Friday September 23 CSL Meeting

Sep 22, 2016 - CSL

Mackenzie Schoemann

Examining Variations in Nutrients and Carbonate System in the Mid-Atlantic Canyons using Desmophyllum dianthus, Cup Corals

Presenter: Mackenzie Schoemann
Time: Friday 23 September, 2:00-3:00 p.m.
Location: 805 O&M

Abstract: Deep-sea corals are a unique paleoceanographic and paleoclimate archive extending our observations of ocean dynamics and climate to periods well before the onset of instrumental records. Here we explore the utility of using laser ablation (LA)-ICP-MS to measure the trace elements and boron isotopes (δ11B) in solitary cup corals collected in the Mid-Atlantic Canyons. Twelve modern and twenty-six sub-fossil cup corals, were collected between a depth ranges of 400 m-1400 m with ambient seawater pH range of 7.89-8.00. Radiocarbon measurements indicate sub-fossil specimens lived as long ago as 600 years. A suite of trace elements including P/Ca, Ba/Ca, and U/Ca were analyzed to reconstruct nutrient changes and carbonate ion concentrations in the Mid-Atlantic Canyons. Along with this study represents one of the first ever LA-ICP-MS measurements of δ11B using modern and sub-fossil cup corals. Results show that the pH-δ11B calibration equation yields higher pH values than in-situ pH values suggesting future calibration work is necessary. Results show promise for using cup corals to reconstruct biogeochemical processes at intermediate and deep waters, to develop a better understanding of the paleoecology of the region.

Top: modern (left) and sub-fossil (right) Desmophyllum dianthus, cup corals collected from Norfolk and Baltimore Canyons in Mid-Atlantic Ocean. Bottom: Reconstruction of nutrients (barium and phosphorous) and the carbonate ion concentration over the last 600 years in Norfolk Canyon.Top: modern (left) and sub-fossil (right) Desmophyllum dianthus, cup corals collected from Norfolk and Baltimore Canyons in Mid-Atlantic Ocean. Bottom: Reconstruction of nutrients (barium and phosphorous) and the carbonate ion concentration over the last 600 years in Norfolk Canyon.Top: modern (left) and sub-fossil (right) Desmophyllum dianthus, cup corals collected from Norfolk and Baltimore Canyons in Mid-Atlantic Ocean. Bottom: Reconstruction of nutrients (barium and phosphorous) and the carbonate ion concentration over the last 600 years in Norfolk Canyon.Top: modern (left) and sub-fossil (right) Desmophyllum dianthus, cup corals collected from Norfolk and Baltimore Canyons in Mid-Atlantic Ocean. Bottom: Reconstruction of nutrients (barium and phosphorous) and the carbonate ion concentration over the last 600 years in Norfolk Canyon.