long-term trends of hch and pcb in soils in india and air ... · akila muthalagu3, ondřej audy 2,...
TRANSCRIPT
Motivation:
• Understand chemodynamics of persistent semivolatile substances (which are bio-
accumulative and toxic)
• which are re-volatilising from ground compartments (multi-hopping)
→ study the processes and understand large scale spatiotemporal trend
Long-term trends of HCH and PCB in soils in India and
air-soil exchange of POPs under the influence of the monsoon Gerhard Lammel1,2, Céline Degrendele1,2, Sachin S. Gunthe3, Qing Mu1,
Akila Muthalagu3, Ondřej Audy2, Petr Kukučka2, Mariëlle Mulder2, Mega Octaviani1,
Petra Příbylová 2, Pourya Shahpoury1, Irene Stemmler4, Aswathi E. Valsan3 1 Max Planck Institute for Chemistry, Multiphase Chemistry Dept., Mainz, Germany
2 Masaryk University, Research Centre for Toxic Compounds in the Environment, Brno, Czech Republic 3 Indian Institute of Technology, Environmental & Water Resources Engineering, Chennai, India
4 Max Planck Institute for Meteorology, Ocean in the Erth System Dept., Hamburg, Germany
Air-sea E Mediterranean 2010 seasonal Mulder et al ACP 2014
E Mediterranean 2012 episode Lammel et al ACP 2016
Air-soil W Balkans 2008 episode Lammel et al. J Env Mon 2011
Pannonian Plain 2013 episode Degrendele et al. EST 2016
India 2014 seasonal
pre-monsoon monsoon
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
pg
/m³
(PA
H:
ng
/m³)
EC
OC
DDX
HCH
PCB
PAH16
100-500
50
0-
10
00
1000-2000 2000-4000 4000-6000
31/05/14
00H00 A A A A O
03H00 A A A A A/O
06H00 A A A A A/O
09H00 A A A A A/O
12H00 A A A A O
15H00 A A A A O
18H00 A A A A O
21H00 A A A A
1/6/2014
00H00 A A A A A/O
03H00 A A A A A
06H00 A A A A A
09H00 A A A A A
12H00 A A A A O
15H00 A A A A A
18H00 A A A A O
21H00 A A A A A
2/6/2014
00H00 A A A A O
03H00 A A A A A
06H00 A A A A O
09H00 A A A A A
12H00 A A A A A/O
15H00 C C A A A
18H00 C C A A A
21H00 C C A A A
3/6/2014
00H00 C C A A A
03H00 C C A A A
06H00 C C A A/O A/O
09H00 C C A A A
12H00 A A A A O
15H00 A A A A O
18H00 A A A A O
21H00 C A O A A/O
4/6/2014
00H00 C C A O
03H00 C C C A A
06H00 C C C A O
09H00 C C C A O
12H00 C C C A O
15H00 C C C A O
18H00 C C C O O
21H00 C C C B O
5/6/2014
00H00 B C C O O
03H00 C C C C O
06H00 C C C B/O O
09H00 C C C B B
12H00 C C C B O
15H00 B B C B O
18H00 B C C C O
21H00 B B C B O
6/6/2014
00H00 B B C C O
03H00 B B C B O
06H00 B B C B O
09H00 B B C B B
12H00 B B C C O
15H00 B B B B O
18H00 B B B B B
21H00 B B B B B
Origin of air masses (Lagrangian
dispersion modelling i.e. FLEXPART)
monsoon
transitio
n
pre
-monsoon
Munnar, Kerala, May-June 2014
high-volume air samples (n = 24)
Canopy and soil at 3 soil sampling plots. Soil type: nitisol (GOI, 1985; FAO,
2014)
Tea garden Shrub Forest
TOC = 4.4% 10.7% 4.0 %
0
50
100
150
200
250
300
tea shrub forest
ng
/g
PBDE (7/10)
DDT (6/6)
HCH (3/5)
PeCB+HCB*100
PCB (7/7)*100
PAH (16/25)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
tea shrub forest
ng
/g
PBDE (7/10)
DDT (6/6)
HCH (3/5)
PeCB+HCB
PCB (7/7)
PAH (16/25)
o,p'-DDE 1.84
p,p'-DDE 12.13
o,p'-DDD 0.49
p,p'-DDD 0.17
o,p'-DDT 11.34
p,p'DDT 1.90
2. Air-soil exchange of trace gases ?
Air-soil exchange India before and during onset of SW monsoon 2014
Change of air-soil fugacity ratio (2-film model; Harner et al., 2001),
fs/fa=cs H(T) ⁄ (0.411 OM KOW)/[ca Rg T], with the onset of SW monsoon
in 3 land-use categories:
↑ upward: PCB28 (forest), -HCH (tea, forest) and -HCH (all)
↓ predominantly downward: (g) PHE, FLT, PYR, - and -HCH, BDE47 and -99
in forest:
Results:
• almost all pollutants addressed were found in air, but
not in soil (LOQ too high for many OCPs and PAH
derivatives)
• direction of vertical flux of some OCPs and PCBs may
change with onset of monsoon from downward to
upward
→ seasonal flux fluctuation, determined by the
large-scale advection pattern ?
Δcadv
Hypothesis:
When propagating northward, the SW monsoon in
India advects air which carries secondary emissions
of semivolatile pollutants previously stored in soils,
the more the further it propagates and - triggered
by itself ! - ?
Δcfug = ?
Δcscav
Volatilisation triggered by the drop of air pollution levels ?
→ Modelling the chemodynamics
cpre monsoon in air (ground level, mean of 1-3 June)
(a) α-HCH, (b) γ-HCH, (c) PCB28, (d) PCB153 (pg m-3)
Response of the air-soil sub-system to meteorological and chemical changes in
advection: episode simulation WRF/Chem model with soil compartment
Air pollution drop due to advection of SW monsoon air (exp-ctrl) 8-10, then 28-30 June 2014
→ In S India the change of
pollutant level reflects the drop in
the advected, clean air, while with
propagation northward the signal
decreases
(%) S India
(Munnar, 9°N)
C India
(22°N)
N India
(29°N)
Δcobs/
cobsa
Δcpred/
cpred
Δcpred/
cpred
Δcpred/
cpred
α-HCH -83 -79 -57 - 7
γ-HCH -87 -83 -60 -10
pp-DDT -73 -42 - 5 +12
pp-DDE < -75 -99.8 -73 -30
PCB28 -55 -79 -57 - 6
PCB153 -55 -38 -23 +10
Seasonal (40 year-) mean PBL heights (ERA-40 data; Patil et al., 2013)
pre-monsoon monsoon
post-monsoon winter
40-year simulation - Input data spatiotemporal variations:
cOH interpolated from 3-monthly climatological data (Spivakovsky et al 2000)
hboundary layer 37-year mean (1965-2002) monthly data (ERA40, ECMWF)
Wt scaled from atmospheric burden and Fwet dep of global MCTM output
(Lammel et al 2012, Stemmler & Lammel 2012, Semeena et al 2006),
2. Long-term regional scale response of soil compartment to
atmospheric pollution and the monsoon cycle ?
Non-steady state 2-compartment box modelling 1965-2014: Model
predicted concentrations in air and top soils in 7 zones (boxes), N to S
southernmost (measurement) box:
Air
Soil
PCB28 PCB153 α-HCH
Air (pg m-3) Soil (pg g-1)
Pre-monsoon 2014 Monsoon 2014 2014
Obs‘d Mod‘ld Obs‘d Mod‘ld Observed Mod‘ld
PCB28 10.5 3.0 5.5 3.0 54-60 1.9
PCB153 0.47 0.22 0.21 0.24 34-40 21
α-HCH 7.7 118 1.3 114 10-36 18
Long-term regional scale response of soil compartment to
atmospheric pollution and the monsoon cycle ?
Non-steady state 2-compartment box modelling 1965-2014:
Model predicted concentrations in air and top soils in 7 zones
(boxes), N to S
Southernmost, central and northernmost boxes:
Air
Soil
α-HCH PCB28
PCB153
→ Reversal of air-soil exchange to volatilisation of PCBs
historically earlier in C and N India later than in S India
… thank you for your attention! acknowledgements: Co-authors: Céline Degrendele, Sachin S. Gunthe, Qing Mu, Akila Muthalagu, Ondřej Audy,
Petr Kukučka, Mariëlle Mulder, Mega Octaviani,Petra Příbylová , Pourya
Shahpoury, Aswathi E. Valsan
On site support MU Brno: Roman Prokeš
IIT Chennai: Aswathy E.Valsan, Tabish Umar Ansari
Laboratory: MU Brno: Lenka Škrdlíková, Rostislav Červenka
Supported by Max Planck Society
India Dept Science & Technol -Max Planck Partner Group at IIT
Czech Ministry of Education, Youth and Sports
Main results and conclusions
• HCH, DDT and PCB are re-volatilising from soil at a S India background site 2014
• Pollution drop in air (when SW monsoon arrives) enhances re-volatilization of some
of the POPs from soils (the deeper the drop, the more)
• Monsoon air arriving in N India is expected to be less clean than in S India due to
mobilisation of pollution stored in soils (besides other pollution sources)
• So far: Seasonality of air-soil exchange flux not explained by box modelling / for
only part of the substances studied