PARENT SESSION
MA7 - Mercury: Fate, Transport, & Bioaccumulation
Chair: Kidd, Karen¹, ¹ Freshwater Institute, Winnipeg, MB
8:00 AM to 12:00 PM - Monday, 18 November 2002
Room Ballroom A

(222) Influences of organic carbon on inorganic and methyl mercury influx into mussel Perna viridis.

Pan, Jin-Fen^*,1, Wang, Wen-Xiong¹, ¹ The Hong Kong University, Kowloon, HK

ABSTRACT- The bioavailability and toxicity of mercury to aquatic organisms are greatly dependent on its species such as inorganic mercury and methylated mercury. We examined the influences of a variety of physico-chemical conditions such as metal concentration, salinity, dissolved organic carbon (DOC) and colloidal organic carbon (COC) on the bioavailability of inorganic mercury (Hg) and monomethylmercury (MeHg) to the green mussel Perna viridis, a bivalve species extensively used as biomonitor in subtropical and tropical waters. Uptake of methylmercury by the green mussels was about 7 times higher than that of inorganic Hg, and was the highest recorded among different metals thus far. Bioavailability of inorganic Hg and MeHg increased by 1.7 times and 2.2 times, respectively, with decreasing salinity from 30 psu to 15 psu. Biogenic derived DOC reduced the uptake of inorganic Hg, but increased the uptake of MeHg. Consistently, there was an inverse relationship between inorganic Hg uptake and DOC concentration and a positive relationship for MeHg when the seawater was collected from various coastal and estuarine locations and UV photo-oxidized. The influence of COC on Hg bioavailability was also dependent on the colloidal geochemical property and the colloid-metal complexation. Binding with colloidal nanoparticles increased the uptake of inorganic Hg (1.1-2.2 times higher than the uptake of low molecular weight complexed Hg), but decreased the uptake of MeHg (by 25-45%). For both inorganic Hg and MeHg, the uptake of uniformly radiolabeled metal was generally lower than the uptake of 2-d aged radiolabeled forms. Furthermore, aging of the colloid-metal binding reduced metal bioavailability to the mussels. For both colloidal inorganic mercury and organic mercury, dissociation may be an important step for their uptake, in addition to other possible uptake mechanisms such as pinocytosis.

Key words: mercury, methylmercury, organic carbon, influx