Lake sediment evidence for long-range transported atmospheric pollutants on the Tibetan Plateau. Presented by Neil Rose at the "Perth II: Global Change and the World's Mountains" conference in Perth, Scotland in September 2010.

1. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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
Global Change and the World’s Mountains. Sept 2010

2. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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)
Global Change and the World’s Mountains. Sept 2010

3. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Lake sediment record
Age
Global Change and the World’s Mountains. Sept 2010

4. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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
Global Change and the World’s Mountains. Sept 2010

5. ENVIRONMENTAL CHANGE RESEARCH CENTRE
North Lakes
Qinghai Hu
Keluke Hu
Ga Hai
Central Lakes
Nam Co
Cuo Na
Cuo E
South Lakes
Peku Co
Cuolong Co
Kemen Co
Global Change and the World’s Mountains. Sept 2010

6. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Qinghai Hu Keluke Hu Ga Hai
North
2006
Cuo Na Tso Ur Nam Co
Central
Chuolong Co Peku Co Kemen Co
South
2007
Global Change and the World’s Mountains. Sept 2010

7. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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)
Global Change and the World’s Mountains. Sept 2010

8. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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
0
10
Depth (cm)
20
30
Qinghai
TPNA1
Keluke
TPNB1
Gaihai
TPNC1
40 Cuo Na
TPCA3
Cuo E
TPCB1
Nam Co
TPCC1
Peku Co
TPSB1
Kemen Co
TPSC1
50
Global Change and the World’s Mountains. Sept 2010

9. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Trace metals 0
Pb (µg/g)
10 20 30 0
Pb (µg/g)
10 20 0 5
Pb (µg/g)
10 15 20 25
0 0 0
(Pb) 5 5 5
Northern lakes 10
10
10
Depth (cm)
Depth (cm)
Depth (cm)
15
15 15
20
20 20
25
25 25
30
TPNA1
30 35 TPNB1 30
TPNC1
35 40 35
Pb (µg/g) Pb (µg/g) Pb (µg/g)
0 10 20 30 0 10 20 0 10 20 30
0 0 0
5 5
10
Central lakes 10 10
Depth (cm)
Depth (cm)
Depth (cm)
15 15
20
20 20
25 25
30
30 TPCA3 30
TPCB1 TPCC1
35 35 40
Pb (µg/g) Pb (µg/g) Pb (µg/g)
0 1 2 3 4 5 0 5 10 15 20 25 0 5 10 15
0 0 0
5
5 10
5
Southern lakes Depth (cm)
15
Depth (cm)
Depth (cm)
10
20
10
25
15
30
15
20 35
TPSA1 40
TPSB1 TPSC1
20 25 45
Global Change and the World’s Mountains. Sept 2010

10. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Trace metals
(normalised data for Qinghai)
Pb/K Pb/Ti Pb/LOI
0 1 2 3 0 10 20 0 0.2 0.4
0 0 0
5 5 5
Pb Depth (cm)
10 10 10
Depth (cm)
Depth (cm)
15 15 15
20 20 20
25 25 25
TPNA1 TPNA1 TPNA1
30 30 30
Zn/K Zn/Ti Zn/LOI
0 50 100 0 50 100 0 50 100
0 0 0
5 5 5
Zn 10 10 10
Depth (cm)
Depth (cm)
Depth (cm)
15 15 15
20 20 20
25 25 25
TPNA1 TPNA1 TPNA1
30 30 30
Global Change and the World’s Mountains. Sept 2010

11. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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.
Global Change and the World’s Mountains. Sept 2010

12. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Lead isotopes:
Qinghai Hu (North)
0 0
2 2
4 4 1950
6 6 1860
8 8
10 10
Sediment depth (cm)
12 12
14 14
16 16
18 18
20 20
22 22
24 24
26 26
28 28
30 30
32 32
0 0.5 1 1.5 2 1.13 1.14 1.15 1.16 1.17 1.18
206 207
Pb (EF) Pb/ Pb
Global Change and the World’s Mountains. Sept 2010

13. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Lead isotopes:
Co E (central)
0 0
2 2
4 4
6 6
8 8
10 10
12 12
14 14
16 16
18 18
20 20
22 22
24 24
26 26
28 28
30 30
32 32
0 0.5 1 1.5 2 1.13 1.15 1.17 1.19 1.21
206
Pb (EF) Pb/ 207Pb
Global Change and the World’s Mountains. Sept 2010

14. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Fly-ash particles
Qinghai
2010
1990
1970
1950
1930
Cuo Na 1910
0 10 20 30
-2 -1
2010 SCP (no. cm yr )
1990
1970
(Source: Jim Knighton, Clear Light Image Products, Copyright 2000)
1950
1930
1910
0 1 2 3
-2 -1
SCP (no. cm yr )
No
SCPs
Global Change and the World’s Mountains. Sept 2010

15. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Trace metals: Mercury fluxes
Hg (mg/m2yr) Hg (mg/m2yr) Hg (mg/m2yr)
0 10 20 0 10 20 30 40 0 20 40 60 80
2010 2010 2010
Northern lakes 1990 1990
1990
1970 1970
1970
1950 1950
date
date
date
1930 1930 1950
1910 TPNA1 1910 TPNB1
1930
1890 1890 TPNC1
1910
1870 1870
1850 1850 1890
Hg (mg/m2yr) Hg (mg/m2yr) Hg (mg/m2yr)
0 150 300 450 600 0 20 40 60 80 100 0 10 20 30
2010 2010 2010
Central lakes 2000
1990
1990 1990
1970
1980 1970
1970 1950
1950
date
date
date
1960 1930
1950 TPCA3 1930
1910
1940 1910
TPCB1 1890 TPCC1
1930
1890 1870
1920
1910 1870 1850
Hg (mg/m2yr) Hg (mg/m2yr)
0 10 20 30 0 10 20 30 40
2010 2010
Southern lakes 2000 1990
1990
1970
1980
date
date
1950
1970
1930
1960
• Significant increase in flux since 1970s 1950
TPSB1
1910
TPSC1
1940 1890
Global Change and the World’s Mountains. Sept 2010

16. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Trace metals:
Central
South
North
• Altitudinally enhanced oxidation of GEM to RGM by tropospheric air?
• RGM water soluble and hence more easily scavenged and deposited
Global Change and the World’s Mountains. Sept 2010

17. ENVIRONMENTAL CHANGE RESEARCH CENTRE
Persistent Organic Pollutants
Fluxes: Qinghai
2010
1990
1970
1950
Year (AD)
1930
1910
1890
1870
S PCBs S HCHs S DDTs
HCB
1850
0 1000 2000 3000 0 100 200 300 400 0 50 100 150 0 1000 2000 3000 4000
ng cm-2 yr-1
• Significant increase in contamination from all sources since 1970s
• Some evidence for earlier contamination. Global signal
Global Change and the World’s Mountains. Sept 2010

18. ENVIRONMENTAL CHANGE RESEARCH CENTRE
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
Global Change and the World’s Mountains. Sept 2010