Spatial coverage and temporal trends of land-based atmospheric mercury measurements in the Northern and Southern Hemispheres

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1 Institut für Küstenforschung Zur Anzeige wird der QuickTime Dekompressor TIFF (LZW) benötigt. Spatial coverage and temporal trends of land-based atmospheric mercury measurements in the Northern and Southern Hemispheres Ralf Ebinghaus, Cathy Banic, Steve Beauchamp, Dan Jaffe, Hans Herbert Kock, Nicola Pirrone, Laurier Poissant, Francesca Sprovieri and Peter Weiss-Penzias

2 Past trends Chemical analysis of lake sediments, ice cores and peat deposits from both hemispheres indicates about a threefold increase of mercury deposition since pre-industrial times

3 Monitoring of more recent change Asian mercury emissions are suggested to be rapidly increasing at least in the past decade (Pacyna et al., 2006). In principal, an increase of the global atmospheric pool should also be reflected in the background concentration in ambient air. Regional differences, temporal trends and potential sources and source regions can be identified by monitoring networks.

4 Monitoring networks on regional scales - ambient air EUROPE

5 MEDITERRANEAN ATMOSPHERIC MERCURY CYCLE SYSTEM (MAMCS) and Mercury Species over Europe (MOE) 1. Mallorca ( N, E); 2. Calabria (39 25 N, E); 3. Sicily (36 40 N, 15 l0 E); 4. Turkey ( N, E); 5. Israel (32 40 N, E); 6. Germany ( N, ); 7. Germany ( N, E); 8. Sweden ( N, ll E); 9. Sweden ( , E); 10. Ireland (53 20 N, 9 54 W)

6 RGM (pg m -3 ) TPM (pg m -3 ) TGM (ng m -3 ) MAMCS / MOE field campaigns TGM MOE MAMCS CAMPAIGNS START DATE STOP DATE MAMCS-1/ MOE-1 MAMCS-2 / MOE-2 MAMCS-3 / MOE-3 MAMCS-4 / MOE TPM MOE MAMCS MOE RGM MOE MAMCS

7 Results of MAMCS / MOE field campaigns Observed concentrations of total gaseous mercury (TGM), particulate mercury (TPM), and reactive gaseous mercury (RGM) were generally slightly higher in the Mediterranean region than in Northwest Europe (Wangberg et al. (2001)

8 Possible explanations for northsouth gradient More geologic sources of Hg 0 in Mediterranean region Enhanced reemission fluxes from warm sea surface More photochemical transformations in Mediterranean MBL

9 Monitoring networks on regional scales - ambient air U.S.A

10 Sites in the U.S. where gaseous Hg species have been measured

11 Spatial characteristics of atmospheric Hg in U.S. Sites near point sources (urban areas and mines (< 50 km) Sites influenced by regional point sources (< 500 km) Background sites High altitude site (3 km) Hg 0 Range of Means (ng/m3) RGM Mean - Max (pg/m3) Hgp Mean - Max (pg/m3) Precip. [Hg T ] Mean - Max (ng/l) NA

12 Monitoring networks on regional scales - ambient air CANADA

13 In 1995 Fitzgerald has plead for and defined the basic requirements of an Atmospheric Mercury Network (AMNET). This has partly been accomplished on a regional scale within the Canadian Atmospheric Mercury Network (CAMNet) that may be considered as seminal in this respect

14 CAMNet Alert CAMNet active other CAMNet closed Little Fox Lake Fort Chipewyan Whistler Bratts Lake Reifel Island Esther Kuujjuarapik Mingan ELA St. Anicet Burnt Island Egbert Pt. Petre South Hampton Kejimkujik St. Andrews Station Code Province Latitude (deg) Longitude (deg) Altitude (meter a.s.l.) Period Alert ALT NU /95-12/05 Kejimkujik KEJ NS /96-12/04 St. Andrews STA NB /96-12/04 St. Anicet WBZ QC /97-12/05 Point Petre PPT ON /96-12/05 Egbert EGB ON /96-12/05 Burnt Island BNT ON /98-12/05 Bratt's Lake BRL SK /01-12/05 Esther EST AB /98-04/01 Fort Chipewyan FCH AB /00-07/01 Reifel Island RFL BC /99-02/04 a.s.l. = above sea level

15 11 CAMNet sites were analyzed for temporal trends ( ) (Temme et al., 2007) decreasing trend for TGM concentrations at several rural sites was seen for the time period 1995 to 2005 (- 2.2 to -16.6%) changes are mostly driven by local or regional changes in mercury emissions other sites reflect hemispherical global background concentrations of airborne mercury, where slight decreases or no statistically significant trend in TGM concentrations exist over the same time period

16 The current global Hg-background concentration General scientific consensus exists about the current global background concentration*: It is currently taken as ca. 1.5 to 1.7 ng m -3 in the Northern Hemisphere and ca. 1.1 to 1.3 ng m -3 in the Southern Hemisphere (Lindberg et al., 2007) *refers to the average sea-level atmospheric Hg(0) at remote sites

17 Long-term monitoring at single background locations The question of trends

18 GAW stations

19 Mercury GAW stations

20 GAW Station Mace Head, Ireland 53,2 o N, 9,5 o W

21 Aug/ 95 Jan/ 96 Jul/ 96 Jan/ 97 Jul/ 97 Jan/ 98 Jul/ 98 Jan/ 99 Jul/ 99 Jan/ 00 Jul/ 00 Jan/ 01 Jun/ 01 Dec/ 01 Jun/ 02 Dec/ 02 Jun/ 03 Dec/ 03 Jun/ 04 Dec/ 04 Jun/ 05 Dec/ 05 Jun/ 06 Dec/ 06 May/ 07 Nov/ 07 Long-term measurements at Mace Head, Irish west coast from today TGM (24 h av. ), Mace Head, Ireland, Since 2003 funded by: Since 2003 funded by:

22 GAW station Cape Point, RSA (34 o 21 S, 18 o 29 E) Cape of Good Hope GAW station

23 Long-term measurements at Cape Point, from Slemr et al. 2008, submitted to GRL, results based on manual methodology with low temporal resolution

24 More recent trends Asian mercury emissions are suggested to be rapidly increasing at least in the past decade however, this is neither reflected in the long-term measurement of TGM at Mace Head, Ireland or Cape Point - covering the period between 1995 to 2007, nor in the precipitation data of the North American Mercury Deposition Network ( MDN - not shown)

25 TGM [ng/m3] An attempt to reconstruct the past 30 years... Slemr et al., 2003 Ship Wank Rörvik Mace Head Lista Ny Alesund Alert Year Automated, highly time resolved measurements

26 Added value of long-term observational data with high time resolution - new insights in emissions and regional transport - unexpected findings -...

27 Emission estimates and source attribution Simultaneous Hg Observations at Mt. Bachelor and Okinawa (Jaffe et al., 2005) 2.7 km asl Okinawa MBO

28 Emission estimates and source attribution Elevated levels were associated with transport from E. Asia Since both Hg(0) and CO are long lived, this ratio should be preserved during long-range transport and be identical to source ratio. Since CO emissions from E. Asia have been quantified and validated, this can be used to estimate Hg(0) emissions from E.Asia. Jaffe et al., 2005; Weiss-Penzias et al., 2007

29 Example of Asian pollution plume detected at Mt. Bachelor Hg 0 / CO ng m -3 ppbv -1 This yields an estimate of 620 tons/yr for Chinese Hg 0 emission, which is 2x higher than estimate by Streets et al., 2005.

30 Unexpected findings...

31 AMDEs in Polar Regions

32 TGM concentrations at temperate and polar coasts Alert Data: Schroeder, Steffen and co-worker Mace Head Data: Ebinghaus, Kock and co-worker

33 TGM (ng Hg/m3) Hg-measurements with high time-resolution at Mace Head and Cape Point in 2007 TGM (ng Hg/m3), 1 h average, Cape Point, South Africa and Mace Head, Ireland, ,5 2,0 1,5 1,0 0,5 0,0 Date

34 Conclusions - monitoring data: - can identify regional differences, temporal trends and are useful scientific tools for source attribution reproducibility of regional changes cannot definitively answer Asian question. - are necessary to evaluate the effectiveness of control measures (on a regional basis) - can be used to verify / improve emission estimates - give new insights, for example based on unexpected observations - help us to understand the global mercury cycle in order to evolve purposeful regulations (on a global basis) The value of long-term atmospheric Hg monitoring stations and the need for additional sites is obvious,