Eco-toxicological bioassay of atmospheric fine particulate matter (PM2.5) with Photobacterium Phosphoreum T3

Abstract A bioluminescent bacterium, Photobacterium phosphoreum T 3 (PPT 3 ) , was used as a bio-indicator for the atmospheric fine particulate matter (PM 2.5 ) to determine the eco-toxicity of PM 2.5 . The PM 2.5 contains toxic chemicals, which reduce light output. The PM 2.5 samples were collected in the period from March 2014 to January 2015 in Nanjing and analyzed for the chemical composition versus their eco-toxicity. The eco-toxicological responses of each toxicant were detected in PM 2.5 samples with PPT 3 . The dose-response curves obtained were verified using the Weibull fitting function. According to the measured EC 50 values (EC 50 , the concentration of a toxicant that inhibits 50% of the bioluminescence), the toxicity sequence was: B[ a ]P>hexa-PCB>tetra-PCB>tri-PCB>Pb 2+ >DEHP>Cu 2+ >DBP>BDE 209 >Zn 2+ >DMP>DEP, where B[ a ]P is benzo(a)pyrene, PCB is polychlorinated biphenyl, DEHP is diethylhexyl phthalate, DBP is dibutyl phthalate, BDE 209 is decabromodiphenyl ether, DMP is dimethyl phthalate, and DEP is diethyl phthalate. All the PM 2.5 samples analyzed proved to be weak toxic for PPT 3 . The toxicity of PM 2.5 was assessed by the dose-addition of organic species and heavy metallic elements existing in PM 2.5 with PPT 3 . The bioluminescence test showed that the metals and organics detected in PM 2.5 promoted PM 2.5 toxicity. The total detectable organics (denoted by ΣOrs) exhibited slightly higher toxicity than the total metals (denoted by ΣMs). In contrast, the sum of water-soluble ions (denoted by ΣIons) was beneficial to PPT 3 . The PM 2.5 toxicity increased as the PM 2.5 trapped more organics or metallic elements from the industrial or densely populated urban areas, where the PM 2.5 had a high inhibition rate of bioluminescence for PPT 3 in contrast to the residential PM 2.5 samples, where the minimum inhibition rate was observed. The toxicity of PM 2.5 samples varied with the mass concentrations, chemical constituents, and sampling locations. The chemicals in PM 2.5 , especially organic species and metallic elements, affected its eco-toxicity. These data provided good understanding of the atmospheric PM 2.5 pollution in the large portion of the East China.