Effects And Mechanisms Of DBP On The Growth Of Marine Microalgae

Dibutyl phthalate (DBP)，which is one of the main plasticzers in the plasticindustry,is a kind of very important phthalate esters (PEAs)，and is included in theblacklist of environmental priority pollutants. In order to further study the effects andmechianisms of DBP on marine microalgae，during the first part of the experiments,nine species marine microalge(including three kinds of dinoflagellates：Prorocentrumdonghaiense，Symbiodinium sp.，Akashiwo sanguinea；two kinds of Haptophyceaes：Prymesium parvum,Phaeocystis globosa; two kinds of diatoms： Skeletonemacostatum, Phaeodactylum tricornutum; one kind Cryptophyta: Rhodomonus salina;one kind of Chlorophyta: Chlorella sp.) were exposed to DBP at5，10，20，50，100，1000μg/L and a control. Chlorophyll fluorescence was measured every day. Thesecond part of experiments Symbiodinium sp. and Phaeocystis globosa were selectedas experimental materials, the concentration of DBP was50μg/L. T-SOD，CAT，MDA，Photosynthetic pigments and PSII were measured. The main results were asfollows:（1）DBP treatment group have interspecific difference on the growth of marinemicroalges. Phaeocystis globosa and Rhodomonus salina exhibited significantpromoting effects, Prorocentrum donghaiense, Prymesium parvum, Akashiwosanguinea, Skeletonema costatum and Chlorella sp. have slight stimulate,Symbiodinium sp. exhibited the strongest inhibitory, just5，10，20μg/L treatmentswere stimulated,50，100，1000treatments were inhibited.(2) The MDA content of both marine microalgae were increased and thendecreased under50μg/L DBP. The activity of T-SOD were decreased. The treatedgroup was lower than control group. CAT activity of Symbiodinium sp. wasdecreased，cell density was reduced. But the CAT activity of Phaeocystis globosa wasreturn to normal gradually, which proved that Phaeocystis globosa was able toremove DBP stress by antioxidant enzyme system.(3) The photosynthetic pigments of Symbiodinium sp. have not significant effects, PSII have maximal inhibition on the second day then restore gradually basedon O-J-I-P chlorophyll fluorescence induction kinetics curve, the growth ofSymbiodinium sp. was inhibited slightly. The photosynthetic pigments of Phaeocystisglobosa were all increased significantly, fluorescence yield was increased comparedwith the control group, the maximum fluorescence yield was appeared until the end ofthe experiment, which proved that the growth of Phaeocystis globosa was stimulated.The results confirmed that DBP displayed different effects to marine microalgae,and discussed the possible mechanisms, which provided some theoretical basis andreference information for more rationally estimate the harm of environmentalhormones bring about.