Mercury emissions, transport and deposition in China and other Asian Countries

Transcription

1 Mercury emissions, transport and deposition in China and other Asian Countries Xinbin Feng State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences

2 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusions Outline

3 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusions Outline

4 Estimation of anthropogenic Hg emissions in China Feng and Hong (1996) calculated that the annual mercury emission from coal combustion in 1994 was 296t. Wang et al. (1999) estimated that mercury emission from coal combustion in 1995 was 214t. Pacyna et al. (2003) estimated that total anthropogenic mercury emission in 1995 was about 500t with coal combustion as the largest source.

5 Emission factors and total mercury emissions from different anthropogenic sources in 1995 (Feng, 2005) Source category Emission factor Total Hg emission (tonnes) 1. Coal combustion 0.12 (g/t) Non-ferrous metal production 27 -Primary Cu 10 (g/t) 6 -Primary Pb 3 (g/t) 2 -Primary Zn 20 (g/t) Pig iron and steel production 0.04 (g/t) 8 4. Cement 0.1 (g/t) Gold extraction 107 -Large scale 0.68 (g/g) 21 -Artisanal 15 (g/g) Hg mining 45 (g/kg) Chlor-alkali production 18 (g/t NaOH) 2 8. Battery, electrical light, thermal meter 5% mercury used Others 10 Total 402

6 Total Hg emissions in China, by source type (t/y) (Streets et al., 2005) Total Hg emissions by sectors (tons) Res. Coal Ind. Coal Power Coal Com. & Trans. Coal Biofuel Cement Gold Smelting Zinc Smelting Lead Smelting Copper Smelting Battery & Lamp Mercury Mining 0 Others SCENARIO 1 SCENARIO 2 S1 =USGS Data S2 =China Data

7 China emitted about 540 t Hg to the atmosphere Gridded total Hg emissions for the year 1999 (30 30 min resolution, unit: t yr -1 per grid cell )(Streets et al., 2005).

8 Speciation of total Hg for each major source type in China (as fraction of total) (streets et al., 2005)

9 302 t Hg 0 Gridded Hg 0 emissions for the year 1999 (30 30 min resolution, unit: t yr -1 per grid cell )(Streets et al., 2005). Gridded Hg 2+ emissions for the year 1999 (30 30 min resolution, unit: t yr -1 per grid cell )(Streets et al., 2005). 173 t Hg 2+

10 56 t P-Hg Gridded Hg p emissions for the year 1999 (30 30 min resolution, unit: t yr -1 per grid cell )(Streets et al., 2005).

11 Uncertainties in Hg emission inventory in China The emission factors used in current mercury emission inventory are generally adopted from data published in Europe and North America. Information on speciation of total mercury emissions from these source categories are also adopted from data published in Europe and North America. Since the processes and pollution control techniques used in the industrial activities in China may differ dramatically from those in developed countries, the mercury emission factors from different source categories in China could significantly differ from the implied assumptions.

12 Uncertainty (%) in Hg emission estimates by sector (95% confidence intervals, ±) (Streets et al., 2005) 500% Power plants: coal Industrial use: coal Residential use: coal Other use: coal Fuel oil for stationary use Gasoline, diesel, kerosene Biofuels Grassland/savanna burning Forest burning Ag residue burning Household waste burning Coal mines spontaneous burning Cement production Iron and steel production Caustic soda production Zinc smelting Copper smelting Lead smelting Gold smelting: large scale Gold smelting: artisanal Mercury mining Battery/lamp production All Sectors: quadrature average 400% 300% 200% 100% 95% confidence interval (+/-) 0%

13 Estimates of global atmospheric emissions (metric tons/year) Continent Fossil fuel combustion Non.ferrous metal production Pig iron and steel production Cement production Waste disposal Artisanal gold mining Sum Europe Africa Asia North America South America Australia and Oceania Summ Source: Pacyna and Pacyna,

14 Global emissions of Hg0 (A), gaseous divalent Hg (B) and particulate Hg (C) from major anthropogenic sources in 1995 (Pacyna and Pacyna, 2002)

15

16 Observation of CO, Hg0 and PHg at Hedo Station during spring 2004 (Jaffe et al., 2005)

17 The scatterplot of Hg 0 and CO for all Okinava data (Jaffe et al., 2005)

18

19 (Jaffe et al., 2005) Using the observed molar Hg 0 /CO ratio of and the CO emissions from Asia, Jaffe and co-authors (2005) calculate Hg 0 emissions from Asia of 1460 metric tons year -1, which is substantially larger than the industrial Hg 0 emissions of 582 metric tons year -1 from the Pacyna et al., (2003) inventory.

20 Overview of ACE-Asia C130 Mercury Observation (Friedli, et al., 2004) Observed concentrations of mercury were typically greater than 1.0 ng/m 3 with the higher values appearing when the flight paths were near to China. The highest value (6.3 ng/m 3 ) was observed on flight 16 over the East China Sea, downwind of Shanghai and Zhejiang provinces.

21 (Friedli, et al., 2004)

22 Nearly 50% mercury is emitted from China in Asia. Mercury concentration model (Li et al., 2005): A regional chemical tracer model, a simplified version of STEM-2K1 was used to estimate the regional Hg distributions.

23 Model-Based Analysis Tracer Transport Model Predictions (Li et al., 2005) The average bias is 0.6 ng/m 3.

24 Hg Over the Yellow Sea Flight 6 April 11, 2001 Mean TGM=2.8 ng/m 3. Max. Model prediction value= 1.5 ng/m 3. Flight 7 April 12, 2001 Mean TGM=2.3 ng/m 3. Mean Model prediction value= 1.5 ng/m 3. This suggests that the actual Hg emissions may be significantly higher than our current estimate indicates.

25 Emission Inventory Evaluation (Li et al., 2005) The above results suggest that the estimated Hg emissions in China (i.e., 510 tons/year) are underestimated. If based on the assumption of a mercury background level of 1.2 ng/m 3. Emissions of China need to be increased by a factor of 2 3. If using a higher background value of 1.5 ng/m 3, the emissions of China need to be increased by 80%.

26 Mercury emissions from global natural sources (Travnikov et al., 2004) Mercury emissions from global anthropogenic sources (Pacyna et al., 2003)

27 Mercury concentrations in global atmosphere (Travnikov et al., 2004)

28 Model simulated global annual-average surface concentrations of Hg 0 (ng m -3 ) (Seigneur et al., 2004)

29 The average annual surface TGM concentrations (ng m -3 ) (from Dastoor and Larocque, 2004)

30

31 Average TGM: 8.40 ng m -3 TGM in airng/m 3 Sampling Date High temporal resolved TGM data in ambient air in Guiyang Feng et al., 2004)

32 Sampling locations 1 - a residential district (RD) 2 - a business district (BD) 3 - an ordinary industrial district (ID) 4 - a tourism district (TD) 5 - a rural district (RD )

33 Mercury speciation in the air measured in in different function districts of Guiyang, China GEM, ng m -3 (GEM/TAM, %) RGM, ng m -3 (RGM/TAM, %) TPM, ng m -3 (TPM/TAM, %) RD (91) 0.14 (1) 0.93 (8) BD 9.64 (92) 0.16 (2) 0.67 (6) ID (83) 0.14 (1) 2.02 (16) TD 6.01 (92) 0.09 (1) 0.46 (7) RD 5.90 (88) 0.10 (1) 0.76 (11) Mean (in urban areas) Global background (90) 0.10 (1) 1.05 (9) <

34 TGM measurements conducted in other urban areas in China Wang et al. (1996) investigated preliminarily TGM concentrations in ambient air in metropolitan Chongqing and its suburb and TGM concentrations varied from 9.2 to ng m -3 with an average of 34.4 ng m -3. Liu et al. (2000) monitored TGM concentrations at one industrial, two urban, three suburban, and two rural sampling locations in January, February and September of 1998 in Beijing. In the three suburban sampling stations, mean TGM concentrations during the winter sampling period were 8.6, 10.7, and 6.2 ng m -3, respectively. In the two urban sampling locations mean TGM concentrations during winter and summer sampling periods were 24.7, 8.3, 10, and 12.7 ng m -3, respectively. In the suburban-industrial and the two rural sampling locations, mean mercury concentrations ranged from ng m -3 in winter to ng m -3 in summer sampling periods.

35

36 14 TGM(per hour) 4.56±2.02 ng m TGM(ng.m -3 ) Hourly average total gaseous mercury concentrations measured in Gongga Mountain area in southwestern China (Feng et al., unpublished data)

37 ±4.44 ng m TGM (ng m -3 ) Sampling date Hourly average total gaseous mercury concentrations measured in Changba Mountain area in Northeastern China (Feng et al., unpublished data)

38 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusions Outline

39 Current Hg measurement programs in China Mercury emission from coal combustion in China- Qinghua University, Zhejiang University, Huazhong University of Science and Technology, China Mining University, and my group Mercury emission from non-ferrous metal smelting in Chinamy group Mercury emission from artisanal mining activities in China- my group Ambient air monitoring at different locations in China: Eco- Environment Research Center, CAS, my group

40 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusion Outline

41 Mercury emission from gold mining in China

42 Figure 8. Distribution of gold mines in China

43 Annual gold production in China from 1977 to 2003 Annual gold production (ton)

44 Mercury emission factors from gold mining The Hg emission factor was estimated to be 0.68 g Hg/ g gold produced for large scale mining activities (Qi, 1997). The mercury emission factor is estimated to be 15 g Hg/ g gold produced for small scale mining activities (Qi, 1997).

45 Mercury emission from gold mining in China One third of annual production of gold produced using amalgamation techniques in China. The annual production of gold from artisanal mining generally constituted about 16% of gold produced using amalgamation techniques during 1980s and 1990s. From 2000, artisanal gold mining activities were officially banned, but a few illegal artisanal mining workshops are still operating in some remote areas. The annual emission of Hg from gold mining in China is 50 metric tons year -1

46 Mercury emission from artisanal zinc smelting in Hezhang, Guizhou, China

47

48 Artisanal zinc smelting in Hezhang, Guizhou

49 Zinc smelting furnace 2ZnCO 3 + C 2Zn + 3CO 2

50 2ZnS + 2C + 5O 2 2 ZnCO 3 + 2SO 2 Desulphurization process

51 Table 1 Mercury concentrations in zinc ores, smelting residue, coal and coal ash. Hg concentration (mg kg -1 ) Min Max Average SD n Sulfide ore Oxide ore Desulfurized ore Smelting residue Coal Coal bottom ash

52 Fs = [A-(1-α)B]/(Dγ) + [B (1- β)c]/[e-(1-β)f] + η2(mθn)/ (Dγ) (1) Fo=[G-C(1-β )]/[H-F(1-β )] + η1(m-θn)/ [H-F(1-β )] (2)

53 Hg emission factors from artisanal zinc smelting average mercury emission factor from Zn smelting using sulfide ores is 155 with a range from 83 to 359 g Hg t -1 of Zn produced; average mercury emission factor of Zn smelting using oxide ores is 79 with a range from 8 to 388 g Hg t -1 of Zn produced

54 Mercury emission from zinc smelting ẗon Annual mercury emission from zinc smelting in Hezhang (Feng et al., AE, 2004)

55 Mercury emission from artisanal Hg smelting in Wuchuan, Guizhou, China

56

57 Artisanal mercury smelting in Wuchuang, Guizhou

58

59

60 F = ( O S) W P 10 6 P 100% F: mercury emission factor (%) O: Hg concentration in ore (mg/kg) S: Hg concentration in calcine (mg/kg) W: Total consumption of Hg ore per day (kg) P: Daily mercury production (kg)

61 Mercury emission factors in different mining areas in Wuchuan Site O (mg/kg) S (mg/kg) W (kg) P (kg) F (%) YQG LX TB Average 20.5

62 Annual Hg emission in Wuchuan Hgmining areas Site YQG LX TB Total Number of furnaces Annual Hg production (t) Annual Hg emission (t)

63 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusions Outline

64 Mercury contamination in soil in China , Geological Survey of China conducted a study to investigate major and trace elements distribution in soil in 20 provinces which covers more than 1/10 of the total land area of China One of the important findings is that soil in urban areas are seriously contaminated with mercury.

65

66 Estimate of mercury emission from soil in Guiyang (Feng et al., JGR, 2005) F1 = S (1) F2= S (2) F3= 0.254S (3) F4 = S (4) Average Hg emission flux: 19.5 ng m -2 h -1 Annual mercury emission: 398 kg/a

67 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusions Outline

68 5. Hot spots and Hg contamination of aquatic and soil system Atmospheric Hg deposition has caused heavily mercury contamination to urban soil and aquatic system. Mining activities caused also serious mercury contamination to local environment

69

70 125.8 million ton tailing Calcine and tailing from Hg mines in Wanshan

71 Smelting residues in Wuchauang Hg mining area

72 Tot-Hg and MeHg in crops in Hg mining area 1500 Tot-Hg ܹ MeHg ¼»ù¹ µ λ º ng/ g 150 Vegetables Êß² ËÀà ÓÍ ² Ë ¾í ÐIJ ËµÈ 1000 Corn Óñà Rice µ¾ã 100 Total Hg MMHg Samples collected Íòɽ Î ñ in»øáú¹ Wanshan, óçøå Î Wuchang ï ܹ and Óë¼»ù¹ Lanmuchang º Á mercury mining areas 0

73 Mercury in Hair samples collected from mercury mining areas and control site Total mercury in hair (mg/kg) Inhabitants in Wanshan Hg mines Inhabitants in control site at Changshun 0 DSX1 DSX14 DSX27 DSX40 XCX4 XCX17 XCX30 CS7 CS20 CS33 CS49 CS65

74 1. Mercury emissions from China and other Asian countries 2. Current Hg measurement programs in China 3. Mercury emissions from artisanal mining activities in China 4. Mercury re-emission from contaminated soil may be an important missing source in China 5. Hot spots and Hg contamination of aquatic and soil system 6. Conclusions Outline

75 Major conclusions China is the largest global anthropogenic Hg emission source, but a large uncertainty is associated with current Hg emission inventory. We may underestimate the total Hg outflow from China and Asia. Mercury emission from artisanal mining activities and reemission from contaminated soil could be important Hg missing sources in current inventoty. Both atmospheric deposition and mercury mining activities caused serious Hg contamination to the local and regional environment.