GEOTRACES Online Seminar Series 2026

The series will run monthly from April to November 2026 (with a break in July), with seminars planned for the last Tuesday of each month. Plus, a special end-of-year seminar around mid-December.

Seminars will be held at either 09:00 CET/CEST or 15:00 CET/CEST, depending on the speakers’ locations, to facilitate participation across different regions. Each seminar will last about one hour.

From adsorption to regional boundary scavenging: bridging scales of trace element removal from the ocean

Prof. Christopher Hayes (University of Southern Mississippi)

Abstract: Particulate matter in seawater acting as a removal term for trace elements, or chemical scavenging, has been recognized since the 1950’s. In this talk, I review the history of the role of scavenging in chemical oceanography and results from our group showing how productive gyres, upwelling zones, hydrothermal plumes and nepheloid layers can all be seen as regional centers of scavenging removal.

Particle composition effect on trace metal scavenging in the global ocean

Asst. Prof. Yang Xiang (Louisiana State University)

Abstract: Different particle phases vary in their ability to scavenge trace elements and their isotopes (TEIs). In this talk, I will highlight the disproportionate importance of manganese oxides in scavenging multiple TEIs in the global ocean, despite their relatively low abundance. I will also discuss recent advancements in particle scavenging models that incorporate surface area into parameterisations.

Aerosols as a source of trace metals to the open ocean
Prof. Cliffton Buck (University of Georgia)

“Particles carried through the atmosphere link the land and open ocean beyond the influences of rivers and the continental shelf. The importance of atmospheric deposition is a function of particle composition and size, atmospheric processing, and flux. Accurately assessing this process is uniquely challenging, and current knowledge gaps hamper our understanding of marine biogeochemical cycles.”

Atmospheric trace elements over the Southern Ocean
Dr. Prema Piyusha Panda (Stellenbosch University)

“In this talk, I will discuss my current work on atmospheric trace elements over the Southern Ocean. I will discuss the possible sources of atmospheric trace elements over the southern hemisphere, impact of wildfires on aerosol trace element composition and their subsequent influence on surface ocean biogeochemistry.”

Are glaciers a source of trace metals to the ocean?
Prof. Jon Hawkings, University of Pennsylvania

“In this talk, I will introduce the idea of glacial systems as producers and exporters of trace metals, focusing on how glaciers mobilize trace metals and the phases (i.e. soluble vs colloidal vs particulate) in which trace metals are delivered to marine systems.”

Trace metals in the coeastal Arctic Ocean
Prof. Laramie Jensen, Columbia University

“In this talk I will discuss my work on trace metals in the Arctic Ocean since the 2015/2016 GEOTRACES cruises and how we can build from the wealth of information provided by GEOTRACES to learn more about the role of rapid climate change on trace metal distribution.”

Bringing it all together: using models to build process understanding
Dr. Gregory De Souza (ETH Zurich, Switzerland) – Senior Scientist

Abstract: Two decades of GEOTRACES observations provide us with a wealth of TEI data at a range of spatial scales. Inferring controlling processes from these data requires an understanding of how sources and sinks — whether in the open ocean or at its margins — interact with ocean circulation to produce observed distributions of dissolved species. In this talk, I will give an overview of the diversity of approaches that have used conceptual and/or numerical models to synthesize observational data into an understanding of TEI cycling in the sea and at its interfaces.

Mapping ocean trace metal distributions: A global data-driven view of lead and its isotopes
Dr. Arianna Olivelli (Flanders Marine Institute, Belgium) – Early Career Scientist

Abstract: Despite the rapid growth of GEOTRACES observations, resolving large-scale distributions of trace metals remains challenging due to their sparse and heterogeneous coverage. In recent years, machine learning (ML) techniques have offered new opportunities to advance data-driven oceanographic research at global and regional scales. In this talk, I will present my work to develop the first global maps of lead (Pb) concentrations and isotope compositions from surface to depth using the tree-ensemble algorithm XGBoost and explainable ML tools. These maps provide an observation-based view of Pb distributions and variability that is difficult to achieve from measurements alone. I will discuss key methodological choices, lessons learned, and potential future applications of these maps. Additionally, I will explore the use of different ML approaches for the synthesis and integration of in situ observations within the wider GEOTRACES context.