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.
