Understanding complex bioaccumulation process of inorganic Hg2+ from zooplankton by a novel aggregation-induced emission fluorogen

Author: Weixin Ou

Ou, Weixin, 2017 Understanding complex bioaccumulation process of inorganic Hg2+ from zooplankton by a novel aggregation-induced emission fluorogen, Flinders University, School of Computer Science, Engineering and Mathematics

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Abstract

Aggregation-induced emission fluorogen (AIEgen) was used as a novel material to determine the complicated process of bioaccumulation in a primary consumer (Daphnia carinata) in an aquatic microcosm. Inorganic mercury ion (Hg2+) was used as the contaminant. Daphnia plays an important role as a primary consumer in the aquatic system, which is essential to develop the understanding of the dynamic of Hg2+ in bioaccumulation and biorelease in zooplankton. The Daphnia carinata was chosen as the experimental organism because it is an essential link to transfer energy from low to high trophic levels. Based on the fluorescence turn-on feature, the specific AIEgen was used to determine the inorganic Hg2+ concentration in the aquatic system by using the built relationship between the ratio of photoluminescence (PL) intensity at the wavelength of 595/480 nm and Hg2+ concentrations in the medium. After reaching an equilibrium, the ratio of PL intensity was used to determine the Hg2+ concentration and then to deduce the quantity of contaminant bioaccumulated by D. carinata. The mortality rate of D. carinata was recorded at two different Hg2+ concentrations. The in vivo visualization of Hg2+ distribution in D. carinata revealed the possible cause of D. carinata mortality. Besides, the response of D. carinata to Hg2+ via environment absorption was compared with that through food intake of algae Euglena gracilis contaminated by Hg2+. The D. carinata was suffered a much higher mortality by direct Hg2+ absorption than through food intake. The reason of high mortality after Hg2+ absorption is possibly due to carapace deformation from the reaction of Hg2+ with chitin in the carapace but the toxicological pathway leading to death warrants further investigation.

Keywords: Hg2+; Bioaccumulation; Daphnia carinata; Aggregation-induced emission fluorogen
Subject: Engineering thesis

Thesis type: Masters
Completed: 2017
School: School of Computer Science, Engineering and Mathematics
Supervisor: Youhong Tang