Environmental Pollution as a Marine Tracer - Measuring and Modelling Anthropogenic Lead in the Indian Ocean

Background: Human activities have increased the flux of lead (Pb) to the environment by more than an order of magnitude. The combustion of leaded gasoline, which peaked in the 1970s before a gradual global phase-out, thereby generated particularly strong Pb emissions. In the oceans, the effect of Pb pollution is clearly recorded, first in rising and then falling Pb concentrations in surface waters of the North Atlantic. However, Pb levels are still increasing in other areas, such as the Indian Ocean, due to the lag in phase-out between different countries and contributions from industrial sources, which also emit large quantities of Pb.
The massive pollution spike of anthropogenic Pb can be used to study the marine cycle of Pb. The rationale is that Pb emissions remain in the atmosphere for only a short time before they are deposited in the ocean. A particular advantage of the Pb tracer is that the element has a distinct isotopic fingerprint. This fingerprint can be traced in the ocean, where it reveals from which source and region and even when the Pb was emitted. This enables, on timescales of decades to centuries, the tracking of marine Pb, regardless of whether it is of natural origin from dust inputs or derived from anthropogenic sources, such as leaded gasoline, coal burning or smelting. As such, the isotopic signature of Pb can also be used to study processes within the ocean, such as the movement of water masses and ocean biogeochemistry.

The Project: This project will target isotopic analysis of unique seawater, aerosol and river samples from India and the Indian Ocean, made possible through a collaboration between Imperial College and the National Institute of Oceanography in India . The new results will allow us to investigate Pb emissions from the rapidly developing countries that border the Indian Ocean, where Pb emissions have increased significantly in the last 40 years. Sample processing and analyses will be carried out in the clean room and mass spectrometry facilities of the MAGIC Laboratories at the Department of Earth Science & Engineering, Imperial College London (http://www.imperial.ac.uk/earth-science/research/research-groups/magic/). The group is one of only a handful of laboratories world-wide where these challenging analyses are routinely conducted. Results will subsequently be used to model the Pb cycle, both in terms of atmospheric inputs, as well as in terms of ocean biogeochemistry.
You will be part of the GEOTRACES program (www.geotraces.org), an international study of the marine cycles of trace elements and isotopes with the mission to identify processes and quantify fluxes hat control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions.

The project is suitable for a student with a background in oceanography, chemistry, geology or an equivalent qualification and can be focused in a variety of directions.