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Bacterial demethylation of methylmercury in the South Florida Ecosystem

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Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator:
Mark Marvin-DiPasquale

Ronald Oremland

Publication_Date: 2005
Title:
Bacterial demethylation of methylmercury in the South Florida Ecosystem
Geospatial_Data_Presentation_Form: spreadsheet
Online_Linkage:
<https://sofia.usgs.gov/projects/index.php?project_url=bact_demeth>
Description:
Abstract:
Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying 14CH4 and 14CO2 production after incubation of anaerobic sediments with 14C-MeHg. Degradation rate constants (k) were consistently <=0.1 per day, and decreased with sediment depth. Higher k values were observed when shorter incubation times and lower MeHg amendment levels were used, and k increased two-fold as in-situ MeHg concentrations were approached. The average floc layer k was 0.046 +/- 0.023/ d (n=17) for 1-2 day incubations. In-situ degradation rates were estimated to be 0.02 to 0.5 ng MeHg/g dry sed/d, increasing from eutrophied to pristine areas. Nitrate-respiring bacteria did not demethylate MeHg, and NO3- addition partially inhibited degradation in some cases. MeHg degradation rates were not affected by PO4-3 addition. 14CO2 production in all samples indicated that oxidative demethylation (OD) was an important degradation mechanism. OD occurred over five orders of magnitude of applied MeHg concentration, with lowest limits (1-18 ng MeHg/g dry sediment) in the range of in-situ MeHg levels. Sulfate reducers and methanogens were the primary agents of anaerobic OD, although it is suggested that methanogens dominate degradation at in-situ MeHg concentrations. Specific pathways of OD by these two microbial groups are proposed.
Purpose:
The objective of this research is to provide ecosystem managers with MeHg degradation rate data from a number of study sites that represent a diversity of hydrologic and nutrient regimes common to the Everglades, and to forge a better understanding of the microbial and geochemical controls regulating MeHg degradation in this system.
Supplemental_Information: This project ended in 1999.
Time_Period_of_Content:
Time_Period_Information:
Multiple_Dates/Times:
Single_Date/Time:
Calendar_Date: 199606
Single_Date/Time:
Calendar_Date: 199612
Single_Date/Time:
Calendar_Date: 199704
Single_Date/Time:
Calendar_Date: 199707
Single_Date/Time:
Calendar_Date: 199801
Single_Date/Time:
Calendar_Date: 199806
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -80.8
East_Bounding_Coordinate: -80.2
North_Bounding_Coordinate: 26.7
South_Bounding_Coordinate: 25.2
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: biogeochemistry
Theme_Keyword: mercury
Theme_Keyword: mercury cycling
Theme_Keyword: methylmercury
Theme_Keyword: sediments
Theme_Keyword: MeHg
Theme_Keyword: peat geochemistry
Theme_Keyword: peat soils
Theme_Keyword: sulfate reduction
Theme_Keyword: geochemistry
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: environment
Theme_Keyword: geoscientificInformation
Theme_Keyword: inlandWaters
Theme_Keyword: 007
Theme_Keyword: 008
Theme_Keyword: 012
Place:
Place_Keyword_Thesaurus:
Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, DC, National Institute of Standards and Technology
Place_Keyword: United States
Place_Keyword: US
Place:
Place_Keyword_Thesaurus:
U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard 5-2): Washington, DC, NIST
Place_Keyword: Florida
Place_Keyword: FL
Place:
Place_Keyword_Thesaurus:
Department of Commerce, 1990, Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas, FIPS 6-3, Washington, DC, National Institute of Standards and Technology
Place_Keyword: Miami-Dade County
Place_Keyword: Monroe County
Place:
Place_Keyword_Thesaurus: USGS Geographic Names Information System
Place_Keyword: Everglades National Park
Place_Keyword: Taylor Slough
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: Central Everglades
Place_Keyword: Greater Lake Okeechobee
Place_Keyword: SW Big Cypress
Place_Keyword: Water Conservation Area 2A
Place_Keyword: Water Conservation Area 3B
Place_Keyword: WCA2B
Place_Keyword: WCA2A
Place_Keyword: WCA3A
Place_Keyword: Water Conservation Area 2B
Access_Constraints: none
Use_Constraints: none
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Mark Marvin-DiPasquale
Contact_Organization: U.S. Geological Survey
Contact_Position: Project manager
Contact_Address:
Address_Type: mailing address
Address:
345 Middlefield Road,

Building 15, McKelvey Building

City: Menlo Park
State_or_Province: CA
Postal_Code: 94025
Country: USA
Contact_Voice_Telephone: 650 329 4442
Contact_Facsimile_Telephone: 650 329-4463
Contact_Electronic_Mail_Address: mmarvin@usgs.gov
Browse_Graphic:
Browse_Graphic_File_Name:
<https://sofia.usgs.gov/exchange/marvin-dipasquale/locationmmd.html>
Browse_Graphic_File_Description: location of sites for methylmercury degradation measurements
Browse_Graphic_File_Type: GIF
Native_Data_Set_Environment: MS Excel spreadsheet
Cross_Reference:
Citation_Information:
Originator:
Marvin-DiPasquale, Mark C.

Oremland, Ronald S.

Publication_Date: 1998
Title:
Bacterial methylmercury degradation in Florida Everglades peat sediment
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: Environmental Science and Technology
Issue_Identification: v. 32, n. 17
Publication_Information:
Publication_Place: Washington, DC
Publisher: American Chemical Society
Other_Citation_Details:
All users may view the abstract of this article. If you are a subscriber, you may view the article. If you are not a subscriber, you may purchase and download the PDF version of the article.
Online_Linkage: <http://pubs.acs.org/doi/abs/10.1021/es971099l>
Cross_Reference:
Citation_Information:
Originator:
Marvin-DiPasquale, Mark C.

Agee, Jennifer; McGowan, Chad; Oremland, Ronald S.; Thomas, Martha; Krabbenhoft, David; Gilmour, Cynthia C.

Publication_Date: 2000
Title:
Methyl-mercury degradation pathways: a comparison among three mercury-impacted ecosystems
Geospatial_Data_Presentation_Form: report
Series_Information:
Series_Name: Environmental Science and Technology
Issue_Identification: v. 34 , n. 23
Publication_Information:
Publication_Place: Washington, DC
Publisher: American Chemical Society
Other_Citation_Details:
All users may view the abstract of this article. If you are a subscriber, you may view the article. If you are not a subscriber, you may purchase and download the PDF version of the article.
Online_Linkage: <http://pubs.acs.org/doi/abs/10.1021/es0013125>

Data_Quality_Information:
Logical_Consistency_Report: not applicable
Completeness_Report: not available
Lineage:
Process_Step:
Process_Description:
Three years of field and laboratory studies research were completed. The specific areas of investigation are outlined below.

1) Field Measurements: Sediment cores were sectioned into three to five discrete 2 to 4 cm horizons, within hours of sample collection. Homogenized sub-samples from each horizon were transferred into crimp sealed serum vials, purged with N2 gas, and injected with radiolabeled 14CH3Hg+. After incubating anaerobically for hours to days, incubations were arrested with either acid or base, depending on the method of 14C endproduct detection. End-products (14CH4 and 14CO2 ) were measured via gas proportional counting (prior to December 1996) or a CH4 combustion / CO2 trapping method (after December 1996). Degradation rate constants are calculated from the fraction of MeHg degraded per incubation time. The relative amounts of CH4 and/or CO2 produced provides an indication as to the relative importance of MC and/or OD. Degradation rates were assessed with respect to both sediment depth and site location.

2) Nutrients and Microbial Inhibitors: The affect of nutrients (NO3-, PO4-3, NH4+) and SO4-2 on the degradation of 14CH3Hg+ was assessed by amending parallel sets of incubation samples with these substrates and processing as described above. Likewise, specific microbial inhibitors of both SRB and MPB were used to determine the relative contribution of these microbial groups to MeHg degradation.

3) The Fate of Hg: Preliminary experiments were conducted exploring the fate of Hg resulting from MeHg degradation. Vapor phase Hg(0) was collected on gold traps by flushing the head-space of samples amended and incubated with MeHg. The concentration of Hg(0) was assayed by cold vapor atomic fluorescence spectroscopy. Our initial (unpublished) results suggest that very little (> 0.01% ) of liberated Hg+2 produced as a result of MeHg degradation is reduced to volatile Hg(0).

4) Kinetic Studies: The dependence of MeHg degradation rates on MeHg amendment concentration was explored over a wide range (1-2000 ng MeH/g dry sed). The low end of this range approached natural in-situ concentrations (0.1-10 ng MeHg/g dry sed). These low levels were achieved by increasing our standard sample size from 3 to 80 cc of sediment, using a custom synthesized high-specific activity 14C-MeHg radiotracer, and employing the sensitive CH4 combustion / CO2 trapping method for 14C end-product quantification.

Process_Date: Unknown
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Mark Marvin-DiPasquale
Contact_Organization: U.S. Geological Survey
Contact_Position: Project manager
Contact_Address:
Address_Type: mailing address
Address:
345 Middlefield Road,

Building 15, McKelvey Building

City: Menlo Park
State_or_Province: CA
Postal_Code: 94025
Country: USA
Contact_Voice_Telephone: 650 329 4442
Contact_Facsimile_Telephone: 650 329-4463
Contact_Electronic_Mail_Address: mmarvin@usgs.gov

Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Data for each site includes: site name, date; sediment depth interval (cm); incubation time (days); C14-MeHg injected (ng/cc wet sed); MeHg degradation first order rate constant (k); and MeHg -degradation potential rate (ng/cc wet sed/d)
Entity_and_Attribute_Detail_Citation: USGS personnel

Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Heather S.Henkel
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address: 600 Fourth St. South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727 803-8747 ext 3028
Contact_Facsimile_Telephone: 727 803-2030
Contact_Electronic_Mail_Address: hhenkel@usgs.gov
Resource_Description: methylmercury degradation rates
Distribution_Liability: The data have no explicit or implied guarantees.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: MS Excel
Format_Version_Number: unknown
Transfer_Size: 0.041
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: <https://sofia.usgs.gov/exchange/marvin-dipasquale/mmdindex.html>
Access_Instructions: Data may be downloaded from the SOFIA website.
Fees: none

Metadata_Reference_Information:
Metadata_Date: 20090803
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Heather Henkel
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: 600 Fourth Street South
City: St. Petersburg
State_or_Province: FL
Postal_Code: 33701
Country: USA
Contact_Voice_Telephone: 727 803-8747 ext 3028
Contact_Facsimile_Telephone: 727 803-2030
Contact_Electronic_Mail_Address: sofia-metadata@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Access_Constraints: none
Metadata_Use_Constraints:
This metadata record may have been copied from the SOFIA website and may not be the most recent version. Please check <https://sofia.usgs.gov/metadata> to be sure you have the most recent version.

This page is <https://sofia.usgs.gov/metadata/sflwww/mmarvin.html>

U.S. Department of the Interior, U.S. Geological Survey
Comments and suggestions? Contact: Heather Henkel - Webmaster
Generated by mp version 2.8.18 on Mon Aug 03 10:30:00 2009