The overall objective of this proposal is to follow important biogeochemical pathways of organic matter recycling in- situ by using carotenoids as tracer compounds. Previous studies have demonstrated that biological and chemical degradation of carotenoids yield highly characteristic transformation products. The distribution of these transformation products in deep-sea particulate matter as it sinks. These studies will focus on the relative abundances of carotenoid dehydrates (indicators of bacterial metabolism), carotenoid free alcohols (indicators of metabolisms by higher heterotrophs), and open epoxides (indicators of chemical degradation) in suspended particulate matter and sediment trap samples collected from the Black Sea and Eastern North Atlantic Ocean. The differences in biogeochemical recycling processes of these two areas, which result from the differences in water column chemistry, are expected to produce large but predictable differences in the distribution of carotenoid transformation products in particulate matter samples. //
