Projects

The increasing level of anthropogenic inputs of CO2 in the atmosphere since the Industrial Revolution not only exacerbates global warming, but also could cause ocean acidification. Scleractinian corals are important reef builders that are foundation to sustain biodiversity in marine coastal ecosystem. However, the knowledge of how the ocean warming and acidification influence the coral biomineralization is limited. Boron isotopes and B/Ca ratio of coral skeletons can help to deconvolve the unresolved questions. Such work is needed given the global and economic importance of ocean warming and acidification, as well as the impact on marine ecosystems. Therefore, in this research work, we aim to 1) assess the effects of seasonal temperature variation on pH and dissolve inorganic carbon of calcification site fluid (pHCF and DICCF) of coral Porites through high resolution δ11B and B/Ca measurements; 2) evaluate to what extent long-term ocean acidification affect boron incorporation and thus the interpretation of pHCF and DICCF of coral Porites speciesby extending the d11B and B/Ca records to about 40 to 50 years old; 3) further investigate the warming effect on coral pHCF and DICCF by reconstructing and comparing δ11B and B/Ca records of coral Porites collected from different latitudes in the northwestern Pacific and the Indian Ocean. (Photo: Huai Su)

Coccolithophores play critical roles in the ocean carbon cycle by both photosynthesizing with carbon and facilitating the sinking of organic carbon through coccolith production. Understanding coccolithophores’ carbon utilization strategies and the control mechanisms behind are therefore crucial for accurately estimating their potential to moderate atmospheric CO2 levels in future climates. Here we propose the first comprehensive study applying both geochemical and molecular biological methods to investigate predominant coccolithophore species and genotypes on their calcification responses to Global Change through pH- or/and temperature- or nutrients-controlled culture experiments. Specifically, we want to: 1) investigate coccolithophore carbon uptake and pH regulation strategies among morphotypes in response to Climate Changes by using stable carbon and boron isotopes, and elemental ratios; and 2) uncover the genetic controls behind the physiological responses by analyzing coccolithophore gene expressions. This should improve our understanding of control mechanisms on coccolithophore calcification and facilitate a better estimation of coccolithophore’s contribution to ocean carbon budget in future climate.

Aeolian dust is one of the most important sources of nutrition supplementing primary productivity in surface ocean, and can further impact on ocean-carbon dynamics. Researches on the source and transportation pathways, and their variabilities are therefore a crucial component to better understand their impacts on the ocean-carbon dynamics. Among various strategies, paired radiogenic Sr isotopes and Nd isotope results are thought to be a powerful tool to tracing source provenances of sediments. In addition, Hf isotopes of in different grain size fraction particles can be a proxy of transportation distance due to the preferential depletion of zircon during the transportation. Therefore, we targeted on using Sr-Nd-Hf isotopes of aeolian dusts, suspended particles, and marine sediments to further understand the dust sources and transport in 3D scale in past and present days.

Boron isotopes (δ11B ) and B/Ca ratios in foraminifera have been widely applied to reconstruct seawater pH in the past. Here we analyze δ11B and B/Ca in plantic and benthic foraminifera collected from the Ontong Java Plateau to reconstruct seawater pH and carbonate chemistry in different depths. In collaboration with Prof. Li Lo from Department of Geosciences, National Taiwan University, we will compile the boron data with δ18O, Mg/Ca records to better understand the ocean circulation at the region, and the relationship to glacial interglacial cycle.