Membrane and Water Treatment, Vol. 11, No. 6 (2020) 391-398 DOI: https://doi.org/10.12989/mwt.2020.11.6.391 391 Copyright © 2020 Techno-Press, Ltd. http://www.techno-press.org/?journal=mwt&subpage=7 ISSN: 2005-8624 (Print), 2092-7037 (Online) 1. Introduction The dissolved organic matter (DOM) normally found in aquatic environments has a wide range of properties (Montserrat, 2009; Jin et al. 2018), and can be classified as either allochthonous or autochthonous (Kornegay, B.H et al. 2000). Allochthonous organic matter originates from soil. It is hydrophobic due to the corrosion of its organic content, which consists mainly of plant and animal matter. Autochthonous organic matter refers to the natural organic matter (NOM) produced by the metabolic activity of microorganisms – typically bacterial and algae byproducts which are characterized by their polarity and hydrophilicity (Thurman 1985). The chemical composition, molecular weight, and structure of organic matter vary depending on regional and environmental characteristics, but typically has a complex molecular structure (Uyguner and Bekbolet 2011). The representative substance for allochthonous Co-Corresponding author, Ph.D. E-mail: bosung@kwater.or.kr Co-Corresponding author, Professor E-mail: ub1905ub@korea.ac.kr NOM is humic acid, which has several functional groups including alcohol, carboxyl, and ketone. These compounds are highly capable of combining with ionic molecules to form complexes (Thurman 1985). Generally, NOM that has high aromatic carbon content, especially that which is hydrophobic and has a high molecular weight, is known to be a precursor to disinfection by-products (DBPs) when reacting with chlorine (Bond et al. 2009, Trang et al. 2012). When algal blooms occur frequently in drinking water reservoirs, general water treatment operators and utility officers typically express concern regarding the role of aesthetic pollutants and toxic substances such as microcystin. Algal blooms are produced by freshwater cyanobacteria, primarily species of the microcystis genus. Microcystin is a toxic substance secreted by blue-green algae or cyanobacteria, such as microcystis, oscillatoria, and anabaena, the chemical structure of which contain a ring peptide (Park et al. 2008). The most common microcystin is microcystin-LR (MCLR), where the variable L-amino acids are leucine (L) and arginine (R) (Dawson 1998). Several researchers found that microcystin ingestion causes liver damage (Ned et al. 2009). For remediating these pollutants, water treatment systems generally use a disinfectant process such as chlorination, which successfully removes algal toxins (Yansen et al. 2016). Chlorine is the most widely used disinfectant in drinking water systems, even though its Impact of DBPs on the fate of zebrafish; Behavioral and lipid profile changes Hyojik Yoon 1,2 , Yunsu Lim 3 , Sungkyu Maeng 4 , Yongsuk Hong 1,2 , Seokjong Byun 5 , Hyun-Chul Kim 6 , Byoungsoo Kim 1,2,7 and Sungpyo Kim 1,2 1 Department of Environmental Engineering, Korea University, Sejong 30019, Republic of Korea 2 Program in Environmental Technology and Policy, Korea University, Sejong 30019, Republic of Korea 3 BKT Co. Ltd., 25 Yuseong-daero 1184 beon-gil, Yuseong-gu, Daejeon 34109, Republic of Korea 4 Department of Civil and Environmental Engineering, Sejong University, Seoul 05006, Republic of Korea 5 Department of Research and Development, Jeollanamdo Environmental Industries Promotion Institute, Jeollanam-do 59205, Republic of Korea 6 Research Institute for Advanced Industrial Technology, Korea University, Sejong 30019, Republic of Korea 7 Department of Clean Water Supply Facilities Maintenance, K-water, Daejeon 34350, Republic of Korea (Received April 28, 2019, Revised November 25, 2020, Accepted November 27, 2020) Abstract. In recent years, the generation of disinfectant by-products (DBPs) in drinking water system has been highlighted for their potential negative impact on humans. A commonly used disinfectant, chlorine, produces a by-product which is highly hazardous and a known carcinogen. This study investigated the toxic effects of DBPs from several organic matter as a function of contact time with chlorine-based disinfectants were investigated using zebrafish. The results indicated that the generation of DBPs was dependent on the composition of dissolved organic matter (DOM) in water. Suwannee river natural organic matter and experimental site water sample (complex DOM) were almost 2.5 times higher than that of a single dissolved organic matter, such as microcystin-LR (MCLR) at 120 min. The behavior of zebrafish was significantly affected by complex composition DOM. In vivo biomarker analysis result from lipid profile analysis, reaction in vivo showed different depending on the composition of the DOM. Through this study, the effect of DBPs were observed via lipid metabolic and movement changes in aquatic organisms can be considered as a new biomarker for the drinking water risk assessment. Keywords: dissolve organic matter(DOM); disinfection byproducts(DBPs); toxicity assessment