Book's abstract: The oceans are vitally important to an understanding of how the Earth works as an integrated system because its chemical composition records transfer of elements through the Earth’s geochemical reservoirs as well as defining how physical, biological and chemical processes combine to influence issues as diverse as climate change and the capacity of the oceans to remove toxic metals. Much modern marine geochemistry aims to link and integrate studies of the modern oceans with work using proxies to define how ocean chemistry and the ocean/atmospheric system has changed through time on a number of different timescales. Special focus in such work is the carbon cycle and its link to changes in greenhouse gases in the atmosphere. Volume 6 covers all the important topics needed for such an integrated approach, ranging from the contemporary ocean composition, transport processes in the ocean, paleoclimatology and paleo-oceanography from marine deposits, to the evolution of seawater composition.