TRICLOCARBAN ENHANCES THE ACUTE TOXICITY OF AS(III) TO PHOTOSYSTEM II OF CHLORELLA PYRENOIDOSA

The present study evaluated the combined effects of arsenic and triclocarban on the photosynthesis of the green algae Chlorella pyrenoidosa. The toxic effects of As(III) (3.75 mg L-1), single triclocarban (10 μg L-1) and their mixture on photosystem II (PSII) of C. pyrenoidosa were investigated using chlorophyll fluorescence tests and oxygen evolution test. Exposure to As(III) only had no obvious effect on oxygen evolution but influenced chlorophyll fluorescences of the tested green algae. Exposure to As(III) and triclocarban together exerted synergistic effects on photosynthesis and oxygen evolution. Exposure to the arsenic and triclocarban mixture led to an inhibition on the donor side and accumulation of P680+, retarded electron transport and affected acceptor side of PSII. The QA- reoxidation tests revealed that combined stresses blocked electron transfer from QA- to QB/QB- and increased S2(QAQB)- charge recombination.