Chemical Oceanography, also referred as ocean chemistry, is the subject dealing with the actions and behavior of the chemical elements within the Earth's oceans. Chemical oceanography describes the cycling of these elements both within the ocean and with the other spheres of the Earth system. The cycles of the biologically active elements such as carbon, nitrogen, and phosphorus and some other important trace elements such as iron are of particular global and climatic significance. The behaviour of isotopes and how they can be used as tracers of past and present oceanographic and climatic processes is considered as another importnat area of chemical oceanography. The subject involves analysis of samples from ocean boundaries such as the river/ocean, air/water, sediment/water interfaces, from within the water column and/or from surficial or deep sediments. Chemical oceanography is an interdisciplinary subject. The ocean chemistry is closely related to ocean circulation, climate, the plants and animals that live in the ocean, and the exchange of material with the atmosphere, cryosphere, continents, and mantle.