ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Lake sediment evidence for long-range transported

atmospheric pollutants on the Tibetan Plateau

Neil Rose, Handong Yang, Simon Turner, Rick Battarbee

Environmental Change Research Centre, University College London

Wu Guangjian, Yang Ruiqiang, Wang Xiaoping, Yao Tandong

Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing

Funded by

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Tibetan Plateau

‘Third Pole’

• North-west one of the most inaccessible

and least populated regions on Earth

• Presumption of pristine status

‘Water Tower of Asia’

• Source of the Ganges, Brahmaputra,

Indus, Yangtse, Yellow, Mekong and

Irrawady Rivers

‘Roof of the World’

• Averages >4000m altitude

• Above atmospheric boundary layer: long-

range pollutant sources

(e.g. intercontinental; hemispheric)

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Lake sediment record

Age

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Project aims:

To use lake sediments to provide data on the temporal and spatial

distribution of atmospherically deposited pollutants (trace metals, POPs,

fly-ash particles) across the Tibetan Plateau.

Allowing us to:

• assess the scale and rates of change of inputs for a suite of contaminants

across the region

• provide ‘baseline’ data to assess future changes in contamination of Plateau

freshwaters and background data for ecological impact studies

• undertake preliminary source apportionment for deposited contaminants

• determine long-term trends as a context for contemporary ITP monitoring

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

North Lakes Qinghai Hu

Keluke Hu

Ga Hai

Central Lakes Nam Co

Cuo Na

Cuo E

South Lakes Peku Co

Cuolong Co

Kemen Co

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

South

Cen

tral

Nort

h

Qinghai Hu Ga Hai

Cuo Na Tso Ur Nam Co

Chuolong Co Peku Co Kemen Co

Keluke Hu

2006

2007

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Sampling strategy

Multiple sediment and soil cores from each lake and catchment

Analyses include:

Lithostratigraphy (water, organic and carbonate content)

Chronologies

Sediment geochemistry (40+ elements; XRF)

Trace metals (Hg, Cd, Pb, Ni, Cu and Zn)

Persistent organic pollutants (PAHs, PCBs, PBDEs)

Fly-ash particles (SCPs and IASs)

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Results

Core chronologies Reliable chronologies (except Chuolong Co)

Great variety of accumulation rates; sub-decadal resolution

Time (AD)

1840 1860 1880 1900 1920 1940 1960 1980 2000

De

pth

(cm

)

0

10

20

30

40

50

TPNA1

TPNB1

TPNC1

TPCA3

TPCB1

TPCC1

TPSB1

TPSC1

Qinghai

Keluke

Gaihai

Cuo Na

Cuo E

Nam Co

Peku Co

Kemen Co

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Trace metals

(Pb)

TPSB1

0

5

10

15

20

25

0 5 10 15 20 25

Pb (µg/g)

Dep

th (

cm)

TPNA1

0

5

10

15

20

25

30

35

0 10 20 30

Pb (µg/g)

Dep

th (

cm)

TPNB1

0

5

10

15

20

25

30

35

40

0 10 20

Pb (µg/g)

Dep

th (

cm)

TPCA3

0

5

10

15

20

25

30

35

0 10 20 30

Pb (µg/g)

Dep

th (

cm)

TPCB1

0

5

10

15

20

25

30

35

0 10 20

Pb (µg/g)

Dep

th (

cm)

TPCC1

0

10

20

30

40

0 10 20 30

Pb (µg/g)

Dep

th (

cm)

TPSA1

0

5

10

15

20

0 1 2 3 4 5

Pb (µg/g)

Dep

th (

cm)

TPNC1

0

5

10

15

20

25

30

35

0 5 10 15 20 25

Pb (µg/g)

Dep

th (

cm)

TPSC1

0

5

10

15

20

25

30

35

40

45

0 5 10 15

Pb (µg/g)

Dep

th (

cm)

Northern lakes

Central lakes

Southern lakes

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Trace metals (normalised data for Qinghai)

TPNA1

0

5

10

15

20

25

30

0 1 2 3

Pb/K

Depth

(cm

)

TPNA1

0

5

10

15

20

25

30

0 10 20

Pb/Ti

Depth

(cm

)

TPNA1

0

5

10

15

20

25

30

0 0.2 0.4

Pb/LOI

Depth

(cm

)

TPNA1

0

5

10

15

20

25

30

0 50 100

Zn/K

Depth

(cm

)

TPNA1

0

5

10

15

20

25

30

0 50 100

Zn/Ti

Depth

(cm

)

TPNA1

0

5

10

15

20

25

30

0 50 100

Zn/LOI

Depth

(cm

)

Pb

Zn

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Lead Isotopes:

• Lead has four stable, naturally occurring isotopes: 204Pb (1.4%), 206Pb (24.1%), 207Pb (22.1%), and 208Pb (52.4%).

• Ratios of these isotopes varies in different minerals and sources.

• 206Pb / 207Pb ratios: Leaded petrol: 1.06 – 1.09

British Pb ore: 1.16 – 1.18

UK coal: 1.16 – 1.19

• Natural Pb ratios in uncontaminated sediments and peats typically 1.2 – 1.5

• Therefore Pb isotope ratio declines with anthropogenic signal.

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

0 0.5 1 1.5 2

Pb (EF)

Se

dim

en

t d

ep

th (

cm

)0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

1.13 1.14 1.15 1.16 1.17 1.18

206Pb/207Pb

Lead isotopes: Qinghai Hu (North)

1950

1860

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

0 0.5 1 1.5 2

Pb (EF)

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

1.13 1.15 1.17 1.19 1.21206Pb/207Pb

Lead isotopes: Co E (central)

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

(Sourc

e:

Jim

Knig

hto

n,

Cle

ar

Lig

ht

Image P

roducts

, C

opyrig

ht

2000)

Fly-ash particles

No

SCPs

Qinghai

1910

1930

1950

1970

1990

2010

0 10 20 30

SCP (no. cm-2

yr-1

)

Cuo Na

1910

1930

1950

1970

1990

2010

0 1 2 3

SCP (no. cm-2

yr-1

)

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Trace metals: Mercury fluxes

TPNA1

1850

1870

1890

1910

1930

1950

1970

1990

2010

0 10 20

Hg (mg/m2yr)

date

TPNB1

1850

1870

1890

1910

1930

1950

1970

1990

2010

0 10 20 30 40

Hg (mg/m2yr)

date

TPNC1

1890

1910

1930

1950

1970

1990

2010

0 20 40 60 80

Hg (mg/m2yr)

date

TPCA3

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

2010

0 150 300 450 600

Hg (mg/m2yr)

date

TPCB1

1870

1890

1910

1930

1950

1970

1990

2010

0 20 40 60 80 100

Hg (mg/m2yr)

date

TPCC1

1850

1870

1890

1910

1930

1950

1970

1990

2010

0 10 20 30

Hg (mg/m2yr)

date

TPSB1

1940

1950

1960

1970

1980

1990

2000

2010

0 10 20 30

Hg (mg/m2yr)

date

TPSC1

1890

1910

1930

1950

1970

1990

2010

0 10 20 30 40

Hg (mg/m2yr)

date

Northern lakes

Central lakes

Southern lakes

• Significant increase in flux since 1970s

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Trace metals:

No

rth

Ce

ntr

al

So

uth

• Altitudinally enhanced oxidation of GEM to RGM by tropospheric air?

• RGM water soluble and hence more easily scavenged and deposited

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Persistent Organic Pollutants Fluxes: Qinghai

0 50 100 150

HCB

0 100 200 300 400

S HCHs1850

1870

1890

1910

1930

1950

1970

1990

2010

0 1000 2000 3000

Ye

ar

(AD

)

S PCBs

0 1000 2000 3000 4000

S DDTs

ng cm-2 yr-1

• Significant increase in contamination from all sources since 1970s

• Some evidence for earlier contamination. Global signal

ENVIRONMENTAL CHANGE RESEARCH CENTRE

Global Change and the World’s Mountains. Sept 2010

Conclusions

Lake sediment archives from across the Tibetan Plateau have shown:

• Evidence for contamination from hemispheric and global sources.

137Cs (weapons testing), mercury and persistent organic pollutant data

• Evidence for additional contamination in the north of the Plateau.

Trace metal (e.g. lead), Pb isotope and fly-ash particle data.

Regional sources such as Lanzhou? Xining?

• Contamination appears to be increasing rapidly.

Continued industrial development (China; N. India)

Suggests future increase in contamination is likely

Furthermore:

• Contaminant transport to the region may be exacerbated by changes to

monsoonal patterns