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研究论文

刘萱,王华,于春艳,石振家,葛林科,刘慧.两种微藻胞外分泌物与NO₂^-、NO₃^-对2，4-D光解的影响[J].环境科学学报,2014,34(4):944-949

Influence of two microalgae extracellular organic matters, NO₂^- and NO₃^- on photodegradation of 2,4-Dichlorophenoxyacetic acid

摘要：在模拟太阳光照射下，利用旋转式光化学反应装置，研究了海水小球藻（Chlorella vulgaris）和新月菱形藻（Nitzschia closterium）的胞外分泌物（EOM），以及分别在NO₂^-或（和）NO₃^-共存条件下对2，4-二氯苯氧乙酸（2，4-D）光解的影响.实验结果表明，2，4-D在海水小球藻和新月菱形藻EOM及分别在NO₂^-、NO₃^-共存下的光解过程均符合准一级动力学反应.研究发现，2，4-D的光解速率随海水小球藻和新月菱形藻EOM浓度的增加而减小，表明这两种微藻EOM可抑制海水中2，4-D的光解.当在微藻EOM溶液中分别加入不同浓度的NO₂^-或NO₃^-后，微藻EOM对2，4-D光解的抑制作用减弱，且随着NO₂^-和NO₃^-浓度的增加，2，4-D光解速率明显增加.特别是当微藻EOM与NO₂^-或NO₃^-三者共存时，可进一步促进2，4-D的光解.

Abstract：The photolysis of 2,4-Dichlorophenoxyacetic acid (2,4-D) was investigated in Chlorella vulgaris or Nitzschia closterium extracellular organic matter (EOM) solutions, and the influence of coexistence with NO₂^- and NO₃^- was also studied in seawater using a rotary photochemical reaction device under the simulated solar light irradiation. The experimental results showed that the photolysis process of 2,4-D was accorded with the pseudo first order kinetics equation both in Chlorella vulgaris or Nitzschia closterium EOM and in the coexistence solutions with different concentrations of NO₂^- and NO₃^-. It has been found that the photolysis rate constant of 2,4-D decreased with the increasing concentration of Chlorella vulgaris or Nitzschia closterium EOM, which indicated that these two species of microalgae EOM could inhibit the 2,4-D photolysis. However, when NO₂^- or NO₃^- was added in the microalgae EOM solution, the photolysis rate constant of 2,4-D increased, which indicated that the inhibition of microalgae EOM decreased with the increasing concentration of NO₂^- or NO₃^-. Especially, the photolysis rate constant of 2,4-D could be further promoted under the coexistence of microalgae EOM with higher concentration of NO₂^- and NO₃^-.