polyethoxylates (NPnEOs) that is used as nonionic surfactant and detergent in industrial and domestic applications in the last five decades (Giger et al., 1984). Although nonylphenol is an endocrine disruptor, many countries consumed large quantity of its parent compound until now because it is inexpensive but pow- erful in its cleaning property. According to our recent studies, high levels of nonylphenol were found in lake (Li et al., 2004a), rivers (Li et al., 2004b) and vicinity of industrial area (Li et al., 2004a; Li et al., 2004c) in Korea. 0025-326X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2004.11.006 * Corresponding author. Tel.: +82 55 649 8672; fax: +82 55 639 8689. E-mail address: dhli@kordi.re.kr (D. Li). www.elsevier.com/locate/marpolbul Marine Pollution Bulletin 51 (2005) 966–974