4. Examine the following marine sediment profiles of organic carbon (Org-C, grey), oxygen (blue), sulfate (yellow), and

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4 Examine The Following Marine Sediment Profiles Of Organic Carbon Org C Grey Oxygen Blue Sulfate Yellow And 1 (159.12 KiB) Viewed 12 times

4 Examine The Following Marine Sediment Profiles Of Organic Carbon Org C Grey Oxygen Blue Sulfate Yellow And 2 (118.66 KiB) Viewed 12 times

4. Examine the following marine sediment profiles of organic carbon (Org-C, grey), oxygen (blue), sulfate (yellow), and sulfide (green) at two sites (A and B) and answer the following questions: Concentration Concentration 0 0 Org-C/ Torg-c -c Oz 5 5 10 10 500 Isoq و کا Depth (cm) Depth (cm) H2S 20 20 25 25-1 Has 30 30 site A site B Figure 4 Sediment profiles of organic carbon, oxygen, sulfate and sulfide at sites A and B. Only species that are measured are shown (e.g., PO4 is not shown, which doesn't mean that PO4 was not present – it was not measured).

a) [3 pts] Which site (site A or site B) would you expect to have higher organic matter sedimentation rate and why? b) [4 pts] Compare the oxygen profiles of the two sites and explain what causes their differences. c) [6 pts] Based on the figures, what are the possible carbon degradation (oxidation) processes at the two sites, respectively, and why? d) [7 pts] Denitrification is the major process that removes fixed nitrogen in the ocean (fixed nitrogen is converted to N2). What are the conditions for denitrification to occur? If we know that there is nitrate in surface the sediments, would you expect denitrification to have occurred at the two sites? If yes, at what depth and why? e) [6 pts] What are the processes that consume oxygen in sediments? Which site you expect to have higher rates of sediment oxygen consumption and why? f) [4 pts] Are sediments sources or sinks of sulfate at the two studied sites and how do you know this?