This area is important to both the economy and the health of the marine environment, and recent reviews, such as the State of the Marine Environment (1996) have noted that there is insufficient specific research directed towards contaminants, land use change, estuarine pollution, global change, oil spills and eutrophication. Through the Marine Biogeochemistry Project, researchers of the Australian Institute of Marine Science are working to fill some of these gaps in our knowledge of the marine environment.

The Institute’s research involves three regional study areas which provide different information about the amount of water and material rivers bring to coastal seas. The North-West Shelf is representative of a pristine, productive tropical marine ecosystem with little river inflow. Here the research team is examining the marine cycles of carbon, petroleum contaminants, and sedimentation, and can document the state of these systems before any major disturbances occur.

The Great Barrier Reef Lagoon has intermediate riverine input. Changing land use in the catchment during the last 200 years can be tracked by the researchers examining coastal sediments, and signatures of climate change and contamination are incorporated into growing coral skeletons.

The third regional site of the study is the coast of Papua New Guinea, where the amount of river water and sediment transported to the ocean is very large. AIMS researchers use a variety of geochemical tracers indicative of the wet tropics to trace carbon and material flows, to track land use changes, and to study the extent of river influence on coastal reefs. Much of the information the researchers gather can potentially be used to address major global issues such as the periodicity of ENSO related drought and flood events, climate warming, and to detail the pathways of carbon cycles and ocean water circulation. This AIMS team works in this region with scientists from Indonesia, Papua New Guinea, and the United States under the international banner of Project TROPICS.

The Marine Biogeochemistry project brings together scientists with a wide range of chemical expertise. The research has been divided into four sub-projects, with each scientist and sub-project leader bringing their own specialised interest to the team working together at the regional study areas.

The focus of one sub-project is for researchers to gain a clearer understanding of the sources and fates of organic matter in the coastal zone. This involves the study of formation and degradation rates of dissolved and particulate organic matter in mangrove swamps and coastal seas. Organic particles transport and scavenge contaminant elements, and non-living organic matter traps materials transported by rivers to estuaries and coastal seas.

Researchers with another sub-project are concentrating on using organic contaminants as tracers of environmental change. Understanding the fluxes, degradation and storage of these large organic molecules is integral to being able to use them as tracers of the history of pollution events, oceanic circulation, and climate change. The study is important in order to understand the consequences of oil spills, pesticides and other organic wastes in the environment.

Layers of sediment, accumulated through time, contain indicators of changing land use through history. Changes in agricultural practices, mining industries and increased development all leave their mark in the mud deposited in the estuaries and coastal seas. Using geochemical and radiochemical methods, AIMS scientists are also studying inorganic sediment composition and deposition rates to show historical land use and climate change during the last several centuries.

Researchers are also examining the possibilities of using coral growth to track environmental history. Geochemical, geomorphological and hydrological studies allow researchers to read the history of land use and climate change recorded in the annual growth bands of corals. The data is derived from cores drilled from massive corals, and utilises coral growth band fluorescence as a signal for historical river run off, while chemical indicators of ocean and climate change, coral ecology, and mangrove tree rings describe the history of land use and climate change over the last several centuries.

The overall objective of the project is to understand the processes controlling the fate of natural and contaminant substances in estuaries, coastal shelves and tropical oceans. The work is allowing researchers to create, validate and publish models of these processes which can then provide practical advice and information for management authorities and industries. AIMS scientists are acquiring new, advanced knowledge in strategic research, using state-of-the-art equipment, much of which has been developed by the project.

Science knows little about the carbon fluxes, the influence of hydrocarbon contaminants and the levels of radiochemical, natural nutrients and trace elements being introduced into the environment in tropical Australia and Southeast Asia. It has long been a concern of environmentalists that the actual levels of contaminants in supposedly clean, remote tropical regions of Australia is not recorded. Knowledge of global and local contaminants in these regions will provide a basis for future protection, management and insight into the sustainable harvest of coastal resources. Information gathered by the researchers will play an important role in shaping recommendations given to management authorities concerning the effects and remediation rates of oil spills, agricultural run off, urban wastes and mining wastes, as well as the influence of global atmospheric contamination.