GLOBAL BIOGEOCHEMICAL CYCLES - PROGRESS AND PROBLEMS

Progress in understanding global biogeochemical cycles has been made on many fronts of organic geochemical study over the last decade. Key questions, however, remain to be answered. These include the following: (1) Is kerogen completely remineralized during the weathering of sedimentary rocks? (2) What types of refractory biochemicals are made by plants? (3) What factors control export of organic matter from the land to the ocean? (4) What are the components, sources and fates of organic materials dissolved in seawater? (5) What types of organic substances accumulate in deltaic and coastal marine sediments? (6) Is better understanding of global biogeochemical cycles possible through new conceptual approaches?