title: The effect of natural organic matter on bioaccumulation and toxicity of chlorobenzenes to green algae.
abstract: The effect of natural organic matter (NOM) on toxicity and bioavailability of hydrophobic organic contaminants (HOCs) to aquatic organisms has been investigated with conflicting results and undefined mechanisms, and few studies have been conducted on volatile HOCs. In this study, six volatile chlorobenzenes (CBs) with 1-6 chlorine substitutions were investigated for their bioaccumulation in an acute toxicity to a green alga (Chlorella pyrenoidosa) in the presence/absence of Suwannee River NOM (SRNOM). The fluorescence quenching efficiency of SRNOM increased as the number of chlorine substitutions of CBs increased. SRNOM increased the cell-surface hydrophobicity of algae and decreased the release rates of algae-accumulated CBs, thus increasing the concentration factor (CF) and accumulation of the CBs in the algae. SRNOM increased the toxicity of monochlorobenzene and 1,2-dichlorobenzene, decreased the toxicity of pentachlorobenzene and hexachlorobenzene, and had no significant effect on the toxicity of 1,2,3-trichlorobenzene and 1,2,3,4-tetrachlorobenzene. Relationships between the 96 h CF/IC50 (i.e., the CB concentration leading to a 50% algal growth reduction compared with the control) and physicochemical properties of CBs with/without SRNOM were established, providing reasonable explanations for the experimental results. These findings will help with the accurate assessment of ecological risks of organic pollutants in the presence of NOM.
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, China; Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China. Electronic address: lindaohui@zju.edu.cn.
authors.forename: Daohui
authors.initials: D
authors.lastname: Lin
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: wufengchang@vip.skleg.cn.
authors.forename: Fengchang
authors.initials: F
authors.lastname: Wu
mesh_terms: D002708:Chlorella / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D002722:Chlorobenzenes / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D006812:Humic Substances; D057927:Hydrophobic and Hydrophilic Interactions; D014835:Volatilization; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity
chemical_list: D002722:Chlorobenzenes; D006812:Humic Substances; D014874:Water Pollutants, Chemical
keywords: Algae; Bioaccumulation; Chlorobenzene; NOM; Toxicity