The oceanic residence time of a dissolved element is the average time it remains in seawater before removal (by precipitation, biological uptake, or adsorption), and is inversely related to its reactivity: highly reactive elements like silicon are removed quickly (short residence time), while conservative, unreactive ions like chloride remain in solution for very long periods (long residence time). The general order from shortest to longest residence time among common seawater constituents is Si < Ca < Mg < Cl.
Residence time = (total mass of element dissolved in ocean) / (rate of input or removal). Reactive elements involved in biological cycling or rapid mineral...
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