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
Proceedings of the National Academy of Sciences,
Год журнала:
2021,
Номер
118(10)
Опубликована: Март 1, 2021
Surface
ozone
is
a
severe
air
pollution
problem
in
the
North
China
Plain,
which
home
to
300
million
people.
Ozone
concentrations
are
highest
summer,
driven
by
fast
photochemical
production
of
hydrogen
oxide
radicals
(HO
Elementa Science of the Anthropocene,
Год журнала:
2021,
Номер
9(1)
Опубликована: Янв. 1, 2021
The
coronavirus-19
(COVID-19)
pandemic
led
to
government
interventions
limit
the
spread
of
disease
which
are
unprecedented
in
recent
history;
for
example,
stay
at
home
orders
sudden
decreases
atmospheric
emissions
from
transportation
sector.
In
this
review
article,
current
understanding
influence
emission
reductions
on
pollutant
concentrations
and
air
quality
is
summarized
nitrogen
dioxide
(NO2),
particulate
matter
(PM2.5),
ozone
(O3),
ammonia,
sulfur
dioxide,
black
carbon,
volatile
organic
compounds,
carbon
monoxide
(CO).
first
7
months
following
onset
pandemic,
more
than
200
papers
were
accepted
by
peer-reviewed
journals
utilizing
observations
ground-based
satellite
instruments.
Only
about
one-third
literature
incorporates
a
specific
method
meteorological
correction
or
normalization
comparing
data
lockdown
period
with
prior
reference
despite
importance
doing
so
interpretation
results.
We
use
stringency
index
(SI)
as
an
indicator
severity
measures
show
how
key
pollutants
change
SI
increases.
observed
decrease
NO2
increasing
general
agreement
inventories
that
account
lockdown.
Other
compounds
such
O3,
PM2.5,
CO
also
broadly
covered.
Due
chemistry
O3
PM2.5
concentrations,
their
responses
may
not
be
linear
respect
primary
pollutants.
At
most
sites,
we
found
increased,
whereas
decreased
slightly,
SI.
Changes
other
understudied.
highlight
future
research
needs
emerging
sets
preview
state
atmosphere
world
targeted
permanent
emissions.
Finally,
emphasize
need
effects
meteorology,
trends,
when
determining
concentrations.
Environmental Science & Technology Letters,
Год журнала:
2022,
Номер
9(2), С. 112 - 119
Опубликована: Янв. 4, 2022
Many
places
on
earth
still
suffer
from
a
high
level
of
atmospheric
fine
particulate
matter
(PM2.5)
pollution.
Formation
pollution
event
or
haze
episode
(HE)
involves
many
factors,
including
meteorology,
emissions,
and
chemistry.
Understanding
the
direct
causes
key
drivers
behind
HE
is
thus
essential.
Traditionally,
this
done
via
chemical
transport
models.
However,
substantial
uncertainties
are
introduced
into
model
estimation
when
there
significant
changes
in
emissions
inventory
due
to
interventions
(e.g.,
COVID-19
lockdown).
Here
we
applied
Random
Forest
coupled
with
Shapley
additive
explanation
algorithm,
post
hoc
technique,
investigate
roles
major
meteorological
primary
chemistry
five
severe
HEs
that
occurred
before
during
lockdown
China.
We
discovered
that,
addition
PM2.5
these
episodes
was
largely
driven
by
effects
(with
average
contributions
30–65
μg
m–3
for
HEs),
followed
(∼15–30
m–3).
Photochemistry
likely
pathway
formation
nitrate,
while
air
humidity
predominant
factor
forming
sulfate.
Our
results
highlight
machine
learning
data
has
potential
be
complementary
tool
predicting
interpreting
Earth system science data,
Год журнала:
2021,
Номер
13(8), С. 4191 - 4206
Опубликована: Авг. 26, 2021
Abstract.
In
order
to
fight
the
spread
of
global
COVID-19
pandemic,
most
world's
countries
have
taken
control
measures
such
as
lockdowns
during
a
few
weeks
months.
These
had
significant
impacts
on
economic
and
personal
activities
in
many
countries.
Several
studies
using
satellite
surface
observations
reported
important
changes
spatial
temporal
distributions
atmospheric
pollutants
greenhouse
gases.
Global
regional
chemistry-transport
model
are
being
performed
analyze
impact
these
distribution
compounds.
modeling
aim
at
evaluating
scale.
provide
input
for
simulations,
dataset
providing
adjustment
factors
(AFs)
that
can
easily
be
applied
current
emission
inventories
has
been
developed.
This
provides,
January–August
2020
period,
gridded
AFs
0.1×0.1
latitude–longitude
degree
resolution
daily
or
monthly
basis
transportation
(road,
air
ship
traffic),
power
generation,
industry
residential
sectors.
The
quantification
is
based
activity
data
collected
from
different
databases
previously
published
studies.
A
range
provided
each
grid
point
sensitivity
developed
this
study
CAMS
inventory
(CAMS-GLOB-ANT_v4.2_R1.1),
emissions
main
discussed
regions
world
first
6
months
2020.
Maximum
decreases
total
found
February
eastern
China,
with
an
average
reduction
20
%–30
%
NOx,
NMVOCs
(non-methane
volatile
organic
compounds)
SO2
relative
reference
emissions.
other
regions,
maximum
occur
April,
reductions
CO
Europe
North
America
larger
(30
%–50
%)
South
America.
India
African
NOx
NMVOC
reduced
by
15
%.
For
species,
generally
less
than
%,
except
America,
where
large
BC
(black
carbon)
estimated.
As
paper,
vary
highly
across
sectors
due
differences
duration
before
partial
complete
recovery.
(average
±
standard
deviation)
called
CONFORM
(COvid-19
adjustmeNt
Factors
fOR
eMissions)
(https://doi.org/10.25326/88;
Doumbia
et
al.,
2020).
It
distributed
Emissions
Compounds
Compilation
Ancillary
Data
(ECCAD)
database
(https://eccad.aeris-data.fr/,
last
access:
23
August
2021).
Environmental Science & Technology,
Год журнала:
2020,
Номер
54(24), С. 15660 - 15670
Опубликована: Ноя. 23, 2020
The
COVID-19
outbreak
greatly
limited
human
activities
and
reduced
primary
emissions
particularly
from
urban
on-road
vehicles
but
coincided
with
Beijing
experiencing
"pandemic
haze,"
raising
the
public
concerns
about
effectiveness
of
imposed
traffic
policies
to
improve
air
quality.
This
paper
explores
relationship
between
local
vehicle
winter
haze
in
before
during
lockdown
based
on
an
integrated
analysis
framework,
which
combines
a
real-time
emission
inventory,
situ
quality
observations,
localized
numerical
modeling
system.
We
found
that
decreased
substantially
pandemic,
its
imbalanced
abatement
NOx
(76%,
125.3
Mg/day)
volatile
organic
compounds
(VOCs,
53%,
52.9
led
significant
rise
atmospheric
oxidants
areas,
resulting
modest
increase
secondary
aerosols
due
inadequate
precursors,
still
offset
emissions.
Moreover,
enhanced
oxidizing
capacity
surrounding
regions
increased
particles
relatively
abundant
was
transported
into
mainly
responsible
for
aggravated
pollution.
recommend
mitigation
should
focus
accelerating
VOC
reduction
synchronously
controlling
regional
sources
release
benefits
control.
