Submarine canyons enhance cross-shelf mass exchanges, which are a key
component of on-shelf nutrient budgets and biogeochemical cycles.
Previous studies assume that canyon-induced tracer flux onto the shelf
only depends on canyon-induced water upwelling. This paper investigates
the validity of this dependence for nutrients, carbon and dissolved
gasses. To estimate the canyon-induced tracer upwelling flux and its
spatial distribution on the shelf, we performed numerical experiments
simulating an upwelling event near an idealized canyon, adding 10
passive tracers with initial profiles representing nutrients, carbon and
dissolved gasses. This paper presents a scaling estimate for
canyon-induced tracer upwelling and for the on-shelf distribution of a
given tracer. We find that tracer upwelling depends on the mean initial
vertical tracer gradient within the canyon, the depth of upwelling and
the upwelling flux. We identify a pool of low oxygen and high nutrient
concentration, methane, dissolved inorganic carbon and total alkalinity
on the shelf bottom, downstream of the canyon. The horizontal extension
of the pool depends on the canyon-induced advective fluxes feeding the
pool and the initial background distribution of tracers on the shelf.
This canyon-induced distribution of tracers has the potential to impact
demersal and benthic ecosystems by lowering dissolved oxygen levels and
spreading corrosive waters along the shelf.