Document Detail


Biogeochemical cycling of methylmercury in lakes and tundra watersheds of Arctic Alaska.
MedLine Citation:
PMID:  16572776     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The fate of atmospherically deposited and environmentally active Hg is uncertain in the Arctic, and of greatest toxicological concern is the transformation to monometh-ylmercury (MMHg). Lake/watershed mass balances were developed to examine MMHg cycling in four northern Alaska lakes near the ecological research station at Toolik Lake (68 degrees 38' N, 149 degrees 36' W). Primary features of the cycle are watershed runoff, sedimentary production and mobilization, burial, and photodecomposition in the water column. The principal source of MMHg is in situ benthic production with 80-91% of total inputs provided by diffusion from sediments. The production and contribution of MMHg from tundra watersheds is modest. Photodecomposition, though confined to a short ice-free season, provides the primary control for MMHg (66-88% of total inputs) and greatly attenuates bioaccumulation. Solid-phase MMHg and gross potential rates of Hg methylation, assayed with an isotopic tracer, vary positively with the level of inorganic Hg in filtered pore water, indicating that MMHg production is Hg-limited in these lakes. Moreover, sediment-waterfluxes of MMHg (i.e., net production at steady state) are related to sediment Hg loadings from the atmosphere. These results suggest that loadings of Hg derived from atmospheric deposition are a major factor affecting MMHg cycling in arctic ecosystems. However, environmental changes associated with warming of the Arctic (e.g., increased weathering, temperature, productivity, and organic loadings) may enhance MMHg bioaccumulation by stimulating Hg methylation and inhibiting photodecomposition.
Authors:
Chad R Hammerschmidt; William F Fitzgerald; Carl H Lamborg; Prentiss H Balcom; C Mao Tseng
Related Documents :
21247426 - Posterior leukoencephalopathy following repair of an ileocecal anastomosis breakdown: a...
969026 - Critical flicker frequency (cff) and subjective fatigue during an oxyhelium saturation ...
18970536 - Pressure effects on resolution in ion mobility spectrometry.
10661496 - High pressure enhanced nmda activity in the striatum and the globus pallidus: relations...
12691506 - The association of peritoneal transport properties with 24-hour blood pressure levels i...
371036 - Evaluation of the efficacy and safety of guanabenz versus clonidine.
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Environmental science & technology     Volume:  40     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2006-03-31     Completed Date:  2006-08-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1204-11     Citation Subset:  IM    
Affiliation:
Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, USA. methylhg@whoi.edu
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Alaska
Environmental Monitoring
Fresh Water / analysis
Geologic Sediments / analysis
Mercury / analysis
Methylmercury Compounds / analysis*,  radiation effects
Photochemistry
Ultraviolet Rays
Water Pollutants, Chemical / analysis*,  radiation effects
Water Supply / analysis
Weather
Chemical
Reg. No./Substance:
0/Methylmercury Compounds; 0/Water Pollutants, Chemical; 7439-97-6/Mercury

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Strong sorption of native PAHs to pyrogenic and unburned carbonaceous geosorbents in sediments.
Next Document:  Photodecomposition of methylmercury in an Arctic Alaskan lake.