The oceanís chemical composition changes vertically and laterally
because of geological and biological parameters. Scientists use sampling
equipment that monitor portions of the oceans. The oceans are vast, so
it is difficult to obtain continuous data, especially with respect to depth.
Chemical composition varies depending on many factors. The gas
exchange with the atmosphere, the ability of compounds and elements to
dissolve, anaerobic bacteria, interaction of the ocean bottom, inflow of
fresh water, freezing and melting of sea ice, and biological process all
play vital roles in determining the chemistry of seawater.