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Transport

Transport refers to the physical processes that move N-containing substances within and between biogeochemical spheres, reservoirs, or pools. Table 1 gives some examples of inter-sphere transport.

Table 1. Examples of Transport between Biogeochemical Spheres

Sphere 1

Sphere 2

Description

Geosphere

Hydrosphere

Submarine hydrothermal vents

Geosphere

Atmosphere

Volcanic emissions

Atmosphere

Hydrosphere

Wet deposition, acid rain

Table 2 gives some examples of inter-pool transport.

Table 2. Examples of Transport between Pools in the Same Sphere

Pool 1

Pool 2

Description

Sediment pore water

Lake

Diffusion

Groundwater

Stream

Baseflow

Earth’s crust

Earth’s mantle

Subduction

Transport within a pool involves advection (movement with the bulk fluid) and dispersion (movement in response to concentration gradients, due to small scale random fluid motion). In water bodies, examples include mixing and dilution of N from point sources such as a wastewater outfalls or landfills.

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