Journal of Geophysical Research Atmospheres,
Год журнала:
2022,
Номер
127(3)
Опубликована: Янв. 28, 2022
Abstract
Unexpectedly
frequent
severe
haze
episodes
were
observed
in
Beijing
during
February–March
2021
after
two
phases
of
clean
air
action
plan
(2013–2020),
yet
the
causes
remained
unclear.
Here,
we
conducted
real‐time
fine
particle
(PM2.5)
composition
measurements
January–March
using
a
time‐of‐flight
aerosol
chemical
speciation
monitor
and
an
aethalometer
compared
with
those
coronavirus
disease
(COVID‐19)
period
2020.
Our
results
showed
ubiquitously
elevated
concentrations
chloride,
black
carbon
(BC),
primary
organic
(POA)
2021,
suggesting
increased
emissions
post‐COVID‐19
period.
By
machine
learning‐based
random
forest
(RF)
algorithm,
found
largely
different
responses
changes
to
meteorology
months.
After
decoupling
effects
meteorology,
PM2.5
from
2020
reduced
−35.6%
−29.0%
January,
−24.1%
−4.5%
February,
+92.6%
+34.2%
March,
respectively.
demonstrate
dominant
roles
stagnant
secondary
production
formation
March
2021.
In
particular,
that
compositions
deweathered
fairly
similar
between
ratios
OA
inorganic
aerosols
close.
study
indicates
influence
meteorological
conditions
is
great
importance
for
better
evaluation
mitigating
strategies
pollution
due
large
impact
on
species
particularly
short
Environmental Pollution,
Год журнала:
2021,
Номер
284, С. 117153 - 117153
Опубликована: Апрель 15, 2021
Lockdowns
amid
the
COVID-19
pandemic
have
offered
a
real-world
opportunity
to
better
understand
air
quality
responses
previously
unseen
anthropogenic
emission
reductions.
Geophysical Research Letters,
Год журнала:
2021,
Номер
48(7)
Опубликована: Март 27, 2021
Abstract
In
late
January
2020,
China’s
rapid
and
strict
control
measures
to
curb
the
COVID‐19
spread
led
a
sharp
halt
in
socio‐economic
activity
significant
reduction
emissions.
Using
ground‐based
observational
data,
authors
synergistically
quantify
nation‐wide
variations
of
major
air
pollutant
as
well
meteorology
during
after
lockdown.
Their
concentrations
(except
O
3
)
exhibited
February
March
by
more
than
24%
lockdown
compared
with
earlier
time
period
17%
that
same
2019.
contrast,
ozone
increased
rapidly
about
60%
across
country
Abnormal
increases
carbon
monoxide
particulate
matter
southwest
China
are
attributed
severe
wildfires
Southeast
Asia.
The
concentration
pollutants
bounced
back
full‐scale
reopen
indicating
decisive
role
emissions
pollution
formation.
Journal of Geophysical Research Atmospheres,
Год журнала:
2022,
Номер
127(3)
Опубликована: Янв. 28, 2022
Abstract
Unexpectedly
frequent
severe
haze
episodes
were
observed
in
Beijing
during
February–March
2021
after
two
phases
of
clean
air
action
plan
(2013–2020),
yet
the
causes
remained
unclear.
Here,
we
conducted
real‐time
fine
particle
(PM2.5)
composition
measurements
January–March
using
a
time‐of‐flight
aerosol
chemical
speciation
monitor
and
an
aethalometer
compared
with
those
coronavirus
disease
(COVID‐19)
period
2020.
Our
results
showed
ubiquitously
elevated
concentrations
chloride,
black
carbon
(BC),
primary
organic
(POA)
2021,
suggesting
increased
emissions
post‐COVID‐19
period.
By
machine
learning‐based
random
forest
(RF)
algorithm,
found
largely
different
responses
changes
to
meteorology
months.
After
decoupling
effects
meteorology,
PM2.5
from
2020
reduced
−35.6%
−29.0%
January,
−24.1%
−4.5%
February,
+92.6%
+34.2%
March,
respectively.
demonstrate
dominant
roles
stagnant
secondary
production
formation
March
2021.
In
particular,
that
compositions
deweathered
fairly
similar
between
ratios
OA
inorganic
aerosols
close.
study
indicates
influence
meteorological
conditions
is
great
importance
for
better
evaluation
mitigating
strategies
pollution
due
large
impact
on
species
particularly
short
