|Abstract Title:||Inhibition of Methylmercury Uptake by Phytoplankton in the Presence of Algae-derived Organic Matter and the Partition Process Modeling|
|Presenter Name:||Zhike Li|
|Session:||Special Session - Assessing the effectiveness of the Minamata Convention on Mercury under climate uncertainties|
|Co-Authors:||Zhike Li,Zhengyu Wu,Bo Shao,Yindong Tong|
Abstract Information :
As the first step of methylmercury (MeHg) entry into aquatic food webs, cellular uptake of dissolved MeHg by phytoplankton is crucial in determining human exposure risks. MeHg availability to phytoplankton is regulated by dissolved organic matter (DOM) in water, while these impacts could vary largely among different DOM sources. In this study, we investigated impacts of DOM to the extents of MeHg bioconcentration by three freshwater algae of S. quadricauda, Chlorella and Microcystis under the combinations of DOM source and concentration in the microcosm system. We found that AOM (algae-derived DOM) would prohibit the extents of MeHg bioconcentration by 75?85 %, yet the soil-derived DOM didn?t show similar inhibition effects. Algal cell?MeHg?DOM system model showed AOM significantly weaken the association with connection between MeHg with algal cells and 84?91 % of MeHg would be associated with the AOM component rather than algal cell in the experimental conditions, with AOM amendment in mediums. DOM characterization with three-dimensional fluorescence(3D-EEM), fourier transform infrared spectroscopy (FTIR) and ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry (UPLC/Q-TOF-MS) indicated that peptide compounds including S-S or C?S bond could be responsible for differential effects on cellular MeHg uptake by different DOM sources. Ongoing warming and nutrient input are impacting the quality and quantity of DOM in the water. Potential impacts of this change on cellular MeHg uptakes together with the other fields should be integrated when accessing the MeHg risks to humans or wild life.