Ocean chemistry and deep-sea sediments

Summary:• Organic matter produced by primary productionin surface waters is a major regulator of seawatercomposition of minor and major constituents.• Major constituents - the nutrients are phophate,nitrate and silica.• They are depleted in surface waters andenriched in intermediate and deep waters.• Maximum oxygen depletion occurs inintermediate waters due to decomposition oforganic material at about 1 km water depth.• Oxygen is brought to the deep ocean bydownwelling (convergence) in polar regions.