Response Of Chlorella Vulgaris To Exposure Of Two PPCPs And Its Adaptive Mechanism

In this study,two typical Pharmaceuticals and personal care products,triclosan(highly toxic)and carbamazepine(highly persistent),were used to investigate the mechanism of photosynthetic toxicity and physiological toxicity of two PPCPs to Chlorella vulgaris.The toxicity and adaptability of natural organic matter to Chlorella vulgaris exposed to PPCPs and PPCPs were studied.The results are as followsTriclosan inhibited the growth of Chlorella vulgaris in a time dose effect manner.Triclosan can reduce the cell activity of Chlorella vulgaris,cause the change of cell internal structure,the accumulation of ROS,the accumulation of ROS in the 1ppm treatment group reached the peak at 12h.the activities of antioxidant enzymes cat and SOD first increased and then decreased,while MDA,the product of lipid peroxidation,continued to increase,and the accumulation of reactive oxygen species in chloroplast,mitochondria and cell membrane,in which mitochondria accumulated the most.Triclosan inhibited and destroyed the synthesis of photosynthetic pigments,and the maximum inhibition rate reached 78.01%,it blocked the electron transfer process from Q_Ato Q_B,significantly inhibited the activity of photosynthetic system II of Chlorella vulgaris,thus inhibited the photosynthetic efficiency of Chlorella vulgaris.Carbamazepine also inhibited Chlorella vulgaris in a time dose effect manner.Carbamazepine can reduce the cell viability of Chlorella vulgaris and induce apoptosis.High concentration of carbamazepine significantly reduced the chlorophyll content per unit cell,decreased the photosynthetic parameters Fv/Fm,Y?,q P and ETR at first,and then recovered slowly,and the maximum inhibition rate reached 78.01%.The NPQ of Chlorella vulgaris in high concentration of carbamazepine treatment group increased significantly thro?ghout the experimental cycle.In addition,carbamazepine significantly inhibited the rapid light response curve of Chlorella vulgaris,and the light energy utilization efficiency(?)and the maximum electron transfer rate ETRmax were significantly decreased.The semi saturated light intensity I_K of Chlorella vulgaris increased significantly in the early stage of the experiment,and decreased significantly in the later stage of high concentration treatment.The growth and Photosynthesis of Chlorella vulgaris were significantly promoted by low concentration of aqueous extract of watermelon peel.The number of cells,photosynthetic efficiency and electron transfer rate of Chlorella vulgaris were significantly increased,and the maximum value is 1.55 times of the control.The effects of water extract from watermelon peel on cell viability and photosynthetic parameters of Chlorella vulgaris treated with triclosan and carbamazepine were significantly different.However,the inhibition of carbamazepine on the growth of algal cells and the degree of cell membrane damage were alleviated.However,carbamazepine was just the opposite.The inhibition of photosynthetic efficiency and electron transfer rate of Chlorella vulgaris was significantly slowed down by carbamazepine.