Oceanography: Sources and Fluxes of Material to the Ocean Reservoir

Vocabulary practice flashcards covering hydrological residence times, oceanic fluxes, mass balance, geochemical reactivity, and conservative vs non-conservative element behaviors.

Residence Time ($\tau$)

The average time a water molecule or chemical constituent spends in a given reservoir, defined under steady state as the total mass ($A$) divided by the rate of input or loss ($\partial A / \partial t$).

Steady State

A reservoir condition where total input rates equal total loss rates ($\text{in} = \text{out}$), resulting in no net change in mass over time.

Excess Volatiles

Volatile elements, such as chlorine ($\text{Cl}$), whose abundance in seawater cannot be explained by continental rock weathering alone and are predominantly supplied via volcanic degassing.

Mean Oceanic Residence Time (MORT)

The mean time an element spends in the ocean, calculated as the total mass of the element in the ocean divided by its flux (dominated by riverine input).

Conservative Behaviour

The behavior of major oceanic constituents with long MORTs relative to ocean mixing time, causing them to accumulate, become well stirred, and maintain constant relative proportions throughout seawater.

Non-Conservative Behaviour

The behavior of minor oceanic constituents with short MORTs that are rapidly removed from seawater by biological uptake, scavenging, adsorption, or precipitation, leading to variable proportions.

Geochemical Reactivity

The propensity of an element to be removed from seawater through processes like precipitation, scavenging, adsorption, and biological uptake, indexed by its Mean Oceanic Residence Time (MORT).

Ocean Mixing Cycle

The period of approximately $\sim 1000\,\text{yr}$ required for a volume of water to sink from the surface, circulate through the ocean basins, and return back to the surface.

Amazon River Water Supply

The single river system responsible for delivering $20\%$ of the global annual river water supply to the ocean.

Himalayan Region Particulate Supply

The geographical area that yields the highest suspended sediment yield globally, dominating particulate supply to the oceans.

Atmospheric Water Residence Time

The average duration water spends in the atmosphere reservoir, calculated as $0.035\,\text{yr}$ or approximately $\sim 13\,\text{days}$.

Oceanic Water Residence Time (wrt Evaporation)

The average residence time of water in the ocean reservoir with respect to evaporation rates, equal to approximately $\sim 3200\,\text{yr}$.

Ocean Conveyor Belt Circulation

The large-scale global ocean current system composed of warm surface currents and cold, saline bottom currents that determines climate and reacts sensitively to global temperature and atmospheric carbon dioxide changes.