Seasonal and spatial distribution of nonylphenol in Shihwa Lake, Korea Zhengyan Li a,b , Donghao Li a, * , Jae-Ryoung Oh a , Jong-Geel Je a a South Sea Institute, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje-shi, Gyungsangnamdo 656-834, South Korea b College of Environmental Science and Engineering, Ocean University of China, 5 Yushan Rd, Qingdao 266003, PR China Received 5 May 2003; received in revised form 24 March 2004; accepted 20 April 2004 Abstract Alkylphenols (APs) have been known as endocrine disruptors and consequently received much environmental concern. This study focused on seasonal variation and spatial distribution of nonylphenol (NP) in various matrixes including dissolved water, particulates, surface sediment, sediment trap and sediment core taken from Shihwa Lake and its adjacent areas. A total of 11 phenolic compounds including nonylphenol, t-octylphenol (t-OP) and bisphenol A (BPA) were measured in February, June and October 2002. NP is the most abundant chemical among the phenolic compounds and its concentrations in dissolved water, particulates and surface sediments from Shihwa Lake were measured as 17.4–1533.1 ng/l, 4.3–831.2 ng/l and 10.4–5054.1 ng/g dw, respectively. NP concentration in dissolved water varied with seasons and generally showed a decreasing order of June > October > February, while the seasonal trend was hardly found in sediment. High levels of NP were measured in surrounding industrial complexes, the con- centrations was decreased gradually with distance from the industrial areas. NP in core samples showed an increasing trend toward the core depth. There exists a reasonable correlation between NP in dissolved water and in particulates, whereas the correlation between NP in dissolved water and in sediments is not significant. APs concentrations in Shihwa Lake were comparable to other highly polluted areas of the world and their possible effects on various organisms in the lake are discussed. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Alkylphenols (APs); Nonylphenol (NP); Endocrine disruptors; Shihwa Lake 1. Introduction Alkylphenol ethoxylates (APEs) are a group of nonionic surfactants, which have been widely used since 1940s (White et al., 1994) in domestic, agricultural and industrial applications such as detergents, pesticide for- mulation, emulsifiers, wetting agents and dispersing agents. Approximately 500,000 tons of APEs are pro- duced globally in each year, in which nonylphenol eth- oxylates (NPEs) account for about 80% (Ying et al., 2002). APEs are unstable in aquatic environment with a half-life of several days and are subject to degradation to alkylphenols (APs) mainly through bio- and photo- degradation (Yoshimura, 1986). APs such as nonyl- phenol (NP) and octylphenol (OP) are, however, much more stable in the environment with a half-life of about two months in water and even years in sediments (Ying * Corresponding author. Tel.: +82-55-639-8672; fax: +82-55- 639-8689. E-mail address: dhli@kordi.re.kr (D. Li). 0045-6535/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2004.04.022 Chemosphere 56 (2004) 611–618 www.elsevier.com/locate/chemosphere