Affiliation:
1. Estuarine Research Center, Academy of Natural Sciences, St. Leonard, Maryland 20685,1 and
2. Chesapeake Biological Laboratory, University of Maryland, Solomons, Maryland 206882
Abstract
ABSTRACT
We have previously hypothesized that sulfide inhibits Hg methylation by decreasing its bioavailability to sulfate-reducing bacteria (SRB), the important methylators of Hg in natural sediments. With a view to designing a bioassay to test this hypothesis, we investigated a number of aspects of Hg methylation by the SRB
Desulfobulbus propionicus
, including (i) the relationship between cell density and methylmercury (MeHg) production, (ii) the time course of Hg methylation relative to growth stage, (iii) changes in the bioavailability of an added inorganic Hg (Hg
I
) spike over time, and (iv) the dependence of methylation on the concentration of dissolved Hg
I
present in the culture. We then tested the effect of sulfide on MeHg production by this microorganism. These experiments demonstrated that under conditions of equal bioavailability, per-cell MeHg production was constant through log-phase culture growth. However, the methylation rate of a new Hg spike dramatically decreased after the first 5 h. This result was seen whether methylation rate was expressed as a fraction of the total added Hg or the filtered Hg
I
concentration, which suggests that Hg bioavailability decreased through both changes in Hg complexation and formation of solid phases. At low sulfide concentration, MeHg production was linearly related to the concentration of filtered Hg
I
. The methylation of filtered Hg
I
decreased about fourfold as sulfide concentration was increased from 10
−6
to 10
−3
M. This decline is consistent with a decrease in the bioavailability of Hg
I
, possibly due to a decline in the dissolved neutral complex, HgS
0
.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Reference38 articles.
1. Copper sensitivity of Gonyaulax tamarensis.;Anderson D. M.;Limnol. Oceanogr.,1978
2. Benoit J. M. C. C. Gilmour and R. P. Mason. The influence of sulfide on solid-phase mercury bioavailability for methylation by pure cultures of Desulfobulbus propionicus (1pr3). Environ. Sci. Technol. in press.
3. Sulfide controls on mercury speciation and bioavailability to methylating bacteria in sediments pore waters.;Benoit J. M.;Environ. Sci. Technol.,1999
4. Behavior of mercury in the Patuxent River estuary.;Benoit J. M.;Biogeochemistry,1998
5. Estimation of mercury-sulfide speciation in sediments pore waters using octanol-water partitioning and implications for availability to methylating bacteria.;Benoit J. M.;Environ. Toxicol. Chem.,1999
Cited by
173 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献