Microplastics
(MPs) have become a problematic pollutant in different
environments. Dry soil aggregates may have a remarkable influence
on the emissions of MPs from surface soil due to wind erosion. Here,
we sampled surface soils and monitored wind erosion events to investigate
the number of MPs distributed in different dry soil aggregate sizes
and the implications for MP emissions induced by wind erosion. Of
the MPs in soils, 35% (453.49 ± 187.62 kg–1) were associated with soil aggregates and 65% (848.69 ± 412.04
kg–1) were dispersed. Only 38% of all fiber and
27% of all nonfiber MPs were associated with soil aggregates. The
abundances of <2.5 mm fibers and <0.5 mm nonfibers decreased
exponentially with an increase in aggregate size. With an increase
in the abundance of microfibers associated with soil aggregates, the
total organic matter and nitrogen contents increased while the mean
soil particle size decreased. The MP size distributions for different
soil aggregate size fractions showed sigmoid trends similar to those
described by logistic models. The aggregate stability and wind speed
were inversely and positively correlated with microfiber enrichment,
respectively, in wind-blown sand and dust. This study provides the
first insights into the number distribution of MPs in different dry
soil aggregate fractions.
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