ABSTRACT
Persistent organic pollutants (POPs) are globally distributed and readily detected in the environment, even in remote regions of Earth with no historical usage (Iwata et al., 1993; Stern et al., 1997; Kallenborn et al., 1998; Yao et al., 2002). POPs encompass a wide range of xenobiotic chemicals, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) such as chlordanes, hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT), and related compounds. Such compounds are of great concern due to their persistence, carcinogenicity, and endocrine-disrupting effects. The tendency of POPs to undergo bioaccumulation in the food chain has also led to concerns regarding their ecotoxicology, and about which residues pose the greatest threat to humans, marine mammals, and other wildlife (Skaare et al., 2002; Tanabe, 2002). POPs have, for example, been reported as having an effect on the endocrine systems of polar bears, thereby indicating the potential of these chemicals to impact mammals at the top of the marine food web (Oskam et al., 2004). The atmosphere is considered to be the predominant pathway for long-range transport of POPs toward polar regions, where condensation and deposition of these compounds occurs on land, sea, and ice. However, less hydrophobic POPs (i.e., HCH isomers) are also carried into the Arctic environment through water currents (Li et al., 2004; Li and Macdonald, 2005), whereas strongly hydrophobic POPs (i.e., highly chlorinated PCBs and brominated PBDEs) are associated with sinking particles and transport pathways in the deep ocean (Gustafsson et al., 1997; Axelman and Broman, 2001). River outflows often carry elevated levels of POPs (i.e., Zhulidov et al., 2000; Zhang et al., 2003; Carroll et al., 2008) and are a major source of such compounds in coastal and estuarine environments. As such, POPs have the potential to threaten fish and bivalve populations (Bayen et al., 2007; Lema et al., 2007) as well as aquaculture operations in coastal waters (Sapkota et al., 2008; Shaw et al., 2008), justifying monitoring programs in these areas.
