Sha Niaffiliated with the university, Bachelor of Science, Doctoral Student, Master of Science
Research areas and keywords
UKÄ subject classification
- Natural Sciences
- paleoclimate, geochemistry, Marine sciences, biogeochemistry
Reconstruction of last interglacial (Eemian) environmental conditions in the western Baltic Sea
We compare low bottom water oxygen events in the present day with the ones happened during the last interglacial, in order to understand the cause, severity and potential outcomes of environmental changes in the present day.
The modern Baltic Sea suffers from increased hypoxia (dissolved oxygen concentration < 1.4 ml/l) over large areas of this enclosed sea. The general expansion of hypoxia in the world’s ocean is primarily attributed to global warming and in coastal areas also to increased eutrophication. The last interglacial, the Eemian Stage (ca. 130–115 ka; MIS 5e), was characterized by rapid changes in ocean circulation, and oceanic heat fluxes, and generally higher global sea level and temperature than today at high northern latitudes. In this study we focus on hypoxia in the Baltic Sea during the Eemian and, its correlation with the higher global sea level and warming.
In my study, we quantify and discuss the hypoxia and ecosystem changes during the Eemian in the western Baltic Sea by combining these new trace element and micro-tomography data with additional available proxy datasets (foraminiferal faunal assemblages, stable C and O isotope records and sedimentology).
Holocene hydrographic variations from the Baltic-North Sea transitional area (IODP 347 Site M0059)
Hypoxia o ccurred in the Holocene a few time, especially during several warm periods. My main focus area is the Danish Straits (Little Belt, IODP Site M0059). I use high resolution sediment cores collected during IODP Expedition 347. Sample preparation and trace element analyses were carried out with LA-ICP-MS. By combining geochemical results with foraminiferal assemblage data, we quantify and discuss the hypoxia and ecosystem changes in the southwestern Baltic Sea over the past ~7.5 ka BP.
Diagenesis in foraminiferal calcite under hypoxic condition in the Landsort Deep (IODP Exp.347) 3kyr BP
Foraminiferal samples are collected from the deepest part of the Baltic Sea (Landsortdjupet, IODP Site M0063). Trace element concentrations are high even after omitting the surface coating with LA-ICP-MS. Mineralogy analyses were carried out with SEM, RAMAN and synchrotron based nano-XRF. We observed secondary minerals forming on the surface of the foraminiferal test and inside the pores. Trace element mapping shows that the coating contains very high Manganese. We use RAMAN and XANES aiming to identify this diagenesis coating.
Mn speciation in calcite of low-Oxygen tolerant benthic foraminifera in modern Santa Barbara
In May. 2018, we went to Santa Barbara Basin for sampling living benthic foraminifera and measuring oxygen conditions of pore water and sediments with microsensor. I will study Mn incorporation into foraminifera calcite with synchrotron-based nano-XRF.