IAP2-23-119

Palaeoenvironmental changes during the Holocene in south-west Guinea-Bissau: a record of the intertropical convergence zone

At present, societies in developed countries are becoming more exposed to the impacts of climate change, however climate and environmental issues have been happening in less developed countries for a much longer time. It has become key to prepare societies to deal with the impacts of climate change. For this reason, climate research and more particularly, past climate change research is key in developing a greater understanding of Earth’s history and future.

Countries in Africa, parts of Asia, Latin America and Oceania do not have the same knowledge about their modern and ancient climate due to a lack of resources and interest. This PhD project will focus on the palaeoenvironmental reconstruction of south-western Guinea-Bissau, a former Portuguese colony. The site of interest is the Lagoas Cufada Natural Park, a conservation site located in southern Guinea-Bissau, that is bordered by small deltas and rias that are connected to the Atlantic in the west. The park is characterized with a diverse array of landscapes and ecosystems ranging from mangrove forests and lagoons (Cufada, Bionra, Bedanha and Bedasse) to forests. The vegetation in the area can be summarised as being in the Guinean-Congolian/Sudanian transitional zone group, between the Sudanese and Sahelian semi-arid zones of arid savannahs and open forests, and the rainforests of the Guinea Gulf.

The Lagoas Cufada Natural Park region is located in the Intertropical Convergence Zone (ITCZ) of western Africa which is particularly sensitive to future climate change. Future projections suggest that the ITCZ will shrink and migrate towards the equator, thus causing the Guinea-Bissau region to become drier having devastating effects on the forests and ecosystems. The project will focus on conducting a modern biogeochemical investigation of plants, water and soil within the region, followed up with the collection of multiple deep lagoon/estuarine cores to reconstruct Holocene climate variability in the region and hence, ITCZ movements.

Specifically, the project will focus on utilizing stable isotope geochemistry, organic geochemistry (biomarkers), palynology and sedimentology to reconstruct the Holocene climate of the area. Modern sample sets and analyses will be used to produce baselines from which to reconstruct ecosystem changes in the past.

The main objectives of the project are:

(1) To understand modern processes in the Lagoas Cufada Natural Park, Guinea-Bissau, through the use of biogeochemical analyses.
(2) To collect Holocene sediment cores from lagoon/estuarine cores for palynology, stable isotopes and organic geochemistry.
(3) Guinea-Bissau Holocene records will be compared to other ITCZ records and incorporated into climate change models.

Methodology

Stable isotope geochemistry, organic geochemistry, palynology and sedimentology will be used throughout this project. Standard techniques and training will be undertaken by the student. Analytical methods will be done under the supervision of each expert supervisor in their respective laboratories. Data analysis will consist of advanced statistical analysis and modelling.

Project Timeline

Year 1

Literature review. Laboratory training. Fieldwork in Guinea-Bissau will be planned and undertaken to collect modern samples around the natural park. Processing samples to generate a modern biogeochemical analysis of the region. In addition, the student will produce a modern palynological database for the area. Grants will be written for radiocarbon dating of the sedimentary cores.

Year 2

Additional fieldwork will produce more modern samples. In addition, this year will involve the collection of several long cores for investigation of Holocene climate/environmental reconstructions. Engaging with the local community and passing knowledge about palaeoclimates and climate change research. This year will also involve the initiation of several manuscripts that will form the basis of the PhD thesis. First international conference to attend.

Year 3

All laboratory work will be completed this year. Data will be compiled and analysed. Modelling of the data into a climatic framework will be conducted. Writing manuscripts as part of the PhD thesis. Second international conference to attend.

Year 3.5

Synthesis of PhD manuscripts for thesis submission.

Training
& Skills

In addition to training undertaken within the IAPETUS2 programme the student will receive training in experimental design, field and laboratory techniques, project management and data analysis and modelling. The student will be conducting fieldwork in Guinea-Bissau and thus, speaking Portuguese will be crucial. Fieldwork will be conducted with the assistance of local authorities in the Lagoas Cufada Natural Park. The student will be trained in many analytical techniques to generate palaeoclimatic records from the Holocene. Training will involve laboratory work and training in St Andrews, Newcastle and Durham. The student will be trained in stable isotope geochemistry, organic geochemistry (biomarkers), palynology and sedimentology.

References & further reading

[1] Alves, P. H. (2007). A geologia sedimentar da Guiné-Bissau: da análise geral e evolução do conhecimento ao estudo do Cenozóico.[2] Alves, P. H. (2010). Geologia da Guiné-Bissau = Geology of Guinea Bissau. In X Congresso de Geoquímica dos Países de Língua Portuguesa e XVI Semana de Geoquímica, 28 de Março a 1 de Abril de 2010.[3] Catarino, L., Martins, E.S. and Diniz, M.A., 2002. Vegetation structure and ecology of the Cufada Lagoon (Guinea‐Bissau). African Journal of Ecology, 40(3), pp.252-259.[4] Catarino, L., E. S. Martins, and M. A. Diniz (2006). “The physiognomic types of the arborean vegetation of the Parque Natural das Lagoas de Cufada (Guiné-Bissau).” Garcia de Orta. Série de Botânica 17.1/2: 69-76.[5] Ndiaye, A., Bentaleb, I., Favier, C., Fourel, F., Sebag, D., Fall, M., Giresse, P. and Diouf, B., 2022. Reconstruction of the Holocene climate and environmental changes of Niayes peat bog in northern coast of Senegal (NW Africa) based on stable isotopes and charcoals analysis. Quaternary Science Reviews, 289, p.107609.

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