Marine geochemistry is the science used to help develop an understanding of the composition of coastal and marine water and sediments. It has become an integrated discipline within Earth sciences and contributes greatly to the understanding of current and past global element distributions and dynamics.
The water and sediment chemistry reflects the source of sedimentary material (e.g. Smith et al. 2008 - Fitzroy River Basin, Queensland, Australia. III. Identification of Sediment Sources in the Coastal Zone) as well as processes at the study site. These processes are mostly mediated by macro- and/or micro-organisms (e.g. Kristensen, Haese and Kostka, 2007 - Coastal and Estuarine Studies: Interactions between Macro- and Microorganisms in Marine Sediments) and consequently, are referred to as biogeochemical processes.
Marine geochemistry is a widely applied science which provides information and knowledge to assist with coastal and marine management. Nutrient and carbon concentrations are used frequently to assess and evaluate water quality in estuaries and coasts (e.g. Radke et al. 2004 - The Relationship between Sediment and Water Quality and Riverine Sediment Loads in the Wave-Dominated Estuaries of Southwest Western Australia) and more recently, the release rate of nutrients from sediments also has been adopted as a condition indicator. The analysis of chemical components in sediment cores from estuaries allow reconstruction of changes in land-use in the catchment and the gradual enrichment of nutrients. This is referred to as eutrophication. (e.g. Murray et al. 2008 - Historic environmental changes and present-day nutrient release from the sediments in Stokes Inlet and Wellstead Estuary, south-western Australia).
Marine geochemistry is increasingly also used to assess and predict the impacts of climate change. For example, the ocean increasingly adsorbs atmospheric carbon dioxide, which leads to ocean acidification and, in turn, a slowdown in the production of calcium carbonate by marine organisms. Marine geochemistry plays a key role in vulnerability assessments of marine ecosystems such as coral reefs.
Marine geochemical variables are being used also as a compliment to sedimentology in Geoscience Australia's surrogacy research into predicting the broad spatial patterns of Australia's marine benthic biodiversity.