Department of Estuarine and Ocean Sciences Seminar
When: Wednesday,
January 24, 2018
12:30 PM
-
1:30 PM
Where: > See description for location
Description: The School for Marine Science and Technology
Department of Estuarine and Ocean Sciences
Seminar Announcement
"Insights into Sulfur and Carbon Cycling in Marine Sediments from
Dissolved Inorganic Carbon and Total Aklalinity Profiles"
Dr. Eyal Wurgaft
Postdoctoral Investigator
Dept. of Marine Chemistry and Geochemistry
Woods Hole Oceanographic Institute
Wednesday, January 24, 2018
12:30 pm to 1:30 pm
SMAST West, Room 204
706 S. Rodney French Blvd, New Bedford
Abstract
Sulfate reduction in marine sediments is coupled to the oxidation of either methane (S-AOM) or organic matter (OSR). These two processes are important components of the geochemical cycles of both sulfur and carbon in marine systems, and often promote other processes such as carbonate and pyrite precipitation. However, estimating their in-situ rates from pore water profiles is challenging, mainly because methane profiles are considered unreliable, and because both pathways consume sulfate and release the same products.
In this talk, I will show that the rates of OSR and S-AOM can be calculated from DIC and total alkalinity (TA) profiles, and will demonstrate such calculation in the Eastern Mediterranean continental shelf. The calculated sulfate reduction rates show that OSR accounts for 70-90% of sulfate flux into the sediment, in spite of the ultra-oligotrophic conditions in the Eastern Mediterranean. In addition, even though OSR accounts for 80-95 % of the carbonate alkalinity increase in the pore waters, S-AOM is the main process promoting the precipitation of authigenic carbonates, because it buffers the pore water at higher pH than OSR. A comparison of the calculated OSR and S-AOM rates with in-situ and ex-situ rates measured in other locations suggests that the effect of sulfur cycling on DIC and TA extends beyond the well-documented effects of S-AOM and OSR, since the reduced products of these pathways take part in additional reactions, which also affect DIC and TA. Finally, it is noteworthy that the application of TA as a proxy for anaerobic oxidation processes, as demonstrated here, is not restricted to sulfate reduction, and can be used as a tracer for other oxidation processes, such as denitrification and iron/manganese reduction.
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To access the live broadcasting, visit https://echo360.org/home, and login the username smast@umassd.edu and password smastumassd. Click "I am not a robot" and then click on ALL CLASSES (MAR 700 - 01 - DEOS Seminar or MAR 700 - 02 - DFO Seminar) and click on the green LIVE streaming.
Access Past seminars
You may also view broadcast of past seminars by clicking the department name under the "Seminar Series Archive" heading below, and selecting the title URL for the video you'd like to view (Adobe Flash Player is required. Download the latest version here).
For additional information, please contact Sue Silva at s1silva@umassd.edu
Department of Estuarine and Ocean Sciences
Seminar Announcement
"Insights into Sulfur and Carbon Cycling in Marine Sediments from
Dissolved Inorganic Carbon and Total Aklalinity Profiles"
Dr. Eyal Wurgaft
Postdoctoral Investigator
Dept. of Marine Chemistry and Geochemistry
Woods Hole Oceanographic Institute
Wednesday, January 24, 2018
12:30 pm to 1:30 pm
SMAST West, Room 204
706 S. Rodney French Blvd, New Bedford
Abstract
Sulfate reduction in marine sediments is coupled to the oxidation of either methane (S-AOM) or organic matter (OSR). These two processes are important components of the geochemical cycles of both sulfur and carbon in marine systems, and often promote other processes such as carbonate and pyrite precipitation. However, estimating their in-situ rates from pore water profiles is challenging, mainly because methane profiles are considered unreliable, and because both pathways consume sulfate and release the same products.
In this talk, I will show that the rates of OSR and S-AOM can be calculated from DIC and total alkalinity (TA) profiles, and will demonstrate such calculation in the Eastern Mediterranean continental shelf. The calculated sulfate reduction rates show that OSR accounts for 70-90% of sulfate flux into the sediment, in spite of the ultra-oligotrophic conditions in the Eastern Mediterranean. In addition, even though OSR accounts for 80-95 % of the carbonate alkalinity increase in the pore waters, S-AOM is the main process promoting the precipitation of authigenic carbonates, because it buffers the pore water at higher pH than OSR. A comparison of the calculated OSR and S-AOM rates with in-situ and ex-situ rates measured in other locations suggests that the effect of sulfur cycling on DIC and TA extends beyond the well-documented effects of S-AOM and OSR, since the reduced products of these pathways take part in additional reactions, which also affect DIC and TA. Finally, it is noteworthy that the application of TA as a proxy for anaerobic oxidation processes, as demonstrated here, is not restricted to sulfate reduction, and can be used as a tracer for other oxidation processes, such as denitrification and iron/manganese reduction.
*********************************************************
Access Live seminars
To access the live broadcasting, visit https://echo360.org/home, and login the username smast@umassd.edu and password smastumassd. Click "I am not a robot" and then click on ALL CLASSES (MAR 700 - 01 - DEOS Seminar or MAR 700 - 02 - DFO Seminar) and click on the green LIVE streaming.
Access Past seminars
You may also view broadcast of past seminars by clicking the department name under the "Seminar Series Archive" heading below, and selecting the title URL for the video you'd like to view (Adobe Flash Player is required. Download the latest version here).
For additional information, please contact Sue Silva at s1silva@umassd.edu
Contact: > See Description for contact information
Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series