Joint toxicity of heavy metals and chlorobenzenes to pyriformis Tetrahymena

• The joint toxicity of chlorobenzenes and metals to Tetrahymena was studied by microcalorimetry.
• The joint toxicity was evaluated by toxic unit (TU) and additional index (AI).
• The cell surface was found the micro destruction by SEM images.
• ATR-FTIR spectra were investigated the decay of functional groups.

Chlorobenzens and heavy metals are frequently detected in the environment, but few studies have assessed the joint toxicity of organic and inorganic contaminants. The joint toxicity of heavy metals and chlorobenzenes was evaluated in the present study. Growth metabolism of the joint toxicity was studied by microcalorimetry at 28 °C, the growth constant (k) and inhibitory ratio (I) were calculated. Toxic unit (TU) and additional index (AI) were introduced to determine the outcome in combined tests, and the coexistence of Cu, Cd, Cr(III) and p-chlorobenzene was antagonism, and the effect of Cu, Cd, Cr(III) and o-chlorobenzene, Cu and 1,2,4-trichlorobenzene were synergism. In addition, micro-situation of the cell membrane surface of pyriformis Tetrahymena   was observed by SEM. The cells suffered serious damage after sufficient acting time. ATR-FTIR spectra revealed that amide groups and PO2- of the phospholipid phospho-diester, both in the hydrophobic end exposed to the outer layer, were the easiest to be damaged.

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