Toxicity of mine dump effluent containing five hexachlorocyclohexane (α, β, γ, δ and ε-HCH, sum 159.4 μg/L) and two trichlorobenzene (TCB, sum 65.2 μg/L) isomers to two microalgae (Scenedesmus quadricauda and Coccomyxa subellipsoidea) was studied over 24 h exposure and also with 2- and 10-fold diluted stock solution (i.e. 1×, 0.5× and 0.1× strength). Individual isomers revealed rather dose-dependent accumulation typically higher in Scenedesmus than in Coccomyxa (max. sum of HCH 14.99 μg/g DW with bioaccumulation factor 94) and δ-HCH was dominant isomer. TCB isomers showed low accumulation in algae. 0.1× dose elevated chlorophylls and carotenoids in Coccomyxa while enzymatic activities (SOD, CAT, and APX), thiols (glutathione and phytochelatin 2) and ascorbic acid were rather elevated by 1× dose in both species. Malic acid, rather than citric acid, increased in response to 0.5× and 1× concentration. Sum of fatty acids was higher in Coccomyxa than in Scenedesmus with palmitic, oleic, linoleic and α-linolenic acids being dominant compounds in both species. Detailed profiling revealed that saturated and monounsaturated fatty acids increased in Coccomyxa while polyunsaturated fatty acids in Scenedesmus in response to increasing dose of organochlorines. Accumulation of organochlorines and metabolic responses in algae are reported here for the first time.

Department of Biology University of Trnava Priemyselná 4 918 43 Trnava Slovak Republic

Department of Plant Physiology Maria Curie Skłodowska University Akademicka 19 20 033 Lublin Poland

Dipartimento di Scienze Chimiche Biologiche Farmaceutiche ed Ambientali University of Messina Polo Annunziata 98168 Messina Italy

Dipartimento di Scienze Chimiche Biologiche Farmaceutiche ed Ambientali University of Messina Polo Annunziata 98168 Messina Italy; Chromaleont s r l c o Dipartimento di Scienze Chimiche Biologiche Farmaceutiche ed Ambientali University of Messina Polo Annunziata 98168 Messina Italy; Unit of Food Science and Nutrition Department of Medicine University Campus Bio Medico of Rome via Alvaro del Portillo 21 00128 Rome Italy

Technical University of Liberec CxI Studentská 2 461 17 Liberec Czech Republic

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