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

India southwest (or ‚summer‘) monsoon 2014 -

Clean SH air

NH

SH

2014:

equator

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