{"id":175,"date":"2017-05-02T17:23:01","date_gmt":"2017-05-02T21:23:01","guid":{"rendered":"https:\/\/www2.whoi.edu\/staff\/khughen\/?page_id=175"},"modified":"2017-06-28T14:24:22","modified_gmt":"2017-06-28T18:24:22","slug":"biomarkers-and-molecular-isotopes","status":"publish","type":"page","link":"https:\/\/www2.whoi.edu\/staff\/khughen\/research\/biomarkers-and-molecular-isotopes\/","title":{"rendered":"Biomarkers and Molecular Isotopes"},"content":{"rendered":"

Biomarkers and Molecular Isotopes<\/h1>\n
\"\"

Mixed forest-grassland ecosystems can shift rapidly following climate change or ecological disturbance.<\/p><\/div>\n

Substantial efforts have gone toward developing and applying plant wax and other molecular biomarkers to paleoclimate investigations. Molecular isotopes (compound specific \u03b413C and \u03b4D) of leaf waxes (alkanoic acids) from Cariaco Basin sediments revealed that deglacial vegetation in northern South America shifted between arid C4 grasslands and more humid C3 forest taxa during cold\/dry and warm\/wet climate intervals (Hughen et al., 2004b; Makou et al., 2007). A 180 ka record of leaf wax \u03b413C from the Cariaco basin revealed complex interactions between high-latitude and local tropical forcing of hydrological variability on millennial to orbital timescales (Drenzek, Ph.D. thesis, 2007; Drenzek et al., in preparation). Records of leaf wax isotopes (\u03b4D, \u03b413C), biomass burning markers, and inorganic proxies from Lake Bosumtwi in West Africa show abrupt non-linear responses of terrestrial vegetation to gradual climate changes, probably due to rapid shifts in fire regime (Shanahan et al., 2016; 2015). \u03b4D in leaf waxes from Lake Titicaca and low-elevation sites show that tropical Andean hydrology changed in concert with high-latitude North Atlantic climate rather than local insolation over the past 55 ka (Fornace et al., 2016; 2014). A study off the Peru Margin revealed independent variability in El Ni\u00f1o and La Ni\u00f1a conditions following the last Glacial period (Makou et al., 2010), and an investigation in the Arabian Sea reflects the potential use of leaf waxes to track monsoon changes (Dahl et al., 2005). We have also studied high-latitude climate change through development of geochemical climate proxies in marine, fjord and lake sediments. \u03b4D in leaf waxes and TEX86 from surface lake sediments in the eastern Canadian Arctic show strong correlations to surface air temperature and promise for reconstructing Arctic climate (Shanahan et al., 2013a; 2013b) and biomarkers for sea-ice diatoms accurately reflect distributions of sea ice (Stoynova et al., 2013).<\/p>\n

\"\"

Leaf waxes, seen here magnified surrounding the stomatal pore on a corn leaf, protect vascular plants from drying out in the hot sun.<\/p><\/div>\n

Relevant Publications<\/h3>\n