Deonarine, A. ., Duke University, Durham, USA, ad46@duke.edu
Lau, B. ., Duke University, Durham, USA, boris.lau@duke.edu
Hsu-Kim, H. ., Duke University, Durham, USA, hsukim@duke.edu

ROLE OF NATURAL ORGANIC MATTER DURING THE PRECIPITATION OF NANOPARTICULATE HGS(S) AND OTHER METAL SULFIDES

Natural organic matter increases the apparent solubility of HgS(s) in sediment porewater and in the water column. This apparent increase in solubility may be explained by the presence of nanoparticulate HgS species. Hg may also adsorb to nanoparticles of other metal-sulfides produced in sulfidic environments. These nanoparticulate Hg species may ultimately be controlling ‘soluble’ Hg speciation in sediment porewater and, thus, controlling biological Hg uptake. In this study we investigated homogeneous nucleation and aggregation of nanoparticulate HgS(S) and ZnS(S) in the presence of low molecular weight organic acids and humic acid in experimental solutions initially containing dissolved metal and S(-II) at concentrations corresponding to oversaturation. Our results demonstrated that the rates of aggregation for HgS(s) and ZnS(s) were significantly slower in the presence of humic acid, cysteine and thioglycolate. In contrast, organics such as oxalate, glycolate and serine had little to no effect on particle growth rates relative to the bare metal-sulfide particles. These results implicate a potential mechanism for stabilizing HgS and other metal-sulfide colloids in natural waters.

Poster presentation

Presentation is given by student: Yes
Session #:187
Date: 03-03-2008
Time: 17:30 - 19:30