en |
The response of reworked aerosols to climate through estimation of inter-particle forces
Assadi Langroudi, A. & Jefferson, I.
Abstract
This paper describes the first use of inter-particle
force measurement in reworked aerosols to better
understand the mechanics of dust deflation and its consequent
ecological ramifications. Dust is likely to carry
hydrocarbons and micro-organisms including human
pathogens and cultured microbes and thereby is a threat to
plants, animals and human. Present-day global aerosol
emissions are substantially greater than in 1850; however,
the projected influx rates are highly disputable. This
uncertainty, in part, has roots in the lack of understanding
of deflation mechanisms. A growing body of literature
shows that whether carbon emission continues to increase,
plant transpiration drops and soil water retention enhances,
allowing more greenery to grow and less dust to flux.
On the other hand, a small but important body of geochemistry
literature shows that increasing emission and
global temperature leads to extreme climates, decalcification
of surface soils containing soluble carbonate
polymorphs and hence a greater chance of deflation. The
consistency of loosely packed reworked silt provides
background data against which the resistance of dust’s
bonding components (carbonates and water) can be
compared. The use of macro-scale phenomenological
approaches to measure dust consistency is trivial. Instead,
consistency can be measured in terms of inter-particle
stress state. This paper describes a semi-empirical
parametrisation of the inter-particle cohesion forces in
terms of the balance of contact-level forces at the instant
of particle motion. We put forward the hypothesis that the
loss of Ca2+-based pedogenic salts is responsible for
much of the dust influx and surficial drying pays a less
significant role.
Keywords
Dust; Deflation; Menisci; Pedogenic; Inter-particle forces
|