Toxicological Effects of Chlorophenols to Green Algae in Case of Coexisting Humic Substances

Abstract

Chlorophenols are well known as various pesticide, herbicide, wood preservative and defoliant. Whereas, they are also known as pollutants having strong toxicity to aquatic organisms such as phytoplankton. Nowadays, they have been discussed about effect of pesticides to the health of human beings, but less to ecosystem. The toxicity of pollutants such as heavy metals and HOPs (Hydrophobic Organic Pollutants) is influenced by coexisting dissolved organic matter (DOM). Majority of DOM consists of humic substances such as fluvic acid and humic acid (HA) derived from microbiological metabolisms in soil environment. The objective of this study is to elucidate the effect of coexisting HA to the toxicity of chlorophenols to Chlorella. Algal growth inhibition (AGI) test was chosen to examine the toxicity of chlorophenols as growth inhibition rate following the OECD guideline 201. Chlorella was selected to test organism as the representative of phytoplankton. Chlorophenols including 2,4,6-trichlorophenol (2,4,6-TCP), 2,4-dichlorophenol (2,4-DCP) and p-chlorophenol (P-CP), and pentachlorophenol (PCP) were examined. Several different concentrations (100, 50, 25, 5, 0.5 ppm) of chlorophenols were exposed to Chlorella. The cell density was measured by absorbance measurement (λ=690 nm) at 24 h and 72 h of administered time. Results of no coexisting and coexisting 10 ppm HA were compared. It was predicted that coexisting HA decreases the toxicity of chlorophenols because of adsorption. Whereas, some enhancement of toxicity was observed at several concentrations in case of 2,4,6-TCP. It was assumed that HA acts as mediator of chlorophenols to the inside of phytoplankton cells, then the toxicity was enhanced. In recent years, interactions of HA to metabolisms of organisms have been studied in fact. This study suggests that HA could be enhancer of toxicity at water environment. Interesting Effects of coexistence of HA to the toxicity of chlorophenols including 2,4,6-DCP and p -CP were also observed. *Corresponding authors: Daisuke Suzuki, Department of Chemical Science and Engineering, National Institute of Technology, Tokyo College, Tokyo 193-0997, Japan, Tel: 81426685111; E-mail: dsuzuki8forb@gmail.com Ryo Shoji, Department of Chemical Science and Engineering, National Institute of Technology, Tokyo College, Tokyo 193-0997, Japan, Tel: 81426685076; E-mail: shoji@tokyo-ct.ac.jp Received August 09, 2018; Accepted August 16, 2018; Published August 21, 2018 Citation: Suzuki D, Shoji R (2018) Toxicological Effects of Chlorophenols to Green Algae in Case of Coexisting Humic Substances. J Environ Anal Toxicol 8: 584. doi: 10.4172/2161-0525.1000584 Copyright: © 2018 Suzuki D, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Citation: Suzuki D, Shoji R (2018) Toxicological Effects of Chlorophenols to Green Algae in Case of Coexisting Humic Substances. J Environ Anal Toxicol 8: 584. doi: 10.4172/2161-0525.1000584