Soil crust formation by dust deposition at Shaartuz, Tadzhik, S.S.R.
Citation
James P Dobrowolski, Soil crust formation by dust deposition at Shaartuz, Tadzhik, S.S.R.: .
Summary
The shrub-steppe area near Shaartuz, Tadzhik, S.S.R., is shown to be a net accumulator of dust despite being an occasional source of dust. For the accumulation of the dust to form the observed surface crust, a net deposition of about 290–490 g m−2 yr−1 of particles smaller than 20 μm is required, depending on the duration of the deposition period. The particles smaller than 20 μm are mixed with particles brought up from the sandy material below the surface crust by bioturbation and are incorporated into the surface crust. Measurements during the 16 and 20 September 1989 dust storms provided a total deposition of 41.1 g m−2 of particles smaller than 20 μm. Because 10–30 dust storms are observed at Shaartuz, [...]
Summary
The shrub-steppe area near Shaartuz, Tadzhik, S.S.R., is shown to be a
net accumulator of dust despite being an occasional source of dust. For
the accumulation of the dust to form the observed surface crust, a net
deposition of about 290–490 g m−2
yr−1 of particles smaller than 20 μm is
required, depending on the duration of the deposition period. The
particles smaller than 20 μm are mixed with particles
brought up from the sandy material below the surface crust by
bioturbation and are incorporated into the surface crust. Measurements
during the 16 and 20 September 1989 dust storms provided a total
deposition of 41.1 g m−2 of particles smaller than 20
μm. Because 10–30 dust storms are
observed at Shaartuz, the measured average dust storm deposition would
yield 206–617 g m−2
yr−1. This range of deposition is of the order of
that needed to provide a mass balance for the observed crust formation.
Cryptogams (including algae, lichen, and moss) and rainwater are the
main agents of incorporation of the aeolian dust into a stable soil
crust. The role that the vascular plants played at the Shaartuz site was
to reduce the rate of soil movement to levels where the cryptogamic
crusting was possible. the observed mechanisms of dust deposition
followed by crust incorporation are possibly an important processes in
loess formation in Central Asia. Published in Atmospheric Environment,
volume 27, issue 16, on pages 2519 - 2525, in 1993.
