Bacterial demethylation of methylmercury in the South Florida Ecosystem

Metadata:

• Identification_Information
• Data_Quality_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

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: <http://sofia.usgs.gov/projects/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: -81.25

East_Bounding_Coordinate: -80.3

North_Bounding_Coordinate: 25.8

South_Bounding_Coordinate: 24.8

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:

<http://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://pubs3.acs.org/acs/journals/doilookup?in_doi=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://pubs3.acs.org/acs/journals/doilookup?in_doi=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: <http://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: 20070220

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

U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal Geology
Comments and suggestions? Contact: Heather Henkel - Webmaster
Generated by mp version 2.8.18 on Wed Feb 21 09:17:16 2007