Project highlights

  • Measure multi-elemental temperature, salinity and runoff proxies on microscale
  • Training in geochemical and micropaleontological reconstructions
  • International collaboration with IODP expedition scientists

Overview

The river system draining in the Bay of Bengal brings particulate and dissolved load of chemicals from the continent during the Indian Summer Monsoon (ISM) months. During these months major rivers (including the Ganges-Brahmaputra-Meghana and Irrawaddy-Salween river systems) bring approximately 943´109 m3 sediments into the Bay of Bengal and Andaman Sea1. Not surprisingly, these sediment input, and dissolved component, alters seawater composition affecting planktic foraminifera shells that grow in these waters. Our recent work has captured some of these elements (Mn, U and Nd) being incorporated in planktic foraminifera tests which were collectively applied as runoff tracers2. This project aims to carry out individual foraminifera analysis (IFA) to test the distribution of Mn, U and Nd (and other trace elements) in planktic foraminifera tests to assess their fidelity as runoff tracers. Commonly applied planktic foraminifera trace elements such as Mg, Sr, Ba and Na data will also be obtained during the analysis3. Further, targeted samples from International Ocean Discovery Programme (IODP) expedition 353 sites (U1445, U1444 and U1443) will be utilised to reconstruct seasonality of seawater temperature, salinity and runoff over a range of time scales.

This project will apply laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) tool to assess distribution of trace elements within planktic foraminifera tests to evaluate runoff proxies. Further, ablated planktic test will be used for measuring oxygen and carbon isotopes to obtain multi-proxy signals for assessing seasonality of seawater temperature, oxygen isotope composition and runoff variability from the core ISM region of the Bay of Bengal (BoB). The project will address following key questions: What is the nature and distribution of runoff tracers (Mn, U and Nd) in planktic foraminifera? What are the seasonal extremes of seawater temperature, oxygen isotope of seawater and runoff during the past cold and warm intervals? How does reconstructed extremes compare with seasonality, guided by modern seasonal mixed layer changes and inferred from multi-species oxygen and carbon isotopes  data, during different time scales?

Host

The Open University

Theme

  • Climate and Environmental Sustainability

Supervisors

Project investigator

  • Pallavi Anand

 

Co-investigators

  • Frances Jenner (OU)
  • Phil Sexton (OU)
  • Katrina Nilsson-Kerr (Herriot Watt)
  • Mel Leng (BGS)
  • Damon Green (Teledyne)
  • Marci Robinson (USGS)

How to apply

Methodology

The deep-sea mud samples will be washed and the coarse fraction (>150 mm) will be used for picking  planktic foraminifera species for geochemical work (trace element and oxygen and carbon isotopes measurements). Depth dependent planktic foraminifera species (from mixed layer, halocline, upper and lower thermocline) will be picked and weighed for individual shell size and mass measurements using microbalance from the same interval on a split of the same sample (as part of the ongoing IODP project) in the fully equipped laboratories at the Open University. Targeted intervals will also be selected for multi-species planktic foraminifera IFA to obtain coupled trace elements and oxygen isotope data to reconstruct seasonality of seawater temperature, oxygen isotope (due to salinity) and runoff in response to ISM strength and changes in wager column stratification.

Training and skills

In addition, the student will receive specific training on LA-ICPMS from Dr Jenner and foraminifera specific knowledge from Dr Nilsson-Kerr (and Dr Hathorne).

The student will receive project specific training with supervisor (PA/FJ) and OU offers a diverse set of training courses throughout their PhD.

Specific skills that will be acquired during this project include:

  • Cutting edge geochemical techniques
  • Data handling and interpretation from a wide variety of sources
  • Scientific communication through writing, poster and oral presentations to academic and non-academic audiences
  • Co-supervision on your own devised OU’s master’s project and teaching research methods to A level Nuffield funded summer students.

Partners and collaboration

This project will benefit from international collaborations and networking opportunities with IODP 353 expedition scientists. In particular, there will be collaboration with scientists working on IFA Ed Hathorne (GEOMAR), planktic foraminifera species depth habitat in Bay of Bengal (Marci Robinson, USGS), and monsoon modelling (Phil Holden, OU).

Further details

Applications should include:

  • an academic CV containing contact details of three academic references
  • a CENTA application form
  • and an Open University application form, downloadable from:

(UK) http://www.open.ac.uk/students/research/system/files/documents/Application%20form%20-%20uk.docx

(Overseas) http://www.open.ac.uk/students/research/system/files/documents/Application%20Form%20-%20Overseas_0_0.docx

Applications should be sent to STEM-EEES-PHD@open.ac.uk  by 11.01.2021

Possible timeline

Year 1

Obtain training in sample processing on laser ablation sample preparation. Measure shell mass and size of depth dependent planktic foraminifera species from Holocene samples. Present data at UK-IODP annual meeting.

Year 2

Generate multi species planktic foraminifera IFA for time slices across Miocene to present from the BoB sites. Present geochemical data at the Geochemistry Research in Progress meeting or Palaeopercs seminar.

Year 3

Finish remaining analytical work, data analyses, and present results at an international conference and write up thesis and manuscripts.

Further reading

  1. Varkey, J.M., (1996) Physical oceanography of the Bay of Bengal and Andaman Sea. Ocean. Mar. Biol. an Annu. Rev. 34, 1–70
  2. Nilsson-Kerr, K., Anand, P., Sexton, P. F., Leng, M. J., Misra, S., Clemens, S.C. and Hammond, S.J. (2019) Inter-hemispheric climate controls on late Pleistocene Asian summer monsoon subsystems, Nature Geoscience, 12, pp. 290-295.
  3. Groeneveld, J., Ho, S. L., Mackensen, A., Mohtadi, M., & Laepple, T. (2019) Deciphering the Variability in Mg/Ca and Stable Oxygen Isotopes of Individual Foraminifera. Paleoceanography and Paleoclimatology, 34(5), 755–773. https://doi.org/10.1029/2018PA003533

COVID-19

We will have a binocular microscope available for student to work from home. Lab protocols video will be available for online training and support via skype/teams. Also, we have a proven online method for training student for foraminifera taxonomy which we will continue to use for training if covid restrictions continue. The project boasts from availability of washed samples, equipment/microscope to take home and online training for washing and taxonomy, providing mitigations for covid restrictions. Once the samples are picked, it will be delivered for oxygen isotope measurements at the British Geological Survey following OU risk assessment for travel.